PCM Diagnostics & Tuning - HPT A4 Shift question with 3:73 Gears ,Rpm=Mph?
07-21-2005, 04:48 PM
Does anyone know what RPMs = MPH in 1st ,2nd and 3rd gear?
I think this is it if I remember right.
1st gear=149 rpm = 1mph
2nd gear=89 rpm = 1mph
3rd gear= 54 rpm = 1mph
07-21-2005, 04:57 PM
depends on your rear tire but I'm getting
1st = 149RPM/MPH
3rd = 49RPM/MPH
I just used the gear calculator on f-body.org (http://www.f-body.org/gears/) and divided appropriately
This was w/the 25.66" diameter rear tear
Keep in mind though you can't go by this w/an A4 w/a bigger aftermarket converter... the converter slips so you're never getting 100% of your RPM as useable (unless you lock the converter)
When I adjust my WOT tables I prefer to just use the RPM tables... I set the MPH real low for WOT shifts, but set the RPM to whatever I want it to shift at minus about 150 RPM
07-21-2005, 05:14 PM
Thanks Horist.I have stock Tire Dia. P275/40 R17 Nitto Drag Radials Is that 25.625?I cant remember???
07-21-2005, 05:22 PM
Horist Thanks for the link ,but is this right?I had to use a 98 f body A4
???? I thought 4th was .6????
07-21-2005, 05:23 PM
Oh Crap I forgot to add Does a Stall Converter Change this?
07-22-2005, 08:54 AM
YES! In fact if you log your Engine Rpm (SAE) and you Trans Input Shaft RPM, you can figure out what your efficiency is. Then mearly multiply your results from F-Body.org by that number for your true reading. I recently verified this with my B&M converter (which is 97% effiecient) and multiplied the results from that calculator and they matched my logged info.
07-22-2005, 04:47 PM
Ok cool Thanks!!