Pietenpol-List: another wooden trailing edge sketch of possible interest
Posted: Sat Feb 16, 2008 10:10 am
Original Posted By: "Cuy, Michael D. (GRC-RXD0)[ASRC]"
MikeD wrote->The torque curves are very close up to A65 rpm levels and if you load it the same>it will perform about the same. You need to load it so that it reaches it's higher>cruise/max rpm to produce full power, therefore you need less load than a 65.Correct. The torque curves should be more than just very close... they shouldbe exactly the same because the A75 is the same engine as the A65. The rods aredrilled to provide more oil at the higher rated RPM and the pistons are different(waffle pattern on the underside or some such thing), plus a few minortweaks, but they are one and the same engine. I've looked at the Continentalspecs for the carb venturi for the two engines (when using the NA-S3A1) and itis unclear but I believe they both use the 1-1/4" venturi, too.Bottom line is that if I put my Hegy 72x42 prop on the A75 it will perform exactlylike my A65 and I'll never see the additional 10HP because I won't be ableto crank it up to 2600 RPM to get full rated 75HP out of it.Oscar ZunigaSan Antonio, TXmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Subject: Pietenpol-List: another wooden trailing edge sketch of possible interestDate: Sat, 16 Feb 2008 10:16:19 -0600
MikeD wrote->The torque curves are very close up to A65 rpm levels and if you load it the same>it will perform about the same. You need to load it so that it reaches it's higher>cruise/max rpm to produce full power, therefore you need less load than a 65.Correct. The torque curves should be more than just very close... they shouldbe exactly the same because the A75 is the same engine as the A65. The rods aredrilled to provide more oil at the higher rated RPM and the pistons are different(waffle pattern on the underside or some such thing), plus a few minortweaks, but they are one and the same engine. I've looked at the Continentalspecs for the carb venturi for the two engines (when using the NA-S3A1) and itis unclear but I believe they both use the 1-1/4" venturi, too.Bottom line is that if I put my Hegy 72x42 prop on the A75 it will perform exactlylike my A65 and I'll never see the additional 10HP because I won't be ableto crank it up to 2600 RPM to get full rated 75HP out of it.Oscar ZunigaSan Antonio, TXmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Subject: Pietenpol-List: another wooden trailing edge sketch of possible interestDate: Sat, 16 Feb 2008 10:16:19 -0600