Ok, sorry to start a new thread, but I got some great advice to stick with my 90' TPI unit for my cruiser, 59' Vette.

But I was also pointed to the article that Comp Cams did using one of their Extreme Cams and a 383 SBC. They compared the stock corvette (90 style) TPI to alternate aftermarket FI units as well as comparing the different aftermarket runners and bases that can be bought for the original TPI unit.

Ok, so with the factory TPI unit on the 383 SBC, their base line was 410HP. I thought the factory unit couldn't make that kind of horse power. So am I missing something? Or if the engine has the power and done right the stock unit can produce 400HP.

Can any one clarify, thanks guys.

 

It can be confusing:

383 stroker is a different animal than the stock 350....this is not comparing apples to apples. Torque is way up on a stroker.....the HP is a measurement based off of torque.

 

There are a bunch of write up like this on the internet that define torque vs HP.

http://www.vettenet.org/torquehp.html

http://www.carcraft.com/techarticles...que/index.html

Stroker stuff in a nut shell:

http://www.383stroker.com/

 

To quote John Lingenfelter..( Horsepower is merely torque over time.) (RPM)....WW

 

So the stock TPI unit has the ability to generate that kind of power?

 

Maybe on a engine dyno with a really built motor w/ aftermarket heads and no accessories hooked up and open headers...but no way in your car at the rear wheels.

 

The question shouldn't be how much power can you make with a TPI intake, the better question is how much more power would I make with the "right" intake for your application on top of the motor.

I once put a bone stock TPI unit on top of my 383-219-AFR 190 motor and ran a 12.0 @ 111-112 mph...... sounds good to some, but with the Superram on that same motor, I was running 11.4 @ 118 mph the weekend before on the same track.

Point being, you can probably make 400 HP with cubic inches with a TPI unit if you try hard enough..... but why not put on the right intake and make 450-500+ HP..... and have a better balanced motor at the same time.

good luck !

 

The TPI intake simply makes a torque peak driven by runner length. So if you increase displacement power would increase also.

I'm thinking that with proper heads, cam, exhaust and tuning the stock TPI on a 383 build could make 400chp or a bit more.

 

Well my engine is a worked 355ci that puts out 430HP and 450lbs tq. So should I just keep with my engine and have fun for a street car that will be driven more like a granny since it is a 59' vette or go with a 383 or different intake. I happen to really like the TPI look.

 

Yep... Everyone cares about HP, but HP is derived from torque...

rpm x T = HP
5252

T= torque
5252 = constant

 

http://www.compcams.com/Community/Ar...?ID=1737510521

It's not a question of how much HP the TPI can make on a bigger motor, rather how much it LIMITS that motor! In that shootout, the 383/TPI 410HP is made at 4400rpms. Above that NO add'l HP is generated. Power FLATLINES above 4400rpms -- because of the TPI's restriction. No matter how much higher you rev that 383, 410HP is all you'll get. (Also, though HP remains level, torque falls. That's due to the HP/TQ relationship).

By comparison, notice the HSR also makes 410HP at 4400rpms but it continues to allow HP to build to the 500HP level. That was some SERIOUS restriction! Right? While the TPI does get a small add'l 30ft/lbs of TQ from 2500-4000rpms, that's seriously shadowed by the 90-100HP advantage of a shorter-runnered intake. Now consider what would happen in a 1/4 mile race...

A 355/TPI would run somewhat close to a bigger 383/TPI. But the 383 would still be faster with ~10% more low-end power. As stated above: Once either motor hits the limit of the TPI breathing, there's not much more power to be had. Swap the TPIs for "better" intakes and the 383 will run away. IOW, that TPI is a restriction for high rpm (power) generation. (Note: If you don't get the relationship between HP and TQ yet, either figure review the thread above, or just take our word for it.)

For a "granny-cruiser" that's NOT driven above 4500rpms, the stock TPI will be fine. It will even punch out a bit more torque/power in that 2500-4000rpm range and provide best mpg. OTOH, if you want the fastest running car, you'd need to rev it higher and use an intake that doesn't create a higher rpm restriction.

A TPI is best used in a truck where lots of weight is hauled and/or to pull tree stumps. That's where you need torque building quickly. Granny cruisers will also fall into that category.

Edit: Also, I meant to ask you... Why would you be impressed by an intake that can make only 410hp on a 383 vs the 430hp you're claiming on your 355? Doesn't something seem wrong with that premise? Hint,,,one of those numbers is wrong! LOL

 

HP is what wins races, not torque. To illustrate, lets race two identical Vettes. You shift a bit past peak torque and I'll shift a bit past peak HP and let see who wins the race.