why don't people put 4.10s in autos? what would be the RPM at 70 MPH? what would be the top speed?

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-Tas
'89 Formula WS-6
[soon to have Hooker 1-5/8" 50 state legal headers installed]

305, TBI, auto, 14x3 chrome flat based open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

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You're a student...why don't you engineer a system that will manufacture the answer!

 

250+



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Eric Natzke
91 Firebird 305 TBI
"It Ain't Stock"
http://members.aol.com/j007golden/91firebird.html
For info on certain parts or mods go to the site below
http://members.aol.com/j007golden/modeval.html

 

smartasses I'm busy doing my multivariable calculus homework thank you

 

Well this calculator says at 65mph you'd be turning 2,558rpm. That's in overdrive of course with the converter locked.

If you count 4500 as the top sustainable RPM then you could go at 114mph 4500rpms.

I used 24.5 inches for mine, I just did a rough measurement though. My wheel and tire size are still stock.

This is the Calculator http://www.prestage.com/carmath/calc_Gears.asp


A transmission lookup table
http://www.prestage.com/db/default.a...b_trans_ratios

[This message has been edited by Keith5 (edited March 18, 2001).]

 

4.10's are a bit on the wild side considering the th700 (aka 4L60) both have deep 1st gears. It might work if you're a drag setup car but I don't see the advantage of 4.10 gears on a street car. I'm looking at 3.73 gears even with the engine swap.

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, Jon (in process of installing new engine)

 

I've got 2.73's now, I'm thinking about 3.23's or 3.42's with a posi unit this summer. I like my low rpm's I have now, I just want a little less "bog/lag" of the 2.73's.

I've drove bullfrawg's car, he has a th700 with a 3.27 ratio, I think that's about optimal for me. I've drove my IROC and my brother's 94Z with 3.42's in both, I didn't like turning the exta RPM's.

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1989 Pontiac Firebird Formula LO3 Auto
-180 degree stat
-Hooker Cat-Back
-vinyl security shade, velcro t-top bag
*****Possible summer '01 mods*****
Dual Snorkle, Auburn Posi, Keyless Entry, Wonder Bar from my IROC, 4th gen seats, T/A tail lights

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