Ma I don't mind having my math corrected, but you didn't. I got the same difference, but at my age, 56% reduction is "about" 50%. :-)
BTW, I cruise at 2150 rpm & rated is 2300 rpm. Also, there was no increase in static RPM with the Champ exhausts (1.5") installed. Ken ----- Original Message ----- From: "Mark Langford" <n5...@hiwaay.net> To: "KRnet" <kr...@mylist.net> Sent: Sunday, September 05, 2004 10:41 AM Subject: Re: KR> Exhaust > > 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 > > > > _______________________________________ > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html
