VairHeads, Yesterday was a calm day, so I did a four way GPS run at 7500' at wide open throttle to see what the new 3100cc engine would do. Bottom line was 172 mph at 3740 rpm, which agrees nicely with indicated airspeed after pressure and temperature correction (TAS). If nothing else, this proves my airspeed indicator is deadly accurate, since I got this same number this weekend without the GPS. I found a similar run done last April using the 2700cc engine, where I got 160 mph at 3390 rpm. That's a 12 mph difference (which is about what I'd expect) and a 350 rpm gain.
These two runs were at almost identical temperature and pressure conditions, but a year apart. Fuel consumption was 7.2 gph vs 6.0 gph. This was using a Sensenich 54 x 54" prop in both cases, but I have added a spinner since then. I did some pretty good comparisons of the spinner improvement then, and concluded that the spinner only helped 1-2 mph at best (if that much), so it looks like a 10-11 mph improvement, which is exactly what I expected. The fuel increase represents a 20% increase in power over the stocker, which is also about what I would have expected, given the 15% increase in displacement and higher rpm. So I think it's pretty safe to say that a typical KR will get a 10 mph increase in speed with a 3100cc engine. In the same breath, let me say that I will run this thing wide open maybe 1% of the time, so you figure out if it's worth it to you. I will say that the climb rate is fairly breathtaking. I now have the equivalent of a "war power" setting on my throttle, but I plan to save it for an appropriate occasion, such as the next time my manhood is challenged! Wheel pants, gear leg fairings, and wing/stub gap seals that don't flap in the breeze will improve this to the extent that 190 mph should be attainable. A better matched prop holds some promise as well. See http://home.hiwaay.net/~langford/corvair/phoenix/ for details on this particular incarnation of the 3100cc engine... Mark Langford, Huntsville, Alabama see KR2S project N56ML at http://home.hiwaay.net/~langford email to N56ML "at" hiwaay.net --------------------------------------------------------------
