to keep it simple, how does one lower tq or keep it at a steady amount while raising hp? lots of modded trucks see close to a 2:1 ratio tq to hp but sometimes u see something like 3:1. personally i like to see say 500hp 1000tq vs 300hp 1000tq. same amount of work being done just a lot faster. how does one intentionally regulate that ratio? thanks guys

 

Hp has to do with speed (RPM) and maintaining the higher torque level at higher engine speed. As the torque curve falls off at high RPM, your HP drops. HP= (tq x RPM) / 5252

If you can tune the engine to have the same torque available at higher RPM, you get higher peak HP. As an example, for 300 hp at 3000 rpm you have a torque of only 525 ft-lbs. For 500 hp you have 875 ft-lbs. Problem usually is getting the engine to flow well enough at higher RPMs to make that peak power.

Hope that helps.

 

so am i safe to assume that its the air that hepls make hp on the top end and fuel more or less controls the tq output? loose terminology here.......lol if the amount of air is sufficient for the amount of fuel, that is to say, a slight haze or managable egts, then tq-hp should b roughly 2-1?

 

The torque is the ability to make power at lower RPM. The long crank and stroke of the Cummins makes that easier than most other V-8 engines. There you have to compensate with more fuel and higher/longer firing pressures (multiple injection events) at low rpm to make the same torque. But the shorter stroke and overall design of the v-8 makes it flow better at higher rpm, more HP.

If you can get the I-6 to breath at higher RPM and still maintain the torque, your HP will be about the 2:1 ratio you speak of. My 12V high end flow isn't great, but the ability to make power at the 2000 RPm mark is the larger torque number.

 

Put a larger turbo on. The slower the spool-up, the less bottom end power you will have. When I was running a 66/73, it wouldn't have much below 2k rpm. Cammed with that turbo, it would pull from about 1700 rpm. With a 75/75 turbo, it was dead below 2500 rpm. With the 80/80 turbo, anything below 3k rpm is non-existant. But, with my twins, I had over 60 psi boost at 1600 rpm. It was fun! These all were on the same setup for fuel, slight injector changes between the two large singles. The 66mm turbo was on the old 12mm pump though.