Idle_wild

O.k. I'm new to this site and I was hoping that I could get some feed back from all the people here. I'm currently building a 420 cid sbc for my 89 IROC-Z and the thing is I want it to look as stock as possible. I like the look of the factory TPI and was hoping that maybe with SLP runners that are fully siamesed and a good base manifold that I could have an engine that'll run realy strong on the street and still look near stock. I think that the LTR TPI set up will choke the engine to much so the other option is a HSR and I just wanted to know what every one elses opinion is. Thanks alot guys!

8Mike9

Welcome to thirdgen.org!!!

Forget the looks of a TPI if you wanty to feed the beast. You'l have to consider aftermarket intakes...you have a lot of cubes to work with, and the stock looking setups will just choke ya out.

Do you have to stay CARB legal or not?

RSFreak

CARB stands for California Air Research Board. He seems to be in Washington.

BTW Idle, check out the link in my sig to hook up with other NW 3rdgen fanatics.

ME Leigh

Yeah you don't want tpi, that will kill all the potential of your cubes. If i were you i would seriously consider converting to carburetor. Your not gonna make any power at all with something that looks stock.

ljnowell

Yeah, installing TPI would be like putting a carb on with a rev limiter set to 4500. It would just suck.

Idle_wild

yeah I thought that the TPI would choke the motor quite a bit, I want to try and keep my power band around 5500 rpm for a good street motor. Money isn't really a concern, so I was thinking of going with the SR, but I think if I went with a HSR on that big of a motor that I could pull of 6000 rpm at my hp peak. The motor will sit in front of a 700r4 and I want to try to keep the power band around were the transmission will operate. I've seen the LPE 420's dyno numbers with the SR and both of the motors are near ideal for what I want.

ljnowell

The transmission will operate fine at any RPM, its the torque and HP that will kill it, not the RPMS.

Idle_wild

no, what I meant about having a automatic, is that the auto when in drive shifts right around 5000 rpm at WOT and 4700 rpm under normal exceleration. I want the power band of the motor to match where the trany likes to shift.

25THRSS

Don't do that. Build the tranny around the engine. All you have to do is change the weights around to get it where you want.

Air_Adam

Yes, TPI would be a mistake to put on something that big IMO. It just can't feed that many inches. TPI shouldn't have even been used on the 350 I think, because even on that its pretty restrictive.

On the plus side though, you'd make enough torque with a 420 TPI setup to pull your house outta the ground