69 rear HP and torque

[Don W.]

For a base 427/390HP with THM400 and 2 inch exhaust; does this Mustand Dyno run look in the right ballpark or i it low for this engine?walker corvette HP on Mustang dyno.pdf

[Duke W.]

Re: 69 rear HP and torque

Mustang dynos typically read 10-15 percent lower than Dynojet inertia dynos. Also, there is no indication on the data sheet what if any type of air density correction was used, so the data is basically useless to compare to any other bonafide dyno test.

I only recommend Dynojet inertia type dynomometers and always recommend using SAE air density correction. Then an estimate of SAE net output at the flywheel can be made by simply dividing the RW data by a suitable drivetrain/tire efficiency, which is typically 0.85 for manual transmissions in direct drive and 0.80 for torque converter autos that don't have a converter lock up feature.

Further, I always recommend that owners determine what type of output device the dyno computer has so they can copy the files, and if the dyno computer is networked to a system with email, they can simply be emailed to the owner. Then the owner can download the free Dynojet Winpep software, load in their data files, and display the output anyway they want including use of a variety of correction factors.

Can you do something similar - at least find out what if any correction was used?

I also recommend starting pulls at no more than 1000-1200 revs and pulling to the redline, but dyno operators always want to start at 2000-3000 and stop the pull before the power even peaks unless you get in their face.

Unfortunately, most ignore my advice, do absolutely no advance planning, and end up with the piece of paper that is basically worthless, which appears to be the case here.

If anyone has plans to do a chassis dyno test I have a prepared set of test guidelines and recommendations that I will be happy to send you, and if you follow them and spend a few minutes inquiring about the dyno and putting together a test plan, you might actually get your money's worth and some useful test data that can be compared with other tests conducted at different times and places.

Data without context is worthless.

Duke

[Don W.]

Re: 69 rear HP and torque

Thanks Duke...Don