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TOPIC: Perplexing Dyno Results

Re: Perplexing Dyno Results 4 years ago #19591

Well, 1st we have the dyno operator get the car warm enough to meet the specs in the rules at a minimum - if the car is cool, that can sometimes take a bit. The benefit of warming the car n the dyno is that is also warms the gearbox. If a the motor is warm, but the gearbox is cold, I've seen it take 7-10 runs to get the number to stabilize. If the car is just off the track, then it is typically warm, and 3-4 runs will often do it. If the car is waiting for others to dyno, then getting it hot on the dyno is often needed. Then there are other variables - cars with big oil coolers take longer, etc.
Eric Kuhns

National Director Emeritus

2007, & 2008 National Champion
2011, 2012 2nd
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Re: Perplexing Dyno Results 4 years ago #19593

  • tcomeau
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  • Posts: 287
I'm not sure the dyno operator would allow 7 or so pulls in order to stabilize readings?
I would love to have them stick the sniffer in the tailpipe to check AND DISPLAY the air fuel ratio, but they charge extra for that, I'm told.
What other resources can we involve to find the unknowns here? I'd like to cut the head off this dragon because it's been the low point of the last two WC Championships in an otherwise stellar showing of comraderie, teamwork and clean, hard racing by the 944 Spec class.
Eric, you seem to have the most experience with the dyno's.
If temp is the biggest factor, we can do something like jack up the rear end of the car and run it at 3,000 rpm for x amount of time in 4th gear just prior to the dyno? It's not a true load, but?
Tim Comeau
SoCal 944 Spec #22 since Feb 2003.
Let's keep building it!
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Re: Perplexing Dyno Results 4 years ago #19596

The dyno operators love turnover for business, but I think this is part of the problem. I think we have to insist on getting good data. 3 runs have to be good ones. I think if we make it a point to have them just run it for a whiel to get the gear temps up, then less actual pulls would be required. I'd agree the A/F is nice if you don't have a display. Alberto's first dyno runs were definitly more rough.

I've never tried putting the car on jack stands before the dyno run. I'm going to put a trans temp gauge in my ST car, I'll see how long it takes to build temps.

I think we've pulled this apart as much as we can for now. We'll follow this with the ECC, and can then have a broader discussion after that. We've been at this a few years, it will be time to review.

Tim I do appreciate the efforts you made to get the cars checked well - check temps, pressures etc.
Eric Kuhns

National Director Emeritus

2007, & 2008 National Champion
2011, 2012 2nd
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Re: Perplexing Dyno Results 4 years ago #19597

  • AgRacer
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I've been running a trans temp gauge in my car for over a year now. Its the right most gauge on my dash so you can watch it build temps through the session. Its a dumb sensor in the drain port on the trans so I cant run data to my traqmate for logging, unfortunately, like I can with my wideband. One VIR event I annotated the gauge reading throughout the session in the video.

youtu.be/rhOVv-Hn_mM
J. Stanley
NASA-SE Region 944 Spec Series Director
Yellow #60
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Re: Perplexing Dyno Results 4 years ago #19600

First I'm glad I'm not racing against you at VIR - nice work!
It looks like it takes a lap and 1/2 or so to get some temp in it (>150), but it keeps building temp through 7 laps to about 210. This is in pretty cool conditions.I'm not sure where the bell curve lies inpower production with regard to temps, but it will be interesting to put your car on the dyno at the ECC, and correlate temps.
Eric Kuhns

National Director Emeritus

2007, & 2008 National Champion
2011, 2012 2nd
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Re: Perplexing Dyno Results 4 years ago #19602

  • afonseca
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  • Junior Racer
  • Posts: 75
Sterling Doc wrote:
The dyno operators love turnover for business, but I think this is part of the problem. I think we have to insist on getting good data. 3 runs have to be good ones. I think if we make it a point to have them just run it for a whiel to get the gear temps up, then less actual pulls would be required.


I'm not sure how many dyno's are available at the ECC but at Laguna Seca there were only 2, and I believe 1 of them was designated the NASA compliance dyno? As such, when I drove up the hill to the dyno I was placed at the back of a long queue of cars and the whole process probably took a couple of hours. This is why I sat in my car idling/fast idling both on Friday and Sunday to keep the temps up. So this may be more of a NASA concern but the long lines might make it a challenge to warm up the cars on the dyno while everyone waits.

#44 Alberto Fonseca
? Region
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