JoeNova

In your situation, I would go 80e.
I recently went with a TH400 in the corvette I'm starting to build, but for very different reasons. If you have a stock ECU, the 80e would be better hands down. You get a free trans brake, and an almost unbreakable trans in stock form. The weight can be offset by the fact you can run shorter gears in an 80e and still cruise the highway, which will help with acceleration vs a TH400 or TH350.

408GT

iTrader: (2)

How do you get a "free" trans brake from an 80? Are you talking about the sloppy trans brake?

JoeNova

Yes. I've been using it all year.

408GT

iTrader: (2)

Good to know, and it's been working very well?

JoeNova

It has about a .8 second delay, but other than that its 100%.

408GT

iTrader: (2)

That's good to hear. Are you using a solid state relay?

Nitroused383

iTrader: (10)

Crank thrust bearings. You need to do the proper converter circuit feed restriction mods. Just search crank thrust problems with th400s.

JoeNova

No, generic 5-pin relay I picked up for $5.
The delay isn't from the relay, its the time it takes to force the trans to downshift into first.

I'm sure I can cut the time in half with changes to the tune, I just haven't felt the need. When I'm full staged and I see yellow, I let off of the button.

Nathaninwa

Proper converter free play on the install is crucial to thus too

Game ova

I've never even heard of this. Seems like everything has gotten complicated over the years. I remember back in the day, just slapping the converter on....three positive engagements....and it was a done deal. Nowadays I hear stuff like "blowing through the converter" almost constantly. Now this. Not doubting what was said, but just making an observation.

Nathaninwa

Clearnace needs checked with any aftermarket converter and flex plate install. With the converter bottomed out there should be about 1/8 inch gap between it and the flex plate This allows for room to grow My own install had 3/16, so I used some shims to take up the slack

Theses days we are making huge power and most try running a 3500 stall Saturday night special converter from summit racing. These converters were never designed to handle the tq the turbo motor makes so a lot of them blow through the converter, meaning it's not hydraulically efficient any more


Edit. Quick link I found

https://ls1tech.com/forums/automatic...installed.html

Game ova

Thanks for the link, good read.

SteenH

Other than the weight penalty, I think you'd be happier with a super high gear like a 2.73 and a th400. The ratio of this combo is very close to a glide with 3.55s (1st and 2nd) you will more than likely have to slam it into drive in he 1/4 depending how fast you go, but it is what it is.
You have yourself a glide with an OD

Game ova

Sounds good, especially since I just swapped the 2:73 in place of the 3:42. I'm hoping for 145-148 with the auto swap. As it is, it runs 137 now.

SLOW SEDAN

iTrader: (13)

Why don't you hook up a two step and leave on boost with the manual?

Game ova

Because I would likely end up like a few other people I've seen on here trying to send a heavy car on a t56 with stock input and output shafts.....busted. Or destroyed gear clusters. And even if I left good, I still can't out shift an automatic....sure I could try and no lift shift. But the FIRST time I missed, it would likely be curtains. Full disclosure, ever since I seen that f body that was in the same boat that I am in right now (slow et..strangely high trap) run 1.4 SECONDS faster....and trap 15 MPhil higher. I've been jonesing for an automatic. I want to be able to put an automatic in.....put a tire under it....and bust off a 9.30ish E.T and run close to 150 at the traps. I just can't see it happening with this t56.

SLOW SEDAN

iTrader: (13)

I've seen T56 run bottom 10's in a heavier car then yours. But I agree they don't like the abuse and will need a rebuild.

I don't think the turbo we have will get anywhere near 150mph. We both got about the same MPH out of it and it wouldn't make any more boost up top. I went a few MPH faster with a billet 7675 so it makes sense the ~50whp difference you saw on the dyno. If you want to stay with a cheap turbo the On3 88mm should get you pretty close to 150.

Game ova

I have a funny data point for ya. This car traps the exact same with this 7876, as it did when I still had the billet pt7675 in play. What's even more strange is, the car backhalves better now than it did with the better breathing pt7675 (top slip is the 7675) On this 6.0, I've seen 22.4psi by accident before (weather change).....now with that said, I didn't see if there was any pressure drop up top or if it was able to sustain it...I just seen the peak when I hit the recall. The reason I'm so optimistic about the trap is, I'm not even using the full track for acceleration right now. I put up a track video a couple weeks ago, and you can see that it doesn't start making steam till at least a 100 or so ft out from the tree....maybe even more. If I can leave the tree in boost, AND sustain it the entire length of the track...I think the trap is going to be a monster. I've got faith in the Lil Ole 7876 . Hopefully I will be able to provide some data points going from this 6 speed...to a hydramatic the beginning of next season.

SLOW SEDAN

iTrader: (13)

What's your vehicle weight? I doubt the cast 7875 has enough jams to even get 700 to the tire through an auto and that's not enough for a vehicle with any weight to it to see 150MPH. I wish you the best of luck but I don't see it happening.

I'm not sure what your issue is with launching because I'm into boost when the clutch lets out without using a two step and with a little 5.3L. A 6.0 should have that little turbo howling at the moon with any throttle input. Something is wrong with the setup if it takes that long to spool. What does your car spool at on the street?

Game ova

Car is 3750 with me in it. I have myself to blame, at least partly...for the lame launches. I'm leaving not to far above idle, scared to break the rear end again (will remedy this next year). But a agree, even with the bog...it should recover quickly and light off this smallish turbo, and I suspect that this tune is the other party to blame here in addition to myself. I think the timing is soft across the board, causing it to take longer to recover. Now on the street, it's a completely different story....spools quick and is very lively...but of course there's no vht on the street either.