grumpyvette Posted March 25, 2002 Share Posted March 25, 2002 ever wonder why your engines torque curve gets higher with the engines rpm level untill about 4000rpm-5500rpm(DEPENDING ON YOUR COMBO) but fades above that rpm level? well it depends on several factors, first as long as the cylinders can fill completely you get a good fuel/air burn so you get a good cylinder pressure curve against the piston each time the cylinder fires,THE ENGINES TORQUE CURVE INCREASES WITH THE NUMBER OF EFFECTIVE POWER STROKES PER SECOND, at very low speeds theres not enough air velocity to mix the fuel correctly or produce a effective ram tuneing effect but as the rpms increase the cylinders fill very efficiently untill the rpms reach a point where the cylinders just don,t have the time necessary to flow enough air through the valves to fill the cylinders , remember a 5000rpm the intake valve out of 720 degs in each cycle opens for about 250degs of effective flow even with a hot roller cam, now thats only about 35% of the time and theres 41.6 intake strokes per second , thats only 1/60th of a second for air to flow into the cylinder, I found this graph that shows the relationship between V.E.(VOLUMETRIC EFFICIENCY) and AN ENGINEs torque CURVE http://www.n2performance.com/lectures/lect1/n2perf5.gif WHAT THAT GRAPH SHOWS RATHER EFFECTIVELY is that its your engines ability to fill the cylinders that increases your power and the more efficiently you do that the higher the rpm level you can acomplish that at the more power your engine makes, remember the formula for hp is (torque x rpm/ 5252=hp)so moveing the torque curve higher in the rpm range increases hp. btw heres info on how to find the effective tuneing lengths for th intake and exhaust lengths, -------------------------------------------------------------------------------- ram tuned and rpm matched cam timeing for the effective use of the headers and intake system can get you to slightly over 100% V.E. at (1) rpm range where the tuneing is most effective, look here, http://www.grapeaperacing.com/GrapeApeRacing/tech/intaketuned.cfm heres how to find the correct tuneing lengths http://www.engr.colostate.edu/~allan/fluids/page7/PipeLength/pipe.html Quote Link to comment Share on other sites More sharing options...
Guest MegaShaft_2000 Posted March 25, 2002 Share Posted March 25, 2002 Hmm, pretty cool. I guess that shows how well certain engines can breathe. The Honda S2000 must breathe pretty good since its peak torque comes at 7500 rpms, and max HP at 8300 rpm. Too bad its peak torque is only 153 lbs. For the same 240hp, I'd rather have a Buick GN engine which makes 345 lbs of torque at 2000 rpm. Quote Link to comment Share on other sites More sharing options...
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