I have a pt-6776 E sitting around. The s-trim is already installed on a big cam, big heads, 396. (Water-air intercooler, methanol injection). Makes about 600 rwhp, but lacks power on the low end.
I'm thinking of installing the turbo after the y-pipe and running its output into the s-trim. I would be cutting the underbody around the passenger side rear seat to fit the turbo. (Why not?) I have Kenny Bell subframe connectors also. The s-trim alone makes 11 psi now at 6300. (The pulley now is undersized so it's spinning a little past Vortech's recommended redline at 6000 RPMs and I don't want to have to rebuild it again, so I'm putting a bigger pulley on it.)
What I want is major torque from 2000 up, which I don't have now. I would also like more peak power. About 100 ft-lbs more from 2000 or lower, up. If I could get the power to come on at 2000 or lower instead of at 4000, I would be very happy.
Opinions? Should I just take the s-trim out and sell it and go with the/a turbo? Other thoughts? (I have to go after I post this so I won't be able to reply for a while.)

check this out by the way. http://www.eng-tips.com/viewthread.cfm?qid=174690

 

I think the Strim will end up become a restriction!

Jay

 

Possibly. I've thought about this before regarding "electronic superchargers" sold on ebay and if the engine is pulling more than the fan can push, all the fan is doing is being a restriction. Likewise here, if the turbo is pushing more than the sc, I don't see how the sc would not be just a restriction, not adding any boost at all. Now if one of the two produced more power down low and the other more up high, then it would make sense to use both even if whichever is blowing less is just a restriction.
Take a look at that link though. This line of reasoning doesn't appear to be the case, at least with a roots type blower.

 

Hmm. I've seen setups here and there like this but never understood how it works any better on gas V8's like ours.

With pumps in series you will yield a larger pressure rise but zero volume flow increase. So if you had two turbo's in series at 1000cfm and 6psi each. You end up with 1000cfm at 12psi. That's just because pumps like this take the inlet pressure and step it up. The second pump's inlet is that of the discharge of the first. We don't necessarily want tons of pressure on our motors - we want volume flow.

I 'guess' in your consideration, the turbo could come in first to get you a power curve you like. But once the blower ramps in you boost pressure is going to skyrocket because it's additive when in series.

I would just pick the turbo you want and run it. Or pulley the crap out the S-trim or upgrade to a T-trim or YSi-trim.

-Scott.

 

i posted a link in another thread to theturboforums.com

read that thread, it explains the whole theory very well. if anything, the turbo will be too small.

 

I say drop them both and get an appropriatly sized turbo....
But all practicality aside you made my day. I'd love to see it even if it didn't work well. 100 shot for good measure?

 

Even if I thought compound-charging was a good idea (which I don't), the T-67 is way to small. It will choke way early and exhaust pressure will be through the roof. A 76 is too small for an NA 383, so a 67 is WAY too small for an FI 396.

 

Too small hey. The 67 is rated for about 750 whereas the S-trim is rated for about 680. It doesn't really surprise me though. Thanks for the advice. Is a 76 really too small also?!! They're rated for 1000 hp.!
Negative about the nitrous jsetzer. I read the rest of the article and only a "positive displacement" supercharger will increase the boost fed from a turbo. It doesn't say specifically but a centrifugal would probably just be a restriction assuming the turbo was pushing more air than the sc.
My S-trim is already pulleyed as much as it can be. It spins at about 55,000 at 6000 rpms when it's Vortech recommended redline is 50,000. I had to rebuild it already because of it spinning too fast and it isn't cheap. About $280 just for two little high speed matched ball bearings. So I don't want to have to do that again. I'll read that thread reamo04. Thanks gentlemen.

 

Be careful about the hp ratings. The 67 will support far more power on a 3.8 than it will a 5.7. It all depends on where it is on the map.

 

I don't understand how that could be at all; not that I doubt you. Very strange though.

 

Mike,

Please correct here if I’m off-base or if you want to add anything. But to blue's point - a larger (or better flowing) motor inherently has greater volume flow rate consumption requirements than a smaller motor. Efficiency is dependant on pressure ratio and volume flow rate. So a smaller motor will yield a higher compressor efficiency at X boost pressure compared to the larger motor. Get too carried away with displacement, or heads, or cam, yada yada and you hit the choke line (that means now your turbo is much undersized for what you are trying to feed).

-Scott.

 

I'll go a little furthur into this compound/series compression stuff to ask this. The T67 is no longer 'feeding' a 396. It will need to feed a supercharged 396. What is the new volume flow rate requirement of the supercharged 396?? Once you approximate that (and by that I mean figure out what your apparent CID has become) you can select a turbo that can meet THAT new requirement of the supercharged motor.

If your S-trim 396 is puttin' out like a 540". Then look at maps and select a turbo that can support a 540.

Long day at Woodward today

 

boosted, you got it dead on.

 

where can i see one of these maps?

 

They're all over the internet. Google it.