Ive lost rpm at 1/4 mile trap from stock build last year to this years build. Last year through the traps I was at 53-5600 rpm, This year Im at 48-5100 though the trap. I am running 275/60/15 with 3.42 rear gear and upped the driveshaft to 1" bigger in dia. due to twisting old one lol. Should I jump p to say 4.11's or change in tire size to get closer to the 6k at traps?Top speed last year was like 114 this year is 107-109 and over a second faster .
Did you dyno the new engine? Where does it make the power? I can tell you that we had 3:42's in our race car, went to 4:10 and will be going back to 3:42's. We only want to go to about 5500 rpm though, with a 28" tire with a high 9 ET we hope. I have heard from several people that say the BBB doesn't work as well with the lower gearing. It has enough torque to use the 3:42. I'm sure someone will chime in.
AH you said your going 1 sec faster...Yes? Well that would mean you have 1 sec less time to build up top speed. So your car IS faster Sometimes the mph does not get faster when you make your car quicker. What cam did you have and what did you go to? What other changes have you done? What shift points 1 2 3 gear compared to the stock motor.
Same cam as last year, And I shift it manually 5-5200 ea gear. I used a set of 275/50/15 last night and it netted me the rpm i want in the 1/4 but at the loss of about a 1/10th on the 60 ft , it did pick up a 1/10 in the 1/4 though also clearing traps at about 55-5600.
Keep tinkering. Jim Some times the smallest details EVEN dirt in the air filter and or carb can be causes of loss in ET and speed. ??? Just never know.
