3.55's & 7800 will it survive

Have to rebuild/ replace rear carrier this winter and what better chance to upgrade the rear gear. I am currently na with stock 3.15s and best trap is 119.3 which was with a decent da.
1) I understand 2 shifts in the 6r80 is optimal
2) current tune is shifting early, need to get them up to 7500-7600
probably around 7000 & 7200 and I am currently trapping around 6800.
projected race weight in spring 3750( currently at 3820)
car should be 60' 1.57-1.56
3.31 will have me trapping 7200-7300 assuming with some weight reduction I have scheduled, tune adjustment and increased trapped speed to 121-122 because of being in the proper power band longer.
and also going to get new shock and struts for the spring time.
3.55's will but me at around 7800 at 122 trap speed with my 28.2 tire height.
Kind of leaning toward the 3.55's so that if and when I go forced induction or spray it maybe late summer I wont be at the bottom of my power band again.
So is 7800 to much for a split second or roll with it.
I don't see the car/driver getting below 3750 anytime soon.
Goal is 11.teens at around 122 on motor. this is a blend of premium and race gas-100-102 octane.
Any thoughts or anyone running 3.55's- I know this limits me to around a 122 trap speed to keep from really over reving the motor.

subbed . in the same situation. everyone I talk to says that I wont want to go with any more gear than 3.31 if I spray it

I'd probably just stick to the popular 3.31/28" setup that most of the fast guys are using. It's proven to work well! It will leave you a little 'headroom' in case you do a few more mods and get closer to the 125mph trap speed region too in the future.

I think you are missing tire squish in your calculations. Your radial tire, even at speed they are probably at least an inch less diameter than the advertised measurement. I also doubt you're going to get more than 7700 RPM. At that RPM and 27", now the limit is just under 123 MPH with the 3.31. If you know someone who can do the right PCM calibration to get you to 7900, which is the most I've ever seen from one, then that would get it to 126, while 3.55 would still be stuck at less than 118.

What about 3.15's and a 26" tire?

cschoening09 said:

What about 3.15's and a 26" tire?

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Why? Is there an issue with running more tire on the car? 3.15 or 3.31 will want a 28" tire to run. 4.17 first gear in the trans means these car's don't need any more rear gear to get a good launch.

Stick with the 3.15 and run a 28" rear tire.

just not 100% understanding the concept of gear vs tire size I guess lol. but I plan to run 100-150 shot one of these days with no stall convertor in the near future plans. so I guess the 3.15 would be a good gear to stick with on nitrous and 28" tires

3rd gear tops out around 130mph with a 3.15 rear on a 28" tire. 6R80. Mine always wants to hit 4th right at the end of the attempt. Not comfortable spinning it higher than 7400 especially with stock oil pump gears.

I'm wondering how the guys trapping much higher than this are able to avoid that shift into 4th.

Riptide said:

3rd gear tops out around 130mph with a 3.15 rear on a 28" tire. 6R80. Mine always wants to hit 4th right at the end of the attempt. Not comfortable spinning it higher than 7400 especially with stock oil pump gears.

I'm wondering how the guys trapping much higher than this are able to avoid that shift into 4th.

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Running less gear/taller tire.. Most everyone fast with a 6R80 is running into 4th.