Single Digit Club - 8 and 9 second guys, gears?

Hey guys, I'm thinking i'm gonna run a th400 tranny and i'm trying to deside on what gears to go with, what are you guys running or recommend? I currently have 4.10s in my Strange 12bolt, planning on a healthy shot of spray 200-250 range and i know what i have will run out of steam way too soon.

Thanks!
Mike

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Ran 8.50 with 4.10's in my slow car. Didn't run out of gear, crossed line exactly where I wanted. Problem is converter & gear work together, so it's not always easy to get right the 1st time on paper. Take tire size, current set up & future mph & try to make a guess or try it with what you have now. Don't forget the new converter will have less slip than what you have now. Good luck.

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I'd go with a 3.70 gear as a good starting point. Bob

What size tires, expected mph and whats your max rpm?

Use a calculator like this

http://www.csgnetwork.com/gearratcalc.html

Figure approx 5-10% converter slip that will raise your rpm through the traps if its an auto.

I use a 3.70, 28" tires and I see around 7200rpm through the traps at 152mph.

I think 3.73s will work absolutly perfect for my application. I'm not sure what it'll trap but i know i'm going to work twards the 150 mph mark. i'm thinking this year with a 200shot i should be close to the 135-140 range. Tire size is 28" tall. The 4.10s i have know will probly even help me for this year but i'm sure i will be limited on the amount of nitrous i can use. I should be able to rev it too 7000 rpm but if i can i'd like to keep it in the 6500 range. At least now i know i'm ballpark with what i have. I really thought the low9 and high 8 second cars might be even lower then 3.70.

mike

3.90 in my 9", 28" tall tire

I'm switching to a 3.50 most likely next season, 7200 is too much for me. Lot of guys with fast turbo cars are 3.20-3.50 with 28" tires, somethimes you just have to experiment a little but a 3.73 will probably do you a lot more good than a 4.10 once you start hitting it with a bigger shot.

I'm switching to a 3.50 most likely next season, 7200 is too much for me. Lot of guys with fast turbo cars are 3.20-3.50 with 28" tires, somethimes you just have to experiment a little but a 3.73 will probably do you a lot more good than a 4.10 once you start hitting it with a bigger shot.

agreed! i'll play it by ear, changing gears isnt a big deal, i can do it in a day, its more just a hassle and smells bad haha. I was gonna say i thought turbo cars ran lower gears like u said. My buddy has a 3rd gen and runs 410s still, running 8.7s in the 1/4, i'm not sure hwat he's shifting at tho, he also has a 29.6" drag radial which plays in too, i'm pretty sure hes going with 3.73s next year.

3.73s and 315/60 (30 inch )175 to 180 mph and 7800 to 8100 rpm 8.teens to 8.30s

I know a guy with a turbo set up that runs 3.08 gears :) watched him get in and out of the throttle and still ran 190 something mph.

3.89's with 30" tires

only 1 problem i don't think anyone makes a 3.73 pro gear for a 12bolt so you'll be stuck with a street gear.

only 1 problem i don't think anyone makes a 3.73 pro gear for a 12bolt so you'll be stuck with a street gear.

Not that i have found. I run moser gears last set went 3 years and went out first pass after braking an axle had to change spool and axles. Car will pull 1.30 to 1.35 every pass and will go 8.20 to 30 @ 173 to 176 mph and 35030lbs. so the street gear is ok . just what i have had.

only 1 problem i don't think anyone makes a 3.73 pro gear for a 12bolt so you'll be stuck with a street gear.

I have a Strange 12bolt, the car is street driven still here and there locally, do i really need more than a street gear? I have 33 sline axles, HD Eaton posi, and 4.10s right now, its been fine for 2 years cutting 1.50 60ft's. I'm considering upgrading to a spool and diff gears if necessary? I didnt think it'd be a good idea running race gears on the street but if it wont effect me anyway then i will. Any advice on this?

Depends on:
-converter slippage
-max rpm
-your goal
-tire size

I'm spraying 150 and went 10.0@133.9 looks like this:

10.00@133.9
3350 raceweight (3300 with me + full tank of gas)
1.38 short time
Shifted at 6800
4.10 gear
28x10.5

I'm guessing a 9.9@134 (maybe 135) if I ran a little lighter, shifted a wee bit lower, and ran 1000 psi bottle pressure rather than the 900 psi I ran.

For me to run say 9.50, I'd need 3.70 gears, and 200 shot at my raceweight.

My turbo car is a underperformer so far, mainly due to lack of seat time. I run a 3.50 gear in it and as I am limited by a hydraulic cam, I could still run maybe 7200-7300 rpms and trap over 160mph.

So pick your tire, max rpm, and start to box in the combo.

I think 3.73s will work absolutly perfect for my application. I'm not sure what it'll trap but i know i'm going to work twards the 150 mph mark. i'm thinking this year with a 200shot i should be close to the 135-140 range. Tire size is 28" tall. The 4.10s i have know will probly even help me for this year but i'm sure i will be limited on the amount of nitrous i can use. I should be able to rev it too 7000 rpm but if i can i'd like to keep it in the 6500 range. At least now i know i'm ballpark with what i have. I really thought the low9 and high 8 second cars might be even lower then 3.70.

mike

What's the duration of your cam @ .050?

What size motor and what size stall?

What's the duration of your cam @ .050?

What size motor and what size stall?

Cam duration is 240/250, motor is a 408, stall is probly gona be 4000ish but still not purchased.

I just ran a 9.61 @ 138 with 4.10's and 28 inch et drags... car went thru the traps about 7100, and I figured the skip at about 10%. Little looser then it probably should be, but for an n/a converter on a 150 shot I'm not complaining.

wow thats awesome JL, are you thinking of changing gears out anytime or are you content with the 4.10s? If i'm limited to a 150 shot i'd change out to 3.73s and go bigger on the spray

Are you still going to street drive this car?

4,000 is pretty good if you're going to spray it, motor only I would probably run more stall, more in the 5,000 range.

wow thats awesome JL, are you thinking of changing gears out anytime or are you content with the 4.10s? If i'm limited to a 150 shot i'd change out to 3.73s and go bigger on the spray



I will probably swap either a set of 3.90's or 3.73's in just to get a little more top end charge and it will probably help with traction/consistancey. I'm aiming to run a 9.5 index next year so I don't need to go alot faster persay, btuI do want to do it on the 100 shot jetting so I have a couple jet sets to go up to if the track goes away or whatever.

Car was 3500 lbs too for those runs, should be down to about 3300 to 3200for next season.

Depends on:
-converter slippage
-max rpm
-your goal
-tire size



Don't forget to add in a bit of tire growth especially if comparing bias-ply to a radial slick or Drag Radials.

Plus, consider the weather, too. If you are tight on rpm in the dead of summer, then, run in mineshaft air in the cool / cold months, you may find yourself at / over your targeted max rpm as you'd be making more power. Take care. Dave

when i called neil chance to spec me a converter they said with the one they specd me go with a 3:50 gear. im also running a th400.

3.73's will probably get you there in the get go. You will be going through the traps near 6,800 rpm.


Just for the sake of the thread though....

28.5" Tires, 4 speed Manual, 5.14 gears. ;) LOL