I just purchased a 1989 IROCZ with the L98. I love it. Previously I had a carbed single plane 377 in a 1982 Camaro.

I have read all stickies and everything I can find regarding the stock TPI system. It looks like TPI is a pretty serious restriction. Coming over from the carb/racing world, I guess I am not used to that. For instance, there was a thread where a big horsepower setup made 80 hp less with stock TPI than with a carb setup/ stealth ram.

What I haven't been able to find is this - am I throwing my money away making changes to the stock TPI system such as runners, base plate, etc? I am starting with a completely stock L98 and want to make sure I make the right changes.

 

Since this has the potential to be an enormous thread going in several different directions, I'll try to avoid tangents like what mods should be done first etc. etc., and I'll assume you've already read "those" type threads.

Dealing directly with your question, in regard to the TPI itself, yes, it IS a huge restriction.
There is the "FIRST" intake, which does look similar, but the base, plenum, runners and TB are all FIRST intake specific. It sure does work, but I don't consider it really a TPI in that it's not a GM style, long tube runner EFI intake.
Then you have the guys who are cutting up, welding and fabbing up modified versions of the GM and or FIRST style intakes. Again, they're seeing big gains, but they're nowhere near off the shelf bolt on intakes. Super impressive. Super cool. NOT just another off the shelf part though.

....If you're gonna stick with a GM style long tube runner intake, and let's assume at the most, you'll do some minor porting, etc. etc., you can see some nice improvements, but you'll never match the peak potential of some of the other more efficient intakes. Now you could argue it's not all about peak HP, but at the end of the day, that TPI is a restriction. If you can spin the tires, and most of us can, then we're not in danger of losing TOO MUCH torque, and we could all use a few more ponies up top. ...and then of course you have cost...

I love the TPI, but I'd never actually recommend anyone use it! That being said, I'm still using it! I would say to read, read, read, make some of the other mods that you'll wanna do first, regardless of intake, take your time and make up you own mind as to your expected power goals, and what intake best suits those needs. This site has a TON of info on all the different intakes!!!!!

 

Very helpful post thanks Abubaca, yes there is so much to read here on the topics you mentioned it is almost overwhelming .

 

everyone here so far has made sense, but since i still hold dearly to my tpi variant and i repeat variant the tpi setup factory oem style is a hog we know that agreed the tpi build and format on the other hand is a really good design when it comes to streetable throttle response, additionally if we talk variants, injector up grades plenum changes throttle assembly changes ie bbk or tpis we are now in a different category some ecm or standalone programming i doubt the feeling of reverting back to aftermarket carbureted intakes is in the dust (past) im not arguing the fact just merely throwing a few of my cents in to the mix

 

I don't totally follow you, but there is the temptation knowing that for $500 I can make maximum horsepower and very good torque that will respond to whatever I do to the motor from here on out. The throttle response on the TPI setup is insane to me, it runs so good and every carb setup I have owned has had a lean/fat spot somewhere. Then again, every carb setup I have raced made horsepower up to 6500+

 

totally different arena you cannot compare a setup with 6500 hp? but yes the tpi has a very good response check out tpis and do some research on it you may be intrigued with your findings. I don't need lots of money to shame higher end cars or people with endless pockets its knowledge that allows me to spank them and adjust my nerd glasses lol!