What RPM for What Gear Ratio???
04-13-2012, 09:21 PM
#1
Burning Brakes
Thread Starter
What RPM for What Gear Ratio???
I have 1986 automatic coupe. I just had the trans rebuilt with a shift kit and a 2300 stall. I was going to install a 3.54 rear. My question is does anyone know what RPM I will be turning at 65 - 75 MPH with the 3.54?? Is there a formula?? Now that the trans is rebuilt the car runs 100% better and I not sure if I want to install a 3.54 now.
thanks for the help
thanks for the help
04-13-2012, 10:01 PM
#2
Le Mans Master
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2240 @70
2400 @75
Play here
http://www.bgsoflex.com/rpmmph.html
Allow 0.70 for trans gearing in 4th (the O/d ratio in auto ) and 26" tires
1.0 for 3rd gear calculation
Last edited by rodj; 04-13-2012 at 10:08 PM.
04-13-2012, 10:06 PM
#3
Le Mans Master
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2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Here is a simple MPH calculator I made in excel. The yellow highlighted boxes are ones where you input values.
Last edited by Kubs; 04-13-2012 at 10:15 PM. Reason: Uploaded wrong file
04-14-2012, 06:12 AM
#4
Team Owner
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With 2.59 rear gears and the A4 in OD my engine turns 2,000rpm at 80mph; you can ratio from there to get RPM at whatever MPH and with whatever rear gears.
04-14-2012, 05:41 PM
#6
I use the one I made all the time.
04-14-2012, 05:57 PM
#7
Le Mans Master
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2023 C5 of the Year Finalist - Modified
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St. Jude Donor '09-'10-'11
The one I made was done in about 30 sec cause I needed it at one point. I never felt the need to make it fancier.
04-14-2012, 09:01 PM
#8
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St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-'18-'19-'20-'21-'22
'23-'24
Just be aware that your long tube runners will be out of breath very quickly with 3.54s. I've found my 3.07s are a great all around choice, but depending on your style of driving you might want a bit more.
Just my opinion mind you, I'm sure others will chime in. Just be aware that an L98 based motor is completely different than an LT.
Just my opinion mind you, I'm sure others will chime in. Just be aware that an L98 based motor is completely different than an LT.
