I was wondering earlier, why if i inject X quantity of fuel, with Y S.O.I. at A rpm and B A.F.R. and C rail pressure, into 3 different engines, do I get such varying torque values. Torque is the rotational force of crankshaft, and if you have a certain amount of fuel to burn, the calorific value that can be turned into kinetic energy will always be the same.

Could it be the cam timing?
Giving different valve overlap periods can drastically shift the engine torque curve up and down the rev range. Also an earlier exhaust opening point may help scavenging, but could also cause cylinder pressure to drop even though it is still rising.

Could it be the piston face swirl design or combustion chamber shape?
This can change the speed at which the fuel burns. A longer, slower burn will increase the pressure more gradually than a faster, shorter burn, and thus still be creating pressure rise longer into the stroke.

Could it be the turbo housing design/a.r. ratio of turbo?
A higher pressure in the exhaust will cause some energy to be wasted forcing the exhaust gas through the exhaust port on the exhaust stroke.

Could it be the design of the injectors?
If the fuel is sprayed in to the cylinder slower, it could make the pressure cycle of the cylinder differ from engine to engine. Also the time it takes the injector to go from fully closed, to fully open, may differ from engine to engine.

Could it be the bore and stroke of the engine?
If the engine has a shorter stroke, then the piston has less to travel to make its power stroke. This could mean that the fuel has much longer to burn in relevance to piston speed, and this longer time to create the pressure within the cylinder between injection and exhaust valve opening = more ability to produce power. Piston speed is not linear to engine speed if the stroke length varies. A slower piston can be acted upon more positively with a pressure rise than a faster moving piston.

If anyone would like to begin some in depth mechanical testing with me on this, or has any theory they would like to input themselves then please fire away. I think this would be something everyone on this forum would enjoy seeing develop.

I want to first try with a vernier camshaft pulley to dial in the camshaft timing, so that i can get the same exhaust valve opening time on 3 engines. A PSA engine, a Korean engine, hyundai U engine most likely, and a multijet engine of some description. I would like to widen this up to a few more engines, so if we have any experimentation lovers here, make yourselves known lol :D

I can imagine there will be some puzzling results lying ahead