what do you reckon it'l do???

[FS5]

got the old girl booked in next tuesday to get some 3.89 diff gears fitted , its currently got 3.45's.
i was out at willowbank last night trying a few things ,so i could do some before and after testing.i found launching at 3500rpm was best ,so i averaged out my 3 best slips and come up with .
60 ty...ET.......MPH
2.009..14.736..93.32
2.047..14.766..93.32
2.030..14.778..93.44
averaged.
2.028..14.760..93.36
so how much difference do you reckon going from 3.45's to 3.89's make ?
thanks guys ,jake

[EvilChief]

**** me ..

i so need to get to willowbank ...

best i got managed a 14.9 at 94.5 mph ...
our drag strip is a skid pan, not a launch pad

[jonbays]

Well hard to say exactly but you would be expecting beter as the 3.9 will be giving around 5000rpm at 145-148kmh so you should just pass the tape under the rev limit in fourth as opposed to pulling around 4500 with the 3.45.

head to head same car track time diff lane
Name Car 60' 330' 660' MPH 1000' ET MPH
uselessT50. 2.312 6.497 9.94 71.37mph 12.929 15.458 89.07mph
jonbaysT130 2.360 6.635 10.109 70.47mph 13.119 15.667 88.53mph
jonbays vs useless0.04800.13800.1690-0.90000.19000.2090-0.5400
jonbays vs useless splits -0.0480-0.0900-0.0310-0.0210-0.0190
This is a run between me and useless with all the splits to show the big difference between me with 3.45 and him with 3.73 and a hi stall was in the 330'. So the diff ratio alone probably giving a 2 to 3 thousandth of a second per split.

That would mean a 3.45 to 3.73 would net maybe a 0.15 second better qtr ET. So a 3.9 say 0,2 second better maybe ?