I am looking at buying the Gm performance motor with 290hp and around 330ft-lbs. I want to use TPI on the motor but the GM websites says use a 600cfm carb. Is this still ok to use the TPI? I would think so but I need over input. Would I gain anymore power with the tpi over a carb?

 

You will most likely lose peak power with TPI vs. carb. However, the low end torque would probably be higher with TPI, as well as fuel economy.

I haven't heard of anyone who's done that particular swap. Remember, though, the 200-something HP the TPI is said to have is a net flywheel rating, meaning powering accessories, with intake and exhaust as installed in the car; while the crate ratings are gross flywheel rating, meaning no accessories powered by the engine, open headers, velocity stack on the carb inlet, etc. That crate engine actually may not end up with as much power as your current engine has.

 

Do you know in witch range the difference between gross and net ratings is?
Say the net ratings for the LB9 is 230hp with everything stock, how much would the gross ratings be?

Thanks
Pat

 

Peak-wise:

Exhaust manifolds cost about 15-30 HP, depending upon what follows.
Accessories such as water pump and alternator, about 15.

TPI cost the 350 HO about 40-50 hp vs. carb rating when SDPC was developing their Vortec TPI base.

The ZZ4 in 3rd gen trim reportedly put out around 300 HP vs. the gross 355 dyno HP the ZZ4 is rated at.

Dual cats was supposed to be worth 10 HP over a single factory 3" cat.

As usual, these things are a little hard to predict because of the variables involved.

What I was primarily trying to address was the originator's question that assumed a HP increase with TPI over carb.

 

Thanks alot for the answer!!!

And sorry for high jacking the thread...

 

No problem. Just didn't want it to appear as though I was offering a formula for net vs. gross HP.

And, just to be clear, the power loss from TPI, and the not-intended-for-TPI aspect of the 290 HP crate are why I cautioned against expecting more power. Of course, if the 305 is FUBAR, then of course the crate is going to do better.

 

It was a good question.