I'm planning to upgrade my rearaxle posiunit, because I have an new engine that is currently being build that has more power (600HP range). So I need info on what will be the beste gearratio for the 1/4 mile? I now have 3.73:1 gears and use 28" tall tires. Let me know what you think! :beers2:
3.73s sounds ok. They might be too low for 28" tires and 600 hp you might just get wheel spin unless you run full slicks. Well now that I think about it I was running 28" drag radials with 3.55s on my truck with about 400 hp with no spin issues at all. 4.10s would be killer on my truck.
So your saying correct me if i'm wrong that the 28" tires are to low, for the 3.73 gears? With my old engine, with BFG 275/60/15 tires I didn't have wheelspin, but then again I didn't stall it, I left the line with 1500rpm max. Your right about slicks, run the car with MT slicks also and pickup up almost 0.10 et time. That was with street shocks in front, hijackers in rear (2005) and 2 airbags in rear an stocksuspension, and best ET 12.52 with slicks and 12.60 with BFG dragradials (275/50/15). Have now KONI dragshocks all round, and TA No hopp bars, and airbags, Best time with Cooper Cobra streettires (275/60/15) on a non sprayed streetraxe track was 13.11 ET. I did stall it one time at 2000rpm and broke my diffplate in the rear axle right after that leaving the line with a pegleg rear, and putting down an 13.51 ET! So I want to change out the 3 series carrier with orginal 12bolt diffplates. For a good POSI unit.
Go on-line and use one of the many free tire calculators. You'll be able to enter various tire diameters, transmissions, etc. That'll allow you to experiment and see what the engine's rpm's would be at the end of the run. That would be the best way to do it.
I have 3.73's. With 26" tires and a the switch pitch in low stall, I go through the traps at about 5600 RPM at 110-112 MPH. The 26" tire gives you a little more numerically than 3.73's. With a 28" tire, the 3.73's are like 3.55's. I would stay with the 3.73's.
All this conjecture is just about worthless without testing.. Just make your best guess and try it.. I changed gears and tires 3 times this year to get the right tire and ratio combo and I'm close but I know I can do better. If your motor makes close to that power you are already close to the right combo. Take it to the track first and test it. :TU:
Is there much drag racing in the Netherlands? Do girls go to the track? My 2 cents would be run you new set up then decide on the rear gears. Tim, Los Angeles.
I'm going to go back and say that 3.73s and 28ish" tires will work great. With 600 hp and 28" tires i think 4.10s will be too low.
What transmission does your car have and how much does it weigh? I used several calculators and if it weighs 3200 lbs. in race weight and you have a th400 transmission, you should be going through the traps at near 6000 rpm's and doing about a 10.5 at 132 mph.
Hell, yeah! http://www.dhra.nl/ http://www.explosiondragracing.com/ http://www.pixeleye-racing.com/photography-drachtennationals-2005.html Devon
