Quote:
Originally Posted by RogerPihlaja
Hi All,
The attached .jpg file is chassis dyno graph with 3 superimposed pulls. The car is my 1970 Porsche 914-6 with a rebuilt 1983 3.0 liter 911 SC engine. The engine has a Clewett Engineering engine management system with manifold pressure FI and coil at plugs electronic ignition, 1-5/8 Inch ID Billy Boat SS headers with heat, and Patrick Motorsports dual outlet SS sport muffler. The engine management system was running closed feedback [Air]/[Fuel] ratio control with a wide range oxygen sensor. The rebuilt engine had about 1100 break-in miles on it and a 6300 rpm redline was observed. I was a little disappointed with the result. I was expecting something like 180 rear wheel bhp. However, I note that the engine was still pulling strongly at 6300 rpm and would have revved higher if I had allowed it. If this engine could be revved to 7000 rpm, extrapolating the bhp curves would yield ~180 bhp. My question is, what's a safe redline for these 911 SC engines? I've seen everything from 6300 to 7100 rpm. I've heard these 3.0 liter 911 SC engines are nearly indestructible, which is why I went with a 3.0 liter. But, what's the limit?
My other question has to do with the shape of the torque vs rpm curve. I was expecting the classic torque vs rpm peak. Instead, we have what I would describe as a "torque platueau". What's going on here? This is a high revving sports car engine not some kind of tractor engine. Also, does anyone have any insight re what's causing the slight depression in the torque curve just off idle? What does everyone think about increasing the fuel flow to enrich the [Air]/[Fuel] just off idle?  |
C3 factory rev limit was 6800+/-200
SC was 6700
the torque and hp curves ought to cross at 5250, a dyno only measures torque and rpm,
the hp is calculated from the torque and rpm data
hp = torque * rpm/5250