Chevy LS conversion.. what are your thoughts?

[rv6ejguy]

Guys, he talking about a Rocket, not a -10.

Insurance could be a problem, resale will probably be lower. It will be a ton of work.

A lot of you skeptics ought to subscribe to Contact! magazine. There are several fairly high time (over 500 hours) V8 conversions like Bud Warren's, Robinson's and Gary Spencer's flying very successfully and with awesome performance.

From actual users, fuel burn for most missions is comparable or better than Lycoming, Continental or Franklin engines in the same airframe.

For the cooling drag thing, I only stated that if you do it right, drag can be comparable and perhaps better than on an air cooled installation. As mentioned previously in other threads, historical comparison of several different WW2 airframes with both air and water cooled engines, unquestionably showed the liquid cooled installations as being noticeably faster. I'd be happy to advise people on possible rad layouts.

The Ag and tow users in Oz told me they were sick of the cost and reliability problems with their Lycomings in these applications, just last week having an IO-540 completely fail after swallowing a mag drive and lunching the the cam and case. They were replacing jugs every few hundred hours. The LS engine now has 200 hours on it on their PA25 and so far only a cracked exhaust pipe which was fixed for $150. Smoother, quieter, better climb performance and 3 more tows per hour due to no shock cooling concerns on the rapid descent after release. They are planning to remove the IO-540s and convert 23 more PA25s to LS power.

This stuff is starting to come of age as information is shared. You will only see more and more RVs fitted with auto conversions in the future as historic problem areas are understood and addressed.

I don't think Van's or Lycoming cares about different engine designs for homebuilders. They are selling lots of product already. Van's is in the airframe business primarily and have always adopted a wait and see attitude on other engines. It will be a long time before they endorse new engines. They have no particular reason to use anything else at this time. Since the Rocket is not Van's, no need to worry about that one.

By all means weigh advantages and disadvantages before deciding but do that with current information. Just be aware that this is a LOT of work.

[gmcjetpilot]

Originally Posted by rv6ejguy

A lot of you skeptics ought to subscribe to Contact! magazine. There are several fairly high time (over 500 hours) V8 conversions like Bud Warren's, Robinson's and Gary Spencer's flying very successfully and with awesome performance.

Have any LS V8's competed in Airventure or Sun-N-Fun or other races (Reno)? I know there's the Lancair IV flying around with a V8.

From actual users, fuel burn for most missions is comparable or better than Lycoming, Continental or Franklin engines in the same airframe.

I don't doubt you Ross, but I would just like to see some data. When ever a Rotary or Subaru are objectively test flown, fuel burn is usually not better when performance is comparable to a Lyc, and when fuel burn is OK performance is off.

For the cooling drag thing, I only stated that if you do it right, drag can be comparable and perhaps better than on an air cooled installation. As mentioned previously in other threads, historical comparison of several different WW2 airframes with both air and water cooled engines, unquestionably showed the liquid cooled installations as being noticeably faster. I'd be happy to advise people on possible rad layouts.

I'M LOOKING FORWARD to seeing RV-10's and others using aluminum Chevy V8's fly. Besides cooling drag, weight & CG and hydraulic prop compatibility are also challenges. The fastest WWII planes and ones winning at Reno are air cooled radials. I know the P-51 are fast, but the Jug P-47 Thunderbolt could take more abuse, again big air cooled radial. For water cooling, the airframe design almost has to be made around cooling (radiators).

The Ag and tow users in Oz told me they were sick of the cost and reliability problems with their Lycomings in these applications, just last week having an IO-540 completely fail after swallowing a mag drive and lunching the the cam and case. They were replacing jugs every few hundred hours. The LS engine now has 200 hours on it on their PA25 and so far only a cracked exhaust pipe which was fixed for $150. Smoother, quieter, better climb performance and 3 more tows per hour due to no shock cooling concerns on the rapid descent after release. They are planning to remove the IO-540s and convert 23 more PA25s to LS power.

How come a debate on the merit of water cooled auto engine conversions comes down to bashing Lycomings? If auto engines in planes are to be great, the argument for them will be made in the future by races won and records set. I wish this glider-port much luck with their PA-25 Pawnee's. Sounds like some cheap IO-540's for sale? Frankly I think Lycoming's ROCK! Yippee!! Seriously, tow/jump plane horror stories are a valid argument for water cooling, where speed is not a key requirement and shock cooling is. I can tell you tow and jump planes are maintained cheaply with welded cylinders. Cylinder cracks are not normal or expected.

This stuff is starting to come of age as information is shared. You will only see more and more RVs fitted with auto conversions in the future as historic problem areas are understood and addressed.

I think every one is looking forward to that, and folks like Ross are in the lead in this area.

I don't think Van's or Lycoming cares about different engine designs for homebuilders. They are selling lots of product already. Van's is in the airframe business primarily and have always adopted a wait and see attitude on other engines. It will be a long time before they endorse new engines. They have no particular reason to use anything else at this time. Since the Rocket is not Van's, no need to worry about that one.

Van the man has written about this many times and you are correct Ross. He adapted the Rotax for the RV-12 and looked at Franklin's and Continentals as well, so he is willing to stray from the boring Lycoming. However the "Flying Dutchman" is a very smart guy, super pragmatic and frugal. He thinks, at this time, auto engines don't offer a big shift in performance, value or reliability, plus weight has always been a challenge. A O-360 new from Mattituck for example, is a bolt in deal, which will give 2000 hours plus of reliable flying over +12 years (iif you don't tow 50 sailplanes a day with your RV). A brand new O-360 is $21,500 (no reduction drive or radiators needed) and an IO-540 brand new $38,500.

The idea of a big, smooth, powerful LS6 (5.7l, 350 cid) V8 crate engine that can make 400 hp at 6,000rpm (max torque 5,000rpm, red-line 6,500rpm) and can be had for $6,300, at one of 7,000 Chevy dealers, is a turn on. It all sounds good, but you'll still need a reduction drive and FI controller and all the custom things to make it work in your plane. Of course you can't expect 400 HP at the prop; running it at 100% or near red line all the time would not be reliable. I think a LS6 could be a reliable 260HP engine. A cheaper solution would be an aluminum 350hp LS1 with a carb. A long block LS1 is on sale for $3,000! I wish I still had my '67 Camaro to drop one into. Keep in mind the out of crate weight for a LS1 is 390lbs! (LS6 weight?) Now add all the accessories, hoses, fluids, reduction drive and so on. It's going to weigh a lot. That is not a trivial or an unimportant consideration. An IO-540 is about 400lbs total, but does not need a reduction drive or radiator'(s) and so on. Hard to compare but there is no doubt the auto engine will weigh a bunch more. Typically when replacing a smaller 4 cyl Lycoming 360's with an auto engine (Rotary/Subaru), the empty weight of the plane is up 100 lbs or more, typically (not always but on average). I suspect with the bigger engine the empty weigh may be 150-200 lbs or more than a IO-540 plane. I'm gussing, but I'd bet you it will be significantly more. Some of the re-drives to handle 400 HP look BIG-N-Heavy. For any disadvantage of air cooling, light weight, system simplicity and efficient cooling with air and simple cowl baffling is an advantage. Not with standing the tow planes cracked cylinder and mag drive example, Lycs are very reliable and cost effective, even when compared to a $6,300 auto engine. There are RV's with 4.3L Chevy V6's and belt drives (Belted Air Power), which do all right, but light weight and low drag is not their thing (yet?). I like their simple belt drive, carb and simple dual points ignition. Here is an interesting article and he touches on why he did not go with a V8: http://www.beltedair.com/KitPlanes.htm (note he mentions the cost of a new Lyc 360 as $27,000 dollars! Pretty cool the price is now about $5,000 less. What is getting cheaper now a days? Lycoming/clones)

By all means weigh advantages and disadvantages before deciding but do that with current information. Just be aware that this is a LOT of work.

Spoken like a man who has done a lot of (great) work. Hats off to ya Ross. Show all us Lyc-O boys what it's about. I am looking forward to your next engineering marvel. That RV-10 is looking awesome and the engine mount is nice.

[Kevin Horton]

Originally Posted by pierre smith

I'd be more concerned with the airplane shedding its rudder or elevators. This was seen to happen to a -4 in Australia. Flutter is usually disastrous so be prepared to spend more money yet on Aero engineers to calculate and design into your airplane what it would take to raise the redline to 300 MPH or more.

I had never heard of an RV flutter accident before this. There ought to be an accident report, but Google doesn't find anything. I'd appreciate any info on this RV-4 event. Did this really happen, or is it just an unsubstantiated rumour?

[TSwezey]

Originally Posted by Kevin Horton

I had never heard of an RV flutter accident before this. There ought to be an accident report, but Google doesn't find anything. I'd appreciate any info on this RV-4 event. Did this really happen, or is it just an unsubstantiated rumour?

There are several people who have gone to the flutter zone but realized they were going to fast and slowed down. The airframe can handle some flutter but if you push it too hard for too long it will come apart just like the recent prototype jet plane that killed both the pilots. I believe there are several posts on this site about flutter.

[pierre smith]

Originally Posted by Kevin Horton

I had never heard of an RV flutter accident before this. There ought to be an accident report, but Google doesn't find anything. I'd appreciate any info on this RV-4 event. Did this really happen, or is it just an unsubstantiated rumour?

Kevin,
It happened in Australia a few months ago. Two guys left for the aerobatic area, way over gross and also a very far aft CG, out of the aft limits.. Seems they fell out of a maneuver and were heading nearly straight down at a very high speed. Witnesses were reported to have seen pieces coming off the airplane before impact. Hopefully some of the Oz guys can elaborate. I did find the Australian equivalent of our NTSB and the accident was/is listed there.

Pierre

[Kevin Horton]

Originally Posted by TSwezey

There are several people who have gone to the flutter zone but realized they were going to fast and slowed down. The airframe can handle some flutter but if you push it too hard for too long it will come apart just like the recent prototype jet plane that killed both the pilots. I believe there are several posts on this site about flutter.

Flutter usually builds so quickly that it leads to an in-flight breakup. I'm not completely convinced that the event that Smokey Ray reported was flutter. It was limited in amplitude, whereas flutter normally increases in amplitude very quickly. It sounded more like a trim tab buzz to me, caused by excessive play. While this could possibly lead to flutter, if the speed went higher, the fact that he is alive to talk about it suggests it probably wasn't flutter.

[Kevin Horton]

Originally Posted by pierre smith

Kevin,
It happened in Australia a few months ago. Two guys left for the aerobatic area, way over gross and also a very far aft CG, out of the aft limits.. Seems they fell out of a maneuver and were heading nearly straight down at a very high speed. Witnesses were reported to have seen pieces coming off the airplane before impact. Hopefully some of the Oz guys can elaborate. I did find the Australian equivalent of our NTSB and the accident was/is listed there.

Thanks for the pointer Pierre. I found the preliminary report from the ATSB. Aircraft descending vertically at high speed. Pieces observed to come off the aircraft. Several tail surfaces found away from the main impact site. This certainly seems to be flutter. It would be interesting to know how fast they were going, but I don't think there is any way to figure that out.

[pierre smith]

A friend and acquaintance who was very active in the PRPA (Professional race pilot's assoc) in the late sixties/early seventies named Nick Jones designed his own thinner wooden wing for his Cassutt F-1 racer. A new airplane has to demonstrate 6 G's on a recording g-meter and dive to 10% over max straight and level flight, plus demonstrate a roll in both directions. During his dive, the too-limber ailerons fluttered and the wing instantly disintegrated and pieces of mahogany skin left the airplane. Nick managed to bodily break through the gyrating Cassutt canopy, with speed near 300 mph, pulling his ripcord and getting a full canopy at about the height of the powerlines . Aside from a hernia from opening shock, he was dragged a long way by the Texas desert wind before he collapsed the 'chute.

This was a first person account by Nick to some of us at Reno one year. I had a Cassutt then and was around many aero-type engineers with a lot of discussion about redlines/prop limitations/resonant modes/nodes and such.

This is why I perk up when I read posts like "going 275-300mph" and so on. Leland Snow had one of his earlier S-2 Snow ag airplanes develop aileron flutter during a high speed ( around 150mph) pass on arrival at an airshow in Texas. He told me that he hadn't had time to balance the ailerons yet and the paint was barely dry for the show. He pulled up hard, managing to stop the flutter and land the airplane. The aileron cables had stretched during the flutter and the ailerons were now sagging a couple of inches

Yes, flutter is real and my suggestion is to believe The Dutchman's airspeed limitations.

'Scuze the long-winded discourse,
Pierre

[TSwezey]

Originally Posted by Kevin Horton

Flutter usually builds so quickly that it leads to an in-flight breakup. I'm not completely convinced that the event that Smokey Ray reported was flutter. It was limited in amplitude, whereas flutter normally increases in amplitude very quickly. It sounded more like a trim tab buzz to me, caused by excessive play. While this could possibly lead to flutter, if the speed went higher, the fact that he is alive to talk about it suggests it probably wasn't flutter.

The speed of flutter development and destruction is related to the speed and strength of the plane. RV's are not traveling at 400 mph so the flutter might not be as violent and destructive as a plane going that fast.

[rv6ejguy]

Originally Posted by gmcjetpilot

Have any LS V8's competed in Airventure or Sun-N-Fun or other races (Reno)? I know there's the Lancair IV flying around with a V8.
I don't doubt you Ross, but I would just like to see some data. When ever a Rotary or Subaru are objectively test flown, fuel burn is usually not better when performance is comparable to a Lyc, and when fuel burn is OK performance is off.I'M LOOKING FORWARD to seeing RV-10's and others using aluminum Chevy V8's fly. Besides cooling drag, weight & CG and hydraulic prop compatibility are also challenges. The fastest WWII planes and ones winning at Reno are air cooled radials. I know the P-51 are fast, but the Jug P-47 Thunderbolt could take more abuse, again big air cooled radial. For water cooling, the airframe design almost has to be made around cooling (radiators). How come a debate on the merit of water cooled auto engine conversions comes down to bashing Lycomings? If auto engines in planes are to be great, the argument for them will be made in the future by races won and records set. I wish this glider-port much luck with their PA-25 Pawnee's. Sounds like some cheap IO-540's for sale? Frankly I think Lycoming's ROCK! Yippee!! Seriously, tow/jump plane horror stories are a valid argument for water cooling, where speed is not a key requirement and shock cooling is. I can tell you tow and jump planes are maintained cheaply with welded cylinders. Cylinder cracks are not normal or expected. I think every one is looking forward to that, and folks like Ross are in the lead in this area.Van the man has written about this many times and you are correct Ross. He adapted the Rotax for the RV-12 and looked at Franklin's and Continentals as well, so he is willing to stray from the boring Lycoming. However the "Flying Dutchman" is a very smart guy, super pragmatic and frugal. He thinks, at this time, auto engines don't offer a big shift in performance, value or reliability, plus weight has always been a challenge. A O-360 new from Mattituck for example, is a bolt in deal, which will give 2000 hours plus of reliable flying over +12 years (iif you don't tow 50 sailplanes a day with your RV). A brand new O-360 is $21,500 (no reduction drive or radiators needed) and an IO-540 brand new $38,500.

The idea of a big, smooth, powerful LS6 (5.7l, 350 cid) V8 crate engine that can make 400 hp at 6,000rpm (max torque 5,000rpm, red-line 6,500rpm) and can be had for $6,300, at one of 7,000 Chevy dealers, is a turn on. It all sounds good, but you'll still need a reduction drive and FI controller and all the custom things to make it work in your plane. Of course you can't expect 400 HP at the prop; running it at 100% or near red line all the time would not be reliable. I think a LS6 could be a reliable 260HP engine. A cheaper solution would be an aluminum 350hp LS1 with a carb. A long block LS1 is on sale for $3,000! I wish I still had my '67 Camaro to drop one into. Keep in mind the out of crate weight for a LS1 is 390lbs! (LS6 weight?) Now add all the accessories, hoses, fluids, reduction drive and so on. It's going to weigh a lot. That is not a trivial or an unimportant consideration. An IO-540 is about 400lbs total, but does not need a reduction drive or radiator'(s) and so on. Hard to compare but there is no doubt the auto engine will weigh a bunch more. Typically when replacing a smaller 4 cyl Lycoming 360's with an auto engine (Rotary/Subaru), the empty weight of the plane is up 100 lbs or more, typically (not always but on average). I suspect with the bigger engine the empty weigh may be 150-200 lbs or more than a IO-540 plane. I'm gussing, but I'd bet you it will be significantly more. Some of the re-drives to handle 400 HP look BIG-N-Heavy. For any disadvantage of air cooling, light weight, system simplicity and efficient cooling with air and simple cowl baffling is an advantage. Not with standing the tow planes cracked cylinder and mag drive example, Lycs are very reliable and cost effective, even when compared to a $6,300 auto engine. There are RV's with 4.3L Chevy V6's and belt drives (Belted Air Power), which do all right, but light weight and low drag is not their thing (yet?). I like their simple belt drive, carb and simple dual points ignition. Here is an interesting article and he touches on why he did not go with a V8: http://www.beltedair.com/KitPlanes.htm (note he mentions the cost of a new Lyc 360 as $27,000 dollars! Pretty cool the price is now about $5,000 less. What is getting cheaper now a days? Lycoming/clones)Spoken like a man who has done a lot of (great) work. Hats off to ya Ross. Show all us Lyc-O boys what it's about. I am looking forward to your next engineering marvel. That RV-10 is looking awesome and the engine mount is nice.

Gary Spencer's Ford powered LongEze has entered and won numerous cross country races. Here is one link: http://www.ez.org/Flyer/0700_03.htm I see some later race speeds in excess of 242mph. Not too shabby for a direct drive auto engine.

Bud Warren's Wheeler Express (SBC) (700+ hours) uses a Hartzell C/S and his drives are capable any using any hydraulic prop. I think the new Variprop will be seen on many more auto conversions because no governor is required on the drive.

I think P51s have won more unlimited races at Reno than any other type. Correct me if I'm wrong someone. Dago Red holds the race lap record at 512 mph set in 2003. The Thunder Mustang holds the absolute piston speed record for naturally aspirated aircraft and the fastest race and qualifying lap in the Sport Class.

I'd dispute that most of the fastest WW2 aircraft were air cooled. While the fastest was the XP47 mainly because it had excellent turbocharging and intercooler technology and 3000hp, the fastest operational aircraft were all liquid cooled.

Your arguments don't hold any water...pun intended.

Not bashing Lycomings, just relaying the experiences of the tow plane guys in Oz and rebuttling the comment made by someone that people were removing auto engines to replace them with aircraft engines. It amazes me that many people think that Lycomings never fail and never need work. The reality is that many do. I know dozens of people who replace jugs, pistons, valves etc. on their engines well before TBO. This is pretty common and one of the reasons people consider alternatives. Cylinder, case cracks are a common occurrence on the higher hp turbo Conti and Lyco engines. Installing the LS engines in the PA25s are as a result of the straight economics of it for this abusive application. A whole engine is the price of 2 jugs for an IO.

It is harder to compete with the weight of the 4 cylinder Lycomings but as the engines become more powerful, the weight gap closes. Bud's 383 weighs 454 lbs. with all accessories except rad and prop. This was lighter than the less powerful twin turbo IO-540 setup normally fitted. The normally aspirated V8s will often be replacing 300-350hp turbocharged IO-540 and IO-550s which are much heavier. Compared to an atmo IO-540, even the LS engines are going to be heavier- no dispute there.

You will not get the rated power from a typical crate motor unless you are willing to spin it up to 6000rpm so people can forget the 400 hp part. I feel the stock LS6 is a solid 300-325hp engine for aircraft use at a reasonable rpm. Warren's drive weighs 63 lbs. EPIs are 10-20 lbs. more depending on model.

Complex cooling systems? No. A look at Warren's simple single rad setup makes this part even less complicated than the typical Lycoming.

The liquid cooled world is changing fast with some smart people applying their talents and proving them by accumulating lots of flight hours now. In many cases, they are making products available for other users. More and more people are choosing auto conversions than ever before- they can't all be dumb.