<VV> Regular Gas and Fuel Economy in a 110hp Corvair

[Mikeamauro at aol.com]

Greetings and  salutations:
 
I posted on this topic several  days ago, and someone (who shall go unnamed) 
promptly responded by saying I'm  full of cr--; near as I could tell, the 
person's position is: "simply  lowering the compression ratio, via thicker 
gaskets, is a sufficient fix  for ping and detonation." Perhaps I, with my first 
post, failed to fully  explain myself and the process taken to come to my 
conclusions. I feel  what I've learned over the years, about making the Corvair engine 
perform  well on today's lower octane pump fuel, is important enough to 
thoroughly  share with the Corvair brethren... here goes. 
 
Since 1970, I've owned and  built Corvairs (before then I was a small block 
Chevy guy, and a head mechanic  on a regional stock car team). Beginning in the 
80s, as high-octane  pump-grade fuel became harder-and-harder to find, I 
began to experiment  with various methods of maintaining a high level of (Corvair) 
engine  efficacy (read: power and fuel economy), while at the same time 
insuring  the engines were capable of holding together for many thousands of miles. 
 
My efforts first centered around simply  lowering compression through thicker 
head gaskets and/or base gaskets. What I  found with this approach was 
engines had less power (than with stock  compression), and fuel economy suffered. 
And, sometimes, especially at higher  ambient temperatures, the engines were 
still prone to knock &  ping. (I drive my Corvairs every day, and the poor 
performance of  lowered-compression engines was simply unacceptable.) My next step 
was to pay  particular attention to the stock cooling system (de-flashing heads 
and removing  the lower shrouds in the summer); with restored stock 
compression ratios:  efficiency was back, but knock & ping remained prevalent in hot  
weather. I then consulted with contacts in the professional race engine  
business, and cross checked what I was told against the body of literature  
available on the topic of modern combustion chamber construction. Now, I (still)  
build my engines paying particular attention to optimizing the stock cooling  
system, maintaining the stock compression (for my 110s... 9.5:1, verified by  
CCing), keeping base ignition timing up near 18 BTDC (about  36-degrees overall), 
but also hold the quench space to about .032. I also  run premium fuel. The 
results are excellent: my cars are very drivable, don't  knock and ping, and get 
very good fuel mileage.
 
I hope some find this information useful. 
 
Regards,
Mike Mauro
Of Various  Corvairs



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