Ron_Stoppable

iTrader: (1)

Anyone running 3.73s with their turbo build? With a 4L80e.??

66Chevellelq4

in the process. Not done yet but free bump!

007FJ

iTrader: (28)

3.70's F1C Pro Charger and a 6 speed. Not a much help anyway since it isn't back together so no run time.

JustAFooL

iTrader: (45)

I've got them on mine. Started car for first time last week. Having my IAT sensor bung welded up tomorrow night. Hoping to start tuning come this weekend. Check with me then and I'll let you know. My prediction is smoke show.

stock48

iTrader: (17)

I run 3.73's in my 4850 lb truck and love them in there but would not go that low in anything under 4500 lbs with a 3-4 speed. I run 3.23's and a glide in my car.

massconfusion

iTrader: (18)

I m running 4.10 (what the rear had) with my m6. I m going to switch to 3.42 though. I personally think too tall is better than too short in a turbo car. Atleast a tall gear can load the turbo/motor. Auto is a little different of a story... Good luck though

Razor

I had 3.70's, 4L80E, and a 26.10 tall tire on my Whipple'd car.

I could skate the car around, at will, below ~50mph. This was with a Yank SC3000 and the instant boost of a Whipple though. I felt it turned to many RPM on the highway at 75. Lots of interstate driving in my area.

Got rid of the Whipple for a turbo and swapped gears to a 3.50. My next tire is going to be a set of 28" tall units for the street.

Gears are like anything else, a compromise. Figure out what you can live with and what you cannot live without then decide.

JustAFooL

iTrader: (45)

Was it bad to blow the tires off in D? my car has had the 3.73 for years and I thought about swapping them during th build but never done it. Figured I may be able to wait until the read end pops and do it then. My thinking is a turbo car is going to be worse to spin than a blown car.

willizm

iTrader: (10)

Had 3.73's on a 26" tire on my car and ran out of gear going through the traps. My rev limit was around 6200rpm though and would hit about 137isjh. I since have gone with 3.54's on a 28" tire and upped my rev limit. I believe I'm good for somewhere in the neighborhood of 150-155 now

rollwithit

What gear would you run in a 3600lb truck with a twin turbo 5.3, 4l80e, and a 33/19.50.15 street tire??

007FJ

iTrader: (28)

(Diameter/340) X (RPM/Ratio)= MPH

Use 355 for non locked automatics.

Switch MPH and Ratio if you need the answer that way.

Never failed since I memorized it from the Direct Connection Chassis Book in about 1981. That and the Formula for CID saved my *** in high school geometry when the mean *** teacher we had wanted to know what relevance that car junk had in her class. Never forgot that one either...
B x B x Stroke x 8 (number of cylinders) x .7854 = cid


That truck with 33's is going to need some leverage to get moving. Start with 4.56 and play with your expected MPH / HP

rollwithit

Would that be a good hwy gear you think?
Building a daily driver with very little track time, maybe.

007FJ

iTrader: (28)

Doing it comparing to my set up, you would be geared about like a 3.42 car with a 25.5 tire. Go from there on what you want to lean toward. I'd be surprised if you can trust a 3600# street weight on that build.

With a turbo engine and your desired purpose, I would back the gear down to 4.10 to 4.30 and put a really good lock up converter. If you put some slicks on it later, buy 32's or 31.5's not only a better gear multiplication but 33's tend to be made for ultra light stuff in the slick world. RED's, Roadsters, and tube chassis door slammers.

007FJ

iTrader: (28)

I missed the tube chassis part so the weight is possible even street legal. Doesn't change the answer though. Be glad to see you finish that truck.

rollwithit

Truck is sitting at 3,154lbs minus twin setup and interior
You can check out my complete build on Facebook!

stock48

iTrader: (17)

Probably a 3.73.