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UNPREDICTABLE DYNO RESULTS


panozracing

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OK…here is the issue.

 

My local dyno (dynojet at Steeda) gives me 1 result.

 

My local race shop (dynotech I think) where we get some work done gives me results 25hp more

 

At Mid-Ohio (dynojet) we got dyno’ed and the results where 30hp less than the dynojet at Steeda and 50hp less than my race shop.

 

How are we supposed to tune the cars to get close to our allowable limits?

 

And just to set the record straight (read some grumblings on the forum) our engine produces the same torque (actually slightly less) as horsepower so there is no torque abuse of the rules coming from my car!

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In my experience you tune at the track, on the dyno you will be tested on.

That is the only way you can be absolutely sure.

 

ideally yes but the dyno is not the most convient thing to do at nationals. it would be nice to have one less thing to deal with and concentrate on the setup and maybe get some sleep.

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Supposed to use Dynojet corrected #'s.......................

 

They are corrected numbers and still all over the map. Have you been tested at diff. facilities and get similar results?

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Supposed to use Dynojet corrected #'s.......................

 

They are corrected numbers and still all over the map. Have you been tested at diff. facilities and get similar results?

 

I do two different Dynojets in Cincinnati and typically they are with ~2-3 rwhp.....

 

I never had the opportunity to be "invited" to spin a number @ Nationals in '08 , but I know for fact that my teammates car dynoed 10-11 more on the dyno at Nationals than back here in town. Caused me to throw in an extra "brick" just in case.............

 

In '07 the dyno @ Nationals (the same one used in '08, same people exact same dyno), read exactly the same as the one in town...........

 

Probably best to use the dyno @ the race facility, if there is one available....you just never know I am finding out.

 

What was your pwr/wt ratio @ Nationals that you were required to run ???? I never had a chance to look at your sheet. If you dont mind me asking.........

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Is it possible NASA could approach one make , say Mustang, and receive a sponsorship/endorsement to have a NASA official dyno company that we all can use to level the disparities.

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Is it possible NASA could approach one make , say Mustang, and receive a sponsorship/endorsement to have a NASA official dyno company that we all can use to level the disparities.

 

They do have an official dyno.

It's Dynojet.

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Yes the DynoJet is the official dyno. I am baffled. I went to Steeda and they dynoed the car and that was what we tuned for. They have a dynojet. Than I got flagged for a dyno at nationals and I was 30+ hp lower. I could have tuned that additional power in if I had prior knowledge.

 

Does anyone know what the dyno operator might be doing to cause the errors or what could cause these variations? I was told that the correction factor of the dyno adjusts for temp and humidity so that is not the cause. When I got checked at Mid-O it was wet. Could that cause wheel spin that resulted in the lower number? They did at least three pulls so I would think that would eliminate wheelspin errors.

 

I want to be able to tune the car to as close of a number (leave some small amount of variation) as possible. I would hate to haul ALL the way to Miller and find out that dyno is 30 hp higher than Steeda and now I am in violation and I cannot correct it so I am DQ'ed.....

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The best advice I can give is make sure that the temp, altitude, and barometric pressure are accurate for the dyno run. The SAE corrected number is worthless without the right info. Don't trust the operator. Check w/ the local weather guys/ flight service,etc..for pressure/ altitude (elevation) and humidity.

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  • National Staff

Also, usually, the Dynojet's are within a few hp of each other regardless of location. However, just because they have a program to adjust to SAE numbers doesn't mean that your car is not actually operating differently under different environmental conditions. Remember, most of our cars now have computers that also take that same info into account (like intake air temps, 02 levels, etc), and then adjust the engine to perform differently (change timing, etc) depending on the situation. A good example is that my turbo car ECU allows the car to make more boost pressure when it is hot outside than when the air is cool and more dense. So, there are more variables in play than just one Dyno vs another. However, Matt is correct that if they do not have the correct air temp and other factors input, you can't expect a reliable results. Garbage data in = garbage data out.

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