What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

RV-7 Egg H-6

YIKES!!

How hot was it? Maybe he wanted to get a good look at the end of the field? Maybe Jan is paying him as a nearly worst case scenario test pilot? Loaded to 3000 lbs???
 
You will note that the pic zoomed in twice------------this causes the apparent distances to be distorted, making the trees at the end look much closer to the departing plane than they actually were.

Dont trust all you see------------

Mike
 
Not

We have a friend with the 4 cyl Sube in his clean -7 and it uses about 1000 feet to get off.....terribly slow. From his fuel burn at 7 GPH, it has been figured that he might make 135 HP. The 200 HP figure is, methinks, a bit optimistic since I've seen many 180 and 200 Lycs take off from grass with two aboard, much, much sooner. The Sube installations are also heavier by far. Oh well, to each his own.

Pierre
 
Jeez John, haven't we been thru this on RB already? :rolleyes:

I have no doubts that that airplane is NOT making 200hp. He has the 1.82 redrive, and at 2700 prop rpm, it's making about 175hp or so.

So, to answer your question...no, it does not look like 200hp.

200hp comes in at around 5400rpm. With the 2.02 drive, you get 200hp at 2700 prop rpm. That is the reason that this particular owner has ordered the new drive.

captainron http://www.youtube.com/watch?v=oM8I...related&search=
I watched the take-off run (inside) and from the start of the T/O run to approx. 500' AGL looked like about 50-55 seconds. Seemed pretty anemic to me. Don't know what all the other conditions were, though.
Click to expand...
Not sure at all how you can tell it seemed anemic from the video. :confused: Idicated climb rate was 1780fpm, and it was an intersection departure. That hanger that I panned over to after we were in the air is 1000' from the interesection we departed from. Probably 5 or 600 feet roll I would estimate.
 
cjensen said:
Not sure at all how you can tell it seemed anemic from the video. :confused: Idicated climb rate was 1780fpm, and it was an intersection departure. That hanger that I panned over to after we were in the air is 1000' from the interesection we departed from. Probably 5 or 600 feet roll I would estimate.
Click to expand...
I noticed your altimeter before take-off indicated 900'MSL. Near the end of the video, and about 50-55 seconds after the engine went to full power, the altimeter was indicating 1400'MSL, or a 500" gain during that period. I assume you weren't deliberately climbing "flat" because of CHT issues with your water-cooled engine.
 
captainron said:
I noticed your altimeter before take-off indicated 900'MSL. Near the end of the video, and about 50-55 seconds after the engine went to full power, the altimeter was indicating 1400'MSL, or a 500" gain during that period. I assume you weren't deliberately climbing "flat" because of CHT issues with your water-cooled engine.
Click to expand...

I time it at about 42 seconds from rotation to 600 AGL at the end of the video.

That's about 850 fpm, which is well below Van's spec for a 160 hp RV.

If the engine is making 175 horsepower at 2700 prop RPM (which it very well may be) then there are significant losses elsewhere in the system. I don't know if it's in the redrive, prop efficiency, or what, but it doesn't perform like a "similarly powered" Lycoming equipped airplane.

I really like the idea of auto-engine conversions. I like the water cooling, smoothness, and potential economies of scale, but I haven't seen one that performs as well yet wasn't either very labor intensive (Tracy Crook) or expensive (Mistral)

As another data point, I found this short clip of a pattern trip in my RV-8. It isn't great video, and I touch down too fast (and skip a few times), but you can see I rotate at about 19-20 seconds in the video, and pass through 600 AGL about 18 seconds later, which is very close to Van' spec for a 200 hp RV-8.

To my best recollection, I was about 250# under gross weight, and temp was about 30 degrees F over standard in the video
 
Well, between here and RB, I feel like I've learned my lesson with posting videos. I thought this would be a neat "fun" idea, but it did nothing but spark arguments and speculation with endless comparison about performance.

I've gained some experience in Lyco and Subie RV's, and no matter what you think you see in the video, it'll never fair well with anything I can say about it, bad or good.

I'll be removing the videos. :rolleyes:

As I told John (Yukon) the other day, imagine if we would've flipped the thing over on landing...Holy ****!! That would've REALLY started something! :eek:

:)
 
cjensen said:
Well, between here and RB, I feel like I've learned my lesson with posting videos. I thought this would be a neat "fun" idea, but it did nothing but spark arguments and speculation with endless comparison about performance.

I've gained some experience in Lyco and Subie RV's, and no matter what you think you see in the video, it'll never fair well with anything I can say about it, bad or good.

I'll be removing the videos. :rolleyes:
Click to expand...

Chad, please don't do that. Like I said, I think there's a lot to be said for the auto conversions, but most people have little experience with them.

Videos like yours are important to open dialog, and you will get some strident opinions, but the videos are what they are.

I have been looking at various conversions for years, but haven't found one yet that meets my personal needs/wants.

My biggest problem with the Sube conversions has been the lack of real world information available about them. Jan Eggenfellner has sold something like 500 packages at an average of maybe $25K each, but still doesn't have any dyno data. He states on the website that flight testing confirms the power output but it doesn't seem to.

In flight videos are hugely helpful in "lifting the veil" and providing more information so that everybody can discuss this with real information.

I didn't post my video to criticise you, but to add another data point. My airplane has pretty typical RV performance. It meets Van' specs right down the line. When I saw your video, the climb rate looked low to me, so I looked to see what I had lying around--my airplane (which has average performance) climbs more than twice as fast as the EggSube RV-7.

I'm curious as to why the performance is what it is. I know that some of the supercharged Egg engines are faster than NA lycomings at altitude, but a fairer comparison would be to supercharged lycs.

I'm not saying that the sube isn't a good engine for these airplanes (it has a lot of advantages) but I don't think it has the performance of a Lycoming currently (I wish it did).
 
Chad,
I 2nd that, please don't remove the videos. You have no idea how many folks enjoyed viewing your videos and simply didn't post a response. Don't let a few ruin it for the masses. I'm sure your vidoes will benefit others in the future.
Tobin
 
I appreciate your comments James, and you are right. The problem is, is that MOST Lyco fanatics just can't take it for some reason. That's the part I DO NOT understand. There is NO ONE out there that isn't going to do their due diligence when it come times to spend $25-30k on an engine...if someone doesn't, they get what they deserve. A lot of people claim that "newbie' just don't understand. That may be true for a very short time. I was once a newbie too, and I've learned a TON about alternative's since then. I am one (among many) who likes 'em. I like Lyco's too...I fly behind them almost daily at work. I have no problem with them, other than the cost to maintain them. I just don't know if I want one for my RV.

This was ONE airplane, and soon enough, it's the standard of all Egg Sube's because people aren't putting video's or real info on the most popular forums. There is PLENTY of data available in the Yahoo group. More and more is being posted all the time, and I truly think the numbers will continue to improve. There are three Gen3's flying on H6's, other than Jan's, that I know of, and one on Gary Newsted's H4. The numbers are better, but these engines are a couple years old, and there have been cooling improvements that have been implemented on the newest engines.

I've already removed the video's, but I will consider putting them up again, however the links are already broken. I apologize to those that did enjoy them. You'll be able to find them again on YouTube at some point.

The RV-9A H6 that I flew in was really different than the 7 H6. I can only report what I saw personally in each airplane, and I'm not interested in everyone breaking down the videos.

Thanks though. :)
 
More Censorship

Therein lies the problem Chad. It's not possible to do due-diligence on this engine. Jan refuses to dyno the engine, his website is nearly devoid of weight and performance numbers, and now you take down the only H6 takeoff video available. If there are impressive videos, let's see them.

There are hundreds of those "165 hp" 4 cylinders out there. You think we would have one good takeoff video by now.
 
Last edited:
cjensen said:
I can only report what I saw personally in each airplane, and I'm not interested in everyone breaking down the videos.
Thanks though. :)
Click to expand...
No, you're not interested, but others are, and are viewing them with critical eyes. Most of us are not "Lycoming fanatics", but we are just looking for solid, proven, and safe performance from our 25K purchases. If we were after all-out performance, we wouldn't be building Vans. What I want, and what I suspect most of us want is the excellent performance that these planes provide, the satisfaction of building it yourself, and the peace of mind that comes from the realization that the powerplant is NOT a somewhat risky unknown.
This is the formula that has made these kits so successful. I'm sure that E-Sub people believe in their product; after all they are trying to make a living from selling them. I'm sure that the Innodyne people believe in themselves and their product also. It's up to us to decide for ourselves what looks good and what doesn't. What apparently several of us saw in the videos wasn't a glowing endorsement for a product that most have already shied away from. The video of the plane flipping over has made us take yet another look at the "A's" and has produced a lively exchange of opinion on this forum. Nobody posted this video with the admonition of "No comments, please". Post, or don't post, but please don't whine when you do and people comment on them. This IS a forum after all.
 
cjensen said:
Here are two video's from Egg's site. Not the best, but they do show some performance. I can't speak for either one since I was not there. I'll repost a couple of the video's along with the 9A takeoff sometime this weekend.

Gary Newsted's 4 cyl Gen3

Andy Parish H6 Gen3
Click to expand...

Thanks Chad.

The video(s) you linked (I'm getting two copies of the same video I think) are entertaining, and give a sense of what the airplanes sound like, and they clearly have at least reasonable performance, but they aren't nearly as infromative and useful as yours.

Your videos showed instruments clearly enough to estimate performance. I can't recall ever seeing that before, and I've been looking with interest for years.

Several years ago, I had the opportunity to fly along side Tracy Crook's Rotary RV4, and then briefly fly it. That airplane, although cosmetically very rough, is clearly capable of outperforming an O-320 powered RV4. His cruise fuel burn is very similar to a Lyc in loose formation (verified by Bernie Kerr, who is a mutual friend). Tracy's RV is very smooth and very loud. It is also a fixture in air races and there is little doubt about his claimed performance.

Ross Farnham's numbers seem to be pretty good too, although he admits his FWF is a little heavier than an o-360 and (in spite of Turbocharging) he is slower below 8000 feet and faster at high altitudes.

Jan, on his website, claims 175 knots/201 mph on 8.9 gph at 8500' with a normally aspirated H-6 on an RV-7A which is a pretty good cruise number, but is typical of an O-320 (160 HP) RV. That's about my economy cruise number (LOP) and I'm burning 10% less fuel (although 100LL is significantly more expensive than mogas). Dan Checkoway and others report similar Lycoming numbers.

Robert Paisley (from Jan's website) is reporting 210 mph/16 gph with his supercharged engine. Our Cirrus SR22 (LOP economy cruise) will do 170 knots on 15% less fuel than Robert's RV at 180 knots.

A lot of us are really interested in these engines, but crave real data. Your video was the best some of us had seen to date.

I would love to see more, and if your friend with the RV-7 is willing, I'd love to swap rides and/or fly formation. I promise if we do I'll post video.
 
James, and others,

I apologize for removing the videos, and I will re-post them with a new link later today (I'm out in the garage working on fuselage top skins right now). I will post the other 9A video that I have as well.

I know none of you are criticizing me, but the owner of that 7 is not on the forums (nor does he have time). I feel like I need to try and defend some of the data that is "drawn" from the video, and all I get is more criticism.

We'll see what happens...

We will do more videos in the coming months after he puts his new redrive on, and I am doing my best to get the real data out there...I'm just as curious as you to see the real numbers. David, Ross, Nathan, among others are doing a great job of posting what they are seeing. None of the newest batch of E6 motors are flying yet, but I hope to see some later this year.
 
flyeyes said:
I really like the idea of auto-engine conversions. I like the water cooling, smoothness, and potential economies of scale, but I haven't seen one that performs as well yet wasn't either very labor intensive (Tracy Crook) or expensive (Mistral)
Click to expand...

The Thunder Mustang is the fastest naturally aspirated engined aircraft in the world and holds the fastest race lap in the Sport Class at Reno. Not bad for an auto/boat engine.http://www.bluethunderairracing.com/about/results.htm

Several auto powered canards easily outperform their Lyco powered sisters.

My Sube RV does 0-60 knots in 8 seconds without holding it up on the brakes and without ramming the throttle ahead.

We trade installation and development time for lower up front costs.

You are correct in stating that no turn key auto conversion is currently available which can match overall Lycoming performance in an RV but properly executed auto conversions can certainly match climb and cruise numbers.

Chad, some people are just very negative about this subject and will attack most anything you post on it. It's not their fault. Being subjected to years of Lycoming vibration levels is bound to result in some sort of brain damage- they seem to turn nasty.
:rolleyes: :)

My initial reaction to the video was negative as well until you enlightened me about the conditions with the shortened grass takeoff area due to an accident and the high density altitude. Naturally the zoomed lens gives an illusion as well. We are quick to jump to conclusions when all the facts are not at hand. It would have been in context only if you had followed the takeoff of other RVs or aircraft to judge relative performance. Thanks for posting.
 
Last edited:
Once I get the pinholes and depressions in the cabin top filled (arrgghh) and my magic coating on the inside of it, I'll get that sucker bolted on. Then it's on to the doors which I understand are the most fun part on a -10. :rolleyes:

Most of the other metal work is done so mainly final wiring, lots of fiberglass "fixing", windows, rebuild the Sube (the fun part for me) and a bit of fab work on the turbine oulet pipes. I'm leaving paint to the shop who did my 6A. I hope to fly it sometime in '08.

I'll be looking for some Lyco -10s to do a flyoff against eventually. A friend has one nearby who just started test flying last week. Maybe we can get together sometime and do a Chevy vs. Subie comparo too. :cool:

You gonna be flying soon?
 
Hopefully we will get this bird in the air next month. Both of us have been swamped with work and life. It is coming together though. All the parts are built. We have to fit the cowl, finish the panel, EFIS/One wiring and some paint and we should be ready to go. Hopefully I can start the engine with the prop on in the next week. It's been a great learning experience but now it needs to be a great flying experience!
 
So, what happens to the horsepower?

rv6ejguy said:
My Sube RV does 0-60 knots in 8 seconds without holding it up on the brakes and without ramming the throttle ahead.
Click to expand...
Where does all that horsepower go? I'm sure that same engine, if you had left it in the car, would do 0-60 in much less time than 8 seconds. And the car probably weighs 3250 pounds and doesn't get any "lighter" on its feet the faster it goes! What does your RV-8 weigh when it's getting this performance?
In the car, horsepower is sapped by the transmission, 4WD running gear, air conditioning, exhaust system, etc..
On your plane, the only thing you're driving is the re-drive and a propeller.
Where's the performance?
 
Sorry to do a little thread stealing but it is about car engines in planes!
img0731ef2.jpg

img0736ev5.jpg
 
captainron said:
Where does all that horsepower go? I'm sure that same engine, if you had left it in the car, would do 0-60 in much less time than 8 seconds. And the car probably weighs 3250 pounds and doesn't get any "lighter" on its feet the faster it goes! What does your RV-8 weigh when it's getting this performance?
In the car, horsepower is sapped by the transmission, 4WD running gear, air conditioning, exhaust system, etc..
On your plane, the only thing you're driving is the re-drive and a propeller.
Where's the performance?
Click to expand...
In a car, the engine's power is transmitted via transmission, CV joints etc. The transmission is very efficient, so the vast majority of the power produced by the engine is available as thrust horsepower. On an aircraft, the engine's power is sent to the propeller, and the prop creates thrust. But, the prop is optimized for high speeds, which is where the aircraft spends most of its time. The prop efficiency is almost certainly less than 60% during the takeoff, and it is probably less than 50% during the early part of the takeoff roll. So, if the prop efficiency is less than 50%, that means that less than 88 hp of the 175 hp is actually used to produce thrust. This is one big reason why an aircraft will have worse low speed acceleration than a car of similar power to weight ratio.
 
Apples to apples Kevin. Doesn't this apply to Lycoming aircraft also? How does Van's claim 350 feet for takeoff for an RV-7 on 88 hp???????
 
captainron said:
Where does all that horsepower go? I'm sure that same engine, if you had left it in the car, would do 0-60 in much less time than 8 seconds. And the car probably weighs 3250 pounds and doesn't get any "lighter" on its feet the faster it goes! What does your RV-8 weigh when it's getting this performance?
In the car, horsepower is sapped by the transmission, 4WD running gear, air conditioning, exhaust system, etc..
On your plane, the only thing you're driving is the re-drive and a propeller.
Where's the performance?
Click to expand...

I'm not following this. First off, will a Subaru car really do that much better that 8 seconds? Secondly, why would it matter if a car was "lighter on its feet"? The car's (or plane's) inertia is a function of its mass which is constant regardless of lift, and is the main thing preventing acceleration. Finally, the fact that the prop is operating in air makes it a completely unfair comparison unless you want to put the tires on some slippery surface.

In any case, I can't for the life of me understand how there can be hundreds of these conversions flying and not one single set of dyno data.
 
Dyno Baby

So that we can know the answer to these questions, I will pay for the dyno test if somebody will make their engine available. Speak up Subie guys!
 
Yukon said:
Apples to apples Kevin. Doesn't this apply to Lycoming aircraft also? How does Van's claim 350 feet for takeoff for an RV-7 on 88 hp???????
Click to expand...

I just went back and looked at my video frame by frame (in much higher resolution than YouTube) and it took my 200 HP airplane about 7.5 seconds to get to 60 mph (54 knots) assuming the IAS is accurate that low while it is increasing at that rate--which is a big assumption.

My daily driver will do 0-60 in under 6 seconds with 240 rated horsepower, in spite of a curb weight more than 2.5 times the RV-8.

Given that Ross is running an in-flight adjustable (but not constant speed) prop I think his number is pretty good.
 
szicree said:
I'm not following this. First off, will a Subaru car really do that much better that 8 seconds? Secondly, why would it matter if a car was "lighter on its feet"? The car's (or plane's) inertia is a function of its mass which is constant regardless of lift, and is the main thing preventing acceleration. Finally, the fact that the prop is operating in air makes it a completely unfair comparison unless you want to put the tires on some slippery surface.

In any case, I can't for the life of me understand how there can be hundreds of these conversions flying and not one single set of dyno data.
Click to expand...

I would think that a turbo-charged Subaru should be capable of good acceleration. The planes rolling resistance decreases with weight off wheels, something the car can't achieve. When the engines rated HP is absorbed by the prop, it is converted to thrust, and not lost. If the car's wheels were on a slick surface, then the max rated HP couldn't be delivered to them.
 
I am certainly no engineer, but the actual rolling resistance offered by my car's wheels against the pavement is a small thing. On the other hand, I would say that the moment of inertia for those wheels is a big thing. Also, I admit that I am ignorant of the finer points of how horsepower is converted to thrust but consider this experiment: Take the grill and radiator off of a 300 hp car to expose the cooling fan, stick car in neutral, floor it and hang on while the car just sits there. If the car has an engine driven fan and no fan clutch all of the horsepower should be going to that fan, but nothing happens. Why not?
 
szicree said:
I'm not following this. First off, will a Subaru car really do that much better that 8 seconds?
Click to expand...

My Subaru daily driver can go faster than most of Jan's customer's airplanes at cruise. Don't ask for details. ;) Oh...and 0-60 mph with the new SPT intake and exhaust is around 4.7 sec. Weeeeee........

Dan
Chicago
RV-9A Tail kit in the garage
WRX STi SPT in the garage too :)
 
Last edited:
Yukon said:
So that we can know the answer to these questions, I will pay for the dyno test if somebody will make their engine available. Speak up Subie guys!
Click to expand...

Curious, how does a dyno test work on an airplane engine?
 
dyno baby Yukon

I get my sube in NOV. come get it we will take it to Gearte and dyno it on your dime. maybe you better call and price how mutch each pull is. Regardless of controlled dyno runs,im mounting it on MY plane. No disrespect intended.
 
Jacksonville Il. I am belly up on airplane money until Nov. until racing is over, and should get it in Nov.I am as interested in the pull numbers as well but I dont think it will sway me. BUT.things can change in 5 months.
 
szicree said:
I am certainly no engineer, but the actual rolling resistance offered by my car's wheels against the pavement is a small thing. On the other hand, I would say that the moment of inertia for those wheels is a big thing. Also, I admit that I am ignorant of the finer points of how horsepower is converted to thrust but consider this experiment: Take the grill and radiator off of a 300 hp car to expose the cooling fan, stick car in neutral, floor it and hang on while the car just sits there. If the car has an engine driven fan and no fan clutch all of the horsepower should be going to that fan, but nothing happens. Why not?
Click to expand...

Gee, where to start here. You are only developing HP when there is a means of absorbing it. Think of an engine on a dyno, you could start the engine up and rev it to its redline, but how much throttle would that take? Probably not much. Now load the engine to the point where you have to have full throttle in to keep the RPM up and now you are doing some work (HP). Think of how you select a fixed-pitch propeller; you want the one that will allow the engine to reach its redline but no more, when flat-out at standard day, sea level conditions. Too much pitch and the engine can't make RPM=HP loss. Too little pitch and you have to reduce throttle so not to exceed redline=HP loss (your car fan theory). The proper propeller will absorb all the engines available HP and convert it to thrust.
Here's a thought for you. Imagine your car with one of its drive wheels sitting on a patch of oiled ice, and the other one sitting on dry asphalt. When you try to move, the wheel on the ice just spins, but the other wheel does nothing. The standard differential (not the limited-slip type) in the drive axle always delivers equal torque to both wheels. (Believe me on this.) It takes very little torque to spin the wheel on the oiled ice, and therefore not enough torque is developed to turn the other wheel at all. There's the same torque acting on that wheel, but it's not enough to move the car. The engine will only develop enough torque, or power to keep the wheel spinning at whatever speed you are requesting with the throttle. Little work (HP) is being done.
 
With my 6A, I cannot release the brakes with full throttle applied as I don't have enough right rudder to keep it on the runway. :cool: :eek:

Kevin rightly points out that the prop is not very efficient at converting power to thrust at low speeds. Lyco or Sube, doesn't matter. Tires and a transmission are way more effective at low speed acceleration than a prop.

I've never seen an RV take off in 350 feet but I believe Van's claim. An O-360 with C/S prop, built light, at SL, standard day and 10 gallons of fuel with a 160 lb. pilot. I have no doubt I could equal this feat with a really wide runway and actually using full fine pitch on my prop. At my 4000 MSL home field, I haven't seen any Lyco RVs use less runway than me and I'm hardly doing max performance takeoffs.

Yes, Subaru cars can be pretty fast. One 2.5L turbo does 179mph in the 1/4 mile. Pretty sure that would beat any RV known to man. Even the stock STI is around 5.5 seconds 0-60. There is no question that Subes can make sufficient power.

While some Sube powered aircraft are obviously lame, mine ain't one of them. Long live the turbo! :D

The old dyno thing crops up again. Be sure to dyno the Lyco and Sube on the same dyno for a valid comparison. I think you'll see something close to the factory dyno chart minus about 5% for drive losses. It is possible that locking out of the AVCS in the high position and a completely different intake manifold is hurting both cruise and top end power on the H6 conversions. Would be interesting to see the results.
 
Last edited:
captainron said:
Gee, where to start here. You are only developing HP when there is a means of absorbing it. Think of an engine on a dyno, you could start the engine up and rev it to its redline, but how much throttle would that take? Probably not much. Now load the engine to the point where you have to have full throttle in to keep the RPM up and now you are doing some work (HP). Think of how you select a fixed-pitch propeller; you want the one that will allow the engine to reach its redline but no more, when flat-out at standard day, sea level conditions. Too much pitch and the engine can't make RPM=HP loss. Too little pitch and you have to reduce throttle so not to exceed redline=HP loss (your car fan theory). The proper propeller will absorb all the engines available HP and convert it to thrust.
Click to expand...

Well said and I think I get it, but I guess I'm picturing a propeller driven vehicle starting from a dead stop as more similar to a high powered car with a locking dif. If you stomp on the gas hard enough you can get the car to just sit there and spin the tires. No over rev, just burning rubber and a car moving slowly forward.
 
Yukon said:
Apples to apples Kevin. Doesn't this apply to Lycoming aircraft also? How does Van's claim 350 feet for takeoff for an RV-7 on 88 hp???????
Click to expand...
Yukon - I was answering a question about why the difference in performance between cars and airplanes. But, yes, a Lycoming powered aircraft would have much worse acceleration than a Lycoming powered car, assuming the engine in the car provided propulsion power by driving the wheels through an appropriately geared transmission, etc.

As far as comparative performance between Lycoming and Subaru powered aircraft, I see no point in commenting unless there is some credible data to look at. Without data everything is just conjecture and opinion.
 
szicree said:
Well said and I think I get it, but I guess I'm picturing a propeller driven vehicle starting from a dead stop as more similar to a high powered car with a locking dif. If you stomp on the gas hard enough you can get the car to just sit there and spin the tires. No over rev, just burning rubber and a car moving slowly forward.
Click to expand...

That's right Steve, once you break the tires loose it doesn't take that much power to keep them spinning and little work is being done. It's when the tires try to hook up again and propel the car that takes HP. Go to the drag races when the top fuelers are there and watch the burn-outs. You can watch this without ear protection, but when they actually stage and launch it's like WW3! The HP required to propel these cars without wheelspin is unbelievable!
Subaru makes some of the fastest cars out there; they make my old turbo-charged Mazda look pretty sad. I like their engines and cars a lot, but I don't want to try to adapt the engine to an aircraft.
We know that a propeller of a certain diameter (what we're using) has to run in a very restricted RPM range. Take a standard fixed-pitch designed for 180-200 HP at 2700 RPM. If we mounted this prop on a O-720, 400 HP Lycoming, we could still get 2700 RPM and the same thrust, but the big Lycoming wouldn't be producing 400HP, more like 180-200 HP and be at partial throttle. Not efficient use of this engine.
Car engines may produce the HP needed to drive airplane propellers, but car engines weren't designed to operate this way. Your car may have 300 HP, but it may take only 45 or so HP, and 1900 RPM to keep it rolling down the highway at 70 MPH. The 300 HP is there, but certainly not full time. Their components were never designed for full HP all the time. Think about it; do you think that car manufacturers would expend their design resources, provide the metallurgy and the stress analysis required thinking that a few of them might end up in airplanes? They are building grocery-getters!
Now, lets hook this car engine up to a re-drive to get the RPM down to a usable propeller range. Who is engineering the prop flange and drive, and the gearbox and mounting itself, to withstand the unbelievable stresses the propeller places upon them. How about during aerobatics? How many "G's" will you be pulling during today's flight?
All this is Lycoming's bread and butter. They've seen it all, done it all, tested it all, produce it and then back it up! How many car engines promise to give you full rated HP for the life of the engine and warranty it? It's your call, but then again it's your b**t hanging up there too!
 
captainron said:
.....All this is Lycoming's bread and butter....How many car engines promise to give you full rated HP for the life of the engine and warranty it? It's your call, but then again it's your b**t hanging up there too!
Click to expand...

Lycoming's bread and butter at full rated HP will not make TBO. That's why the Flyer recommends cruising at much less than 100% for "long life". I believe the number is 65%.

Lycoming engines had a 500 hour/1 year warrantee when I was in that world. It's probably better now with all the clones in the market, but I doubt it is over 1000 hours.

Beyond that, they are good engines, just not quite that good. :)
 
captainron said:
Car engines may produce the HP needed to drive airplane propellers, but car engines weren't designed to operate this way. Your car may have 300 HP, but it may take only 45 or so HP, and 1900 RPM to keep it rolling down the highway at 70 MPH. The 300 HP is there, but certainly not full time. Their components were never designed for full HP all the time. Think about it; do you think that car manufacturers would expend their design resources, provide the metallurgy and the stress analysis required thinking that a few of them might end up in airplanes?
Click to expand...

This misconception has been visited many times before. The statement is totally unsupported by fact. Standard testing and validation today sees auto engines pushed to far higher standards than certified aircraft engines require. They are quite capable of running at 75% power for many hundreds of hours. Proven on the test tracks, dynos and in aircraft as well. You can search previous threads for the numerous details I have posted of these tests. The EJ255 (STI) has produced a staggering 960hp with stock case and crank- the equivalent of 2300hp from an O-360!

The design, manufacturing, metallurgy and QC far exceed what is employed in aircraft engines.

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

rv6ejguy said:
This misconception has been visited many times before. The statement is totally unsupported by fact. Standard testing and validation today sees auto engines pushed to far higher standards than certified aircraft engines require. They are quite capable of running at 75% power for many hundreds of hours. Proven on the test tracks, dynos and in aircraft as well. You can search previous threads for the numerous details I have posted of these tests. The EJ255 (STI) has produced a staggering 960hp with stock case and crank- the equivalent of 2300hp from an O-360!

The design, manufacturing, metallurgy and QC far exceed what is employed in aircraft engines.

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

Ross,

This is a "red herring" argument. How long did it produce 960 hp? A dragster will produce 7000 hp, but after a couple of runs it's torn down. So what?

No doubt the Subie has a strong lower end. But momentary brute
horsepower displays have no meaning in sport aviation. Long term,
reliable efficiency is what the GA pilot is looking for. Show me the beef!
 
Yukon said:
Show me the beef!
Click to expand...
The first Egg H4 Glastar just past 450 hours with no issues.

Charlie Walker's 2.5 Twin Cam has 800 hours with no issues.

The high time H6 has 500 hours on it with no issues.

I know these are not REALLY high numbers, but they do represent 15-20 years of flying with no problems. The beef is coming! :D
 
strength vs. stamina

Yukon said:
...This is a "red herring" argument. How long did it produce 960 hp? A dragster will produce 7000 hp, but after a couple of runs it's torn down. So what?...
Click to expand...
If a guy can bench press 960 lbs once, how many times do you think he could bench press 250 lbs?
 
rv6ejguy said:
This misconception has been visited many times before. The statement is totally unsupported by fact. Standard testing and validation today sees auto engines pushed to far higher standards than certified aircraft engines require. They are quite capable of running at 75% power for many hundreds of hours. Proven on the test tracks, dynos and in aircraft as well. You can search previous threads for the numerous details I have posted of these tests. The EJ255 (STI) has produced a staggering 960hp with stock case and crank- the equivalent of 2300hp from an O-360!

The design, manufacturing, metallurgy and QC far exceed what is employed in aircraft engines.

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

Well, I could be completely wrong. I guess I missed all the tech articles where modern auto engines were proclaimed to be superior due to "design, manufacturing, metallurgy and QC far exceed what is employed in aircraft engines." Are there any shops you could direct me to that overhaul or rebuild these car engine variants after they have served for what would have to be a much longer TBO due to their design and construction that is "far higher standards than certified aircraft engines require"?
I'd really like to know, maybe spending the same money for an auto engine conversion would pay-off over the much longer service life that these engines must enjoy.
 
You must log in or register to reply here.
Back
Top