Dyno Consistency Technical Question

Sanctus · Oct 6, 2006

Alright so i understand that these mustangs have anywhere from 255-280 rear wheel horsepower on the stock engine. but what i dont understand is how that number can vary so greatly. With two cars made around the same time, with the same options, tested by the same type of dyno, shouldnt they produce numbers that are more consistent?

I want to know is it the differences in the cars or in the factors of the dyno, like Temperature, humidity, elevation ect...

I would expect the cars with the sophisticated computer technology they intrinsically have, to have less outliers on this distribution of horsepower figures.

anyone have any technical reasons for this discrepency?

anthony05gt · Oct 6, 2006

I'm not a dyno guru, but there are different types of dynos out there. For example, a Dynojet measures hp and tq by turning a massive roller to give what are considered inflated numbers unless corrected using some math. A Mustang dyno has the car turning a massive roller which also has a contraption similar to an electric motor which applies a load to the roller which simulates the actual vehicle's weight. I believe it also needs other information about the vehicle entered into the dyno's computer which is also taken into account. The result is a more accurate and usually lower hp figure than a Dynojet would show unless corrected. My car showed 490 peak hp on a Mustang dyno and probably would have shown about 515 peak hp on a Dynojet. I don't know how true it is, but I've even heard of some different results between Mustang dynos. Not only that, but a car that's just a little hotter than another or atmospheric conditions such as temp, humidity, etc. play a huge roll in the differences.

red05bullitgt · Oct 6, 2006

Another reason is not all dynojets are calibrated the same, in addition the S-197 Mustang also has 10 different ECM's in which each one also has a different calibration as well, which also plays a significant role in how the readings are affected..

bronco78 · Oct 7, 2006

Your question, the answers, are the reason people interested in finding out who has more HP, race on the drag strip, and not on the dyno. There are to many variables, those mentioned, plus the operator them self, and temp, atmosphere, hundreds of possible settings between the dyno and vehicle itself all effect dyno numbers. No one in the know tries to compare dyno numbers from one car to another, unless they were both run on the same dyno, on the same day, by the same operator. What you can do very successfully is use a dyno to tune your car based on real world needs while it is running. And if you have a local tuner with a dyno,, you can use that same dyno to mark and gauge power increase as you mod your vehicle.

The Dyno of today is a very complicated testing instrument.. and the readings printed out at the end of the run are only partially determined by how much HP and TQ the motor produced.

anthony05gt · Oct 7, 2006

That's not completely true. Even though you'll have variables on the dynos that are beyond control, there are even more on the race track. You could have 2 identical cars on the track except one has a little more power than the other and it will still lose the race due to driver, tire choice, lane choice, etc.

Why are you typing huge letters? It's not any louder.

JTGrant · Oct 7, 2006

take it to the track

bronco78 · Oct 7, 2006

anthony05gt said:
That's not completely true. Even though you'll have variables on the dynos that are beyond control, there are even more on the race track. You could have 2 identical cars on the track except one has a little more power than the other and it will still lose the race due to driver, tire choice, lane choice, etc.

Why are you typing huge letters? It's not any louder.

Of course your correct,, driver, set up, lane choice, ect all play into it. My point in that sentence was not meant to be literal.. Racers find out who is best on the track, bench racing (with I'm faster because my dyno sheet says so) is a enjoyable pass time for some, but much removed from racing.

Not typing any loulder.. thanks for the hint, as I'm new to the internet. (Pasting in a reply from a text editer like Word will do that sometimes)

anthony05gt · Oct 7, 2006

I hear you man. All I know how to do is log on and type. I've got to get my son to do everything else for me.

Dyno Consistency Technical Question

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