economisTTwo

i just spoke with the guys at apr about both the apparent lack of increased horsepower and the sharp falloff in the air/fuel ratio.

1) they refered me to brett's previous post about the shortcomings of inertial dynos like the dynojet for measuring hp and torque;
2) they said that measuring the air/fuel mixture through the tailpipe would always result in inaccurate measurements -- they have seen these problems many times. the only way to get an accurate reading on this is to do it before the cat.


comments?

i still think that this was a useful exercise (and many thanks to dan at mach v and chris for setting this up) -- but now i really want to try one of the newer non-inertial dynos and get an air/fuel measurement before the cat!

225TTR

improvement over stock on the 225. My personal feeling is that something else is going on with the 180.

economisTTwo

your results showed an approx 20 hp increase over most of the rpm range (i'm doing this from memory, so 20 may not be the actual number), which is a pretty good gain from a chip. since the tests were done on the same equipment in the same way, the differences between the runs should be a valid measure of the impact of the chip. i think they are saying that the absolute numbers may be off, however.

i should have done a second run with my chip set to stock.

also, the differences between our results (about 48 hp) is the result we would expect between a 180 and a 225. again, same test, same machine -- so the results can be accurately compared between us. but the absolute figures should not be compared with other results.

does this make sense? is it right?

undrway

the results after I chip it. I will use the same dyno if possible. Comparing results before and after the chip should be straightforward. Since I used an inertial dyno pre-chip, I should see an improvement in the inertial dyno results post-chip. I believe the error of the dyno is eliminated if I use the same machine (& same gear) for both runs. Is this reasonable thought?

economisTTwo

even if apr is correct about the inherent problems with inertial dynos, comparisons run in the same way on the same dyno should be valid -- hence, you should get a valid reading on the impact of the chip (just as i think ellen got a valid reading on the impact of her chip when she did runs in both stock and performance modes). that's why i wish i had done another run, this time in stock mode ;-(

225TTR

Sounds reasonable.

smallTTs

as of now. It'll do inertia only, steady state via eddy current brakes, and any combination. Part throttle, etc. are all possible, and the software is super. So is the correlation to flywheel hp/torque numbers.

Other than no 4WD capability, the downside is cost...about twice+ what an inertial only dyno costs. ROI is the problem. Would you pay twice as much for dyno time as you do now? Sure, you'd get better data, but dyno owners have to do volume to pay the bills. There aren't many AutoDyns out there.

We watched a demo with a Viper doing a 203mph run at full throttle on an AutoDyn. Not just inertial either. Impressive from 10 feet away! With their correction/correlation software, they calc'd 450 hp @ flywheel, right on the rated numbers. The same thing happened with a 800+ hp BB Chevy in a drag car. They ran the engine on a 901 engine dyno one day, installed it in the car, and ran the car on the chassis dyno the next day. Correlation was within 2%. Impressive.

BTW, Superflow's 4WD/truck models aren't for high-speed high performance use. Usually they are OEM testing of every new OTR tractor.

My $.02<ul><li><a href="http://www.superflow.com/products/products-chasdyno.html">http://www.superflow.com/products/products-chasdyno.html</a</li></ul>