[NoDOHC]

I apologize, I was unaware of this technique for determining BSFC (fuel economy cycle average). The BSFC numbers that I use to compare engines for work are all taken at a certain speed and WOT, this is what I am attempting to document.

If we could find a way to simulate this driving cycle repeatably on different dynos with different cars, we could use that instead. Especially if there is a large amount of piston engine data available for this cycle. The closest thing I can find to data on BSFC during this driving cycle is largely computed from fuel economy numbers on the EPA cycle. We already have this data for RX7s, the EPA fuel mileage rating of the RX7 is awful.

The main reason that I am attempting to produce this chart is because I think rotaries are very inefficient at high manifold vacuums, but not bad at all under full throttle.

I am aware that many online calculators use BSFC for determining injector sizing. This is considering the engine at maximum output. Most users out there are interested in the number for this reason, not to determine average fuel economy.

Engine BSFC is well-documented at WOT on a typical (piston) gasoline engine. I can get curves when I get back home (traveling right now).

Basically Ted, I see your point, but I am mostly looking for a benchmark that we can use to compare. The only benchmark that we have right now is using a terribly tuned stock ECU with retarded ignition timing and non-optimal gearing for fuel economy to compare against the fuel economy of competing piston engines.

Let's not turn this into an arguing match over whether BSFC is an EPA driving cycle or determined at peak torque at WOT....

Because peak torque is what we can measure easily on a dyno and because the EPA driving cycle is not something that we can measure easily on a dyno. I recommend that we take our benchmark at WOT and peak torque.

This information is well documented for piston engines and will give us a good opportunity for comparison without having to account for gear ratios, engine load, poor tuning on the factory ECU, etc.