Mustang Dyno #s disappointing

[rayjay]

Local college opened their Mustang Dyno to public as a beneift for their Mustang Drag Car project. I pulled 230.9 HP @ 5000 RPM with 248.8 TQ at 4250 RPM. Needless to say I expected better with a chip and intake mods. Their print out also showed 227.8 HP @ 105 MPH and 375.4 TQ at 91 MPH. Not quite sure what to make of these numbers??? This is the only dyno of any kind in my area. I also did not have a baseline from stock to compare to. I guess I'll do it again next year once the engines broken in and see where shes at. She really dogged it once it hit top gear, never even came close to redline. In a simulated 1/4 mile I ran 15.22 @ 94.64 MPH. Anyone have a similiar experience with a Mustang Dyno?

[Smokie]

Does your car burn rubber from a dead start, not using the brake pedal ??? If the answer is yes, the numbers are wrong, if you can't burn rubber at all....they may be correct.

[CRUZTAKER]

The numbers are wrong....period. Baseline stock MM's always show 234-240 RWHP.

If you have a chip, you should be pulling at minimum 258-263 rwhp or better. The pulls should have been done at 6000+ rpm as well.

[rayjay]

On the simulated 1/4 mile pull, the HP spiked on the graph at about 265 just before the car shifted. I wonder if my pulls should have been done in second gear? They targeted 90mph on the speedo as when I was to hammer it, going up to 130. As I said the engine was a dog at that point and really did not open up and climb quickly as it normally does. The car will chirp the tires, even with traction control on, normally. Atleast I found out the traction control does work. Forgot to turn it off before the 1st run and she would only go 20mph. The car only has 4160 miles on her, so shes not broke in yet.

[Smokie]

The more I read, the more I believe your results are not accurate. The pull should be in 3rd gear, your car should not shift, O/D should be turned off, should go to 6000 rpm's and traction control should not matter on or off; you are not going to lose traction during the pull.

[rayjay]

Smokie, they had me accelerate slowly until it hit third gear. Then stand on it until they told me to shut down. I never reached 6000 rpm. The Lidio chip bumps the rev limiter to 6600. Like I said the car felt like it was dogging it. Normally, with the chip, PHP airbox and spacer, she gets to 4000 rpm and then screams to redline. This did not happen today. Maybe I should make the 9hr trip out to Lidio's place next spring and let him tune it.

[Smokie]

You would know better than anyone else if your car is not pulling like what you are used to, if it's not, give Lidio a call and see what he suggests.

I would not be too concerned with the numbers, unless your car doesn't feel right when you drive it.

[rayjay]

Well, coming home from work this morning I left it in 2nd, once she shifted I stood on it, bam, like a shot to 6600 rpm. Next time I'll do the pull with it in second and see what it shows. 230hp my azz.... :toss:

[Silver_04]

It may be the dyno itself. Mustang Dyno's have been reported to yield numbers lower than what we are used to seeing from a Dynojet.

Also, during my dyno runs (on a Dynojet) the car hit the speed limiter in third gear well before redline. Still scratching my head over that one.

[SergntMac]

Anyone have a similiar experience with a Mustang Dyno?
Yep...And the problem here, is not your MM. It's the Mustang dyno, and untrained/skilled dyno operators. I've got a Mustang dyno report lying around here that says my MM with just a DR Stage 1, produced 385 RWHP and over 1200 RWTQ...Really. I've posted about this before. Dennis should love that, all that power from a chip and 4:10s...WhooHooo! Let me explain?

First, the "Mustang" name is the dyno's brand, the builder of one of the oldest technologies out there, the last of the "eddy-current" methods of simulating road conditions. It uses a weighted drum that's controlled with magnetic friction. The resistance, or, "road force" is adjustable throughout the dyno pull. The shortcomming is that it is adjustable, and if the operator doesn't know how to setup or manipulate the machine, you get a false reading.

Likewise, if you want a false reading, all you need to do is imput false information of the car, such as gross weight, rear end gearing, redline and so on. Mustang dynos are typically used just to simulate road conditions, not as serious test tools for tuning, and measuring RWHP and AFR. BTW, betcha didn't get an air fuel study too, because Mustang dynos don't typically include that, nor are they typically SAE corrected.

A Mustang dyno can be setup and run correctly, but it cost a lot more money, and takes a lot more work to accomplish and maintain that. With it's popularity waning against the Dynojet (and WinPep software), it's not a good investment for the small businessman looking into dyno tuning, and it's not that popular anymore. More on DynoJets another time...

Secondly, at 4000 miles, your MM is broke in. There's no magic number on when it will "loosen up" and drive better, someone who drives hard can achieve that in 500 miles. But, considering our customary driving habits, 3-4000 miles seems about normal, and I'd say you have passed your break-in point.

Third, the 4.6 DOHC make most of it's power in the 4000 to 6000 RPM range, and if the operator shut you off before 6200 RPM, you didn't measure anything, no matter what gear you were in. If he didn't guess weight and gearing correctly, the numbers could shift low or high, as in my case. If he didn't let you get into your powerband, your numbers will be low. Even incorrect tire pressure on a dyno will affect the outcome as well.

Nothing wrong with your car, rayjay, but if you want accurate numbers (at least as accurate with drum style dynos) get a dyno test on a DynoJet, and include an air/fuel study too. That 411 will save you an engine rebuild...IMHO.