I put my race car on the chassis dyno a couple weeks ago. I thought you all may be interested in the results. If I did everything right the dyno sheet is posted below.
This motor has ported exhaust manifolds and a relatively free exhaust. I'm running Joe Wynman's computer chip. Other than that it is completely stock and it has about 160k miles on it. Peak torque was 149.8 lb-ft at about 3600 rpm. Peak hp was 115.8 at about 4600 rpm. This is a 17% loss from the 140 hp at the crank that GM claimed, so it sounds about right.
One thing I found interesting is that the tach isn't accurate. On both runs I didn't back out of the throttle until the tach said about 6200 - 6300. The dyno sheet shows that this is really 5600 - 5700.
For those of you who don't know me from other lists, I have an '85 GT that I rally. I'm in the process of building a new motor for it so I wanted to dyno the old one for a base line. The new motor should be in the car some time in May and I'll get it on the dyno.
My next rally is Oregon Trail (http://www.oregontrailrally.com) near Hillsboro, OR on April 19-21. If anybody is interested in attending let me know.
Doug Chase Duvall, WA '88 Fiero Formula 5-spd (autocrosser) '88 Fiero GT 5-spd (daily driver) '85 Fiero GT 4-spd (rally car) '86 Fiero GT 5-spd (organ doner for rally car) '86 Fiero GT 4-spd (fixer-upper, 4 sale soon)
Originally posted by Mach10: Is it an auto? If not, maybe you have a slipping clutch?
The tach error wouldn't be caused by a slipping clutch. They usually use an inductive pickup in order to get the tach reading. Otherwise they would need to calculate gear ratios, tire sizes etc. which wouldn't be very accurate and could cause that much of an error.
I am not sure if this is what you meant though due to your limited response. Would you care to clarify?
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02:49 PM
Doug Chase Member
Posts: 1487 From: Seattle area, Washington State, USA Registered: Sep 2001
looks like your having ign. mapping issues in the upper rpm range... with 160k it should still pull better.. have you done a leak down or compression test? i just dynoed an 85 that made 124/153 (MylesF7s new toy) https://www.fiero.nl/uploads/mylesf7dyno.jpg
put the stock chip back in it.. i bet it'd run better.
Since the exhaust mainfold mod is documented good for 8 hp that would put the driveline loss at >25% that makes more sense when you look at recent 3.4 dyno runs.
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03:02 PM
vortecfiero Member
Posts: 996 From: Toronto Area, Canada Registered: Feb 2002
Originally posted by 1FST2M6: put the stock chip back in it.. i bet it'd run better.
From what I remember Wynman's chip only altered a few things from the stock one. So the fuel curve is still the same. The major thing it eliminated was that annoying bump when the fuel cuts in at around 2000 RPM.
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06:16 PM
vortecfiero Member
Posts: 996 From: Toronto Area, Canada Registered: Feb 2002
Originally posted by Jefrysuko: From what I remember Wynman's chip only altered a few things from the stock one. So the fuel curve is still the same. The major thing it eliminated was that annoying bump when the fuel cuts in at around 2000 RPM.
Yep. And he disables the EGR in software. That's the primary reason I have it since I removed the EGR hardware.
I noticed no seat-of-the-pants performance difference between the stock chip and Joe's.
------------------ Doug Chase Duvall, WA '88 Fiero Formula 5-spd (autocrosser) '88 Fiero GT 5-spd (daily driver) '85 Fiero GT 4-spd (rally car) '86 Fiero GT 5-spd (organ doner for rally car) '86 Fiero GT 4-spd (fixer-upper, 4 sale soon)
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06:30 PM
PFF
System Bot
lou_dias Member
Posts: 5350 From: Warwick, RI Registered: Jun 2000
Hrm, does Joe's chip add enrichment when it removes the EGR?
If so, I'd definately be intrested (fscking solonid crapped out on me.)
I won't run an ERG equiped car withought an EGR-delete PROM though.
Best! Ben.
------------------ Ben Cannon 88 Formula, T-top, Metalic Red. "Every Man Dies, not every man really Lives" 88 Formula, Northstar, Silver, In-Progreess. -Mel Gibson, "Braveheart"
