Originally Posted by DanEC (Post 1238191)

Chas may have that right.

Originally Posted by blykins (Post 1238150)

It's a reasonable set of numbers. Some dynos operate differently than others and a peak torque curve there is reasonable and realistic.

Keep in mind that you can't always pull an engine down that low, and most of the time it's not warranted, nor is it safe to do so. A wide open throttle pull at 2000-2500 can induce detonation and modern performance engines with larger heads and cams are not meant to have their guts pulled out at such a low rpm. You would see that kind of operation in a dump truck engine, which is meant to be fully loaded not too far off of idle....with compression ratios, dynamic compression ratios, piston design, ring gap, etc., to handle that kind of load and heat.

To make a long story short, I wouldn't advise asking a dyno operator to pull one down that far....

A reasonable starting point is 3500-4000. A dyno is more for determining issues with the engine, general A/F curves, and peak horsepower/torque numbers. You can't drive a dyno, and the poster that made the comment that everything changes once the engine is in the car, is correct. Different air cleaners, different headers, etc. make differences. While I'm ranting, I'll also point out that different ignition boxes (even of the same brand) will give different timing settings, so be sure and double check the timing once it's in the car and running.

Originally Posted by Barry_R (Post 1238371)

If you ever get the chance you are welcome to bring one of your engines up here to dyno and compare to your local guy. Free (you buy gas and lunch). It would be good data for all of us to have.

Having done the EMC deal for a few years I know that many dyno installations give different numbers, and that it has nothing to do with the intentions of the builder or operator - but more to do with room venting, exhaust layout, and physical hookups. I've compared mine to several local pumps, as well as the ones at the contest in Ohio - but more info is always good for everybody.

Originally Posted by DAVID GAGNARD (Post 1238379)

I'm looking at my last dyno session and all the pulls started at 3500 rpms.....That part I understand,looking the water temp,it stayed between 145 and 150......
looking at your dyno sheet,your water temp was in the 138 to 145 range,any particular reason for these water temps vs. running the water temp at 180 degrees,more closely to the "normal" operating water temp.???
Just curious.....

David

Originally Posted by Barry_R (Post 1238326)

We generally do our WOT pulls from 2500 or 3000 on up. No real reason not to - sometimes the 2500 is hard to grab on a bigger or torque oriented engine so I have gone to 3000 as something of a standard. Not that unusual to hammer the throttle from a 60or 70 MPH freeway cruise without downshifting.

My DTS does not monitor inlet air volume, and I have become pretty reliant upon O2 sensor readings for fuel tuning. You can usually hear it when things are going well or wrong, and should spend the time chasing the power data - its rarely a wrong move when power is going up no matter what the "numbers" are.

Originally Posted by Dwight (Post 1238437)

I don't understand

do you get better hp number with the water temp low?

Dwight