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09-07-2010, 01:13 PM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Jeff, you will get the usual answers from the Lyco crowd here and the usual hostility for wanting to experiment. Few people here on VAF are true experimenters and have little or no first hand experience in this field.
Most people here don't understand car engines and in fact apply little logic or evidence when they attack them in aircraft.
As a moderator, I'm not going to let this thread degenerate into the usual attack. Jeff has asked some legit questions here so let's be civil.
I'll state this first off- If you just want to go flying with the least likelihood of problems and extra time spent and if resale value is high on your list of important things, install a Lyco and forget the alternative engine. If you want to experiment and have the background in engines, tuning, structures, fabricating and welding and a few hundred spare hours and plenty of patience to devote to a project like this, then this MAY be for you. For most people, alternative engines are not the right choice. You must realistically evaluate what you want from your project.
The VR6 engine is probably not as well suited as some other sixes having aluminum blocks like the Subaru, Suzuki and Honda which have many thousands of flight hours on them plus a wide variety of available gearboxes. These are all much lighter and in most cases more powerful at lower revs.
The modern auto engines are much more extensively tested and validated than traditional aircraft engines as the standards are much higher before acceptance into production. This includes running at full rated power for many hundreds of hours so we don't worry too much about core engine reliability if the engine is essentially stock- with certain things understood at least.
If you are building a 7, 8 or 9, all auto V6s will be heavier than a standard Lyco so be prepared for that. A four may be more suitable weight wise. For a -10 you would want to use one of the larger V6s- at least 3.2 liters. Weight is more competitive with the 540 Lyco and several modern designs are over 300hp stock at reasonable rpms.
Be aware that there are many challenges to installing an auto engine from engine mounts, exhaust, reduction gear, propeller, fuel and spark control, fuel system design, electrical system, oiling and cooling.
It is a real challenge to get everything right but that is how we learn. Just be very aware of the realities before going forward with this project and do plenty of ground testing first.
Last edited by rv6ejguy : 09-07-2010 at 01:35 PM.
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09-07-2010, 01:31 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by rv6ejguy
As a moderator, I'm not going to let this thread degenerate into the usual attack. Jeff has asked some legit questions here so let's be civil.
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Got your back, Ross.
Quote:
Originally Posted by rv6ejguy
I'll state this first off- If you just want to go flying with the least likelihood of problems and extra time spent and if resale value is high on your list of important things, install a Lyco and forget the alternative engine. If you want to experiment and have the background in engines, tuning, structures, fabricating and welding and a few hundred spare hours and plenty of patience to devote to a project like this, then this MAY be for you. For most people, alternative engines are not the right choice. You must realistically evaluate what you want from your project.
If you are building a 7, 8 or 9, all auto V6s will be heavier than a standard Lyco so be prepared for that. A four may be more suitable weight wise. For a -10 you would want to use one of the larger V6s- at least 3.2 liters. Weight is more competitive with the 540 Lyco and several modern designs are over 300hp stock at reasonable rpms.
Be aware that there are many challenges to installing an auto engine from engine mounts, exhaust, reduction gear, propeller, fuel and spark control, fuel system design, electrical system, oiling and cooling.
It is a real challenge to get everything right but that is how we learn. Just be very aware of the realities before going forward with this project and do plenty of ground testing first.
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Good advice. Good honest advice.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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09-07-2010, 01:48 PM
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Join Date: Jan 2005
Location: SoCal
Posts: 2,061
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I hope my comment that cars and planes have different power requirements was not perceived as an uncivil attack, as that was not my intention. At the risk of painting with a broad brush, I think its fair to assume that many alt. engine inquiries are driven by major sticker shock at the $25000 price tag on what appears to be an overgrown Beetle motor. I hope we can agree that a car motor will not save you money, especially if you factor in resale. I felt sick writing that check to Superior, but got it all back when I sold the plane. I look at it now as simply a place to park some money and won't cry as much when I do it again.
Now, if the desire to go alt. is driven by recreation, education, research, wanting to be different, etc., then I'd have to say go for it. Modern auto engines are soooo good compared to the crud we drove when I was a teen, it's real hard not to want one in a plane.
__________________
Steve Zicree
Fullerton, Ca. w/beautiful 2.5 year old son 
RV-4 99% built  and sold 
Rag and tube project well under way
paid =VAF= dues through June 2013
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09-07-2010, 02:28 PM
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Join Date: Dec 2007
Location: Conyers GA
Posts: 347
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Be aware that there are many challenges to installing an auto engine from engine mounts, exhaust, reduction gear, propeller, fuel and spark control, fuel system design, electrical system, oiling and cooling.
It is a real challenge to get everything right but that is how we learn. Just be very aware of the realities before going forward with this project and do plenty of ground testing first.[/quote]
I too have flown behind an alternative engine, and I too would like for us to have choices besides the Lycosauras, but as Ross pointed out there are a lot of things to engineer for an auto engine to perform well in an aircraft and in my mind the problem becomes one where we cannot test some of these things without flying the plane. If our initial engineering was not on the mark, we are faced with dead sticking it back to the airport, if we can reach one.
I have lost several friends and known of more folks that were sure that their designs were going to pass muster and went off flying only to have one of the periphal items fail and the motor quit.
What is needed is a good safe way to test our creations before flying. Lots of aircraft and lives could be saved if we could test completely on the ground before committing to flight.
I am afraid that some folks are motivated by $$ only to later realize that the savings potential was a myth. They then are left with the motivation being educational. Without a good safe way to test over a long period of time, some have paid the ultimate price for that education.
Gary Specketer
Tech Counselor, Flight Advisor
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09-07-2010, 03:20 PM
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Join Date: Apr 2005
Location: KSLC
Posts: 4,021
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Quote:
Originally Posted by jcaplins
The gear reduction unit would be the only thing left for new design/testing/research/etc. for auto conversions.
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Do a lot of reading, and you'll find that "cooling" is also very high on the list of problem solving. Much of the time, it's required quite an aray of cowl modifications for both the inlets, and outlets.
L.Adamson --- RV6A
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09-07-2010, 03:42 PM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Gary is quite right. Saving some $$ initially should not be the the only reason for installing an alternative engine. In many cases, people have found that they spend more by the time they are done and they still may not be happy with the results. Many end up replacing their auto engines with Lycomings after a few years of frustrations.
As I said, for most, writing that killer check for a Lycoming or clone is the best choice.
Regimented flight testing in the safest environment (over the airport, with a long runway and no ground obstructions) is something you should spend a lot of time at. At least the RV airframes are well proven so you are mainly testing the powerplant system. Combining a new engine and new airplane design would have to be approached even more carefully. Using an alternative engine statistically increases your chances of of forced landing.
As far as cooling issues goes, most of these can be traced to poorly thought out cheek mounted installations. Under pan and belly mounted radiators with proper ducting more often than not work well but this is even more work of course- usually in the plumbing and fiberglass departments. Some RVs do not lend themselves to easy belly rad installations.
In short, the whole concept of auto engines in airplanes is not as simple as it might seem at first look. If it was, many more airplanes might have something different under the cowling.
All this is not to discourage you but rather to give you some insight as to the possible pitfalls of rolling your own FF installation.
Last edited by rv6ejguy : 09-07-2010 at 03:47 PM.
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09-07-2010, 03:44 PM
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Join Date: Oct 2005
Location: Savannah, GA
Posts: 1,849
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There is nothing sweeter then a Chevy LS2 engine purring in a RV-10. When I build again it will be another Chevy powered RV-10. No doubt about it.
__________________
Todd
N110TD
RV-10 Vesta V8 LS2/BMA EFIS/One formerly flying at 3J1 Hobbs stopped at 150 hours
Savannah, GA and Ridgeland, SC
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09-07-2010, 06:25 PM
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Join Date: Mar 2010
Location: Scappoose
Posts: 119
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Quote:
Originally Posted by jcaplins
Can you be more specific, Richard? And what do you mean by high strung?
I don't want this to be a "if you want to fly, get a lycombing..."
It seems all engines will have cooling issues to work out and anything other than an O-3xx will need cowling mods.
The Rotax engine is liquid cooled, requires a gear reduction unit, and has 2 carbs that need to be balanced, and people seem to love them. How is any auto conversion different?
(I should also note that I'm years away from finishing and my VW has over 100K on it, so I won't be using this engine anyway (maybe  ). Just thinking out loud here.)
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When I say high strung, they seem to be more of a high performance engine that requires extra special care and feeding. The cam chain guides are prone to failure when run hard or run hot, and in an aircraft, it is very likely they will get hot, and they will definitely be run hard.
The ones that I have seen (Granted only a couple) have needed more frequent oil changes than most other cars would need and this was not the driver's fault. The drivers for the ones that I saw were fairly mild. I don't think frequent oil changes in an auto are going to translate into acceptable oil change intervals in an airplane.
One of the engines I took apart had literally 1/4 inch of sludge on the topside of the valve train. This was not even after extreme use. The oil changes were drawn out a little longer than they should have been, but the car was used primarily for long distance commuting.
I am by no means trying to say that Lycomings are the only thing that should be in a plane. I am all for getting some modern technology in an aircraft engine, but from what I have seen, this is not one I would consider for a project of my own.
Some may have not seen the same things with a VR6, but this is just one persons experience.
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09-07-2010, 07:52 PM
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Join Date: Aug 2007
Location: S21, Oregon
Posts: 161
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Different engine, but.......
the VW 1.8T is supposed to be prone to sludge, and this is what mine looked like when I pulled the valve cover off after 125,000 miles making more than double the stock power, Mobil 1 from 2500 miles on:
Just a data point......
__________________
Kelly
RV-7 empennage done, wings done, fuselage to QB stage.
1973 Maule M4-220C flying
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09-08-2010, 07:10 AM
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Join Date: Feb 2006
Location: Davis, CA, USA
Posts: 540
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Lot's of good info rolling in.
Ross-
Thanks for the support.
Richard-
Thanks for clarifying . Basically your saying the engine is already tuned for the minimum requirements needed for the plane and can't be de-rated for reliability and still perform well enough.
Todd-
Did you consider other engines vs. the LS2? or are you a corvette guy, and that was the only way to go. As suggested by Kelly the VW W-12 looks pretty sweet.
As far as data points. I think we all need to look at where that data point comes from (no insults intended).
For example: If I try a VW engine and fail miserably, This is no indication that the engine is a bad fit for the RV, since I don't know what I'm doing.
I think there are many failed alt engine installs that fall into this category.
If many people with lots of engine experience can't get a engine to work well, then perhaps it wasn't meant to be.
Looking at the Subaru engine; everyone complained that the weak point was the PRSU and had cooling issues. But they all used the same PRSU's (then gen 2, 3, 4..) and all the cooling setups were very similar. So if there was a problem it manifested itself in all of them.
In conclusion: The VR6 is probably not a good fit for an RV, but I'll keep thinking about one that will be.
Thanks for the responses everyone.
__________________
Jeff Caplins
California
RV7 N76CX
(started: Feb 2002 --> Completed: May 2016)
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