<VV> Re: engines for airplanes

[Rad Davis]

I lurk on the Corvaircraft mailing list, so I guess I'm qualified to answer 
this question:

Corvair guy and aviation A&P William Wynne has been doing comparison 
testing and benchmarking of stock and aftermarket Corvair engine parts for 
aviation use for quite some time now.  He has focused on direct drive (no 
reduction gear) applications for both weight and cost reasons.  He sells 
manuals, services and parts to support people doing an aviation conversion 
of a Corvair engine.  The primary design criteria are 1) reliability, 2) 
simplicity, and 3) power output in that order.  I can't argue with his 
reasoning given the nature of the application...

His standard cookbook engine is a long-stroke engine with flat-top (forged) 
pistons, a slightly warmer than stock cam (no need for significant torque 
below 2000 RPM frees you up to get another horsepower or two above 3000), 
and high compression small valve heads.

Why not 140 HP heads?  simple - the prop redlines below 3500 RPM in most 
cases.  A small-valve head breathes significantly better in the 2000-3500 
RPM region than the 140 head, has more fin area, and is less prone to 
losing intake valve seats (see criterion 1).  They're also a good bit cheaper.

Obviously, this is going to nudge people toward a 65-67 110 HP engine as a 
first choice for a core engine because most of the parts are what they need 
for the standard build.  He doesn't specifically steer people away from 95 
HP heads, but he does steer them away from smog heads.  Again, I can't 
argue with the reasoning - why leave horsepower on the table when you're 
carrying a fixed amount of weight into the air?

A lot of the newbies on the Corvaircraft list have had real problems 
finding good core engines--they're not in touch with the CORSA 
mothership.  In more than one case, a newbie got a car with a core engine 
in it, then decided that the car was both too good and too cool to steal 
the engine from.  Presto - another Corvair owner is born.

Yes, they are very much our kind of people:  They're gearheads, they're 
cheap, and they like arcane, well-engineered solutions to mundane 
problems.  And yes, they buy lots of shiny new engine parts, which helps 
keep them available for everybody - you don't reuse things that are 
"probably OK" on an airplane engine.

I live so close to Alliance, OH that it would be no problem for me to drive 
up that Saturday.  The bad news is that my one Pennsylvania Corvair is the 
Twinki, which, while a workhorse, is pretty danged ugly these 
days.  Hopefully somebody will show up with a pretty (and sexier) Corvair 
to avoid scaring everybody off.


At 12:05 PM 3/24/2006 -0500, Louis C. Armer,Jr. wrote:
>Wade, why would the 110 engines from only those be used? Why would they not
>use 110 engines from 1964 through 1969? If you don.t know the answer then 
>can you
>get the answer from the airplane gurus?
>
>Chuck Armer
>////////////////////////////////////////////////////////////////
>
>
>At 11:29 AM 3/24/2006, you wrote:
>>Actually, engines are not the "hard to find" part of a decent Corvair. If 
>>you find a decent body, mechanical parts are much easier to come by. The 
>>aircraft builders are mostly interested in the block, crank, and heads 
>>from 1966-67 110 engines. They have a "formula" list of parts and 
>>procedures to build tested and reliable engines suitable for aircraft. 
>>For the most part, they don't use starters, fuel system, cooling system, 
>>exhaust system, camshaft, flywheel, harmonic balancer etc etc from the 
>>core engines they buy. All those used parts are still available to the 
>>Corvair car hobby. I think we can afford to share a few 110 cores with 
>>these guys. They support our vendors too. I'm  looking forward to their 
>>fly-in in June.
>>Wade
>>_______________________________________________

__________________________________________________________________________
Rad Davis:                                        rad.davis at comcast.net
Corvairs--65, 66 Corsa coupes, '65 'brier Deluxe   http://www.corvair.org/
Keeper of the Forward Control Corvair Primer: 
http://www.mindspring.com/~corvair/fc1.html
"We did Nebraska in seven minutes today. I think that's probably the best 
way to do Nebraska."                            --Brian Shul, _Sled Driver_