NetHeads, I made the comment last night that I'm flying 93 octane auto fuel with a 9.3:1 compression ratio. Dan Weseman in Jacksonville has a Corvair with 9.5:1 cr. That sounds insane, but it works on a Corvair with proper quench distances (distance between the "deck" and the piston at TDC). Steve at Great Plains recommends much lower compression ratios for his engines, and as soon as he reads my message from yesterday, is going to worry that a bunch of VW guys are going to start melting engines with 9:1 compression ratios. The 2100cc VW engine in my '74 Karmann Ghia ( http://home.hiwaay.net/~langford/ghia2.jpg ) has an 8.9:1 compression ratio and WILL ping if I put anything less than 93 octane in it, and if I didn't have a giant pair of Webers sitting on the heads dumping copious amounts of fuel down the ports, it would ping like crazy any time the throttle is wide open. And even with 93 octane, wide open for more than a half a minute would probably have the same results. I don't have that problem in the car, because I can't do 145 mph on the highway...for long, but it would be an engine killer in an airplane where full power can be required for 10 minutes on a long climbout. Just for the record, I often fly my Corvair wide open on a cross country, until I get in the pattern for landing.
My point is that just because that works for a Corvair, I'm not saying that it will work for a VW. If I had a GPASC engine, I'd follow Steve's recommendations. He ought to know what works and what doesn't in his engines. Gorgeous blue skies outside, and I have a new Airmap 1000 to try out, so I'm headed to the airport to do a little testing... Mark Langford, Harvest, AL see homebuilt airplane at http://www.N56ML.com email to N56ML "at" hiwaay.net
