I've got a good lead on a built 4.11 rearend to put in my '88 Trans Am. I've already got a LT1/T56 swapped in now. The LT1's basically stock with a march underdrive crank pulley, I'll have a Delteq setup soon, it's also got a mild grind cam.
How well do you think this setup will perform with 4.11's in the 1/4 and MPG-wise? Those of you with this setup, what are your comments?

 

With 2 OD's you should be just fine as far as MPG and everything goes on the street. I'm assuming this is a 10 bolt with 4.11's? If so, my concern would be in the strength. Even if it's built it's still a moderate unit. With street tires you should be fine, but anything stickier, which you'll eventually need. I would be worried. They just don't hold up to much abuse with good traction. Even on an unmodified car. The car is going to be a blast to drive, just stay away from those clutch sidesteps until you get the cash for a stronger rear. Other than that you should be fine.

 

GREAT !!!!
Had the 10 bolt torsen with 4.10 and loved it,6th becomes a pulling gear,never downshift on the highway again. 65 mph= 2100-2200 rpm,mileage is great.

Switched to 9" with 4.11 and it was just as good but stronger.

Swapped to A4[4L60E] but kept the 4.11s and still get 22.7 mpg on the highway at 65 mph[2600-2800 rpm],GEARS are GREAT,go for it!!!!!

 

The rear's a 9". It's built to handle the power! Wow, with T56 ad 4.11's, the RPMs are only 2200 at 65!? That's bad ***! Do youhave any MPG city/highway numbers or anything?

 

Never went on a long enough trip with it to really find out,must have been in the 26mpg range,most of the highway mileage was to/from track which means enough gas to get there and run no more.

The reason I know the mpg with the A4 was I filled up and drove home non stop[455 kilometers=300 miles] on less than a tank!

I am talking canadian gallons,a little bigger than U.S. gallon.

 

My T56 with 3.73s turned 1900rpm at 75mph... and couldn't complain with regular 27mpg either on the interstates. I doubt 4.10/11's will turn much more since that .5:1 reduction 6th gear really cuts down overall gearing at speed. But now with the A4/3.23s i turn roughly 2350 at 75.


But you can check/verify for yourself to get a rough estimate....

www.f-body.org/gears

 

Oh if the rear's a 9 inch by all means give er hell. Slide your foot off the clutch at 5000rpms with some sticky tires and hold on to your ****. Now it's time to consider a strong clutch if you don't already have one, that'll be your only bottleneck. Wish I had a 6spd with a 9" and 4.11's. That would be fun.

 

The T56 came with a Spec clutch..I'm hopin' to give the local 4th genners hell with this setup. Any ideas on what I'll run, assuming I can drive?

 

How heavy is the car,how much HP and TQ,do you have traction[DR'S]?

Anywhere from 15.s down to high 13.s,depends on a lot of variables!!!!!!

 

Well I don't me exact weight, but the car's basically a stock '88 Trans Am. 3rd gens are a tad lighter than 4th gens I believe. I have very minumal mods on the LT1, underdrive crank pulley, soon to have a Delteq setup, B&M shifter, coated Hooker 2055 headers with coated y-pipe, cutout. That's about it, I'll probably be able to borrow a set of DR's from a friend until I can afford a set of my own.