smokeshow

iTrader: (17)

Looks to hold boost ok. Timing is a little lower than I'd like to see. But as stock48 said, the shift extensions are real short. So you're definitely losing some power to the converter. And the exhaust housing obviously doesn't flow enough either. Looks like its probably pretty fun to drive though lol.

gpr

iTrader: (6)

I have never heard of this before. Why does it tighten up the converter? Is it because it is thicker than normal trans fluid? Is it safe to run hydrolic fluid in a transmission?

Reason I ask is I would like to tighten up my converter a bit, and our farm has a 55 gallon drum of john deere hygurd. I just don't want to ruin my converter or trans running it all the time if it is something that works for race cars and not recommended on the street/everyday use.

chiaj144

iTrader: (4)

I've ran hydraulic fluid in my transmission for years with no issues.

stock48

iTrader: (17)

Yes it will tighten you up a bit long as it's the high viscocity oil. They have a low vis as well so you need to find out which oil it is. I've never had a problem with the hygard in any trans except for my Duramax allison, and only thing it did with that was made converter so tight truck was laggy. Tightened that thing up like 600 rpm lol. You don't want to run it in a dd in really really cold climet

gpr

iTrader: (6)

Sweet. I will have to give that a try and see how much it tightens up the converter.

Troy5061

iTrader: (19)

I am by no means a turbo expert like some of the guys in here but I have been pretty happy with the Billet PT7675 on my 383. With the stalled auto it would spool instantly which was awesome for a street driver, I had never been in a turbo car before that felt like it. Mine was on low boost about 10psi I am not sure if I would run into back pressure issues at 15-20psi though. My only advice is stay away fromt the old school PT88s a buddy has one on his 408 and it makes crazy power but it does have a bit of lag and I can imagine on a 383 it would be pretty bad. The new 88s are fine though from what ive heard.

HUGGER ORANGE SS

iTrader: (2)

Comp Turbo!, their housings are on the smaller size and what a great product!! A local guy got one on his 1st gen CTS-V. It's a 91mm on a t4 housing



Here is a video in action.

DEFYANT

Forced Inductions can do a 91mm T4 as well, but why? Too small of a turbine and exhaust housing to actually make use of the compressor.

Vetal

iTrader: (3)

I took another look and it APPEARS that I might fit also considerably bigger turbo. My comp cover is right near crank pulley because turbo is so short. between centers of covers there's only 4.5". If turbo would be longer, comp cover would clear the pulley much better, so even some 9" would fit provided it is further away from T4 flange... Pics will illustrate this
So what are next best turbos, bit bigger but with good flow and price?
BW's are still huge, right, almost 10" diameter cover?

HUGGER ORANGE SS

iTrader: (2)

I agree somewhat.

Vetal

iTrader: (3)

DrTurbo, you wrote that your SX and ST series are smaller then off the shelf S400's, and also "spool ALOT faster then a standard S400".
So SX/ST are smaller than this S400-75?

Vetal

iTrader: (3)

Any new powerful but compact turbos came out over past 7 months?

yenkomike

iTrader: (2)

did you ever get that convertor tightened up on that tc-78 . if you tighten that convertor 1000 I bet it picks up 10-15 mph top end .

Vetal

iTrader: (3)

em, no, I didn't. Shipping expenses alone would be 300-400$, didn't made up my mind yet to do this...
P.S. I would tighten it maybe 300rpm at most, definitely not 1000
Though, I also wanted to put much longer final gear

yenkomike

iTrader: (2)

I don't think you need to lower the stall but if you could get it to keep from blowing thru the convertor it will be faster no mater what turbo you run .

know mater what turbo or cam you run your torque peak is going to be less than 6200 and if you are slipping past the torque peak your not going to get the best et out of the setup. if your convertor was a good 3200-3400 stall that has low slippage by 5000 you whould think you had a completely different car.

is your current convertor locking up at 6200 or is that just the rpm where your power falls off to the point that it can hold it?

Vetal

iTrader: (3)

Here is a bit more detailed info, last page:
https://ls1tech.com/forums/automatic...ld-work-3.html

But in short, engine rpm climb to 6000 fast and converter output is 5200 at this moment. Past 6000 engine rpms climb very slowly and TC is catching up with the engine.
So it's 6000 input vs 5200 output, even with my short 3.73 gear

Does it look right? Or is it "blowing through converter"?

geoff17

I would have that converter taken care of correctly first before putting another turbo on. Then run it for a while and make a decision from there. My TC-76 on a 6.0 lq4 and 4l80e with a ptc converter that was tight was able to manage a 9.8@140 and I think it still had more in it. That was at 15psi. I just now switched over to a PT7675 CEA billet wheel and am supposed to get tuned tomorrow, not sure when I'll head back to the track for real results from the turbo swap. (I don't believe in dyno #'s too much as no one believes me anyways since I only made 585whp but ran 9.8@140)

yenkomike

iTrader: (2)

sounds like it is blowing thru the convertor. if setup right you should be able to go faster with the turbo you have if you can keep the rpm down.

Vetal

iTrader: (3)

Guys, could you please give your advises in this thread? As to what rpms drop or converter slippage is OK and what's "blowing"...
https://ls1tech.com/forums/automatic...ld-work-5.html

Vetal

iTrader: (3)

Found logs from runs with a bit more power and it's even worse - at 6000rpm TC slips 1000rpm, at 6200 - around 900. Too much??