Auto Engine Conversion Gearbox for Experimental Aircraft - RV-10

Watch and listen as Stuart Davis of Auto PSRU's talks about his RV-10 auto engine conversion using a PSRU Propeller convertor.
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[@skyking6989]

Amazing. About damm time GA engines enter the 21st century

[@stuartpsrus5413]

Ben, there are a lot of opinions all over the internet, including here, that think the radiators and coolant must make the LS3 engine heavier. In fact if you unbolt everything from the firewall for the IO-540 and one with an LS3 with the same propeller and fully wet our installations typically weigh 2-3 pounds less with a smaller alternator and light weight starter. We have weighed both for the RV-10. Using the stock alternator and starter will add 5 to 6 pounds, but we like to go with the lighter parts. Many people think that the radiators add a lot of drag too. But the inlet area of our scoops is slightly less than the area of the inlets on either side of the spinner that we eliminate. The scoops moved to the side of the cowling is more efficient due to being further out on the propeller blades where they blow a lot more air into them, especially on the ground. The exit area is larger than the inlet area to create low pressure that helps to pull the air through the radiators as well. The fixed cowling exit shown in the video aft of the nose gear strut has been replaced with an adjustable cowl flap that works the same as the one on a P-51 belly scoop. We hope testing will prove that this will reduce the overall drag further. We are already faster than an IO-540 and burn 30% less fuel at the same power setting, but saving more on fuel costs is always a good thing to have.

[@allendavis5302]

That depends on what you want to compare to. The LS3 as we install it puts out 375 HP at our 4500 rpm limit. So for take-off through cruise settings the fuel burns are; 4500 rpm 100% - 375 HP = 22.5 gph 3700 rpm 75% - 283 HP = 17.0 gph 3400 rpm 65% - 247 HP = 14.8 gph 3000 rpm 55% - 210 HP = 12.6 gph None of those power settings compares to the IO-540D that it replaces. A bigger engine puts out higher horsepower and consumes more fuel, even with water cooling allowing for 20 to 30% lower gph/HP. The closest that we can get to a similar power setting for the IO-540D is: 2700 rpm 100% - 260 HP = 19.9 gph compares to on the LS3 at 3500 rpm 69% - 258.6 HP = 15.5 gph, or 22% less 2340 rpm 75% - 195 HP = 14.3 gph compares to on the LS3 at 2800 rpm 69% - 194.2 HP = 11.3 gph, or 21% less All of these numbers are based on dyno data corrected for standard sea level conditions. Actual rpm and MAP settings will vary the performance and fuel flows. The physics of density altitude that effect engine performance is the same for all engines.

[@chippyjohn1]

Is that power what the propeller actually uses? 217g/kwh is very good for an old engine. that is is it is actually using the stated fuel at the stated power. I'm guessing the power stated is what it is rated to and not what the propeller consumes. It is still a 200kg engine though. And having such a wide rpm range reduces propeller efficiency.

[@stuartpsrus5413]

That is a good question that no one has asked on this platform before and worthy of a full explanation. This explanation will be for a true certification, not a temporary certification under Experimental Exhibition or Experimental Test that other people have been done recently. Yes, the LS3 could be certified, but it's not practical. It would cost 2 to 3 million and take 2 to 4 years. The certification process requires a lot of paperwork, approvals, and testing. That process will eventually destroy 4 to 6 engines to learn how long they last and how they fail under several conditions like lack of oil, low pressure, abusive uses, loss of coolant, etc. Each failure mode requires it's own engine and the results might require repeating the test with another engine. The worst part is the certification would be good for only that specific version of the LS3. As soon as GM "upgrades" anything or substitutes/replaces any part from another supplier (GM tracks this by issuing a new part number for the same engine with the different parts) the original FAA certification is voided. History has shown that GM changes the part number for the base LS3 about every 10 to 16 months, so the version of the engines you started testing with will be outdated before you finish. It is possible to get a modification to the certification by proving to the FAA that the new part(s) are equivalent or better than the old part(s) making the new part number engine compliant with the certification. Again, more money and time, the possibility of having to repeat some or all of the testing, plus a risk that it will be rejected. The only way to improve on that situation is to invest a few million more and warehouse (more money) as many of the current version of the engine as you can get in the beginning. The risk there is if testing proves that any modifications are required then all of the engines in the warehouse will also need to be modified exactly the same way. But when the supply of those engines run out you have to start over, or file for a modification to the original certification and refill the warehouse. It tends to become a bottomless rabbit hole to throw money and time into. The only way around the central issue of not being in control of the engine configuration is to manufacture the engines under license, if GM will let you do that. Either way you end up with an certified engine that costs as much or more than a Lycoming IO-540 or Continental IO-550, and that is an even tougher selling point to overcome. To me this is not a good way to promote aviation. In recent aviation history over the past 30 years there have been three companies that invested all the money and effort to certify different auto engines. All three went bankrupt in less than 7 years. This company, under two owners and two names, has survived over 22 years without certifying anything, so we don't feel any need to change that. But if you are rich and in need of a huge tax deduction call me. :) Thanks for asking.

[@stuartpsrus5413]

The main conversion for an LS3 engine to do unlimited aerobatics is changing it to a dry sump oil system with 5 pickup points. That is not required to do "Gentleman" type aerobatics without negative G's. The only issue you might have without a dry sump oil system is with a bad PCV valve allowing too much oil into the intake. Replacing the $5 PCV valve during annual inspections will prevent that from developing. The difficult part of using any diesel engine for the gearbox and the propeller is how the explosive combustion cycle pulses are dealt with. The combustion cycle pulses on a gas engine is a much slower burn. The older mechanically injected diesel combustion cycle is an instantaneous explosion. This causes the loads on the gears, bearings, shafts, propeller hub, and propeller blades to increase by 12+ times. The modern electronic diesel injection systems will pulse the fuel 10 times during each combustion cycle to dampen the power into more of a sin wave instead of one massive pulse. That helps a lot but the loads form the power pulses are still 3+ times that of a gas engine. That is a big improvement but still requires structural upgrades to everything. This is why certified aircraft diesel engines have a 500-1000 hour TBR instead of a 2000 hour TBO. The weight that you quoted for the R2.8 engine is 20-24 pounds heavier than an LS3. To that you have to add a heavier duty gearbox and propeller. I can't estimate the weight increase for the propeller, but the last time I studied this issue the gearbox would go up at least 45-50 pounds. Adding 65-74 pounds to the engine installation makes any aircraft too nose heavy.

[@benh2134]

Loved it! Starts to let me think building an rv10 could be in my budget one day. Keep the KZbin updates coming. Awesome work!

[@jimydoolittle3129]

Awesome aircraft ✈️ with impressive engine

[@stuartdavis2297]

Tett, the weight of an IO-540 installation and our LS3 installation are virtually identical. I found that the internet is full of miss-leading weight information. This is due mainly to the fact no one gives the details of what their weight includes. Is it just the engine, did they include all of the accessories, wet or dry? Because of that I now own several types and styles of scales to get my own actual weights. Both installations including everything between the firewall and propeller weighing within +/-5 lbs of each other. That includes all fluids and mounting frames for both installations. If we downsize the alternator from 150 amps to 100 amps and use a light weight high torque aftermarket starter we can get down to 5 lbs less. The need for a three bladed propeller to handle going from 260 hp to 370 hp is the only and by far the biggest weight issue. That is why you see an MT composite propeller on this RV-10.

[@taproom113]

Awesome! Would Love to hang this setup on my Maule ... :-) Thanx Stuart! ^v^

[@tetttettamilli6761]

From the Taking Off YT channel - kzbin.info/www/bejne/qKrPkIOAesard5o - Engine upgrade installer is interviewed, he gives his thoughts on new aircraft piston engines - "In order to get certification, these engines have to run 100% for 160hrs, car engines just can't do that." Any thoughts?

[@stuartdavis2297]

@@tetttettamilli6761 GM tested several LS1's during development on a dyno at 100% power for several days straight to prove the durability of their aluminum block for general marketing purposes because they knew that their Corvette market held them to high standards. NASA repeated those tests to FAR33 standards for their report on viable automotive engines for aircraft titled "NASA Personal Air Transportation Technologies" by Mark Moore in 2006 with 8 LS1 engines. That report concluded that the LS1 was the best choice because it passed the FAA requirements. All of the LS V8's since the LS1 have had several improvements incorporated into them making the LS3 the toughest of all the naturally aspirated small block variants. GM is not interested in certifying their engines because the demand does not justify the excessive expense, and they are not willing to abide by FAA restrictions on production part numbers they can use in building a certified configuration. FYI - your Lycoming won't handle 100% power for much more than 15 to 30 minutes tops in actual use. The LS V8 conversions are operated the same way, but limited to 4500 rpm producing 370 hp of the 430 hp they are capable of making at max take-off setting. That's only 86% at take-off and economy cruise is only 46%. That's why we fully expect to get 3000 hrs.

[@tetttettamilli6761]

@@stuartdavis2297 I hope I don't give the impression of being lined-up against ur engine/reduction drive; nothing could be further from the truth! It's like that Austrlian guy with that Raptor canard with that Audi V6 diesel - no one more than I wanted to see him make it work. Contineltal/Lycoming has the entire GA in a choke hold and isn't thinking about letting go. So more power to you and your reduction unit/engine.

[@stuartdavis2297]

@@tetttettamilli6761 Thank you Tett. I get all the Lycoming die hard miss quotes that you can possibly imagine. Almost all of it is based on miss information and miss placed opinion. There are a lot more failures out there than successes, so they tend to propagate and grow that trend. Then there are the Eggenfellner's that screw old customers in the name of moving on. I fear that there will be another conversion company failure soon. I hope I'm wrong, but they keep repeating the same mistakes hoping for a different result. I would rather deal with competition than some else's failures. Feel free to pass on the information on the LS1 testing and NASA report.

[@stuartpsrus5413]

Turbo normalizing to 15,000 feet is already available. With sea level engine performance and less drag cruise speed will increase dramatically. The biggest issue with turbo charging to 700 hp is the torque goes up to 1300 lb-ft. That would be like putting a PT-6 in these small air frames. That would twist them up like an empty soda can. But wait, there are weirder things than that coming by this time next year with bigger engines on bigger air frames that can handle the power.

[@stuartpsrus5413]

Martin, Thanks for your enthusiasm. If you can drop in for a visit and we will take you up for a ride that you will always remember. The side scoops are to get better airflow than what is available with the stock openings next to the spinner (closed off), especially while taxiing. We have never had an over heating problem on the ground no matter how long ground control makes you wait. The side scoops stick out far enough to allow for the boundary layer looses next to the skin. The new inlet area is roughly the same as the old inlet area. The pressure drop across the radiator core is achieved with an exit flap at the bottom of the firewall (behind the nose gear) that is at least 150% larger than the inlet area. The larger exit area also accounts for the expanded volume of air after absorbing heat from the radiators as well as creating a slight vacuum drop. After this video was made we replace the fixed exit area flap with an adjustable cowl flap to do more testing for ground versus flight cooling requirements. Our hope is to reduce drag in flight without sacrificing cooling on the ground, assuming the difference is big enough to measure.

[@ultimajp]

I have an ls1 In my rv7. Currently trying to optimize it. Thank you for the info

[@gsxr600rafii]

Could you please do some videos on that!!!!! I so want to build a velocity with an ls1. What mods have you done do the engine? We NEED information from people that have actually done this no one shows it off or talks about it.

[@stuartdavis2297]

Bob, with out a doubt there are better ways of setting up the throttle and propeller governor linkages than what the original builder installed. The 18 months since we bought the airplane has been filled with making updates like that. Thanks for the suggestion on the propeller governor linkage.

[@planker]

You got a cool looking airplane, and it sounds sweet. Perhaps some FlowMasters to make it super sweet. Nice job.

[@mackenzienowak6346]

That is so cool

[@stevenwinegar9355]

I'd really like to see you guys offer a custom cowling with a rounded nose and NACA ducts. The blocked-off cowling looks really clunky.

[@CardinalsFan11]

Add a big boy turbo and a built blick with upgraded internals to last and you got a 700 hp that will last you for a very long time, only thing that would need replacing is tranny and turbo after a while

[@gtgodbear6320]

It was a little hard to hear but the engine did sound pretty good flying by.

[@RussellTelker]

My only real concern with that setup is the ECU used. I've seen more than a few Atomic ECUs crap out real early, and most went out while driving. Hopefully you have better luck than they did.

[@kowkunt8710]

Hi can you tell me the make and model of gear box and clutch. I m wanting to put an LS3 on a pusher kit aircraft Cheers

[@BobKuykendall]

At 1:21 the way that prop governor lever extension loads the lever and input shaft in bending is downright scary. You'd be much better off using a walking beam bellcrank like Van's does for the RV-8 IO360 mixture.

[@willonthewing2860]

Fantastic! I look forward to learning more. I'm building an RV-10 and will follow your progress. Two questions I don't see addressed in your FAQ are regarding high altitude performance and engine noise. Does the standard ECU work well at high altitude, or do you reprogram it or use a special ECU? How does the high altitude performance of the LS3 engine compare to the IO-540 (normally aspirated)? Regarding engine noise, are you using a muffler with the LS3 engine? How does the LS3 engine noise compare to the IO-540? Thanks!

[@allendavis5302]

Will, sorry for the late reply. It's taken longer than normal to get back to normal after AirVenture this year. I was told that the standard requirement for the tables in many automotive ECU's was set at 5.25 Kilometers, or 17,224 ft. If they didn't cars could not get through many mountain passes with a low pressure system in place. Above that altitude the ECU we use will interpolate and continue to adjust timing an mixture based on sensor data only. The LS3 will loose power as altitude increases just like any other engine will. It will loose roughly 3.5% power for every 1,000 ft above sea level. The difference between the LS3 and the IO-540 is we start out 370 HP vs 260 HP, or 42.3% more power, and will maintain that percentage increase as altitude increases. Another way to look at it the LS3 will still be producing 260 HP at 12,085 ft, or what the IO-540 produced as sea level. At that altitude the IO-540 will produce about 182 HP. We don't normally use a muffler. We will use a cross over pipe if there is enough room for one in the cowling which increases torque and mellows out the noise a little. The noise level is considered by most people to be less than an IO-540. It certainly isn't more noise, and is different. We have not tested it with a DB meter. If we could find another RV-10 with an IO-540 to test side by side with I would rent/buy/borrow an DB meter to find out. We had one customer several years ago in California that had to meet strict noise limitations at his home airport. So he added two small Borla mufflers on his LS1. The noise reduction was well below the noise limits set for the airport without any noticeable loss in performance.

[@Mike-01234]

I would like to see some of the new modern turbocharged V6 engines that are in production in aircraft makes sense to use the turbo charging already engineered by auto manufactures. LS3 is a great engine and it could be turbocharged but the don't need the 2 extra cylinders more then enough power with a V6. The big benefit of the LS3 is the aftermarket support lots of it and parts are low cost. GM current turbo engine is the 2.7L V6 L3B puts out 310 HP. The direct injection issues can be mitigated by just dumping the crank case fumes to outside instead of sucking it back into the intake. I also see the issue of sourcing these engines auto manufactures probably don't want anything to do with supplying new crate engines for aviation I could see why the LS series is easy to get.

[@Jonathan-xv5zi]

I had the same idea with a Audi 3l v6tdi engine for maximum efficiency

[@Mike-01234]

@@Jonathan-xv5zi The only issue is the cost American made, or Japanese made is cheaper for us. Not sure if would need a gear reduction for the Audi TDI need a thrust bearing to handle the load of the prop. That Audi engine makes over 330 lbs of torque at 1400 RPM.

[@TheAvaiator23]

What’s the fuel burn per hour

[@tinolino58]

Cooling inlets with higher velocity for better cooling? Please! Lower velocity provides higher pressure at the grill and therefore more flow and more cooling. Yes, I like your airplane very much! Enjoy many many flights with it!!

[@tetttettamilli6761]

With the additional weight of coolant and the reduction drive, I don't expect that engine to be pound-for-pound a comparison to the 540 series of engines. With that said, what's the comparitive weights of the two? And what's the benefit of having a clutch between the prop and gearbox - vibration/harmonics? How much less payload can that airplane now handle with the additional weight of that engine? Were any "hardened" engine parts used?

[@devonlove9095]

My God what a buzz killer.

[@kalancosta7650]

Idk about this specific setup but you can build 4 cylinder Subaru engines upwards of 600hp and they way 300ish which is much lighter than an o-550 just saying and it would be FAR cheaper as aircraft engines are way overpriced

[@RussellTelker]

@@kalancosta7650 as someone who has built a couple 600+hp Subarus... There is NO WAY IN HELL I would run one in an airplane! WAY too unreliable/temperamental. Hell, at 400hp they're sketchy.

[@kalancosta7650]

@@RussellTelker idk man if you build the short block to withstand 800+ then back it off to run at 350hp ish shed prolly last all day

[@kalancosta7650]

And it prolly still come out cheaper than a lycoming or continental

[@highpocket888]

That is awesome!!, if all goes well I want to order my Vans kit within 2 years . Is there a model you recommend for a 6'4" person?

[@stuartdavis2297]

Wow! I thought I was at a disadvantage at 6'1". Back in the 70's everything was plans built from scratch and all plans were designed around the FAA standard 170 lb male, which was 5'6". But you could modify the plans and parts to fit your body, and you can still do that with plans built aircraft today. With modern kit built aircraft you have to consult with the kit manufacturer to learn what you can do to safely modify their preformed parts, or how to build replacement parts to make the cabin bigger. I can get in and out of an RV-10 with only minor contortions. My best advice is to ask someone with an aircraft you are interested in if they would let you try it on for size. Other aircraft with large cabins and doors are the BearHawk5 and the Murphy Moose which is coming back. Both companies will be at AirVenture as well as Vans with all their models. We have also done a BearHawk4 which is very similar to the 5 forward of the firewall, and we are currently working on a Murphy Moose. Some kit manufacturers in the past have advertised the height range that their seats/cabins will accommodate. If they don't advertise it they do know what size person their design was built around. So ask them, and ask if it's possible to modify it to fit you.

[@highpocket888]

@@stuartdavis2297 I really appreciate the detailed response to my question. I'm definitely a fan of this channel, keep up the great work!

[@PatrickJWenzel]

6’4” here. Can confirm, RV7 and 9 will fit comfortably sitting on just the foam wedges beneath the cushions (removed). It’ll be tight around the shoulders with a similar sized person next to you. Spent about 30 hours travelling across Australia in a 9 like this. I’ve only sat in a 14 however it’s much roomier across the shoulders. This would be the kit I’d look at in your case. I’ve also sat in a 10 and while it looks very roomy I’m actually limited by head height. So Torso length is a consideration, as well as seat design - given that they are stand-alone units rather than cushions placed on top of aluminium sheeting fuselage structure, as is the case with the 7/9/14. And then there’s the much anticipated 15. That may be worth waiting for if you don’t need to buy a kit asap.

[@highpocket888]

@@PatrickJWenzel Thanks Patrick, I really appreciate the info. Have a great day my friend! Abe here BTW.

[@timduncan8450]

Awesome where canI learn more. What were your speeds, climbing and level, temps, etc?

[@stuartdavis2297]

Hi Tim. You can learn more on my website www.autopsrus.com. With the right propeller we can cruise at Vne. The current MT propeller is too small for this engine making the max speed 195 knots. We just started testing with this new LS3 engine. So far the best climb has been 1750 fpm with 80% cruise at 180 knots using the smaller propeller. Engine coolant temps are 170 to 190F, oil temps close at 175 to 195F, and gearbox oil at 180 to 190F.

[@timduncan8450]

@@stuartdavis2297 Thx Stuart

[@RussellTelker]

@@stuartdavis2297 Vne on the RV10 is 211mph, or 183 knots... Or is it different than what they list on their website as "max speed"?

[@timduncan8450]

@@stuartdavis2297 we’re almost a year in. Have you found the right prop? What are the speeds and fuel burn now?

[@stuartpsrus5413]

You are like a lot of interested watchers that have all sorts of ideas on how we should spend a lot of money. But we need to be a lot more practical than artsy. NACA ducts are internal structures and ducts that size will not fit inside the cowling. Each radiator is 15x18 for 270 in2 of area and are within 1.0" average of the inner cowling. That space is required for the silicon rubber baffling between the radiators and the cowling to eliminate cooling air from being lost around the radiator. There is no room to move the radiators further inboard for NACA scoops large enough to supply the same air volume as our scoops, especially during slow ground operations on a hot day. Your comment about the clunky appearance of the front corners does have good merit. We have had discussions with James Aircraft (close to us by Texas standards) to develop at least the lower cowling for us to replace the two scoops and center tunnel that we currently give customers to modify the Vans cowling that they get in their kit. If that plan were expanded to include the upper cowling as a set then modifying those corners could make the RV-10 look at least 10 knots faster without much extra effort. The big questions is always how much more would customers be willing to pay for a custom cowling than what Vans charges for the standard cowling. With that subject opened up, would anyone like to comment on how much more they would pay for a ready made cowling versus doing their own fiberglass work to modify a Vans cowling?

[@Blackcloud_Garage]

Can it go inverted (ie loops and rolls)?

[@stuartpsrus5413]

Loops and rolls with an LS3 are the same as with an IO-540. As long as you don't sustain negative G's for more than a few seconds the oil pressure will recover before any damage is done. If the loops and rolls are done right that won't happen. Any amount of positive G's will keep the oil flowing to the oil pickup in the oil pan. We have done one installation with full inverted oil systems on the LS3 and gearbox. It fills the cowling with a lot of oil hoses but works very well. To be honest, only the one customer has ever liked to hang upside down at more than 1G for any length of time.

[@Blackcloud_Garage]

@@stuartpsrus5413 Thanks for the information. I was thinking of using a dry sump system so the oil would be under pressure at all times. How adaptable are your products to other auto engines? I am researching the Cummins R2.8 diesel (only weighs 503lbs).

[@salimnasir5231]

Does it possible to get FAA certificate ?

[@Seadoo233]

This is an experimental aircraft, approved to fly

[@TrollFalcon]

For 60 more pounds, why not go with a far better OM606

[@bennyhill5938]

why dont all airplanes use these engines if theyre so efficient and cheap to replace after time to overhaul?

[@TheBrennan90]

Because the airplanes that are built at factorys are certified by the faa and must have every single part tested extensively and certified. It's an expensive process and only a few companies can fund it. There are other car engine manufacturers for experimental aircraft like viking motors (using a honda 4 cylinder. That company had some weird news comeout years ago) And some others I forget.

[@jonasbaine3538]

Also with these auto conversions I suspect any issue away from home airport will be interesting finding a mechanic to work on an untraditional powertrain setup, plus they are usually already very busy working on normal setups. Like that centrifugal clutch setup, what mechanic will be familiar to fix that if you are stuck hundreds of miles away on cross country. Just my thoughts. Really cool though.

[@hordi1ful]

Because of... most of pilots are smart enough to use the proven equipment )))

[@OleDiaBole]

​@@hordi1ful because most pilots are forced to endure Lyco/Conty monopoly, and their ABSURD prices.

[@mrphyslaw]

I don’t see them being that much cheaper. The setup for a ls3 and gearbox fwf from them is $44k. What’s a comparable lyn/conti considering it’s simpler and easier to run? The benefit isn’t likely big enough for many(most) to go out and do all the re-engineering required.

[@forestgimblett2364]

Like it but you need way more prop. Should be running,cruse ing 2700--3200 rpm.

[@PDZ1122]

Why? Slow running props are way more efficient.

[@dennisowen3717]

This is awesome. What's the weight on that LS-3. What kind of G-figures will it tolerate. Is there a kit for the new RV-15 coming out.

[@SEALwannabe100]

@VansAircraftBuilders.com. Are you still building the 12?