I am tring to further my education....What the heck am I looking at? What does it all mean?

 

Dyno chart from a N/A 350Z...decent output for a Z. Must have a few mods. Probably intake and exhaust work because the a/f readings are a bit leaner than stock. Looks like a fairly typical 350z dyno sheet. Progressive power climb to redline with torque falling off after 5000 rpm's. You could probably use an ecu flash to richen up the a/f ratio a little and pick up a few more hp's...get the a/f ration down to around 13-13.5 across the graph.

 

Can I hurt my engine running in this condition?

 

probably not due to the knock sensor pulling time, but you wont be making near optimum power either. a tune would get at least 5 at most 10hp

 

agreed.....she needs more fuel

 

Why does the Torque drop off while the RPM increases..What is the physics involved. I appreciate the HP conversion from Torque and the Dyno measures T but I would like to understand why T drops. Appreciation ahead of time..

 

Every engine behaves differently and produces different characteristic "torque curves". Depending on camshafts, compression, v6 or v8, ecu programming, etc can move the torque peak up and down the rpm range. Nissan has tried to minimize the drop in torque by advancing the ignition timing from 22 degrees to 28 degrees above the 5000-5500 rpm point. It helps a little but T still drops regardless of most mods.....except forced induction.

 

Appreciate the response but I'm still not there yet. All of the variables you mentioned , camshafts , compression, etc. don,t change with increasing RPM or do they. the only variable that might have a significant impact would be thr ECU but looking at the A/F curve it does not show an appreciable change to account for the T drop off..Is it the timing change that plays the significant factor? Thanks again..

 

Horsepower = (Torque * RPM)/5252

that is why the torque line always crosses the horsepower line at 5252rpm

This looks like a good site to answer your question, http://www.newcovenant.com/speedcraf...ors/intake.htm
"Peak Torque occurs in an engine at the RPM where the engine is enjoying its highest volumetric efficiency"

according to this site peak torque seems to be a function of Engine Displacement (cubic inches), Number of Cylinders, and Intake runner area

 

Ask SP Engineering, they will be happy to help you find your optimum AF ratio.

 

A quick Google search answered my question.. The limiting factor on T is several fold..The rate of combustion of the fuel is not sufficient to enough (too slow) to allow the full compression pressure ratio as it is at lower RPM's. Also the lack of effective engine cooling, the intake and exhaust valves have less time to do there job not allowing removal of gasses ..all of which result in a significant decrease in enigine performance and efficiency..