I have decided to go with a T76 GTS turbo along with Real Quick's hot parts.

Car is going to be a street (not a lot of street time and no bad weather)/strip setup.

What are the advantages/disadvantages of going with a 355, 383 or 396?

Also, what length rods are generally used on Turbo appliactions?

 

I would go 383 ci. if I were you. They "tiny" bit of extra torque from the 396 is not worth it when you consider the extra problems people often run into when building 396's. Plus, you are going forced induction.

As far as rod legnth, I would recommend probably the stock legnth, which is 5.7" inches. You could also go with the 5.85" rods. The 6" rods may allow your engine to rev a little faster, but it would probably not be a good idea because you would need to sacrafice piston mass. And that is the last thing you want to do if you plan on running a decent amount of boost....

 

Honestly, I think it boils down to personal preference. Personally, I think the LT1 is torque enough "as is", and if you plan on adding lots of boost, you're not helping the situation any. Personally, I plan on running 15lbs+ of boost, so I plan on boring, but not stroking my engine, something like a 355 or 357ci...

 

I agree, all the extra expense in stroking it and you really dont get that much more out of it. the $/HP just doesnt justify doing a stroker on a boosted setup. spend the money else were and have a 355/357 thats indestructible....

 

So far, I've owned . . .

NA:
305
350
360
383

Roots blown:
355

Centrifugal (T-trim LT1):
355
383

Turbocharged (T-76GTS LT1)
383
363
388

(Dang, I didn't realize til now how many engines I've been through.)

I say 383 all the way. When I blew up my 383, I destroked it down to 363 because of all the people telling me that the 76GTS will make more power on a smaller motor. That was a mistake, so the next chance I got, I put the stroke back in it (along with a .060 bore) and never looked back. The car certainly didn't lose any power, but the off-boost response and torque was much improved.

Along with adding stroke, I also advanced the cam 4 deg and swapped the wheels and tires. It dropped .5 and gained 3 mph at the track, running a new best of 9.9 at 146 mph at full weight.

396 is a PITA because you risk breaking through to water when clearancing the block, and it doesn't leave much room on the pistons for ring lands. Speaking of which, don't bother going over 5.7 rods because you need the room for thicker ring lands.

Mike

 

Hmm, that's some good info! I was always under the impression that it was better to run on a smaller engine, but coming from your extensive experiences, it would seem I've been swayed to reconsider more cubes. Since the prices for the rotating assembly for a 383 vs a 355 is negligibly small, I'm now leaning more towards going with a 385ci, over my originally-planned 357ci...

One question, though...With the stroker motor, would it be better-suited to run a T-88, rather than a t-76???

 

Yes, it would. However, the T88 isn't the greatest choice. It's old tech. Even the T76GTS is new tech aero. Before doing an 88, consider the BWA ST80 or the GT4508RC. Both are roughly the same size, but newer/better tech that will produce more power per psi boost.

Mike

 

When I went through this same decision, I went with the the 355 as it appeared as though it would have a little better geometry inside the motor to hopefully help it stand up to the boost.

 

So when the heck are one of these turbo manufacturers gonna bring the newer technologies to the older T-88?

Also, what boost levels are you running your T-76 @ with the 388?

 

Who cares? Just get something different. The PT88 is a strange combo of geometry anyway. It's almost as if they put a large inducer on a small everything-else just so you could say you have an 88 mm turbo and everyone will be impressed. Notice how it won't support nearly the power of the PT-91 (300 hp less, actually), and not even as much power as the smaller-inducer ST80.

I'm running 17 psi with mine. That's the lowest the Tial 40 mm wastegate will let me go. I pulled the spring out of it one time and it still made 17 psi (but spool was terrible). I'd kinda' like to swap to a JGS 50 mm WG so I could drop the boost down to ~15 and be safer and more controllable on the street, but it's hard for me to spend money on something that will actually slow the car down.

Mike

 

Mike,

T6 PT91 versus the T4 PT88... definitely a big difference between them. Just the larger exhaust housing itself makes a difference. The PT88 stalls out at ~1050-1100rwhp.

I have yet to see any posts on a ST80 making more power than PT88. Purevil (local to me) took me for a ride in his 408ci LSX with a PT88 and he made 840rwhp @ 14psi on 93 pump gas and an intercooler (no injection of any type). Parish has made 102Xrwhp in his truck and PTK's customer made over 1000rwhp with a LT1 PT88. PT88 may be an old design, but it still kicks every T4 turbo in the nuts.

If you have any links of results on these ST80's results then I love to see them.

 

Fill everyone in on what your hp/track goals are... that will help with people's recommendation of a turbo.

 

The closest I can come is where Jose swapped from a T76GTS to a PT88 on an LT1 and it gained only ~20 rwhp. Other tests have shown the ST80 to pick up 100 rwhp over the 76GTS.

Mike

 

Jose has posted on this when I questioned that same point before I picked up a T88, and he said the t76 spiked to 24 or 26psi and fell of fast immediately. Realistically he says 900rwhp was it pretty much for that turbo with a constant boost level and the 88 will make more than 100rwhp over the 76GTS. Besides that one customer that Jose posted, nobody has made over 850rwhp with an LS1 or LT1 and T76GTS (or any T4 T76 for that matter) and that turbo on these forums such as cz28 or ls1tech . The only guys to make it that high has been the small ci mustang guys.

 

Some LS1 results with a PT88... it still makes monster power.
http://www.ls1tech.com/forums/showth...highlight=pt88

(Parish's PT88 thru a 4l80 setup) 1011rwhp. He says the boost spiked to 26 but fell immediately to 20psi for the run - http://www.ls1tech.com/forums/showth...highlight=pt88

Another 408LSX with stock LS1 heads (which I dont understand why you build a big motor like that and keep stock heads):
http://www.ls1tech.com/forums/showth...=precision+t88

Someone trying to work the bugs out of his 408 PT88 setup:
http://www.ls1tech.com/forums/showth...ght=t88&page=2

This mention's Purevil's initial dyno numbers with his PT88: http://www.ls1tech.com/forums/showth...&highlight=t88

All these are big ci builds... but it shows you it can make power.

I am having a hard time finding any T76 setups on ls1 tech with more than 900rwhp.