Turbo & Gearing
Turbo & Gearing I know this belongs in the Gears section, but it is focused on the turbo crowd, so i posted it here.
I currently have 3.42's in my street/strip turbo car with a TH400. i've gotten down to a 1.342 60ft with the 3.42s with little work, and am confident i can hit 1.2's. The thing is, i might be doing some changes with my rear-end, and would like to take some gear out. I sort of want the car nicer to drive in the street (still trying to get used to the lack of O/D, used to be an M6 car), but not at the noticeable expense of track performance.....
With my 12 bolt, unfortunately i can only go from my 3.42's to 3.08's. What are your thoughts?
I MAY be going the 9" route, in which i would be going to a 3.2x gear. Thoughts?
What are you bigger guns running? The car went 9.1's, and I'm planning to be down towards 8.5.... but i'm still learning the Auto world, and what does and doesn't typically work. Thanks for any advice
I currently have 3.42's in my street/strip turbo car with a TH400. i've gotten down to a 1.342 60ft with the 3.42s with little work, and am confident i can hit 1.2's. The thing is, i might be doing some changes with my rear-end, and would like to take some gear out. I sort of want the car nicer to drive in the street (still trying to get used to the lack of O/D, used to be an M6 car), but not at the noticeable expense of track performance.....
With my 12 bolt, unfortunately i can only go from my 3.42's to 3.08's. What are your thoughts?
I MAY be going the 9" route, in which i would be going to a 3.2x gear. Thoughts?
What are you bigger guns running? The car went 9.1's, and I'm planning to be down towards 8.5.... but i'm still learning the Auto world, and what does and doesn't typically work. Thanks for any advice
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Verdad Gallardo well i was trying to figure out how much TC slip i will have. at the end of the year i had my TC replaced with something much tighter and stronger. my first one was giving up by the 1/8th (but rocked at the line!). the second one lasted me through the traps, but i think when i start to really push the turbo, i might be in the red zone with the 3.42's and the current stall.
i shift around 6500-6600, but will rev to 7200ish if i need to, which i don't yet with this converter and boost.
all that aside, when i turn up the wick, i think i can band aid the stall with gears, but again, i think 3.25's would be optimal, not 3.08s. I'm still teetering between a 9inch and my 12. problem is, if i go 9inch, i want shortened axles, which would force me to get new rear wheels and drag brakes, UGHHH!!!
i shift around 6500-6600, but will rev to 7200ish if i need to, which i don't yet with this converter and boost.
all that aside, when i turn up the wick, i think i can band aid the stall with gears, but again, i think 3.25's would be optimal, not 3.08s. I'm still teetering between a 9inch and my 12. problem is, if i go 9inch, i want shortened axles, which would force me to get new rear wheels and drag brakes, UGHHH!!!
I did not mean any gear in the 3.xx range, he said he was considering going to a small numerical gear. So Ill stick with my comment that anything from 3.42 to 3.08 will be fine. If either gear turns out to be not absolutely perfect he could change tire heigth to fix it.
You want the car to go through the traps at the peak rpm, ideally. A 3.25 gear on a 28 in. tall tire will go 160 mph with 10% slippage. That gear should be perfectly fine for what your goals are. On the other hand a 3.08 will add about 10 mph with the same slippage. If you put the 3.08 in it, it will probably slip alittle more on the top end, but again I think either would be fine. the 3.08 will be better on the street and give up a small amount on the track, and the 3.25 will work vise-versa.
ya that's pretty much what i figured going into it. 160 is probably where i'll be at all said and done. im done messing around in the street, other than just giving it a quick blurp. been there, done that; outa that scene. ideally i'd go with a 9", but like i said, if i do that, i'm going to want the goods! 
I did not mean any gear in the 3.xx range, he said he was considering going to a small numerical gear. So Ill stick with my comment that anything from 3.42 to 3.08 will be fine. If either gear turns out to be not absolutely perfect he could change tire heigth to fix it.
Why do people just "try" gears and hope for the best, then think about changing a tire to compensate? Why not just do the simple math equation, get the right gear, and not have to **** with setting up a car for a different size tire?
i understand 100% how to choose an optimal gear for the track. im just having an issue with drive ability and gear availability
Are you reading this thread or just the part that concerns you and responding? I did the math above, and not everyone can accurately predict exactly what there combo is going to run.
I ran a 3.50 with a 32" tire and it worked out great. this time it's going to be 3.08's with a 28" tire since that is the lowest numerical gear I can get. but, if I could get a 2.73 for this 12 bolt, that's what I would be running.
I don't believe in that redline at the end of the traps theory when it comes to turbo STREET cars. that is na math. it's always nice to have a little extra headroom on the gear because when you up the boost, you are going to get more converter slip and more rpms through the traps.
I don't believe in that redline at the end of the traps theory when it comes to turbo STREET cars. that is na math. it's always nice to have a little extra headroom on the gear because when you up the boost, you are going to get more converter slip and more rpms through the traps.
trap speed is the one thing you need to know. then you need to know your max rpm.
then you can play with tire size and gears.
but if you use a 28" tire th-400 (3rd gear 1.0) with a 3.08 gear and a max rpm of 7000 you can go 189mph not including converter slip
same set up but 3.23 gears is max or 181
3.42 170
2.73 214
then you can play with tire size and gears.
but if you use a 28" tire th-400 (3rd gear 1.0) with a 3.08 gear and a max rpm of 7000 you can go 189mph not including converter slip
same set up but 3.23 gears is max or 181
3.42 170
2.73 214
