455GTO

iTrader: (18)

I just swapped to a built 4L80e from an M6 and have a question for you auto guys. I have 3.90 gears with 26" tall tires and im needing to hit 4th gear from my street testing... Does this seem normal given my trans and gears?

Ls1
H/C/I
232/234 tv2 cam
Shifting at 6500 rpms...

I hit 4th at about 109 mph... Anyone else experience this?

Thanks

poltergeist 02

iTrader: (65)

What converter are you running? Also have you had it tuned for those gears? Is the speedo accurate?

poltergeist 02

iTrader: (65)

Also, have you tried taking it out of OD to make a pass? You may have to run it out with more rpm in 3rd. This also depends on where your rev limiter is set and how short you are coming up in the 1/4.

mrvedit

According to the following calculator, 6500rpm with a 3.90 rear, 26" tire and 3rd gear (1.00 ratio) corresponds to nearly 129 mph:

http://www.wallaceracing.com/gear-speed.php

Either your converter is slipping badly, your speed or RPM measurement is way off, or your have a different rear end ratio than you think.
I would start by confirming your rear end ratio as this has been a "surprise" in previous threads.