Is it me or do those dyno numbers in CHP seem slightly inflated in their engine combo section? They say that it is RWHP, but it seems more like flywheel HP to me :confused:

Oh boy, here we go again with Westech. I do not know the article you are refering too, but they have been accused of this in the past...several times.

Westech is infamous for their generous dyno. And for that reason most of the rags use them for engine article projects.
Must be that good CA air... ;)

Say, was that Bomber67's EC in that issue?

I think all the magazines and manufacturers are too generous on the HP figures.

JMO :D

Anybody read the story about the guy who invented the Dynojet? I think it's in this month's Hot Rod magazine. He admits they couldn't make the math work for accurate numbers, so they just arbitrarily add a certain percentage of torque/hp. Probably your best bet for an accurate dyno is still the dragstrip and a time slip :)

Maybe they calibrate it using Desktop Dyno....

Maybe they calibrate it using Desktop Dyno....
It seems that all the dyno figures are somewhat optimistic. I had a S/S engine builder tell me you either had to calibrate the engine dyno right before a pull or know how much too high it read and subtract that amount to arrive at realistic readings. The dynojet is a completely different animal and any engine that is backed up by an automatic with a high stall converter must start the pull above the stall speed to get real, meaningful, results. The driveline losses are also not reliable and can vary from car to car, even if they are the same type and engine. If you estimate the power output by your Dragstrip MPH be sure to first convert it by using Meaux's correction figure of 1.0072 which changes it back to the old, real, 1320 foot MPH as measured 66ft. before the E.T. line and 66ft. after the E.T. line. Then use the old Mopar ((.00426 x MPH) squared) x car weight = H.P. This last method generally shows about 20-40 lower H.P. figures than the magazines but is probably more accurate. The Moroso power speed calculator is O.K. but all these methods are only guesses and should only be used to guage if you are making changes that help or hurt your performance.

If you estimate the power output by your Dragstrip MPH be sure to first convert it by using Meaux's correction figure of 1.0072 which changes it back to the old, real, 1320 foot MPH as measured 66ft. before the E.T. line and 66ft. after the E.T. line. Then use the old Mopar ((.00426 x MPH) squared) x car weight = H.P.

Does this give flywheel horsepower or rear wheel horsepower?

Does this give flywheel horsepower or rear wheel horsepower?
=
Flywheel

I have not yet seen the newest issue of CHP, but yes that is my '65 El Camino in the "Chassis Dyno Proven" article. I was at Westech for the Chevelle dyno day literally the day after I found and fixed this incredible exhaust fubar http://www.chevelles.com/forums/showthread.php?t=105713. Without doing any tuning to take advantage of the newfound exhaust flow I made 514 rwhp at the Westech dyno on my first pull, and 506 rwhp on my second pull. The next week I went to Superior Automotive and had Don rework my Dominator's air bleeds and jetting etc. The baseline dyno at Superior started at 497 rwhp, and ended with 564 rwhp. The very next day I ran my old brick down the Fontana 1/4 mile and made a tire spinning 10.97 e.t. at 124.95 mph pass. Because my rear sway bar twisted a mounting bracket and my new exhaust hit my driveshaft I didn't get any more runs in that day. After fixing those issues I next ran the Irwindale 1/8th mile and made a best of 6.93 e.t. at 101.84 mph - which is .12 quicker e.t. and a full 1 mph more than my 1/8th mile incrementals from my 10.97 1/4 pass at Fontana.

In the end it really doesn't matter what the Westech or Superior chassis dyno results were - the dragstrip is still the ultimate dyno. What a chassis dyno will always be best at is speeding up the comparisson of different parts and tuning on a car.

Thomas

I wish they would have given qtr mile times/mph with each car as well.