What is the practical HP limit for a stock TPI intake in a turbo application. Forget about fuel and ECM. Just wondering at level the intake becomes a huge restriction.

I am building a turbo TPI 383 for torque, as an everyday driver. Turbos will most likely be HY35 from the auto dodge diesel. I can get the HY35s for free. I am shooting for 500HP and the crankshaft.

Thanks
Steve

 

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Preston Smith had one on his turbo'd drag car, in the 9's from what I remember... Stock TPI is VERY different from a modified TPI (58mm tb, hogged plenum, cast & ported runners/TPI base, etc). I'd have to guess you could squeeze out 600+ hp, but even at that point, a different intake design would get you more hp (HSR, MiniRam, LT1, SinglePlane). Build it w/ the TPI, and as you get bored with the HP, change the intake down the road. No need to do it all at once.

 

like Andris said,
Preston has a Stock lower base. (extrudhoned)
AS&M runners,AS&M 58mm TB and Ported plenum.
Trickflow G2 - 2.02” int. (275 CFM) – 1.6” exh. (210 cfm)


10.92@126 on 93 and 16psi of boost.
9.92@136 on 117 gas and 25lbs of boost.


Forcing that much boost (25psi) is a TON. He oculd deff get the same times with less boost if he had a better intake setup.

 

WHy would you use TPI? It isn't the best way to make power

 

I am sure it is what he has already. he needs to start with something. when time and money allows you upgrade

 

Well I don't have a TPI setup yet and I am fully aware of their breathing limitations. But what a TPI does very well is torque. I could easily go with a blow through carb and make way more horsepower then a TPI could ever come close to, but HP is not my only goal. I may still go with a carb setup. I get my Wideband O2 sensor in a few days

My main goal is drivability, and some sort of gas mileage. I have 91 Cavalier, so I am no stranger to the 730 ECM's and tuning shouldn't be too much of a problem.

I just wanted to make sure the stock TPI didn't completely die at a certain level, or if there were any serious fuel distribution problems under boost.

Thanks again.
Steve

 

May not be the best way but you cant look deny the fact that you can run 9's with a slightly modded one. but for the $800 invested in Prestons (400something for the AS&M runners, and $400ish for the extrude hone work) you can pick up a HSR/LT1/maybe used SR.)

 

i would suggest against a TPI intake. a turbo v8 (or any turbo motor for that matter) will make a TON of torque. a 383 is a very torquey motor NA, then you add a power adder that makes lots of torque on top of that and you are gonna have more than enough. i say look into a different kinda of intake. there comes a time when too much torque makes a street car undriveable.

like always, thats my opinion anyway.

 

I'd say it totally depends on your budget and ultimate Power goals.

Last weekend I saw an 87 TA, bone stock 5.7 TPI with a 6 speed put down something like 340 HP and WELL over 400 Ft lbs to the wheels using an SYS turbo kit.
This was on only 5 Pounds of boost! Think about when he gets the tuning complete, Adds an inter-cooler or Meth. Injection and turns up the boost to 10#s. AWSOME! I would have little doubt that he will see 400+ RWHP and save allot of money as a bonus!

The forced induction will not really change the rpms that the TPI motor will make its power. It just really boosts the curve to the next level.

As a minimum rule. If you are doing an engine overhaul in conjunction with your F/I install, stay with a stock TPI cam or maybe upgrade to one with a little bit extra lift and exhaust duration. Get some forged pistons and upgrade your Connecting rods. Focus on making power below 5000 rpm.

Dave