lt1 t56 or ls1

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Mar 28, 2014 | 08:04 AM

kraftada

Thread Starter

Intermediate

Joined: Sep 2011

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lt1 t56 or ls1

Hi to all the t56ers
Which unit do I start with for a start from scratch t56 swap.
1981 vette org. auto with dart 400 block 2 piece main going in
complete frame off with interior gutted at the moment. Great time to do it
if I am going to. I have heard and read so many conflicting perspectives
on which donner to start with. LS1 or LT1 T56 ?

Thanks

Mar 29, 2014 | 06:51 PM

Kacyc3

Drifting

Joined: Jun 2012

Posts: 1,990

Likes: 183

From: Port St. Lucie Fl

the lt1 t56 uses the same mounting bolts as the sbc based dart block, using a two piece rear main will require a specific flywheel as the t56 is designed for use with 1 pc rear main. The 93 lt1 had different gears (cant remember the specs) and was also rated at a lower hp/tq, I have heard the ls1 t56 uses a different throw out baring set up than the lt1 (please someone chime in if you know for a fact). I believe stock t56s were rated at a best of 450 tq, why not pick up a 5spd from richmond or another company so you can run numerically lower gear and still have performance and overdrive for highways.

Mar 29, 2014 | 11:00 PM

AeroDog

Instructor

Joined: Jan 2007

Posts: 179

Likes: 2

From: Carolina raised but in Loveland CO for tha duration

Quote:

Originally Posted by kraftada

I put a T-56 and LT1 (from a 95) in my 68. The tranny was a bear and the LT-1 didn't have enough power (added roller 1.6 rockers, dynoed 330 hp). I just built a Dart 400 ci with all trick parts, dynoed 544 hp. With the T-56 it should be a fun ride. E-mail me if you have questions.

Jerre
hill@uncc.edu

Mar 29, 2014 | 11:08 PM

MIKE80

Drifting

Joined: May 2005

Posts: 1,968

Likes: 44

From: East TN

The LS1 T56 trans are a bit stronger than the LT1 and I believe use a hydraulic throw out bearing. On the LT1 T56 stick with 94-97 as they are stronger than the 93' and can also be upgraded to LS T56 strength, but still are pretty tough stock. I bought one out of a 94' Trans Am with 80,000 miles on it and was used to drag race with slicks and nitrous, run 10 sec quarters. Fluid was clean, has a some whining in 5th and 6th gears, but runs and shifts nice. I'll rebuild it with upgraded parts when I get around to it.

Here's a thread I did on my trans swap.

http://forums.corvetteforum.com/c3-t...gs-list-8.html

Mar 30, 2014 | 10:36 AM

74modified

Burning Brakes

Joined: Oct 2008

Posts: 1,037

Likes: 14

From: Mobile Alabama

Quote:

Originally Posted by kraftada

Most any used T56 will now have a lot of miles and would need a freshen up. The LS version is a little stronger, and has an internal hydraulic throwout bearing. I don't know what input/pilot bearing problems you would have with LS to small block (LS block here). If you decide on the LS, there are several versions depending on the donor car, or new aftermarket versions(T56 Magnum). Most folk would use the F body version, as is is the easiest.

Another thing to think about is gear ratios. The double overdrive T56 was used with injected vehicles that can turn the 6th gear at a lower RPM. Depending on your cam and power/torque band of the engine, it might not be happy with just a trans swap. Just sayin - I would match engine, trans, rear gear, and tire diameter for best results.

Last edited by 74modified; Mar 30, 2014 at 10:49 AM.

Mar 30, 2014 | 06:36 PM

vette427-sbc

Burning Brakes

Joined: Oct 2008

Posts: 955

Likes: 50

From: Jersey Shore

GTO T56, QuicktimeT56 to SBC bellhousing. SBC clutch/flywheel and the GTO hydro throwout bearing. Ive done 2 other sbc cars with the LT trans and bellhousing. Very limited clutch options (pull type clutch) and the flywheel is expensive if you have a 2pc rms.

Mar 30, 2014 | 06:46 PM

billla

Le Mans Master

Joined: Jun 2004

Posts: 6,231

Likes: 65

From: Seattle WA

St. Jude Donor '14

Being a relatively short-term and to some extent unloved engine series, the LT1/LT4 wouldn't be my choice. I did a swap of an LT1/460 in a buddy's Nova, and while it was relatively straight-forward I didn't think it was a great swap in terms of HP/$

There's some aftermarket stuff out there, but nowhere near what there is for GEN I and GEN III+

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