> I recently realized that the KR-2 that I purchased has a very restricted > exhaust system. The engine exhaust ports are 1.5" while the exhaust pipes > are 1.0". (Champs and Cubs have 1.5" exhausts.) This means that the > exhaust area is reduced by about 50%.
Actually, it's a lot worse than that. Remember it's radius squared times pi, so it's really 1.77 square inches versus .78", a factor of about 2.25x. Pretty big difference. I don't claim to be a VW aircraft power expert, but I'd think 1" would be too small too, although 1.5 might be too much, considering the rpm we're running. 1.25" might be a good guess for the individual runners, before they meet up into a Y or something. GPASC's catalog doesn't mention how big their pipes are. I guess the thing to do is see what everybody else is sucessfully running and go with that, which is probably what you were looking for, rather than having your math corrected. Hope to have rudder and tailwheel permanently installed before the day is over... Mark Langford, Huntsville, Alabama N56ML "at" hiwaay.net see KR2S project at http://home.hiwaay.net/~langford
