FrontEngineDragsters.Org Forum
Drag Racing Discussions => Front Engine Dragsters => Topic started by: retroboy on April 19, 2015, 03:56:28 AM
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Howdy. I've just finished the rebuild of an old FED just in time for our Aussie winter so I stripped it this afternoon to get ready for paint and detail.
I have a 31" tyre, 4.3 gears and no trans brake so will leave around 3/3,500 RPM. I'm going to change to 4.56 gears. What RPM are you guys with similar set up's running on the top end of the eighth.
Cheers
Tony
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Howdy. I've just finished the rebuild of an old FED just in time for our Aussie winter so I stripped it this afternoon to get ready for paint and detail.
I have a 31" tyre, 4.3 gears and no trans brake so will leave around 3/3,500 RPM. I'm going to change to 4.56 gears. What RPM are you guys with similar set up's running on the top end of the eighth.
Cheers
Tony
Lots of good calculators here. http://www.wallaceracing.com/Calculators.htm
Plug in some numbers and away you go. George
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Thanks George I looked at there race simulator a while back and aI thought it read a bit high so I was just looking for a few "real world" results from any similar combos
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I just looked at my RacePak, with my 4.56 gear and 31x12x15 Goodyear D2585 on 12" wide wheels, my 1/8 mile ET was 4.488, 152.54 mph, and 8365 RPM, on another run my 1/8 ET was 4.463, @ 157 mph, and 8440 rpm. The difference is in the converter, and we were making more power when we ran 157mph. BTW that run was 7.029 1/4, @ 187.52 mph, racing our Hemi in JrFuel Heritage.
I hope this "real world numbers" helps you. One thing to keep in mind is the D2585's will grow more when on 10" rims than 12" rims.
I have been asked about tire growth, but my Computer confirms the on-line calculations on gear-tire dia-mph-rpm, because the tire growth seems to cancel-out with the converter slip. Just trust the math.
Jon