2 sundays ago I ran 7.20@96 with a 1.52 60ft. with a 3.70 gear on motor
Sprayed 175 Had a 1.40 60ft. but was all over the track when it set the wheels down so I didnt get to make a full pass. 2nd juice pass I left and just about the time it started to lift the tires it broke 12 teeth off the ring gear causing the case to break in half and rip the driveshaft in half.

Last sunday I ran with my 4.86 gear because that was all i had.
Motor 1.52 60ft. 7.21@96
Juice I put in a 100HP shot because i was afraid it would kill the tires on 175
1.41 60ft. 6.73@102

What gives motor times are basiclly the same and juice times are close (60ft. wise) I have tried these gears before and the 3.70 was faster motor and juice This new cam loves high rpm I thought the 4.86 would help on motor since it would spin up faster I'm just confused now

I'm thinking of trying a 3.50 gear if lower dosent help maybe higher will be what do you guys think? The 4.86 sucks on the street with a TH350 I want to go 6.99 on motor what do you guys suggest I try?
Thanks in advance

 

torque converter. 3.70s making it stall higher. 4.86s letting the car leave easier netting the same results.
In other words, your converter is better matched to the 3.70s. Now the 4.86s with a little more stall rpm could gain.?

 

I am using a TCI 4000 rpm converter with ballooning plates. I am leaving at 2000 rpm with both gears letting the converter flash.

 

My car ran 7.19@96.8mph 1/8th mi with 3.42's and a 26" slick so I know where you are coming from. I am going to try some 3.90 gears and my newly installed transbrake to see if i can run 6.90's-7.00's to run high 10's on motor and 6.40's/9.90's is my goal on n2o. Later Clint

 

Could have to do with the extra parasitic loss from the bigger gears, which you're probably losing an extra 10hp from. Also nitrous likes to pull, ie likes a smaller gear rather than a larger one.

 

it is in the converter imo.i have this happen to several friends of mine.a tighter converter will help it on the juice.but without much slippage it will run a bunch of rpm's with that much gear.i run a 4.10 gear and a 10inch 32000 stall that nearly locks up at 4200 even on the juice.but it is a pig on motor only.