1/10ths difference on ratios?

mid-low 11 sec car - 3700lbs - 4000 converter

Swapping back from 4.10 to 3.91.....assuming all things are equal, how much will my ET suffer?

Mal ,
At 3690lbs my plymouth ran 11.30 with 3.91 . Went 4.1 ran 11.18

😁

Tex

you may not loose at all. Way too much missing information to know your outcome.

My old pump gas Duster ran within 1/10 second using ratio from 3.55, 3.73,3.91, 4.10 and finally 4.30.
Traction and fuel supply will determine how much your car and motor like or don't like that ratio change.
Your deal is 4.7 % ratio change so it may not change your results at the track at all What RPM are you shifting at now? BB or SB motor?

What you would accomplish is slow the engine down a few hundred RPM at the top end and take away a half point of SLR, assuming a 3 speed automatic. That might help reduce wheel spin on a marginal track.

Motor is a 6.1 Gen3 Hemi.
Ive raced the motor before in an A nidy,but not in the current 67 B Body.
Traction gasnt been a major ussue
Fuel supply never a problem.

60 ft doesnt change much when launching from idle and launching at 2500. Never foot braked it higher than that..

Sounds like Tex’s 1/10th might be a fair indication....

Mal
Isnt Heathcote faster in one lane than the other ?
Have you run Calder or Portland ?

Tex

PS . Biggest change/improvement at that level was getting quality converter . Went from 4200-5000 very noticable

With a 4000 converter you probably won't notice a thing.

All my drag cars with decent converters like to be foot stall as high as possible to get the best reaction and 60 ft. times
Test it to see if your deal likes that or not

This. And gear change effects smaller cid engines more than larger. Plus the B body is probably weighs more than the A body.