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Originally Posted by hotrod
In effect you already have a peak cylinder pressure indicator. Engine torque is directly related to the MEP in the cylinders. In theory all you need to do, is run a delta dash log and sit down with a calculator and figure out the engine torque at key rpms in a specific gear. Then you use those reference points as a measuring stick. If you make a change and the index for that rpm goes up you did good, if not go back one step and try something else. Larry
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Yes, computing torque and HP from average cylinder pressure (MEP) is a very accurate method to get "at the flywheel" values. Peak cylinder pressure can also be infered. However, a grapical plot of actual PCP vs crank position is what is needed for tuning purposes, especially to adjust timing. There is lots of software available that will do just that, also plot torque, HP, etc. A possible complication is how long (total degrees of crank) that the cylinder pressure is at work. Fuel burn time comes into play. Slower burn, such as with higher octane fuel, and especially when injecting alcohol, will spread out the energy (as much as 100 degrees of crank rotation). As far as computing wheel HP, it is easy enough to do because drive train losses are reasonably constant over a wide range of RPM and load.