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Trying to figure engine rpm's

1K views 4 replies 4 participants last post by  PhattyBanks 
#1 ·
I maybe am searching for the wrong things I don't know. I have searched all over Google and many forums and I haven't found what I'm trying to figure.

I am planning on swapping a 1990 7.3idi into my bronco, I am going to use a ZF6 transmission out of a 2000 powerstroke.

I'm trying to figure what my engine rpm's are going to run. It is mainly going to be a road vehicle with limited off road use *Hopefully it will see moab a couple times*.

The zf has a 0.72 6th gear ratio, my Bronco has a 3.50 geared 9" rear end and 32" tires. If I swap it right now using all this what will my rpm's be at 55 mph or 60.

If I overlooked something let me know I cant find anything right now though......
 
#4 ·
Here's all the formulas you'll need. You can figure out any of the following if you have the necessary information.



Tire Diameter = (Speed * Transmission Gear Ratio* Final Drive * 336) / RPM

Speed = (Tire Diameter * RPM) / (Transmission Gear Ratio * Final Drive * 336)

Transmission Gear Ratio = (RPM * Tire Diameter) / (Speed * Final Drive * 336)

Final Drive = (RPM * Tire Diameter) / (Speed * Transmission Gear Ratio * 336)

RPM = (Speed * Transmission Gear Ratio * Final Drive * 336) / Tire Diameter
 
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