jed5161

Wondering what you guys out there are running for rear gear ratios and tire sizes. heres what i got:

250" 4 link dragster 1800 lbs
605 Ci BBC around 1050-1100 hp no bottle
1.80 glide
4.10
33.5x16.5x16 weld beadlocks/mickey thompson tire

I've been running low 4.80's 140-142 mph 1/8th mile. I've noticed mojority of guys run 34.5's. i swapped a set of hoosier 34.5's onto our car thinkin it may help. Well i ended fallin off to 4.88 to 4.90 range and 136-137 mph. The car feels as if its launching harder and it pulls the front end better with same 60 ft, but looses everything down track.

gnsrule

whats the MPH thru the traps ?

jed5161

we run all 1/8th mile exept for maybe two races a year. (a 10k race and et finals) With 33.5's we do 140-142 mph. with 34.5's it fell off to 136-138 mph range. im not sure RPM wise what we do on the 1/8th. I'm guessing 6600-6800. I know for sure on quarter mile with 33.5's its 7100 through the traps. We shift at 7200-7400 and launch at 5600. 6000-6200 outta the convertor

gnsrule

My bad..I ment to ask what RPM. Guessing on that would leave only guess's on what you need for a gear swap.

hammertime

I've used both the 4.10 and 4.30 gear along with both the 33.5 and 34.5 in tire. Some cars like the 34.5 others do not. I assune 1800lbs is a empty car no driver ? Whats it weigh with driver ?

Id run a 4.10 and a 33.5 hoosier on the beadlocks if it were mine. 34.5 and the beadlock are to much for that et of a car, its lugging it down which is why your seeing the slower et/mph. If you do decide to go back the 33.5 tire, Avoid the 3185 MT.. that tire has major issues in dewy/cold weather. Converter comes into play a lot here also you have to tweak converters towards the big tire if you want to stay with it. Was the hoosier new ?

jed5161

car is right at 2000 with driver. we put the mickey 33.5's back on the car. The hoosiers were not new. they were ran on our pro mod car for a short 6-8 race season and then our spitzer Pro Top Outlaw dragster for about half season before going to a 36" top fuel tire.

Were changing from conventional heads (profiler cnc ported 365's) to either big chiefs or big dukes. Debating on shooting it with 200-300 shot of nitrous.

I'd like to be in low 4.70's high 4.60s on motor.

hammertime

I dont think you need the dukes to get there, maybe some tweaking on what you have now. The profiler head seems to be a decent head, if it were mine Id loose the converter up a touch 6400-6500ish. You are launching very high also, which might be hurting more then helping.
My motor makes peak 1013hp but avg 985 and runs low 4.7's all day @ almost the same weight as yours, I launch @ 4200 shift on time @ 6700rpms, cross 1/4 @ 7100. My converter is 6800 9" spragless coan, its much more agressive and faster with my 6400 stall stuff though.