I trap around 6400rpm right now and want to know how much it would drop if I went to a 3.23 gear. I am out of my little cam's power band and want to bring it down a few 100 or so. Couldn't find a good calculator on the web to determine this. Thanks.
3.42 to 3.23. How much trap RPM drop?
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thunderace31
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Try Using OD (4th gear) will drop your rpm and most likely get you more MPH325DR said:
Worked for me
The short answer is 3.23/3.42*6400=6044, but this doesn't take into account converter slippage. If your converter is not locked up you will see less of a drop. There are some useful calculators at http://www.tciauto.com/tech_info/calculators.htm
I just did this and here were my results.
mine dropped about 250 RPM when i did this change. Sometimes if you have a loose converter then the gear change will load the converter more making it slip more which equates to less change in RPM than expected.
It did not seem to affect the 60' times at all. The car felt more sluggish on the street even though it picked up at the track.
mine dropped about 250 RPM when i did this change. Sometimes if you have a loose converter then the gear change will load the converter more making it slip more which equates to less change in RPM than expected.
It did not seem to affect the 60' times at all. The car felt more sluggish on the street even though it picked up at the track.
Jason, how did it affect your et and mph at the track? Most converter efficiency plots I've seen are pretty flat that far above the stall speed so the slippage should be approximately a constant number of rpm, so subtract that from the engine rpm and then multiply the remainder by the gear change ratio, then add back the slippage to get the final rpm. So if he is at 6400 rpm and has 400 rpm of slippage, than his rpm after the change would be 6400-400=6000, *3.23/3.42=5667, +400=6067 rpm, compared to just taking 6400*3.23/3.42=6044, so with 400 rpm slippage he would see 23 rpm less of a drop than expected. I guess you could compare the rpm drop on the 2-3 shift with the 3-4 shift to see if the slippage is different but my guess is that there isn't going to be much of a change in slippage with that load change that far over the stall speed.
I changed to many things at once to tell where i was picking up what.
In theory and on paper what you are saying is correct but it did not turn out like that when i actually did it and the only thing i can really attribute the difference or error from is the added load.
In theory and on paper what you are saying is correct but it did not turn out like that when i actually did it and the only thing i can really attribute the difference or error from is the added load.
