Ok, I'm switching from 2.73 to 3.55. How much will I gain on 1/4 mile ?


i'm right now running 13.8 and 98 mph.

 

That's a huge jump in gearing. I would expect 5 tenths or so, maybe more.

 

Cool to me !, will my mpg really reduce ????

 

If you are already in the 13's, don't expect much improvement ....Do expect lots more tire smoke. Rear launching mods may accomodate those gears though.

 

You can't accurately guess your improvement in et. You could be slower if you have traction problems--3.55's will have more trouble hooking up.
The same goes for mileage. The reduction is usually never as bad as people say. With the right combination of stuff, you could get better mileage.

 

RICHRAD
Senior Member said :

If you are already in the 13's, don't expect much improvement ....Do expect lots more tire smoke. Rear launching mods may accomodate those gears though.

------------------------------------------------------------------


Richrad, if I have lots more tire smoke like you said it means I can do a better lunch, if so, be faster. right ???? You don't make sense

I don't have any traction problems right now with my 265, why not much improvements if gears are bigger ???, anybody else could confirm that.

My car is non-posi , if I order a posi from SLP will that help alot or what ?

 

If you don't have posi now and also don't have any traction problems, the additions of a posi won't help. Deeper gears make it harder to hook-up off the line, if you spin the tires you will hurt your time. Tire smoke bad. The posi will help the traction problem. This isn't an exact science. Gears and posi don't equal a better e.t. You may have to mod the rear suspension to hook-up to realize the gain with the deeper gears.

 

Yeah, what 82camaro said....couldn't have put it better, Thanks 82

 

Ok well I think there's something I just don't get. sorry.

OK I DON'T have any traction problem, so by upgrading the rear gears I get chances that my car will spin alot more. Altought I don't lunch the car to do 13.8's.

Now since I add bigger gears, doesn't that make my car accelerate faster since there's ALOT of torque from low to high rpm with my LT1?

let's say I DON'T get traction problems and i'm able to hook my street tires, will I gain ????, if yes what should it look like ???? (that's my question since the beginning)

I have a set of Mickey Thompson Et street , I could always use these worst case scenario but I don't like the height of the rear with that and also the cornering.

 

Heh heh. You can tell that your first language isn't english!

The term is "launch," not "lunch." I'm not being picky, just figured I'd point that one out. One means "dejeuner," and the other is sort of like "part" or "lancer."

Anyways, your signature says that you have limited slip. This is the same thing as positraction. Positraction (or "posi") is the GM copywrited verison of a limited slip system. Ford has Trac-Loc, or maybe that's Mopar. Anyways, your sig says that you already have posi. Therefore, I don't think that the increase in gears will create that many problems for you. I think your car should launch just fine with 3.55's, and if you have the T-56, you may be able to get aways with something even higher. The T-56 has a 0.5 overdrive, which is really deep. Lots of guys go with 4.11's, without a major reduction in gas mileage.

The higher gears will tend to put the RPM's deeper into the power band. When I lost overdrive in my T-5, and had to run in 4th gear, I noticed VERY little change in the fuel economy. I was running at exactly 3 grand on the highway, which isn't high enough to affect engine wear greatly, but into the power band, so I had to use LESS THROTTLE to keep the speed maintained.

Highway fuel economy is not always about "the lower the RPM's, the better."