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Stock Motor Dyno Question

Stock Motor Dyno Question

Old 01-31-2007, 02:01 PM
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Hey everyone, got a question I have a fantom dyno and I was using the oval gearing calculator and the pinions and spurs...It told me that I should run a 72/34 and I am running a Tc4...The biggest problem I am having is that the 34 pinion will not fit in my car...Do you guys have any suggestions and input on how acurate the gearing program is on the dyno? Or what I should do to check whether or not the gear ratio is correct? thanks in advance Jeff
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Old 01-31-2007, 02:04 PM
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Originally Posted by jeffbhhs
Hey everyone, got a question I have a fantom dyno and I was using the oval gearing calculator and the pinions and spurs...It told me that I should run a 72/34 and I am running a Tc4...The biggest problem I am having is that the 34 pinion will not fit in my car...Do you guys have any suggestions and input on how acurate the gearing program is on the dyno? Or what I should do to check whether or not the gear ratio is correct? thanks in advance Jeff
go to a smaller spur
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Old 01-31-2007, 02:08 PM
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I could be wrong but if you find the roll out your looking for with the gear the computer tells you then change your spur gear and pinion gear sizes but keeping the same roll out you should be fine. Basically if thats the roll out your wanting to run you will have to find the gear that fits the car. This happens alot with oval cars as well. Its just a simple change.
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Old 01-31-2007, 04:00 PM
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Default TC4 large pinion

Get you Dremel out.

You need to remove a little from the webbing under the pinion. Also, fit the aluminium cam to the motor and turn it as far as it will go for a big pinion. Note where it touches (and is stopping you turning any further) and file material away to make it turn further. You will need to do this in two places on the cam. I did this and managed to get a 37/72 combination with no problems.

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Old 02-02-2007, 09:57 AM
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Originally Posted by donwhit
Get you Dremel out.

You need to remove a little from the webbing under the pinion. Also, fit the aluminium cam to the motor and turn it as far as it will go for a big pinion. Note where it touches (and is stopping you turning any further) and file material away to make it turn further. You will need to do this in two places on the cam. I did this and managed to get a 37/72 combination with no problems.

regards

Don
Thanks for the replies, I may just try going to a smaller spur prior to using the dremel. Hopefully that will work, Is it just me or does that ratio seem like the car would be overgeared? Up until I purchased the dyno I was running a 29/72 combination and I was doing well, it seems like a huge jump to me... That why I was thinking that the numbers may be wrong somehow...

Also how does the RPM Factor work for the gearing? I was told by someone at the track that I should simply enter in the number that is on the bottom of the screen, says something like 47% at 13000 rpm i think so my rpm factor would be 47%? is that correct?

Last edited by jeffbhhs; 02-02-2007 at 10:33 AM.
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