RV-7 Egg H-6

[Yukon]

Enough!!!!!!

If a guy can bench press 960 lbs once, how many times do you think he could bench press 250 lbs?

Jeez Mickey, as if drag cars wasn't far enough afield, now we've got to consider bench pressing too? Get out to the garage......that's where I'm going!

 

[captainron]

The long haul....

"Running along at 4000-4500 rpm all day long is a non-issue with modern auto engines."

Probably true! A long day in one of these planes might be around 7 hours. I suppose another 285 days of this same type of operation would yield the same reliable results.

Just a thought-don't you need 5400 rpm at a 2/1 ratio to get 2700 rpm at the prop?

 

[cjensen]

"Running along at 4000-4500 rpm all day long is a non-issue with modern auto engines."

Probably true! A long day in one of these planes might be around 7 hours. I suppose another 285 days of this same type of operation would yield the same reliable results.

Just a thought-don't you need 5400 rpm at a 2/1 ratio to get 2700 rpm at the prop?

That's why the new gearbox is 2.02/1...

 

[captainron]

That's why the new gearbox is 2.02/1...

Sorry, so now you only need 5454rpm?

 

[rv6ejguy]

Please guys, the 960hp example is merely to illustrate a point that several lay people have expounded on in the past- that auto engines are not designed for, cannot take extended periods of high rpm/hp. As a professional race engine builder for many years I can state that ultimate strength of an engine has a lot to do with life at lower power settings. The 960hp drag engine I mentioned had over 90 passes on on it. The point being that a 3 main bearing Lycoming would disintegrate at even 1/4 of this specific output- instantly, let alone last for say 10 minutes.

The Subaru is very well flight proven in the 4000-5000 rpm range in the RAF 2000 gyros, having accumulated well over 100,000 flight hours in the last decade or so. They are generally freshened up at 1000-1500 hours for about the cost of one jug on a Lycoming.

The economy of operation is really at overhaul time where in the case of Subaru and LS engines, new crate motors can be had for between $5000 and $7000. True zero time. Should you care to overhaul yourself, parts and machine work would be on the order of $2000.

I would suggest skeptical members become SAE members and order any of the hundreds of tech papers available on the design and testing of many modern engines. To quote Frank Thielert from a TAC 2005 interview " ...automotive suppliers normally have better quality and better process capability than the typical general aviation supplier". I assume he would know, as they do machining for Superior. He continues- ..."we have to meet the design requirements of FAR 33 or JAR E. Yes, they are much lower standards than the automotive standards are. In general, the requirements regarding process control are higher in the automotive industry than they are in the general aviation industry".

Since I assume that most of you commenting about your belief that auto engines will wear out and blow up running at 4000-5000 rpm actually don't build engines for a living nor have any knowledge of the testing that goes into modern auto engines- maybe give us some facts to support your stance like Subies throwing rods etc. Something that contradicts things like the flat out, 6000 rpm 100,000 km. Subaru speed record back in 1989?

Your comments hold no water from an engine design or operation standpoint with regards to mechanical stresses at the typical aviation specific outputs required. The assumption that auto engines are only designed for low rpm/ low power use is invalid and is based on feeling not facts.

 

[captainron]

I would suggest skeptical members become SAE members and order any of the hundreds of tech papers available on the design and testing of many modern engines. To quote Frank Thielert from a TAC 2005 interview " ...automotive suppliers normally have better quality and better process capability than the typical general aviation supplier". I assume he would know, as they do machining for Superior. He continues- ..."we have to meet the design requirements of FAR 33 or JAR E. Yes, they are much lower standards than the automotive standards are. In general, the requirements regarding process control are higher in the automotive industry than they are in the general aviation industry".

Yes, we certainly thought that a manufacturer like Porsche, with the backing of an airframe manufacturer like Mooney could do it and show the rest how it's done. The results spoke volumes.

 

[rv6ejguy]

Yes, we certainly thought that a manufacturer like Porsche, with the backing of an airframe manufacturer like Mooney could do it and show the rest how it's done. The results spoke volumes.

Huh. Porsche got cold feet and pulled the plug because of liability concerns. They paid to pull engines off the market. This was 20 years ago and a LOT has changed.

The auto industry has shown Lycoming and Continental how to do it. Both have embraced Six Sigma type QC and validation pioneered decades ago by the Japanese auto giants.

 

[captainron]

Please guys, the 960hp example is merely to illustrate a point that several lay people have expounded on in the past- that auto engines are not designed for, cannot take extended periods of high rpm/hp. As a professional race engine builder for many years I can state that ultimate strength of an engine has a lot to do with life at lower power settings. The 960hp drag engine I mentioned had over 90 passes on on it. The point being that a 3 main bearing Lycoming would disintegrate at even 1/4 of this specific output- instantly, let alone last for say 10 minutes.



Your comments hold no water from an engine design or operation standpoint with regards to mechanical stresses at the typical aviation specific outputs required. The assumption that auto engines are only designed for low rpm/ low power use is invalid and is based on feeling not facts.

"The point being that a 3 main bearing Lycoming would disintegrate at even 1/4 of this specific output- instantly, let alone last for say 10 minutes."

Hmmm... having trouble with that one... 1/4 of 960hp I think is 240hp. Not too sure that the Lyc would instantly disintegrate. I'm thinking it might last the whole ten minutes.

 

[rv6ejguy]

"The point being that a 3 main bearing Lycoming would disintegrate at even 1/4 of this specific output- instantly, let alone last for say 10 minutes."

Hmmm... having trouble with that one... 1/4 of 960hp I think is 240hp. Not too sure that the Lyc would instantly disintegrate. I'm thinking it might last the whole ten minutes.

Specific output is a relative measure of an engines power capability per unit displacement. The EJ255 in question 960hp from 2.5L= 384hp/L. Stock Lyco 200 hp from 6L= 33hp/L. So what I am saying here is that even at 96 hp/L, the Lyco would be junk in less than 5 seconds putting out 576hp. The reason is the design of the case, bearing system for the crank and the base bolted cylinder method with free standing cylinders. This is not a rigid structure so high deflections and stresses take place as cylinder pressures are increased. The result is shrapnel.

I've seen people flogging Honda S2000s on the race track between 6500 and 8500 rpm all day long during driver's schools and track days, SOLO 1 etc. Never seen one blow up yet. Stock specific output- over 100hp/L- triple what a Lycoming produces. Certainly idling along at 4500rpm is essentially no stress on these engines and they last for thousands of hours.

Primer is dry on cabin top- back to sanding.

 

[captainron]

Specific output is a relative measure of an engines power capability per unit displacement. The EJ255 in question 960hp from 2.5L= 384hp/L. Stock Lyco 200 hp from 6L= 33hp/L. So what I am saying here is that even at 96 hp/L, the Lyco would be junk in less than 5 seconds putting out 576hp. The reason is the design of the case, bearing system for the crank and the base bolted cylinder method with free standing cylinders. This is not a rigid structure so high deflections and stresses take place as cylinder pressures are increased. The result is shrapnel.

I've seen people flogging Honda S2000s on the race track between 6500 and 8500 rpm all day long during driver's schools and track days, SOLO 1 etc. Never seen one blow up yet. Stock specific output- over 100hp/L- triple what a Lycoming produces. Certainly idling along at 4500rpm is essentially no stress on these engines and they last for thousands of hours.

Primer is dry on cabin top- back to sanding.

Yeah, I'm bored as well. Plus, it's time to go fly the two main bearing, always flown oversquare, 1425hp single. How long can that last?

 

[osxuser]

Nice...

Anyway, it's not even an arguement. We KNOW a lycoming won't be able to put out 100hp/L, and we KNOW that a Sube in an airplane won't put out 100hp/L. Who cares what it'll do on a car?

The main problem associated is getting rid of the heat involved with making power. To get the Sube cool, you have a ton of drag out there, the more power, the more heat, the more radiator you need.

Lycomings are good up to about .5hp/cubic inch or 30.5hp/L, can be pushed a bit up to about .65hp/cubic inch or 39.6hp/L. However you choose to do that is up to you, more compression, turbo, EI, whatever. This is all turning 2700rpm direct drive.

I'm no expert on Subes so I can't say what they are capible of in hp/cubic inch in aircraft, but displacement wise, they will be better, but that is because they are turning TWICE the RPM, therefore in theory they should get be able to get at least 1hp/cu inch so 61hp/L, and and probably 1.3hp/cu inch or 79.2hp/L. Sure enough the turbo Egg is right at 73hp/L and the NA is right at 67hp/L.

At these HP/displacement ratios, heat is once again the biggest issue, yeah the sube is capible of more power than the egg kit, but only if you have enough water to cool them down .

There is no free ride. Whatever these engines are capible of on cars is completely irrelievant to airplanes. The numbers will always catch up. Feel free to correct anything I've said, it's overly simplistic, but I've tried to be fair and unbiased. The Subes work in airplanes, just not as well as a purpose built-engine... yet.

Yeah, I'm bored as well. Plus, it's time to go fly the two main bearing, always flown oversquare, 1425hp single. How long can that last?

 

[rv6ejguy]

Nice...

Anyway, it's not even an arguement. We KNOW a lycoming won't be able to put out 100hp/L, and we KNOW that a Sube in an airplane won't put out 100hp/L. Who cares what it'll do on a car?

The main problem associated is getting rid of the heat involved with making power. To get the Sube cool, you have a ton of drag out there, the more power, the more heat, the more radiator you need.

Lycomings are good up to about .5hp/cubic inch or 30.5hp/L, can be pushed a bit up to about .65hp/cubic inch or 39.6hp/L. However you choose to do that is up to you, more compression, turbo, EI, whatever. This is all turning 2700rpm direct drive.

I'm no expert on Subes so I can't say what they are capible of in hp/cubic inch in aircraft, but displacement wise, they will be better, but that is because they are turning TWICE the RPM, therefore in theory they should get be able to get at least 1hp/cu inch so 61hp/L, and and probably 1.3hp/cu inch or 79.2hp/L. Sure enough the turbo Egg is right at 73hp/L and the NA is right at 67hp/L.

At these HP/displacement ratios, heat is once again the biggest issue, yeah the sube is capible of more power than the egg kit, but only if you have enough water to cool them down .

There is no free ride. Whatever these engines are capible of on cars is completely irrelievant to airplanes. The numbers will always catch up. Feel free to correct anything I've said, it's overly simplistic, but I've tried to be fair and unbiased. The Subes work in airplanes, just not as well as a purpose built-engine... yet.

Well let me start correcting then. The fisrt argument is simply to discount the notion that auto engines are in some way weaker than aircraft engines. Obviously not the case.

Properly geared, the current naturally aspirated Subes produce between 69 and 83 hp/L stock. Yes this higher specific output is due to better breathing and higher rpm than aircraft engines. This offers the possibility that power to weight ratios (what we really care about in aircraft) can be competitive.

I have done numerous studies on liquid cooled aircraft engines vs. air cooled in the same airframe (WW2 aircraft). In each case, the liquid cooled installations were faster than the air cooled ones, often by substantial margins. Hp per unit displacement does not enter into the equation for cooling heat dissipation on liquid cooled engines. This is strictly TE X HP. With the higher CRs on auto engines, their TE, thus heat rejection per unit hp is actually very similar despite higher frictional losses due to higher rpm. TE per unit IMEP is better on auto engines for many reasons but we need to compare actual, delivered hp here.

The mechanism for heat removal favors liquid cooling despite lower Delta T using coolant. This is because of proximity of the cooling medium to parts with highest heat flux- combustion chambers and exhaust valve areas and the fact that modern radiators are many times more efficient per unit frontal area compared to cooling fins in heat rejection. By transferring heat to a remote radiator in a dedicated divergent, convergent duct, HE face pressure recovered easily exceeds air cooled installations with lower overall drag. Overall system drag for the studied liquid cooled engines was between 4% and 20% less than the air cooled ones.

Most liquid cooled installations in light aircraft today are far from optimal and can easily be worse than their air cooled counterparts. Cheek mounted HEs are quite poor. They are often used for simplicity in mounting/ packaging and to use existing cowling inlets. Optimal configurations such as a belly duct create many additional design and fabrication considerations. Those who have gone this route such as Reg Clarke with his direct drive turbo Sube Dragonfly and Russ Sherwood with his EG33 Glasair have reported excellent results.

Finally, the EJ255 produces 228hp at only 4000 rpm. This shows the potential of the engine for aviation use at moderate rpms. By using something down around 3000-3500 rpm for cruise, where SFCs are highest, the power to weight ratio and fuel flows can be very competitive with the Lycoming.

 

[Yukon]

Taking a Break from the Canopy

Ross,

When are we going to see these advantages come to fruition? I started my RV project three years ago LOOKING for a good alternative engine. What's happened in 3 years time? NSI and Crossflow are gone, Egg dropped the 4 cyl engine I was considering, Powersport looks done, Belted Airpower the same.
After several years of intensive developement, you call your own Subaru installation a "test mule", and have moved on.

How many more years is it going to take for this superior technology to make it to market? Why so many false starts? If these advantages are so noteworthy, they should be easily adapted and marketed.

World War 2 engines were heavily boosted, alcohol injected, and had extremely short service lives. Sure the Mustang was fast, but it had 2200 horsepower and drank 150 gph. I really don't think you should make comparisons to those engines, nor draw any conclusions. If this engine
configuration was so beneficial, I would think that post war GA developement would have gone that way. It didn't.

 

[osxuser]

Well let me start correcting then. The fisrt argument is simply to discount the notion that auto engines are in some way weaker than aircraft engines. Obviously not the case.

Properly geared, the current naturally aspirated Subes produce between 69 and 83 hp/L stock. Yes this higher specific output is due to better breathing and higher rpm than aircraft engines. This offers the possibility that power to weight ratios (what we really care about in aircraft) can be competitive.

Yes, CAN be, but we still haven't seen it in something usable for the average builder TODAY or in the next few years even. I agree that the big deal is the power/weight and power/drag.

Also, remember we aren't talking stock car HP, we are talking what it makes in the airplane. The 67 and 73hp/L I quoted above are based off Egg's advertised HP from their website on the NA H6 3.0 and the turbo H6 3.0 respectively. If know of a better output available let me know. I disregard for sake of simplicy (and this is perhaps misguided) unproven numbers from people (claims for 175-190HP 2.5 Turbo 4's for instance)

I have done numerous studies on liquid cooled aircraft engines vs. air cooled in the same airframe (WW2 aircraft). In each case, the liquid cooled installations were faster than the air cooled ones, often by substantial margins. Hp per unit displacement does not enter into the equation for cooling heat dissipation on liquid cooled engines. This is strictly TE X HP. With the higher CRs on auto engines, their TE, thus heat rejection per unit hp is actually very similar despite higher frictional losses due to higher rpm. TE per unit IMEP is better on auto engines for many reasons but we need to compare actual, delivered hp here.

agreed

The mechanism for heat removal favors liquid cooling despite lower Delta T using coolant. This is because of proximity of the cooling medium to parts with highest heat flux- combustion chambers and exhaust valve areas and the fact that modern radiators are many times more efficient per unit frontal area compared to cooling fins in heat rejection. By transferring heat to a remote radiator in a dedicated divergent, convergent duct, HE face pressure recovered easily exceeds air cooled installations with lower overall drag. Overall system drag for the studied liquid cooled engines was between 4% and 20% less than the air cooled ones.

Most liquid cooled installations in light aircraft today are far from optimal and can easily be worse than their air cooled counterparts. Cheek mounted HEs are quite poor. They are often used for simplicity in mounting/ packaging and to use existing cowling inlets. Optimal configurations such as a belly duct create many additional design and fabrication considerations. Those who have gone this route such as Reg Clarke with his direct drive turbo Sube Dragonfly and Russ Sherwood with his EG33 Glasair have reported excellent results.

But we are RV builders talking about RV's. What other solutions are we seeing that won't DOUBLE the build time for US other than the cheek mounted HE?

Finally, the EJ255 produces 228hp at only 4000 rpm. This shows the potential of the engine for aviation use at moderate rpms. By using something down around 3000-3500 rpm for cruise, where SFCs are highest, the power to weight ratio and fuel flows can be very competitive with the Lycoming.

Where can I buy it? And can I use a responsive CS prop with it? I really don't want to be a skeptic, I WANT something besides a Lyc.

 

[rv6ejguy]

Covered with dust, next application of micro/ resin curing...

The Egg engines are delivered in a crate with all HEs bolted up, mount on, almost everything. This is the best part of his packages. You install your 6 bolts through the firewall and the engine is hung. Compromises to allow this include a rad setup that is not as good as it could be but you have to understand what it would entail to do this better- way more time and money spent, more hoses and lines to install and shield, more airframe mods, major cowling mods... The list goes on. This is especially difficult when working with about a dozen different airframe, mount combos. Anyone who wants to tackle an aftermarket rad setup for these packages- well go to it. A pretty big undertaking with plenty of headaches and relatively little reward.

I haven't done much to the 6A lately, concentrating on the -10 mainly but much was learned on the 6A. I am hoping to see a good jump in performance with less problems this time around. When the -10 is sorted, I'm gonna modify the 6A to correct its deficiencies.

There are so few liquid cooled engines today flying that I look to history where hundreds of thousands of examples were developed and flown. Many smart people were involved and much data collected. As an apples to apples comparison, these studies unquestionably show the speed advantages of liquid cooling vs. air cooling and point to what we might achieve today in this field. These guys knew more than we ever will about this topic I suspect. My favorite rad setup was on the Westland Whirlwind twin engined fighter. This used leading edge inlets, a hollow, truss type spar made from streamlined tubing for the air to pass though the wing mounted rads. All completely internal and I suspect very low drag with an exit just above the flaps.

I think people will be waiting some time for really good liquid cooled auto engine packages to hit the market. It would take the right group of people with proper funding to do this. What has gone wrong? I see people who have no idea how to run a business as the cause, when you don't do enough testing, rip people off and BS them- well you don't last long.

The performance benefits of water cooled car engines are minimal at best in RVs even with a proper package due to the airframe not being designed around these engines. I am hoping to just equal IO-540 performance with my -10 at medium altitudes. The main benefits would be lower life cycle costs over the long run especially in maintenance and overhaul. Things like lower vibration, lower oil consumption are relatively minor to most I would think. I pursue this avenue because it is very interesting from a technical standpoint not because it is easy. Hundreds of people fly with auto power these days, including 600+ Subaru powered RAF and Groen gyros- there must be reasons. They can't all be idiots-well I suppose they could be.

If these engines do not appeal to you, there is the tried and true Lycoming- still the choice of the vast majority.

 

[rv6ejguy]

Yes, CAN be, but we still haven't seen it in something usable for the average builder TODAY or in the next few years even. I agree that the big deal is the power/weight and power/drag.

Also, remember we aren't talking stock car HP, we are talking what it makes in the airplane. The 67 and 73hp/L I quoted above are based off Egg's advertised HP from their website on the NA H6 3.0 and the turbo H6 3.0 respectively. If know of a better output available let me know. I disregard for sake of simplicy (and this is perhaps misguided) unproven numbers from people (claims for 175-190HP 2.5 Turbo 4's for instance)
agreed But we are RV builders talking about RV's. What other solutions are we seeing that won't DOUBLE the build time for US other than the cheek mounted HE?
Where can I buy it? And can I use a responsive CS prop with it? I really don't want to be a skeptic, I WANT something besides a Lyc.

You are absolutely correct. At this time, no alternative to the Lycoming for RVs exists in a commercially available package which can match its speed, light weight and fuel economy.

I'm quoting OEM hp and torque ratings as these are actually compiled under a JIS or SAE dictated dyno run. Other sources are just guesses. The Eggenfellner STIs (300hp @6000 and 300 lb./ft. @4000 factory) had their OE turbo systems and intercoolers removed and replaced with less efficient Eaton superchargers, restrictive plumbing and initially no intercooler. A substantial drop in hp resulted due to high intake charge temperatures and high parasitic losses from the blower. Taking into account weight, it was clear from flight tests (especially climb performance) that these were capable of more like 150-160hp at the recommended manifold pressures and rpm. They were saddled with a redrive not allowing the engine to reach its power peak rpm as well. These are not excuses, just facts.

A Lycoming has low specific output but quite a good power to weight ratio for an atmo engine. This is where atmo (naturally aspirated) car engines struggle to match when weighed down with the requisite redrive. Clean sheet designs such as the Rotax 912S show how advantageous a properly executed geared engine can be with hybrid air/ liquid cooling as far as power to weight ratios are concerned. It's figures are substantially better than comparable air cooled engines.

Some drives do allow the use of hydraulic C/S props and at least one other new composite C/S prop in under development using a self contained hybrid mechanism. None currently available as you note.

I hope we are entertaining VAF members out there. Always a hot topic. Seems to be plenty of interest judging by the views. I'm not sure if the debate or the information is the reason however!

 

[osxuser]

If the Egg could provide a 2.5 in the 160HP range with or without the turbo, and an improved CS prop setup, I think he'd have more interest. I've heard of way more interest in the 2.5 than the H6 from almost everyone with a 2 place RV. I don't see people dieing to put the H6 on either the -7 or -8 (too heavy) or the -10 (too little power).

So why did he drop the STi development? Seems like a poor business decision.

 

[Yukon]

Breakthrough

Holy Cow! We've reached the end of a very long road...... Ross just said what many of us have suspected all along:

"The performance benefits of water cooled car engines are minimal at best in RVs even with a proper package due to the airframe not being designed around these engines. I am hoping to just equal IO-540 performance with my -10 at medium altitudes."

Ross, you are a gentleman and a scholar! Appreciate your honesty. I would think your low drag rad installation should be the best opportunity to explore
the benefits of water cooling. Now we just have to contend with reduction losses, friction and pumping losses from high rpm. Looking forward to your numbers.

 

[rv6ejguy]

If the Egg could provide a 2.5 in the 160HP range with or without the turbo, and an improved CS prop setup, I think he'd have more interest. I've heard of way more interest in the 2.5 than the H6 from almost everyone with a 2 place RV. I don't see people dieing to put the H6 on either the -7 or -8 (too heavy) or the -10 (too little power).

So why did he drop the STi development? Seems like a poor business decision.

Interestingly Jan reinstated the availability of the 2.5 many months ago because so many showed "interest" in it again for -9s. After about 3 months and only one order I think, he canned it. To offer two engines is a LOT more work than one. Interest doesn't pay the bills in business, deposits or orders do so there you have that one.

My opinion is also that the H6 is somewhat heavy for a -9 and that in non-intercooled turbo form, essentially normalized and turning relatively low revs, it will not measure up to an IO-540 in an RV10 below 10,000 feet. Until we see some solid flight tests with the latest setup we don't know of course. I hope I'm wrong.

The supercharged 2.5 was a step in the wrong direction I think due to a turbo phobia. With the demonstrated hp and torque of the factory STI setup, the path would have seemed to be more clear. I suppose it is easy for us "experts" to criticize sitting here. With the complexity and scope of what Jan has done, there are bound to be a few missteps. Clearly some don't like how he has run his business while many others praise him. You have to give him credit for what he has accomplished nevertheless.

I don't think the STI offering will go down in history as Jan's best. Clearly more testing would have resulted in a more evolved package but as I've said before, testing has to stop sometime to freeze the design and get production and deliveries going.

Like them or not, the Egg conversions are the only ones shipping in any quantity and have more fixed wing flight hours on them than all the others combined.

 

[rv6ejguy]

Holy Cow! We've reached the end of a very long road...... Ross just said what many of us have suspected all along:

"The performance benefits of water cooled car engines are minimal at best in RVs even with a proper package due to the airframe not being designed around these engines. I am hoping to just equal IO-540 performance with my -10 at medium altitudes."

Ross, you are a gentleman and a scholar! Appreciate your honesty. I would think your low drag rad installation should be the best opportunity to explore
the benefits of water cooling. Now we just have to contend with reduction losses, friction and pumping losses from high rpm. Looking forward to your numbers.

Well I could publish nonsense like my 6A does 220 knots on 10 GPH and that my -10 will liquidate any Lyco powered -10. I just read what the gauges are telling me. The 6A will true about 160-165 knots at 10,000-12,000 on about 9.5-10 GPH and the -10, well it hasn't even flown yet. The magic belly rad could be a total bust for all I know.

The engine on the -10 will be turning slow in cruise with high MAP for lowest friction, highest VE and lowest pumping losses while keeping the MT in a more efficient range. Turbine housings have been sized to get some boost as low as 3500 rpm at altitude.

Back to the misery of sanding- oh the pain.

 

[osxuser]

Well I wish you the best Ross, I read your build site with interest every now and again... definitely know you've got some other 'lycoming' dudes watching you with interest and... hope?

 

[captainron]

So, what's the problem

The auto industry has shown Lycoming and Continental how to do it. Both have embraced Six Sigma type QC and validation pioneered decades ago by the Japanese auto giants.

Shouldn't this improve what are already great airplane engines? It worked well for Harley-Davidson.
I had always thought that the Lycoming and the Continental were good engines, and served well in airplanes. The airframe manufacturers must agree, as does Vans, who specify them (Lycoming) for their aircraft. Now that both Lycoming and Continental have embraced the QC and manufacturing technology that Ross says makes car engines superior, what would be the rational for not wanting them in your airplane?

 

[rv6ejguy]

Shouldn't this improve what are already great airplane engines? It worked well for Harley-Davidson.
I had always thought that the Lycoming and the Continental were good engines, and served well in airplanes. The airframe manufacturers must agree, as does Vans, who specify them (Lycoming) for their aircraft. Now that both Lycoming and Continental have embraced the QC and manufacturing technology that Ross says makes car engines superior, what would be the rational for not wanting them in your airplane?

Both Textron and TCM started looking at these ideas not out of routine business practice but as a result of serious problems with failing parts due to poor QC and process control. The older Lycoming engines in particular were very reliable. Once more subcontractors were brought in and certain manufacturing processes were changed without proper oversight, Lycoming had a string of serious problems as we all know. We are fortunate that Textron just didn't pull the plug on the division as they certainly lost money for a few years.

If these new measures are followed properly, I'd expect both Lycoming and TCM engines to meet or exceed their "old" reliability and life expectations. This is a very good thing for them, us and GA as a whole.

As far as Van's recommending Lycomings, well he sells them and they do offer the best blend of weight, reliability, fuel economy and familiarity with service personnel. Those are 4 really good reasons to using them for most builders.

 

[captainron]

Agreed!

Both Textron and TCM started looking at these ideas not out of routine business practice but as a result of serious problems with failing parts due to poor QC and process control. The older Lycoming engines in particular were very reliable. Once more subcontractors were brought in and certain manufacturing processes were changed without proper oversight, Lycoming had a string of serious problems as we all know. We are fortunate that Textron just didn't pull the plug on the division as they certainly lost money for a few years.

If these new measures are followed properly, I'd expect both Lycoming and TCM engines to meet or exceed there "old" reliability and life expectations. This is a very good thing for them, us and GA as a whole.

As far as Van's recommending Lycomings, well he sells them and they do offer the best blend of weight, reliability, fuel economy and familiarity with service personnel. Those are 4 really good reasons to using them for most builders.

Ross, I have to agree with you on all these points, but I'm seriously considering a Subaru for my next car!
Regards.

 

[osxuser]

Ross, I have to agree with you on all these points, but I'm seriously considering a Subaru for my next car!
Regards.

Huh... and all this time I was thinking about putting a Lyc in mine...

 

[captainron]

Funny....

Huh... and all this time I was thinking about putting a Lyc in mine...

You could try a Lamborghini, but apparently they can't out-accelerate a Cessna taxiing at 8 mph.

 

[Rotary10-RV]

Yes, we certainly thought that a manufacturer like Porsche, with the backing of an airframe manufacturer like Mooney could do it and show the rest how it's done. The results spoke volumes.

Ron,
My small input here is that all modern automotive manufacturers put their engines through amazing tests. As an example, Harley Davidson recently put their V-Rod engine on the streets. Before they would even consider releasing it they (Harley) required it pass a 400 hour maximum output test. Full rated HP for 400 hours as a minimum. It fact by the release date they had the Max power test up to 800 hours. The Discovery channel even did a program on it. The point is that Harley (love em or hate em) doesn't even have a super reliability rep. All the major manufacturers (auto) have even tougher standards. Does this automatically make a superior engine installed in your plane? No of course not. The major cause of failures is ancillory equipment, even on Lycomings. The entire package needs to work together. Egg is getting there. Tracy Crook is getting there with the Mazda. I believe Mistral is there now, just too expensive for my pauperish tastes.
Bill Jepson

 

[captainron]

Ron,
My small input here is that all modern automotive manufacturers put their engines through amazing tests. As an example, Harley Davidson recently put their V-Rod engine on the streets. Before they would even consider releasing it they (Harley) required it pass a 400 hour maximum output test. Full rated HP for 400 hours as a minimum. It fact by the release date they had the Max power test up to 800 hours. The Discovery channel even did a program on it. The point is that Harley (love em or hate em) doesn't even have a super reliability rep. All the major manufacturers (auto) have even tougher standards. Does this automatically make a superior engine installed in your plane? No of course not. The major cause of failures is ancillory equipment, even on Lycomings. The entire package needs to work together. Egg is getting there. Tracy Crook is getting there with the Mazda. I believe Mistral is there now, just too expensive for my pauperish tastes.
Bill Jepson

Hi Bill,
I will be glad when the DeltaHawk gets to market; better yet-when Lycoming buys and develops it and gets it to market. I'm not sure how it would be in the smaller Vans, but in a -10 or larger plane that can carry a little more weight, I believe that it will be an engine of the future. If you look at what's required, our aircraft run 72" or so props that have to run at around 2700rpm. This means the traditional Lyc type engine, or a slow-turning diesel engine if we want direct-drive. Direct is the strongest, lightest, and simplest way to go, IMO. The block and cylinders are cast as one unit, making it extremely rigid. It's a two-stroke, so each cylinder makes power with every revolution of the crankshaft. It has fewer moving parts with no valve train and no ignition, not even for starting. It's a diesel, meaning it can use jet-A, bio-diesel, home heating oil, kerosene, Mc Donalds french-fry grease-well, maybe not. The diesel has a lower BTU output, so the cooling demands aren't as great as a gasoline engine. It's turbocharged, for retaining power at altitude. It has a lot of pluses, and few drawbacks that I can see. I hope DH or someone can make this engine happen.

 

[cjensen]

Yeah, I'm bored as well. Plus, it's time to go fly the two main bearing, always flown oversquare, 1425hp single. How long can that last?

Hey Ron,

This is off the subject of the thread a bit, but doesn't your T-28 have a reduction gearbox on it? What RPM is the engine turning on TO and cruise?

Again, just curious here...

Sorry, so now you only need 5454rpm?

To answer this question...yes, 5400rpm is needed to get 200hp from the H6.

 

[captainron]

T-28

Hey Ron,

This is off the subject of the thread a bit, but doesn't your T-28 have a reduction gearbox on it? What RPM is the engine turning on TO and cruise?

Again, just curious here...


To answer this question...yes, 5400rpm is needed to get 200hp from the H6.

The T-28 pulls 2700 rpm (engine) on T/O and about 47.5" of MP. When the Navy had it, and we still had purple gas, you could pull 52.5" on T/O.
After T/O, it's 36" and 2400 rpm. Cruise is around 30" and 2000rpm, but it will cruise as low as 1800rpm. Low blower is usually good to around 13,000', then you can shift into high. You always have to carry more MP than rpm's, or the engine can (will!) self destruct! I would have to look through the manual to find what the reduction is, but that huge prop is going much slower than the engine! The -28 is a "C" model With a Wright 1820, 9 cylinder radial. Each cylinder is over 3.3 liters, or bigger than the V6 in my car!
Regards, Ron

 

[rv6ejguy]

Most big radials, Merlins, Allisons, PT6s etc. have reduction gears. Way more of these engines have been built than all the TCM and Lyco direct drives put together. I fail to see why some people are so adverse to reduction gears. Auto engines need them to get the power to weight ratios competitive with much larger air cooled engines. Simple physics. Of course we need GOOD ones or they are a liability.

 

[gmcjetpilot]

Bad vibes and urban myth?

I fail to see why some people are so adverse to reduction gears. Auto engines need them to get the power to weight ratios competitive with much larger air cooled engines. Simple physics. Of course we need GOOD ones or they are a liability.

Because they are a pain in the?

P&W, Lycoming and Continental all have engines with reduction drives. However none of these geared models are in current production.

Geared aircraft engines (except radials) are unpopular. Why? I'll be honest it may be fear and loathing from urban legend. However there are down sides with the examples of gear reduction you mention. First your little engine has to turn faster, more wear and tear. Second they tend to be more maintenance and overhauls cost more. Operational they can be quirky. One thing is they don't like to be back driven (prop driving engine). They never took off in popularity and few people know how to work on them or want to. Direct drive is gosh darn simple, direct, nuff said.

The radials in particular have almost bullet proof planetary gear reduction, but than these reductions are not little after thoughts bolted onto the end of the engine. The P&W's, Wrights have integral gear boxes with the engine. There's a difference.

Bottom line reduction gear boxes need to be engineered and two you have to make them stout, no short cuts, ie overbuilt. The up side is you can turn the engine faster (more HP) and prop slower (more efficiency). Kind of a win win but it comes at a price. Direct drive has its own charm, no gear box to worry about.

Reduction Ratios of some Selected engines
0.375:1 Pratt & Whitney R-4360 Wasp Major max rpm 2,700 (3,500 hp wet)
0.388:1 Rotax 852UL (2 cycle) max rpm 6,200 rpm (66 hp)
0.500:1 Pratt & Whitney R-2800 Double Wasp max rpm 2,700 (2,000 rpm)
0.640:1 Lycoming IGO-540 max rpm 3,400 rpm (350 hp)
0.670:1 Pratt & Whitney R-1340 Wasp max RPM 2,250 (600 hp)
0.750:1 Continental GO-300 max RPM 3,200 (175 hp)
1.000:1 Pratt & Whitney R-985 Wasp Junior max RPM 2,300 (450 hp)


PS: Reduction on a turbine is a whole different ball of wax. A Turbine is smooth of course, not sucking, squeezing, banging and blowing, mostly banging the gear box. Turbine gear reductions are not small light things. It's an economy of scale; you can handle a few extra pounds for a gear box, when the engine is making 1,000-3,500 hp with a high power / weight ratio. Usually double planetary gears or very large gear boxes are incorporated. Even these gear boxes can fail. I know a P-3 pilot (Lockheed Electra) that had some scary stories about gear boxes going amuck. Ironically the Allison T56 uses a separate gear box. http://www.geocities.com/egnnews/T56b.jpg

 

[captainron]

I fail to see the point....

Most big radials, Merlins, Allisons, PT6s etc. have reduction gears. Way more of these engines have been built than all the TCM and Lyco direct drives put together. I fail to see why some people are so adverse to reduction gears. Auto engines need them to get the power to weight ratios competitive with much larger air cooled engines. Simple physics. Of course we need GOOD ones or they are a liability.

Ross, The T-28 does indeed have a gear reduction to drive the propeller. It also has a 16 gallon oil capacity to lubricate all this, and there is 2000 pounds that sits on the nose wheel!
In the RV community, we are risking serious injury using fly-cutters to remove what might add up to 5 oz. of weight in our planes. People go on diets to justify the installation of a Hartzell over a lightweight prop.
With RV's, you're talking about 1000 lb airplanes. If the installation of a converted car engine, complete with gear reduction, cooling system, coolant, etc. adds 100 more pounds than a Lycoming installation, then you've increased the empty weight by 10%, and still don't have enough hp to cover it.
Think about how much performance is lost when there is a passenger on board! That might explain why the videos didn't look too exciting with Chad in there filming the panel on take-off.
Everything has a trade-off, but when we only have 1000 or so pounds to work with there just aren't too many options. You are right when you talk of water cooling making a more efficient engine, but think of the weight and logistics involved in putting this in an airplane. And correct me if I'm wrong, but isn't everything eventually air-cooled anyway? Why have a middle step in what is an ideal platform for an air-cooled engine?

 

[Steve A]

RV-7 Egg H-6 Performance

I thought we had been through this already. Fact: Robert Paisley (Egg Engine) smoked Dan Checkoway (Lycoming 360) in a fly off. Head to head. Man o' man. And Robert had a passenger and Dan didn't.

Now that the performance issue is settled, let's move on. In my mind, Jan Eggenfellner's and Gary Newsted's Subaru FWF "package" has the following advantages. Builders who follow Gary Newsted's application manual on the Egg website have a fail-over relay to automatically detect a pressure drop in the fuel pressure system and switches to the second fuel pump. Additionally the electronic system has two batteries as well as the alternator. Great redundancy in both systems. I have seen way too many RV and other experimental aircraft have "issues", coming out of the sky for fuel or electrical problems. The nasty little secret is way too many experimental planes are not as reliable as they could be. This is what we should be concentrating upon. Not how we can get a few knots faster but how we can be more reliable and safe.

Furthermore, with the Egg FWF fuel system returning unused fuel to the tank, you never have to worry about dumping fuel on a hot engine after shut down. The Subaru engine is smoother, and of course gives the owner the option to use either automobile 93 octane or leaded 110 octane aviation fuel.

As with any engine product, there are advantages and disadvantages. It is up to the builder to decide what they are willing to live with. And as builders, we all have areas of expertise that make our planes a reflection of us, for better or worse. The debate continues... But why?

 

[captainron]

I thought we had been through this already. Fact: Robert Paisley (Egg Engine) smoked Dan Checkoway (Lycoming 360) in a fly off. Head to head. Man o' man. And Robert had a passenger and Dan didn't.

Now that the performance issue is settled, let's move on. In my mind, Jan Eggenfellner's and Gary Newsted's Subaru FWF "package" has the following advantages. Builders who follow Gary Newsted's application manual on the Egg website have a fail-over relay to automatically detect a pressure drop in the fuel pressure system and switches to the second fuel pump. Additionally the electronic system has two batteries as well as the alternator. Great redundancy in both systems. I have seen way too many RV and other experimental aircraft have "issues", coming out of the sky for fuel or electrical problems. The nasty little secret is way too many experimental planes are not as reliable as they could be. This is what we should be concentrating upon. Not how we can get a few knots faster but how we can be more reliable and safe.

Furthermore, with the Egg FWF fuel system returning unused fuel to the tank, you never have to worry about dumping fuel on a hot engine after shut down. The Subaru engine is smoother, and of course gives the owner the option to use either automobile 93 octane or leaded 110 octane aviation fuel.

As with any engine product, there are advantages and disadvantages. It is up to the builder to decide what they are willing to live with. And as builders, we all have areas of expertise that make our planes a reflection of us, for better or worse. The debate continues... But why?

"The MiG-25 that was clocked at Mach 3.2 by the Israelis achieved this speed while running from an intercepting F-4 (which can barely manage Mach 2 on a good day--before running out of fuel). Upon landing, both engines in the MiG had to be replaced."

Excerpt from "Mig Pilot", a book about Victor Belenko, the Soviet pilot who defected in the fabled Mig-25.

I haven't heard how many hours Dan has now on his Lycoming-powered -7, but I know he flies a lot. How's Robert Paisley's Subaru-powered plane holding up?

 

[Rotary10-RV]

Ross, The T-28 does indeed have a gear reduction to drive the propeller. It also has a 16 gallon oil capacity to lubricate all this, and there is 2000 pounds that sits on the nose wheel!

Ron and George,
It isn't a question of how many gallons of oil there is in the engine. The key is weather or not the engineer designed in ENOUGH. It doesn't matter if it's ounces or acre-feet. Proper design is key here. IF you do the design research needed and design accordingly you can build a durable product. George, you know why the geared Lycs didn't do well, it is OBVIOUS. The flat engine has several ranges of tortional resonance, witness the RPM prohibitions on several prop/engine combinations. Adding a gearbox to these engines was bandaid for the mission they were intended to perform. The problem isn't the gearbox, it's the designer or perhaps even the bean counter behind the scenes not allowing them to do their job properly. My hat is off to Jan Eggenfellner for following through and building a new and stronger gearbox. But even good design might not be enough if the public doesn't accept the product. Duesenberg built the most advanced cars of their day, with both styling and design features that were ahead of their time. The point is though they are no longer here. Many times the causes of a products demise have NOTHING to do with the designs quality. We the public have our own prejudices and often we don't want to be confused by facts. Ron the Deltahawk engine you mentioned is a classic case in point. I believe they have done a good job of design. They even did the necessary flip to an inverted version to make the product conform to the shape of the cowling designed for air-cooled engines. But reguardless of the quality of the product, if the public is upset by it's "wierdness factor" they may not sell and the company could fail. I am just saddened when we lose a good source of products or engines because people aren't used to the way they "look".
Bill Jepson

 

[Mike S]

P&W, Lycoming and Continental all have engines with reduction drives. However none of these geared models are in current production.

Geared aircraft engines (except radials) are unpopular.

I suspect that the reason that the above is correct is the jet engine.

Just a short bit of history here-------------

The need for heavy----(bombers), and fast----(fighters) planes in WW2 drove development or engines and airframes at the time. The above criteria dictated high horsepower needs. To absorb all that HP, the props had to get larger in diameter. To keep the tip speed down, the prop had to spin slower, yet to make the hp, most of the engines had to spin faster.

The gear reduction unit was the result.

We are not designing/building Mustangs, Flying Forts, Bearcats etc these days, we are designing and building planes that weigh less than the fuel load of some of these planes. And fly slower. And lower.

Therefore, a 150---260 hp, direct drive engine turning a 80" or so prop is all that is needed.

Sorry to be pedantic here, but things need to be looked at in perspective. It makes a bit more sense when you take a look at the larger picture.

Mike

 

[Yukon]

I thought we had been through this already. Fact: Robert Paisley (Egg Engine) smoked Dan Checkoway (Lycoming 360) in a fly off. Head to head. Man o' man. And Robert had a passenger and Dan didn't.

Now that the performance issue is settled, let's move on. In my mind, Jan Eggenfellner's and Gary Newsted's Subaru FWF "package" has the following advantages. Builders who follow Gary Newsted's application manual on the Egg website have a fail-over relay to automatically detect a pressure drop in the fuel pressure system and switches to the second fuel pump. Additionally the electronic system has two batteries as well as the alternator. Great redundancy in both systems. I have seen way too many RV and other experimental aircraft have "issues", coming out of the sky for fuel or electrical problems. The nasty little secret is way too many experimental planes are not as reliable as they could be. This is what we should be concentrating upon. Not how we can get a few knots faster but how we can be more reliable and safe.

Furthermore, with the Egg FWF fuel system returning unused fuel to the tank, you never have to worry about dumping fuel on a hot engine after shut down. The Subaru engine is smoother, and of course gives the owner the option to use either automobile 93 octane or leaded 110 octane aviation fuel.

As with any engine product, there are advantages and disadvantages. It is up to the builder to decide what they are willing to live with. And as builders, we all have areas of expertise that make our planes a reflection of us, for better or worse. The debate continues... But why?

Let's not move on quite yet.......Paisely was flying a supercharged engine at an altitude that precluded Dan's engine from producing no more than 150 hp.
So with a supposed 220 supercharged horsepower, Paisely bested Dan by maybe 15mph, while burning 16 gph. You consider this a victory?

Mr Paisely was so happy with the performance of that engine, he removed it from his airplane to give the h6 a try. Have yet to see his numbers on the H6.

Why is it that every time there is a flyoff between a Lycoming ship and a Subaru, the Subaru is blown?

 

[Rotary10-RV]

Let's not move on quite yet.......Paisely was flying a supercharged engine at an altitude that precluded Dan's engine from producing no more than 150 hp.
So with a supposed 220 supercharged horsepower, Paisely bested Dan by maybe 15mph, while burning 16 gph. You consider this a victory?

Mr Paisely was so happy with the performance of that engine, he removed it from his airplane to give the h6 a try. Have yet to see his numbers on the H6.

Why is it that every time there is a flyoff between a Lycoming ship and a Subaru, the Subaru is blown?

Perhaps because the Subaru is 1/3 the displacement? The Honda 1.5L formula 1 era showed that turbo engines can make unreal power. The cost and complexity is a different matter. The fact that the Subaru makes even close to equivilent power is amazing. Well made little engines. I'm not going the Subaru direction, but I'm still impressed at how they handle pressure. I'm not an anti-Lyc person either, I just maintain that they should cost half as much new. They are a good fit for the task as they should be, being that is what they were designed for. I'm just troubled that you could buy a small block chevy for $6,000 new as a crate engine ANYTIME and often less sometimes a LOT less. Lyc's tooling and design cost is paid for, they simply cost too much. That's all, just too much for the product. If this wasn't true there wouldn't be any clone manufacturers.
Bill Jepson

 

[rv6ejguy]

Oh boy, where do I start?

One writer is quite correct. Jets replaced radials, wasn't anything to do with reduction gears.

You don't need 16 gallons of oil to lube a redrive. Radials needed this amount because they spew and burn so much. Cars get by on 2-3 quarts of hypoid type fluid in their gearboxes and differentials which doesn't have to be changed any more thanks to synthetics and these typically require zero maintenance for the life of the vehicle. The gearset on an aircraft redrive in most cases is way simpler than either a manual gearbox or differential. I built and modified racing drive trains for many years and have seen it all. You don't worry about this stuff in your car. I don't worry about it in my plane.

The Marcotte drives I use are totally bulletproof and don't care if the prop drives the engine. They have massive Timken tapered roller bearings for the main shaft which is also massive. Drives like the old Ross ones were not great at all, have many design and manufacturing issues and they are no longer around. I count more than 8 drive manufacturers currently with Sube offerings so there are plenty of choices today. Torsional vibration is an issue on all engines, direct drive or with redrives. That is why we have to do testing and validation.

Gearbox weight has more to do with hp capability and design safety factors. The Rotax 912 ones are very light and have proven very reliable when following manufacturers recommendations.

Man, you Lyco guys just whine about everything. After hacking at Subaru performance for years and saying that NO Sube would EVER beat a Lycoming, Robert beats one of the fastest RVs around. Grudgingly you accept the facts then start saying well it was burning a lot more fuel. Of course it was, it was making more power. Paisley waxed Dan at the typical mission altitudes RV cruise at. You want to run the test at SL? Who cruises at SL? What would the IO-360 burn WOT at SL? probably 14+GPH.

This reminds me of the people I used to race against with 2.9 to 6 lliter atmo engines. They laughed at our little 1.4 and 1.7 and 2.4 liter turbo 4 Toyotas until we destroyed them on the track. More power, better reliability, cheaper and 7 championships later, these people were reduced to whining dogs, calling for a ban on little turbo engines.

Supercharged and turbocharged engines perform better at altitude, just a fact of life. My -6A has trued 181 knots at 14,000. Also faster than Dan's -7 but a good 15+ knots slower at 8,000 feet and maybe 20+ knots slower at SL. Again just fact. I've only got 2.2L and I'm only running 30-35 inches. Not bad in my view and I've currently got pretty draggy cooling.

No one is saying that an atmo 2.5L Sube is going to match a 6L IO360 in speed. Not going to happen without internal mods and twisting it over 6000 rpm. The forced induction is just closing the gap on having less than half the displacement. I know people will say, well you could add a turbo to the Lycoming and go faster. Yes, you could but you will ultimately lose that battle because the Sube is a way stronger engine and will always win the hp and life war at 300+ hp levels.

Robert removed the STI to do R&D on the H6 for Jan. It wasn't worn out. In fact a friend has his old engine and it is going into a new RV. I'm assisting on that project. The H6 in Robert's -7 is slower. I saw a claimed 201mph I think. Does not have all the latest stuff yet so it may or may not do a bit better. Not bad for no blower and half the displacement.

The standard JIS endurance test used by most Japanese manufacturers today is 400 hours at power peak. On the STI that is 6000 rpm at 14.5 psi for 400 hours- 300hp. They must pass this with several engines before going into test cars for more track miles being flogged. 220 hp at 4900 rpm is nothin'. Do these engine really make 300hp? Made the top 6 fastest accelerating cars in CR I saw today 5.2 seconds 0-60, in there with Porsche, Corvette, Viper. Might be true? Do ya think?

Contrary to many people's feelings that auto engines are going to wear out doing this, the weight of evidence does not support this. The Egg and RAF Subes are not wearing out in a few hundred hours. They are not blowing up. They just run along with almost zero oil consumption. Their good design, ultra stiff construction, tight tolerances, synthetic oil, great temperature stability and great metallurgy contribute to this life.

You doubters, show me some FACTS that Subes are wearing out running along at 4000-4500 in cruise. Show me.

 

[Radomir]

No one is saying that an atmo 2.5L Sube is going to match a 6L IO360 in speed. Not going to happen without internal mods and twisting it over 6000 rpm.

I think Egg is (or at least was....)... How else would he sell his package?

What's an average Egg customer getting performance-wise? I don't care what Paisley is getting -- he worked hard on his setup to improve numbers.. what are they out of the box? I'm yet to see any "stellar" reports.. most I've seen were under (some way under) what was expected (expected = meet Lyc numbers)

 

[Yukon]

Ross,

Doubling the RPM via a heavy, complex and troublesome gearbox used to be how a Sube developed it's horsepower on half the cubes. Now that it doesn't seem to be measuring up, your're now saying that a fair comparison
can only be made blown to atmo. I don't buy it.

 

[rv6ejguy]

I think Egg is (or at least was....)... How else would he sell his package?

What's an average Egg customer getting performance-wise? I don't care what Paisley is getting -- he worked hard on his setup to improve numbers.. what are they out of the box? I'm yet to see any "stellar" reports.. most I've seen were under (some way under) what was expected (expected = meet Lyc numbers)

The atmo 2.5 is no longer being sold. It was fairly lame compared to even an O-320. There are no stellar numbers that I have seen for either the old atmo 2.5 nor the H6. The H6 with old MT, old ECU and Gen 3 drive looks to be able to cruise at something around 165 knots if you want to burn between 10.5-11.5 GPH, certainly not in O-360 territory.

I have not seen numbers from an Egg H6 with all the latest parts on- EZ30-R, new ECU, new prop, exhaust and Gen 3 drive. Until we see this test we don't know what the latest batch will do. I doubt if they will be faster and burn less than an O-360 C/S though.

The EZ30-R does develop 250hp at 6600 rpm in stock form. As discussed previously, lower rpm and changes to the intake manifold and exhaust may affect this figure and naturally they are not being spun up to this rpm. I'd wait for climb test figures to judge relative power output.

My point about forced induction Subes is just to point out that a turbo 2.5 running well below 4500 and mild boost would be an easy match for an O-360 in hp and should be close in weight and fuel economy as well. This would be the best starting point for an optimal package.

 

[rv8ch]

2.5 L boosted

...My point about forced induction Subes is just to point out that a turbo 2.5 running well below 4500 and mild boost would be an easy match for an O-360 in hp and should be close in weight and fuel economy as well. This would be the best starting point for an optimal package...

I agree. We're standing by for your ECU and turbo package, Ross!

 

[rv6ejguy]

I agree. We're standing by for your ECU and turbo package, Ross!

I'm starting on that one right now along with the secret formula to add 50 years to my lifespan so I can do all this before I croak!

Seriously, for those STI guys who want to install a turbo in place of the Eaton and have a simpler ECU solution, I should be able to supply the ECUs, wiring, crank sensor etc. within a month or two. This will drive the OE coil on plug ignition and be able to control the variable cams if desired.

I can match turbos for your intended mission altitudes and hp and tell you where to buy these. Same goes for intercooler cores and wastegate controllers.

Exhaust piping would have to be custom done to suit the airframe and mount configuration. If the STI guy here goes this route, I'll take photos and document on my site for ideas. This would have to be .058-063 wall 321 stainless with slip joints. I might be able to offer a partial parts kit (weld your own)- flanges and generic pipes, slip joints etc. if there is enough interest to warrant CNCing some pieces. Be aware that it is impossible to make a bolt on kit without having all the airframe/ cowling/ mount configurations in hand. We have a -7 to work with here so it might not be very applicable to A models.

I'm not a composite guy so any revised rad stuff would not be something I would get into. One of the custom cowling makers might get into this but someone would have to do the legwork on installation and flight testing the parts to validate. I'm 2 years away to do this on my 6A at least.

This is a big project to do right. The intercooler should be relocated as well. It must all fit in the cowling without being a nightmare to inspect and work on so careful considerations on layout of components is required.

 

[Jconard]

Man, you Lyco guys just whine about everything. After hacking at Subaru performance for years and saying that NO Sube would EVER beat a Lycoming, Robert beats one of the fastest RVs around. Grudgingly you accept the facts then start saying well it was burning a lot more fuel. Of course it was, it was making more power. Paisley waxed Dan at the typical mission altitudes RV cruise at. You want to run the test at SL? Who cruises at SL? What would the IO-360 burn WOT at SL? probably 14+GPH.

Just a point,

I do not think that the comparison was ever speed alone, it was always speed/fuel burn. I just point this out because, if the question was simply speed, without regard to fuel burn, then a twin turbo V8 would win....it would be a ridiculous question.

On the other hand, speed for a given fuel burn takes the factors of aircraft performance into effect because weight and drag are key. Who would install even a 1000HP engine if the intallation weighes so much or caused so much drag that speed was only available at high burn in realistic operating conditions?

 

[rv6ejguy]

Well the contest used to be speed and hp but since the STI won that one it is now about fuel flow. I don't see the current crop of atmo, port injected Subarus ever winning this contest against a Lycoming. If you compare torque curves and SFC curves on the Subarus, the only place they are superior is down below 3300 rpm where they don't make much power. This is the point where high volumetric efficiency and lowest frictional losses occur. If the variable valve timing and secondary butterflies have been deactivated as in the Egg conversions, the SFCs might be even higher than the stock engine.

I see some Egg users do fly at these very low power settings on very low fuel flow but they are also going very slow. You can do the same with a Lycoming if you are not in a hurry so there is no real advantage there.

Turbos change all this which is why I advocate them, You can make good power well below 4000 rpm so VE is high, frictional losses and pumping losses are low.

When newer direct injection engines become available, we may see equal fuel flows from atmo auto engines at medium to high revs. Some of these engines are doing better than .4 lbs./hp/ hr. today.

As we sit today, I don't see Subes matching Lycomings in the 165-175 knot ranges in an RV. Advantage Lycoming.

It will be interesting to see what Todd's LS powered RV10 will perform like.

I think many factors come into play. Speed, weight, fuel flow, initial and operating costs and eventually overhaul costs. Auto engines will win a few of these categories and lose a few.

 

[SteinAir]

Hey Ross....Just curious here, but how many hours does your ole' -6 have on it now? I'm truly not trying to start anything here, I'm just trying to find out how the graybeards who've been around for awhile are holding up.

As an aside, does anyone know what the highest time subie RV out there is right now? I'm truly interested.....

Cheers,
Stein.

 

[Jconard]

Well the contest used to be speed and hp but since the STI won that one it is now about fuel flow. I don't see the current crop of atmo, port injected Subarus ever winning this contest against a Lycoming. If you compare torque curves and SFC curves on the Subarus, the only place they are superior is down below 3300 rpm where they don't make much power. This is the point where high volumetric efficiency and lowest frictional losses occur. If the variable valve timing and secondary butterflies have been deactivated as in the Egg conversions, the SFCs might be even higher than the stock engine.

YOU CANNOT SAY THAT THE CONTEST WAS EVER ABSOLUTE POWER OR SPEED AT ANY FUEL FLOW.

If it really was, in your mind just absolute output and top speed at any airflow, why compare the 6 cylinder subes against four cylinder lycs...why not eight cylinder lycomings, etc...??? What possible use could the top output or speed at any fuel flow have to an airplane conversion.

But you are correct that an engine is at its top volumetric efficiency AT ITS TORQUE PEAK. This is a point that the aircraft engine crowd has been making for years now as a suggestion that for speed per unit of fuel, a gear drive high HP engine is INHERENTLY LESS EFFICIENT.

This is why a direct drive engine operating in cruise at its TORQUE peak is the most efficient way to convert fuel into force. It seems you now agree. And I am glad we all finally agree that endlessly spining a small engine for HP, and above torque peak, will always generate power at a higher cost in fuel....duh!

The rest of it result from what to do once the fuel becomes force, and then weight and drag are important, again it is an airplane specific application.

Which gets us all back to the original question all along: If it truly were better in an airplane environment to have small displacement, high reving engines which are water cooled, do you think it would be done????

Or is it more likely that the reason aircraft engines are light weight, direct drive, large displacement engines is because that is the simplest way to get enough power, at the torque peak, to run the engine most efficiently, and hence deliver the best thrust per unit of fuel?

 

[rv6ejguy]

Hey Ross....Just curious here, but how many hours does your ole' -6 have on it now? I'm truly not trying to start anything here, I'm just trying to find out how the graybeards who've been around for awhile are holding up.

As an aside, does anyone know what the highest time subie RV out there is right now? I'm truly interested.....

Cheers,
Stein.

My 6A has only 117 flight hours and something like 214 engine hours to date. Building on the -10 and being very busy at work here means very little recent flying on the 6A. I'm planning a partial retirement in 3 years here maybe to be able to spend more time flying the two planes. The -10 is a real grind, like building two -6s. Do you build or fly? I just use the 6A mostly to stay current at present.

I have heard of many of the RAF EJs going well over 1500 hours (recommended overhaul). It seems several Egg Subes are near the 1000 hour mark and users report perfect compression, low leakdown and usually near zero oil consumption. It would seem that 2000 hours is not unreasonable at this time for TBO but I'd wait for more data.

There have been a few instances of HG failures on EJ25s that have been persistently overheated. I'm not sure the engine can be blamed for that.