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Please stay away from the "engine should run at peak torque rpm blah blah blah" uneducated BS. We all know that's not true in the real world. If it were true, our cars would get amazing mileage at 4000 rpm.




Gee, didn't know it bugged you so much. Thanks for the underhanded compliment.

If you paid attention to what I said in those types of posts, I always used the caveat "within reason" of rpm range, being that even an uneducated BSer can tell that a 4000 rpm torque peak is a stupid place to run a cruise rpm.

I've always said to build so you have as low an rpm torque peak as possible. That is how I built my truck engine. Doing so allowed me to maximize the cruising performance and mileage in the rpm range I most typically use during driving. The fact that my torque peak was within that range was the result. Sometime in the last few months the target chart posted further up above was posted and I started comparing my build info to its data. Interestingly enough, while not in the sweet spot, I am not too far away from it either. So while WOT torque peaks are not an exact indicator of efficiency, combine that with vacuum readings and piston speed and you can get dialed in pretty close to building exactly what you want. So don't wholesale discount the WOT torque peak as an efficiency indicator. It is a fact that torque production and volumetric efficiency go hand in hand. Use that as an additional tool in caclulating the peices you need for the build.

In one of the recent enthusiasts rags they had an article recently regarding the GM 8.1 big blocks. The are really big, inefficient pigs with no aftermarket support until just recently. Dart has taken to building a lot of parts for them lately because some oil field came to them requesting big torque, low rpm motors to replace some of their pump units. Seems they produced some gas engines that make some crazy amount of torque at stupid low rpm range. Performance is almost diesel like. Sounds like a build of this sort may be exactly what your after in a car that cruises at 2000 rpm or lower. I'll try to find it an post up some info if no one else beats me to it.