Peak Torque High vs Low RPM

[TARM]

This is why fuel burn rate and combustion chamber efficiency is so critical. Anything that can be done to increase the burn rate, improve combustion efficiency and improve turbulent mixing of the cylinders can allow these motors to be turned harder and turned faster. The more efficent the burn (well atomized, highly mixed, fine droplets) the faster the burn, the faster the burn the more easier it is to create and maintain cylinder pressure at higher RPMs thus giving you more torque in the higher RPMs and higher power as a result.

This is also why at lower RPMs (say cruise and mid throttle positions) it is best to keep the ICP in the mid range and lengthen the PW out a bit - the decrease in combustion efficiency actually improves performance by lowering the peak cylinder pressures and prolonging the burn so the cylinder pressures are acting on the pistons for a longer period of time. Its all about the burn rate and how to control it.

This is where I was eventually wanting to go with this and what actually got me started down the path of considering these things. Then looking at some CP curves that had been on the net etc .. Something Charles once posted a while back I had dug up which also gave me serious thought on it. I recall him posting on fuel furn and smoke. When he got things really clean and crisp he felt that there was likley a serious sharp CP spike and fast curve which had to do with the way the fuel was injected. This lead me down the path that the same TQ average TQ can be made from very different CP curves. That got me wanting to consider the low versus high RPM tq and the whys of it all. Down low when things are moving slower you want a CP peak that more evenly matches the speed of the engine. As rpms climb things need /can be made to happen faster. I think CP testing equip now that its coming way down in price it can really aid in getting our tuning much more refined.

During munitions and fire arms load development it could take literally hundreds of rounds to finally get the ideal load for a particular length barrel, bullet, powder combo. Once I purchased Cylinder pressure system combined with dual chronographs and load software we were able to bring this down to 3-5 rounds to get a particular combine to its ideal combo that also had the broadest what we call sweet spot.

I think the same can be said of engine tune development. To do this right and in the most efficient manner you really should have Tuning software of course, Load dyno, and Cylinder Pressure System ( at a min 1 cylinder ideal all 8). IMO of the two I think CP testing equip over a dyno to be the most critical to tuning