Well, after getting my new ride that has an LT4 powered motor in it, I have decided not to go carb with my new setup that is going in my 91'.

I have also opted for a T56 instead of a built 700r4.

Here's the dilemma:

I don't know what heads to get. I already have a set of STOCK LT1 heads, and an intake, in great shape. I also have the 57cc Vortecs that are on the car now that could really be worked an produce serious power. Another option is to get a set of TRICKFLOW heads. 23 degree or Twisted Wedge series, I don't know which is best for my application.

Here are some of my ideas:

Work the LT1 heads and intake for optimal power. ( What ecm, I don't know)

Use my Vortec heads ( after porting etc.), get a TPI base from Scoggin Dickey, and run A high rpm plenlum and runners.

Get some trickflow heads ( for 87 up motors) and port the LT1 intake I have. I think this might be the best bet.

I want to supercharge this motor later on, to produce at least 600 horsepower.

I want this setup, naturally aspirated to produce upwards of 450 horsepower. The SPECS ON THE SHORTBLOCK are:

mid 70's 4 bolt block
bored .030 over
Sealed power hyperuectic pistons
Comp XE 268 cam ( will have 1.6 rockers for more lift)

I would prefer out of the box performance but whatever would work best and produce OPTIMAL power is what I want.

Let me know some thoughts fellas...

Thanks in advance.

 

I think first you need to decide if you want the motor to be strong on the low end or strong on the top end. After driving a LT4 and deciding you want a T56 over the 700r4 I get the impression that you find the top end (high rev) power more fun. If this is the case then I would go with the LT1 intake for sure. To make power you want alot of flow (cfm) and bigger injectors. If your 91 RS is a TPI motor, you can use the stock 730 ECM but you will need to burn a new chip. If you plan to boost the motor later on then you might want to look into a 749 ECM swap and custom chip (can calculate up to 14.5 psi of boost for later use, but would also work great for the current N/A plans). Or you can ditch the GM ECM stuff and go aftermarket from the start but expect to spend at least $1000 for a good system (Holley Commander 950) or even $2000-3000 for the high end systems (F.A.S.T. or Gen IIV). The heads and cam would be up to you, but I always believe the cam should match the powerband the intake will give you.

 

I want a T56 to row through the gears, it's so freakin' fun. I want to go the injection route because the throttle response is so crisp, not because I want a high revver. The LT4 does redline pretty darn high ( still making over 350rwhp above 6600 rpm) but the torque is just incredible. 1st gear will flat out snap your neck if the pedal hits the floor at say a mere 2500 rpms.

The computer in my RS is STOCK, tbi.
Anyway I go I'll need a new setup.
One thing for sure is I don't want a low revver. I don't want over 450 horsepower peaking at like 5300 rpms.

Does anyone know which TRICKFLOW heads are best? ( must be for 88 up roller motors, centerbolt style)

I think the LT1 intake with the Trickflow heads and a TPI custom programmed computer setup would really kick ***.

 

Yup that would be a great setup. As long as you're sticking N/A then a 730 ECM would be good. Only possible hard part would be the chip. Do you know anyone locally that can burn chips? To make 450 HP you're going to need bigger injectors, maybe 30 pph.

 

Bigger than stock TPI, or Bigger than Stock LT1???

I am not 100 percent positve but I think the Injectors on my LT4 are stock.

 

LT1 injectors are rated at 24#'s. LT4 injectors are rated at 28#'s. To make 450 hp I think you'll need 30# injectors. A new set of Accell 30# injectors (8) should be around $250.