91_5.7_TPI

iTrader: (2)

Hey all!
I have been considering replacing my 700R4 (3.23s, no stall, stock) with a T56 this summer. I would most likely run 4.10 rear with the T56. Do you think this would lower my ET?
Some local LS1 cars have gained nearly a second in the quater with 4.10s over what they ran with the 3.42s. I know I can't hope to see that much of a gain, but could a couple of tenths be a reasonalbe expectation?

atc3434

iTrader: (4)

I can't see TPI liking a 4.10 rear, the LS1 benefits more from the gear swap because it likes being rev'd up for its peak power, TPI like broader gearing, which takes advantage of its strong bottom and midrange better. T-56 would be awesome, maybe a more moderate rear like a 3.55 or 3.73. How modded is the motor?

91_5.7_TPI

iTrader: (2)

My car is a 305 TBI. The screen name is from when I first joined and was working on a deal for with a 91 350 Z28 that fell through.
The 305 doesn't have any mods to speak of. Just a open element and Jet II (woo!!). What you are saying about the TPI applies to the TBI as well. I hadn't considered that.
I plan to swap in a Gen III 6.0 with L92 heads and a Texas Speed cam at some point. That set-up would like the 4.10s much more than the L03. (I know about the bell-housing and input shaft issues)
But then there is the issue with the L03 not making enough power to make 6th gear usefull with 3.42 range gears. I don't think that it could pull the car at 70 @ around 1600RPMs The 4.10s would be at around 2000 @ 70 in 6th.

atc3434

iTrader: (4)

Well, I guess a few things depend. If you're for sure about getting the Lo3 out of there at some point in the near future, the trans and rear you suggested would work great with the LS2. However, if you're looking for immediate gains, you're money is probably best spent elsewhere. Exhaust would be my starting place, followed w/ some good tuning. But, I wouldn't go spending money for the Lo3 if the motor swap is definte.

91_5.7_TPI

iTrader: (2)

That's my train of though. I have looked into getting power from the L03 for a while, but I'd rather do a complete swap when I get the money to do so...and a T56 with 4.10s would greatly help the LS2/LQ9.
Do you guys think they're would be any gains (with the L03) from the T56 and 4.10s over the 700R4 and 3.23s? When he mentioned the power band issue, it seems that time might be lost...?

ShiftyCapone

iTrader: (7)

The T56 is far more efficient than the slushy 700R4. However, 4.10 gears is too much for a stock LO3. You would be keeping the motor out of its peak powerband. That in itself could make the car slower. A 3.42 gear would be ideal. The 3.23 would be pretty low and the car would likely lag (all T56 4th gens came with a 3.42 gear, and 3.73 in some '93 models).

One thing to keep in mind. If you do have plans for a Gen III mill in the future I would not bother with the T56 swap now. The T56 you use on your LO3 will not work with the GenIII. You are better off waiting to get the LSX T56 (bellhousing, input shaft, clutch ect ect are different). I would only do a T56 now if you wanted to use an LTX Gen II mill which can be used with your LO3.

91_5.7_TPI

iTrader: (2)

I am having problems - again - with my 700R4 is why I am thinking about replacing it with a T56. I was going to wait and get the correct T56 for the Gen III engine, but....one does need a working transmission. Can I get a T56 for the Gen I and IIs now and replace the input shaft/bell housing, etc later for the Gen III and IVs?

ShiftyCapone

iTrader: (7)

You you do go with a Gen i/II T56 set-up now it would be easier to sell the whole set-up for that of a GenIII set-up when that time comes. You could break even on the cost but it is not worth the effort to try to convert one to another. You will certianly lose money that way.

91_5.7_TPI

iTrader: (2)

Ok. Thank you for the input. If I can find a deal on one, I may go that route. If not...700R4 wooo!

87LS

Ig you are going to make this car run well, you can work with the700R4..
I am swapping minte to qa T-56 but I already have a stick and its pretty easy for me..

I would say take the money have it rebuilt, put some 3.73 string gears and girdle on your rear/ If you have money left over put in a stall and you will b quicker then swapping to the T-56 and 4.10's

Its not as much fun, but you have a nice tranny there...

91_5.7_TPI

iTrader: (2)

Yeah, the car would be quicker, but I would be concerned with the gas mileage (not to meantion extra wear on the engine when cruising) with 3.73s and the auto. Good idea, though. Thanks for the input.

TransAm12sec

I don't know the exact weights, but I could imagine the T-56 weighs a small amount more than the 700R4. Just one more thing to keep in consideration.

87LS

My buddy has 3.73 and a built 700R4.
I know 65mph is 2,000 rpm...he drives it on the highway all the time....
I have always heard you need to keep it below 3,000 in a V-8 for extended times...
Give it a shot
I agree Transam the T-56 is a heavy sucker...good call on it weighing more that is true!

91_5.7_TPI

iTrader: (2)

Either his or my tach must be messed up (or something else). My car is over 2000 at 65 with my 3.23s

atc3434

iTrader: (4)

Yea, I'm about 2400rpm at 65mph, 2800rpm at 76mph. I don't trust my speed much, but thats pretty close.