Heavier Wheels/Tires = Lower Dyno HP
#1
10-10-2004, 09:44 AM
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Heavier Wheels/Tires = Lower Dyno HP
I was reading my latest copy of European Car (Dec 2004), and there is an update on Project Street S MINI -- Part 7: Bigger intercooler and gauge kit.
First, some background, before I talk about the subject of this thread:
They are trying to get 200 whp. They had gotten 191 whp last year on the dyno (runs performed by evosport), but this year with 10k more miles on the car, they got over 25 hp less. They found their (old) spark plugs were gapped at .045, too large for a 12 psi boost. The new plugs had a gap of .040, but they made them .035 to be safe, then the car dyno'd at 188.2 whp. They were happy.
They added an Alta MINI performance intercooler and oil catch can. With the intercooler they got the option for a nozzle that sprays (ambient temp) water onto the face of the intercooler for even better cooling. However, the dyno runs showed little to no gain. They could not understand why that was. The new intercooler was much cooler to the touch than the stock, however (a good thing). They tried Sunoco 104 octane and got 196 whp. They had a slightly leaner air/fuel mixture measurement of about 12.1:1, probably due to the larger volume in the intercooler core. They speculated that using a gallon or two of 104 unleaded race gas for every tank (with 91 octane) -- bringing the overall mixture up to 92 to 93, should bring spirited driving during the California summers. If you visit a hot road course, they suggested using a mixture closer to 100, blaming the rising intake temperatures. Overall, they had gotten a good boost, registering 12.5 to 13 psi at full throttle, measured on newly installed Promini's twin gauge pod (mounted on the steering column on either side of the speedometer) -- electric Autometer boost and oil pressure gauges -- they said every Cooper S should have these gauges.
Back to the point of this thread:
They said, "The heavier 18-in. wheels and 225mm tire setup could be the culprit in not reaching the goal, but we'll move forward regardless. Next time we should see over 200 whp, even with these wheels and tires. Stay tuned."
So, this is evidence of a big-name magazine saying that (probably) heavier wheels/tires make a difference on the dyno. I know this is not conclusive, but it leans heavily in that direction. :smile:
First, some background, before I talk about the subject of this thread:
They are trying to get 200 whp. They had gotten 191 whp last year on the dyno (runs performed by evosport), but this year with 10k more miles on the car, they got over 25 hp less. They found their (old) spark plugs were gapped at .045, too large for a 12 psi boost. The new plugs had a gap of .040, but they made them .035 to be safe, then the car dyno'd at 188.2 whp. They were happy.
They added an Alta MINI performance intercooler and oil catch can. With the intercooler they got the option for a nozzle that sprays (ambient temp) water onto the face of the intercooler for even better cooling. However, the dyno runs showed little to no gain. They could not understand why that was. The new intercooler was much cooler to the touch than the stock, however (a good thing). They tried Sunoco 104 octane and got 196 whp. They had a slightly leaner air/fuel mixture measurement of about 12.1:1, probably due to the larger volume in the intercooler core. They speculated that using a gallon or two of 104 unleaded race gas for every tank (with 91 octane) -- bringing the overall mixture up to 92 to 93, should bring spirited driving during the California summers. If you visit a hot road course, they suggested using a mixture closer to 100, blaming the rising intake temperatures. Overall, they had gotten a good boost, registering 12.5 to 13 psi at full throttle, measured on newly installed Promini's twin gauge pod (mounted on the steering column on either side of the speedometer) -- electric Autometer boost and oil pressure gauges -- they said every Cooper S should have these gauges.
Back to the point of this thread:
They said, "The heavier 18-in. wheels and 225mm tire setup could be the culprit in not reaching the goal, but we'll move forward regardless. Next time we should see over 200 whp, even with these wheels and tires. Stay tuned."
So, this is evidence of a big-name magazine saying that (probably) heavier wheels/tires make a difference on the dyno. I know this is not conclusive, but it leans heavily in that direction. :smile:
#2
10-10-2004, 05:24 PM
This subject has been discussed before-
https://www.northamericanmotoring.co...ad.php?t=24843
Bottomline- with a load dyno there will be little difference caused by the weight of the wheels.
There is a link to a dyno done with two sets of wheels (light and heavy) that showed the results are the same.
Also see comments by Helix13.
Careful how you interpret dyno numbers as they are only a rough measure of performance.
https://www.northamericanmotoring.co...ad.php?t=24843
Bottomline- with a load dyno there will be little difference caused by the weight of the wheels.
There is a link to a dyno done with two sets of wheels (light and heavy) that showed the results are the same.
Also see comments by Helix13.
Careful how you interpret dyno numbers as they are only a rough measure of performance.
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