how much does a t-56 weigh compared to a 700-r4? has anyone shown decreaes in 1/4 time because of the swap?

 

I had decreases in the 1/4. With the L98, 700r4, and 2.77 rear I was running a best of 14.7. That same combo with t56 mid 16's. L98, t56, 4.11's low 15's.

Alot of people will say that sucks, but I just went with to steep a gear for the tpi, but whenever I get around to either siamising the tpi or getting a shot runner intake it'll be in the low 14's.

 

I think youre asking a BIG mouthful of a question, on two bases that are completely unrelated.

First off, lets answer your first question. Side by side, the T56 is much heavier than the 700R4. In terms of curb weight though, they might even out.

Keep in mind the 700 has the torque converter, and flexplate, and the T56 has its own weight, flywheel, clutch etc...

In my car, it would have been heavier, but i also swapped out the old 70s starter for a new 1995 Lt1 starter which is quite a bit lighter. However, that was probably offset again, but the heavy spohn x-member.

I wasnt counting pounds, for weight reduction, so i didnt measure each item (maybe i should have), but you would need to add and subtract all the weights and the weight of tranny fluid to get your answer for which is lighter.

Next up, you have to keep in mind, that the torque converter will have some slip, but the T56 depending on the clutch will not. Also depending on the clutch it may hook a little harder or not so hard.

However, you dont get torque multiplication with the T56 like you would with a stall converter.

And finally, the gear ratios are a little different in the T56 than the 700R4. So if your engine is built for low end torque and power like a TPI, and you start winding it up high, it wont fair so well.

Theres alot of factors here, and you cant just gauge whether the T56 will slow you down or speed you up..... You have to factor in everything to make an educated decision, and its a case by case scenario.

 

Ok lets say, stock cars:

305TPI/5 speed car got 3.42s, so lets put that with the 6 speed which is what the 4th gens came with which is the lowest gear ratio i would run with a 6 speed.

So if you took the same car, 3.23/L98/auto vs a 3.42/L98/6 spd it would be a drivers race.

Most likely i feel the 6 speed car would win if he knows how to launch and get traction, because an auto with a stock converter can only stall around 1400ish rpm the 6 speed car on the other hand you can set your own "stall" speed. Good drivers on both sides and the 6 speed car would win. STOCK cars, assuming you run a steeper rear gear for the manual car.

 

Total weight between the two would be about the same, a 700r4 is around 170ibs with everything and a t-56 is 120 or so then add in your flywheel and clutch. For speed difference you might be 1-2 tenths faster with the t-56 if you up your gears to 3.7, the t-56 has a really shitty first gear IMO.

 

I see. So, after that my opinion of the swap and it's necessity starts to decline.