FWD guys, 7500 rpms in 3rd = what mph?

Saxrulez · Jul 5, 2004

I cant quite figure this out. According to most gear/rpm calculators, I should be able to go much faster than 105mph in 3rd gear @ 7500 rpms, but that is EXACTLY what my car does when I leave it in 3rd at the strip...

I must have one of the variables wrong for the calculations...

Tranmission final ratio for fwd: 4.153
3rd gear = .88
Tire diameter = 24"

Is one of these wrong?

rrk5485 · Jul 5, 2004

Why would you want to drive past redline anyway?

Saxrulez · Jul 5, 2004

rrk5485 said:
Why would you want to drive past redline anyway?

I'm curious b/c eventually I plan on having a setup that pulls past 7500 rpms, not to mention the shift to 4th right now is currently at EXACTLY the wrong time. As soon as I get into 4th its time to shut it down.

noreaga0221 · Jul 5, 2004

rrk5485 said:
Why would you want to drive past redline anyway?

Sometimes when you trap around 103-105, you loose a tenth or two if you don't hit 4th quick enough.

Saxrulez · Jul 5, 2004

noreaga0221 said:
Sometimes when you trap around 103-105, you loose a tenth or two if you don't hit 4th quick enough.

werd!

Best time staying in 3rd(hitting rev limiter)
13.179 @ 105.11

Best time shifting to 4th
13.203 @ 106.26

Noreaga: Have you stayed in 3rd through the traps before? Kinda curious what mph you were at(sounds like ~the same as me though). Oh and check these out http://www.dsmtalk.com/forums/showthread.php?s=&threadid=121927 Right behind ya

diambo4life · Jul 5, 2004

Saxrulez said:
werd!

Best time staying in 3rd(hitting rev limiter)
13.179 @ 105.11

Best time shifting to 4th
13.203 @ 106.26

Noreaga: Have you stayed in 3rd through the traps before? Kinda curious what mph you were at(sounds like ~the same as me though). Oh and check these out http://www.dsmtalk.com/forums/showthread.php?s=&threadid=121927 Right behind ya

Personally, I don't think it would make that big of a difference. You can not absolutely pin-point your 3-4 shift to a higher ET. Maybe you were just slower through that run and not necessarily due to the shift. You cannot really say I had a 13.2 because I shifted to 4th in that run. Too many variables.

I am reading this months SCC and David Coleman (their engineering editor) says this...

...but even as you coast through a cumulative 1-second of shifting, the car is still rolling toward the end of the quarter mile, so quicker shift times actually have minimal effect on your e.t.

I would agree with him since it makes sense, he does alot of car tests and probably has the data to back up his statement.

Saxrulez · Jul 5, 2004

diambo4life said:
Personally, I don't think it would make that big of a difference. You can not absolutely pin-point your 3-4 shift to a higher ET. Maybe you were just slower through that run and not necessarily due to the shift. You cannot really say I had a 13.2 because I shifted to 4th in that run. Too many variables.

I am reading this months SCC and David Coleman (their engineering editor) says this...

...but even as you coast through a cumulative 1-second of shifting, the car is still rolling toward the end of the quarter mile, so quicker shift times actually have minimal effect on your e.t.

I would agree with him since he does that stuff for a living and probably has the data to back up his statement.

My whole run was faster

60', 330', 1/8, 1000'

just the 1/4 slower

Only by a little more than two one hundredths though.

Saxrulez · Jul 5, 2004

Oh and i just found my problem in calculations 3rd is 1.217

doh!

diambo4life · Jul 5, 2004

I also think since your car is FWD and loss of traction can skew that. I know with my AWD, when my MPH is different even by 1 mph and I get a slightly better 60", 330 etc, the ET drops automaticaly. So, I really don't know. FWD's could be different. I have run traps that were .5 mph apart and get better ET's with say a 1.90 to 1.87 60' improvement.

noreaga0221 · Jul 6, 2004

I did like 103 @ redline in third gear going through the traps once.

FWD guys, 7500 rpms in 3rd = what mph?

Saxrulez

rrk5485

Saxrulez

noreaga0221

Saxrulez

diambo4life

Saxrulez

Saxrulez

diambo4life

noreaga0221

Top Contributors this Month

Recommended Communities