Rebuilding an EG33.

[cjensen]

Ross...unrelated to this topic, but check your PM's...

[rv6ejguy]

Chad,

Replied to your PM this morning.

[cjensen]

That's weird...I never got it. Can you resend it? I haven't had a new PM arrive all day today...

[rtry9a]

Originally Posted by akschu

My understanding of the rotary engines is that they need a turbo to make the HP I want and that they run real hot.

Being that a subaru is a AWD car, they are extremely popular in AK so I can get parts anywhere, where the rotary is a bit more difficult to come by.

I'll take a look at them, but so far I'm inclined to stick with what I know and rotaries are uncharted waters for me.

schu

You will likely have more heat problems with the Subi, and the Renesis only needs a turbo if you want 300-400hp. A recent test of a peripheral ported Renesis, with carbs, gave 265 hp on Mazdatrix's dyno. The RX-8 OEM rating is 210 or 240 hp depending on which port arrangement you pick.

FWIW, Id guess the rotary engine, with its light weight and only 3 beefy moving parts that do not break in normal service, would be a real advantage in AK. Check out Tracy Crooks website at http://www.rotaryaviation.com/

[rv6ejguy]

I don't want to get into a Wankel vs. piston debate here but the Subies are not breaking in service either and the Renesis has not had the best longevity reviews by people in the Mazda servicing, racing/ rebuilding world like Rob at Pineapple Racing and Paul Yaw at Yaw Power. They both say the earlier engines last a lot longer than the Renesis in hard use. Paul should know, he had pre-production engines from Mazda for technical review before they were released.

I've dynoed my share of 13Bs and you are not going to see over 200 hp on any mildly ported atmo one running under 6500 rpm. High sound levels, consequent required muffling with the high EGTs are other drawbacks. A turbo gets them quiet and gives you a lot more power at very low boost without running the rpms up past 7500. Same as on a Subaru, which is why I'm an advocate of turbos on auto conversions.

The Wankel is an engine with small volume and relatively high power to weight ratios. Makes it a good choice for those needing 160-180 hp. The EG33 is 230hp stock at a low 5400 rpm and the long block weighs just over 250 pounds. It is more in the hp/ weight class of a 20B.

Cooling is just a matter of getting the right heat exchangers installed and properly ducted- irregardless of engine type.

Servicing the Wankel in Alaska won't be quite as easy either IMO but if nothing goes wrong with it, it is a moot point anyway.

[rtry9a]

I too don't want to make this a Mazda vs Subaru argument. I am bothered a bit when critics continue to confuse old with new Mazda technology. We are not locked to 1970s technology today; Mazda has made great improvements on the engine in the last 30 years, as has Subaru, not so sure about Lycomming.

I really like the Subaru engines. Mazda and Subi are both excellent alternatives for our use, each has strengths. Both are extremely smooth running compared to the air-cooled options. The power to weight advantage is clearly rotary, Id give sound issues to the Subi, though the Renesis side port exhaust is much better than older designs. I also like the mechanical stress advantages of the rotary's continual motion over any reciprocating piston/crankshaft arrangement.

I mentioned the heat thing only because the Subi engine envelope is larger and generally requires small front mounted heat exchangers in an RV cowl- a system that is not working out very well (same problem with that arrangement with Mazda, btw)- I agree that a good cooling system should work just fine, it is just that most of the Subi's Ive seen are not cooled all that well at full power... The small rotary package allows radiator mounting either on the side or under the engine where "better" layout options exist.

Id also have to take an issue with Ross's comment about Renesis longevity- it has been reported in a few RX-8's on the road, but not in the air. Breaking it down, the problems Ive seen reported are related to engines that use the OEM oiling system that uses crankcase oil to cool/lubricate the rotors- the detergent oils eventually gum up apex seals. The aviation guys mix clean burning 2-cycle oil with fuel, or install a separate oil reservoir for the rotor pump, which solves the gumming problem.

You can see the actual dyno video and data sheet on PL's website if you want to take issue with the measured 265 HP numbers on the initial P-port intake Renesis experiment. The Rotary loves a turbo if you want more than 250, up to 400+ if you want to push it, but not really needed in RV service. The Renesis is good for an easy 180 hp @ 6000 or 165hp @ 5500 rpm (the torque peak and best efficiency range). Just goose the throttle if you want more speed (and higher fuel burn) for as long as you want- no operating limits up to the 8500 rpm peak.

I have no idea why you would want to limit rpm to 6500 on your Renesis motor comparison, though it might make some sense with earlier 13B's limited by intake design. Intake system capacity has been the power limiting factor with Rotary engines historically, since they were compromised to maximize low end torque in road use. Rotary output rises linearly with rpm until breathing cuts it off. The huge Renesis side ports breathe much better than earlier designs (intake p-ports even better), and particularly so with tuned intakes that target aviation engine speeds. The 6-intake port OEM Renesis engine is rated 250hp @ 8500 rpm; the discontinued 4-intake port version 210hp @ 7500rpm.

IMHO, it appears to me that redrive ratio offerings have been the big problem with the Subi's so far; it hinders them from delivering rated hp levels to the propeller. I'm sure the increased torque from turbocharging helps a lot with that problem. The Renesis aviation guys are using Tracy's 2.85:1 redrive to take advantage of its extended rpm and power capability to actually deliver full power to the prop.

[rv6ejguy]

Originally Posted by rtry9a

I too don't want to make this a Mazda vs Subaru argument. I am bothered a bit when critics continue to confuse old with new Mazda technology. We are not locked to 1970s technology today; Mazda has made great improvements on the engine in the last 30 years, as has Subaru, not so sure about Lycomming.

I really like the Subaru engines. Mazda and Subi are both excellent alternatives for our use, each has strengths. Both are extremely smooth running compared to the air-cooled options. The power to weight advantage is clearly rotary, Id give sound issues to the Subi, though the Renesis side port exhaust is much better than older designs. I also like the mechanical stress advantages of the rotary's continual motion over any reciprocating piston/crankshaft arrangement.

I mentioned the heat thing only because the Subi engine envelope is larger and generally requires small front mounted heat exchangers in an RV cowl- a system that is not working out very well (same problem with that arrangement with Mazda, btw)- I agree that a good cooling system should work just fine, it is just that most of the Subi's Ive seen are not cooled all that well at full power... The small rotary package allows radiator mounting either on the side or under the engine where "better" layout options exist.

Id also have to take an issue with Ross's comment about Renesis longevity- it has been reported in a few RX-8's on the road, but not in the air. Breaking it down, the problems Ive seen reported are related to engines that use the OEM oiling system that uses crankcase oil to cool/lubricate the rotors- the detergent oils eventually gum up apex seals. The aviation guys mix clean burning 2-cycle oil with fuel, or install a separate oil reservoir for the rotor pump, which solves the gumming problem.

You can see the actual dyno video and data sheet on PL's website if you want to take issue with the measured 265 HP numbers on the initial P-port Renesis experiment. The Rotary loves a turbo if you want more than 250, up to 400+ if you want to push it, but not really needed in RV service. The Renesis is good for an easy 180 hp @ 6000 or 165hp @ 5500 rpm (the torque peak and best efficiency range). Just goose the throttle if you want more speed (and higher fuel burn) for as long as you want- no operating limits up to the 8500 rpm peak.

I have no idea why you would want to limit rpm to 6500 on your Renesis motor comparison, though it might make some sense with earlier 13B's limited by intake design. Intake system capacity has been the power limiting factor with Rotary engines historically, since they were compromised to maximize low end torque in road use. Rotary output rises linearly with rpm until breathing cuts it off. The huge Renesis side ports breathe much better than earlier designs (p-ports even better), and particularly so with tuned intakes that target aviation engine speeds. The 6-port OEM Renesis engine is rated 250hp @ 8500 rpm; the discontinued 4-port version 210hp @ 7500rpm.

IMHO, it appears to me that redrive ratio offerings have been the big problem with the Subi's so far; it hinders them from delivering rated hp levels to the propeller. I'm sure the increased torque from turbocharging helps a lot with that problem. The Renesis aviation guys are using Tracy's 2.85:1 redrive to take advantage of its extended rpm and power capability to actually deliver full power to the prop.

Since this is a Sube thread, I'm gonna defend the honor here:

The Renesis has not demonstrated superior durability to the earlier Gen engines. More power, yes, life before extreme oil consumption and low compression takes hold, no. While the Wankel is never likely to suffer a catastrophic failure in aviation use at the lower rpms, they don't offer the lifespan that most modern Japanese piston engines do. They are inexpensive to freshen up however so that makes it really not much of an issue. No Renesis engine has accumulated even 500 hours of flight time yet, so we don't know how they will actually hold up. Perhaps the pre-mix oil negates this problem entirely- only time will tell.

I think we can say that all liquid cooled engines have suffered poor cooling when saddled with a poorly designed cooling system- not a particular engine's fault here. The Wankel also demands a good oil cooler setup. Under engine rad setups are generally superior to cheek setups. In this respect, the flat Sube is about the same height as a Wankel.

If you want to spin the Renesis up to 8000-8500 it will produce the power, the question is for how long and at what noise and fuel consumption level. It is completely unproven in aviation apps at this time and power levels. Breathing ability affects the power bands of all engine types. We have a number of factory piston engines with redlines above 8000 rpm as well and race piston engines rev far above where the best Wankels run.

There are many different PSRUs available for Subes with ratios from 1.64 to 2.20 so this has never been a limitation for DIYers.

As far as power to weight ratios go, the modern Subes are not too far off a Wankel. The EZ30 is better than 1 pound/hp of long block weight and the new EJ25 is at about 1.14.

It really comes down to what you like. I personally like anything that is innovative and different and I'm intrigued by rotary powered aircraft and how they perform.

[akschu]

Ross,

I have several more questions if you don't mind:

1. What boost levels do you run on a single turbo EG33 with the stock 10.1 compression.

2. Is the ECUTune engine at 9.3:1 compression going to be a much better setup when running a turbo? I suspect it will be a much better setup.

3. Which turbo do I need to run and how do I know it's sized up correctly. In other words how can I match up the engine to the correct compressor wheel, etc.

4. How do you deal with the waistgate? I saw that the egg engines use a servo actuated waistgate and a computer controller. Does your ECU have provisions for turbo control?

5. What kind of HP should I look for at sea level or normalized? Is 250hp reasonable?

6. What will my cruise rpm be? Do you think I can get it under 4k rpm given the lower compression and higher boost levels?

7. How do I verify that I'm not overboosting the engine? Will that show up on a knock sensor?

8. Last, but certainly not least, are there PSRUs that run the prop the correct direction? The bearhawk uses an offset vertical stab to handle the left engine torque, so finding a PSRU that turns the correct direction would save me from some cutting and welding on the fuse.

I think that's it for now.... I'm just trying to get my hands around what it will take to build my own system since I really like the ECUTune/turbo setup.

THANKS!!!

schu

[rv6ejguy]

Originally Posted by akschu

Ross,

I have several more questions if you don't mind:

1. What boost levels do you run on a single turbo EG33 with the stock 10.1 compression.

2. Is the ECUTune engine at 9.3:1 compression going to be a much better setup when running a turbo? I suspect it will be a much better setup.

3. Which turbo do I need to run and how do I know it's sized up correctly. In other words how can I match up the engine to the correct compressor wheel, etc.

4. How do you deal with the waistgate? I saw that the egg engines use a servo actuated waistgate and a computer controller. Does your ECU have provisions for turbo control?

5. What kind of HP should I look for at sea level or normalized? Is 250hp reasonable?

6. What will my cruise rpm be? Do you think I can get it under 4k rpm given the lower compression and higher boost levels?

7. How do I verify that I'm not overboosting the engine? Will that show up on a knock sensor?

8. Last, but certainly not least, are there PSRUs that run the prop the correct direction? The bearhawk uses an offset vertical stab to handle the left engine torque, so finding a PSRU that turns the correct direction would save me from some cutting and welding on the fuse.

I think that's it for now.... I'm just trying to get my hands around what it will take to build my own system since I really like the ECUTune/turbo setup.

THANKS!!!

schu

The boost level needs to be kept low with 91 octane fuel and 10 to 1- maybe 34 inches to be safe. With 100LL, you can run up to 50 inches.

The forged pistons are a really good idea when turbocharging this engine as it does not have under piston oil jets like the factory turboed engines do. The lower compression would allow you to run maybe 36 inches on 91 octane which should give you well in excess of 260hp for takeoff.

I can help match a turbo for you if you know the hp and typical altitudes you operate at. Be aware that the turbo system with intercooler will add a good 40-50 lbs.

We don't control the wastegate actuator but you can use a standard pneumatic actuator and integral wastegate or an external wastegate. Advantages to both. I like the integral stuff but we are limited in turbine housing choices a bit with these.

With a turbo, you should be able to get cruise rpms below 4000-depends on how much power you need for cruise. Without a turbo, you'll have to spin up at least 4500.

I'd monitor MAP to be sure you don't overboost, but the wastegate will control max boost automatically. Just shove the throttle up. You can have a knock sensor as a backup to control detonation but there are some limitations to be aware of.

The Marcotte will retain the correct prop rotation direction and give you about 2 inches of prop hub offset which helps with intake manifold clearance from the cowling. The newer RWS drives maintain direction too I think. Autoflight, I'm not sure but you can ask the other guy up there in AK as he uses a special high hp version of that PSRU.

The turbo will require an oil scavenge pump unless you can mount it very high under the cowling. This can be engine driven or electric but it is a critical system. I'm using a new, lightweight electric gear pump now.

[akschu]

Originally Posted by rv6ejguy

The boost level needs to be kept low with 91 octane fuel and 10 to 1- maybe 34 inches to be safe. With 100LL, you can run up to 50 inches.

I'm not at all interested in 100LL so it sounds like lower compression pistons are the way to go.

Originally Posted by rv6ejguy

The forged pistons are a really good idea when turbocharging this engine as it does not have under piston oil jets like the factory turboed engines do. The lower compression would allow you to run maybe 36 inches on 91 octane which should give you well in excess of 260hp for takeoff.

That makes this ECUTune engine even better. It has the forced oiled pistons.

Originally Posted by rv6ejguy

I can help match a turbo for you if you know the hp and typical altitudes you operate at. Be aware that the turbo system with intercooler will add a good 40-50 lbs.

Sure, but I'll be into a muffler at least 10lbs and I am looking for something a little quieter than a lycombing. You think the total weight will be less than an o-540?

Originally Posted by rv6ejguy

We don't control the wastegate actuator but you can use a standard pneumatic actuator and integral wastegate or an external wastegate. Advantages to both. I like the integral stuff but we are limited in turbine housing choices a bit with these.

That sounds reliable, what kind of money will I be into one of these?

Originally Posted by rv6ejguy

With a turbo, you should be able to get cruise rpms below 4000-depends on how much power you need for cruise. Without a turbo, you'll have to spin up at least 4500.

I suppose it depends on how fast I want to go. Remember many people are flying this with 170hp so I really only need 150hp to go which should be fairly low.

Originally Posted by rv6ejguy

The Marcotte will retain the correct prop rotation direction and give you about 2 inches of prop hub offset which helps with intake manifold clearance from the cowling. The newer RWS drives maintain direction too I think. Autoflight, I'm not sure but you can ask the other guy up there in AK as he uses a special high hp version of that PSRU.

Is the marcotte worth it to not move the stab or should I just get an autoflight, and move the stab and be happy with reverse prop? Where do I buy a marcotte?

Thanks,
schu