canbaufo

My engine is only built to handle about 9 - 10 PSI (355 - 9.5:1 and studded 2-bolt mains, "lower-end" forged rotating assembly). Therefore even though I'd like to upgrade my ~7 PSI Powerdyne to something better 9 - 10 PSI is about all I can safely push. Between 2 - 3 extra lbs of boost, a better (more efficient) blower and intercooling/tuning I'm hoping to pick up ~75 rwhp over my current ~450 - 475.

Comparing the S-Trim to the T-Trim on my engine with either pullied to make the same peak PSI, which would perform better overall and have the flattest torque curve with better low and mid range? The same question applies to the ATI blowers mentioned below.

This comparison is often mulled over in various forums but I can't get consistent data as to which makes more torque at low to mid RPM. For example, everyone agrees that the 1400 cfm D1SC will make more peak HP than the 1200 cfm P1SC at the same PSI due to lower air-charge temps and being better suited for higher boost applications (more efficient). Some say that the P1SC makes more torque at lower RPM because of it's lower 1200 cfm rating being more efficient for low RPM use. lol others say the opposite, that the P1SC makes less torque at lower RPM because of it's lower 1200 cfm rating.

I figure comparing a P1SC to D1SC for my engine ...knowing I'll never go beyond 10 PSI, either would suffice just fine for peak HP but what about the whole power curve?

This exact same question applies to S-Trim vs T-Trim. What have your experiences been, or has it been too much of an apples to oranges comparison from one setup to another? I am aware of the various benefits of bigger blowers (more ribs on pullies, less belt tension needed, run cooler, better prepared for future, etc).

EDIT: One thing that just occurred to me is that bigger blowers may make more power per PSI across the board due to flowing better which means less parasitic drag and less heat.....

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z28ke

I don't know for sure but like you said in your edit, I "assume" that due to the higher cfm at any given boost level the larger blower would make more power. Just my .02

Purple Poncho

I can speak from experience here.

I switched from an S trim to a T trim a few years back. Using the same pulleys gave me the same boost on both (6.66/2.75) which was 10psi.

On a very mild 383 I ran a 10.9x with the S trim and a 10.6x with the T trim.

That S trim is still on the shelf if you are looking for one. A nice medium would be the new Si trim IMO.

Edit: Now that the old memory is working; I dynoed 557rw non-cutout in its initial configured S trim/383 and 563 with the Trim with cutout. Almost the same. I usually see 15rw with the cutout open.....just to contradict what I wrote above..lol

Kevin Blown 95 TA

A larger blower moves or compresses more air and takes more horsepower from the engine to turn.