Pro

When I mean disadvantages, Im talking fuel flow, air flow, computer chips. ETC. For example, I own a 95 Silverado (TBI 5.7) and I have learned through the years how much it SUCKS when it comes to air flow and effeciency. Obviously the TBI setup is a bottleneck, but something about intake and exhaust design as well. Does the same apply to, say, a 91 Z28 with 5.7? What are some of the major bottlenecks of this motor?

FyreLance

What exactly are you looking for disadvantages for?

Sounds like you're saying compared to TBI.

I don't think that TBI has any advantages over TPI, except a TBI car probably has less traction issues.

Seriously though, the downside of TPI engines is their top-end. Their powerband dies off really quickly in the upper RPMs, and the motor can't rev too high.

91Zman

The only thing about the 350 is that it supposedly runs out of breath at 4500rpms due to the airflow restrictions of the tpi unit,tpi manifold and also maybe it's exhaust manifolds since I think that they're the same ones for the 305.Get larger runner tubes, an aftermarket tpi manifold,port the plenum and get headers.That will help it out greatly as for how much it helps I have yet to try that.

Pro

Yea, this is what Im talking about. Air flow I suppose. Will vortec heads fit? What kind of prices are we talking with what you mentioned?

Black6SpdTA

Vortec heads will fit, the only downside is that you need the $400 Scoggin-Dickey TPI Intake. The heads are so cheap though, by the time you pay the 400 you're at another set of heads that probably don't even flow as well. I'm planning on that combo next year.

The MiniRam is the only "Ram" that will fit vortecs and it's around 11-1200 bucks (you need their fuel lines too $300).

Although you can't use them with vortec hads, you might want to look into the StealthRam, SuperRam, etc.
-Rippin

Pro

Hmm Scoggin Dickey. About 5 miles from here. Cool.

jd13

The TBI setup is not the bottleneck by anycase. By no means do many people run it, as it's not the most practical, but power can be made with it. I don't know about how it is in truck engines, but in the 5.0l TBI Camaros/Birds, the bottle neck was the ****ty heads and small cam. Not to mention that all the exhaust manifolds on thirdgens could have used quite a bit of help.

Like said, the 5.7l TPI cars run out of breath at the upper rpms. This is mainly due to the intake. Think about it, the same parts are used on the 5.0l TPI cars. You could buy some larger runners, intake manifold, port some stuff, and you would see some decent gains from it. The motor will more than likely runout of breath if you decide to run a different cam, and definatly will if heads are added. That being said, TPI really is not the best to make raw hp with, but makes awesome torque. In my opinion, this makes it a very good truck setup, especially for towing and the likes.

Anyways, I'm not trying to turn you away from TPI. I love it to be honest with you. I'll never get rid of my thirdgen. After I'm done with my LS1, my project car is going to be an early 70s stingray Vette with a 383. It won't be all it could be, but that's ok. Guess what? Yep, the setup I'll be running on it will be TPI.

91Zman

Well it depends on what company you get these things from.SLP siamesed runner tubes are $269+$20 for the gaskets,then Edelbrock has the manifold(non-vortec type I think) for $400 and as for the exhaust-headers usually run $299 and up but there are cheaper(not as good quality though) and the exhaust-$150 per catalytic converter(there are 2) and about $250 for the catback system.It's not cheap but it is worth it from what I hear.I myself have the SLP siamesed runner tubes(yet to be installed),MAC 1 5/8"headers(should have gotten 1 3/4") and 3"y-pipe and 3" catback w/Flowmaster 40series muffler. When I'll have the time and money I'll get the intake,port the plenum/intake and maybe get a 52mm throttlebody.Go here for more info on what else to modify.

Dapper

Well I know mine could probly breath alittle better but my 89 L98 350 IROC does pretty good to 6,000 RPM, but I have modified the air filter box, installed K&N Air Filters, eliminated the coolant flow through the Throttle Body, installed Edelbrock TES Headers, modded my Pressure regulator, modified the cat. plus a host of other mods to the exhaust and bolt-ons to help performance that I'm sure help it turn a few more RPM's.

Pro

Sorry for the dumb questions... I just bought a 91, so Im not all that familiar with these cars yet. I bought this car from a really nice guy in Plano, TX. He seems to be a newer LS1 model fan, but he might be a member here on the board.

Here is my car and black truck:

http://webpages.acs.ttu.edu/blincoln/car/1.jpg

http://webpages.acs.ttu.edu/blincoln/car/2.jpg

http://webpages.acs.ttu.edu/blincoln/car/3.jpg

http://webpages.acs.ttu.edu/blincoln/car/4.jpg

http://webpages.acs.ttu.edu/blincoln/car/5.jpg

But anyways, how does modifying the coolant flow through the TBI help? Why is it even designed that way?

91Zman

Very nice Z you have there,very clean.As for the coolant bypass,by doing that mod coolant will no longer flow through the tb hence no heat,made by the flow,will no longer hinder airflow performance but aid it.Go here-> Coolant by pass

Makaveli

invest in a modified LT1 intake ive heard of a lot of happy people with LT1 intakes from john m. (cant spell last name) thatll get your motor past the 4500 rpm wall

Black6SpdTA

$300 from Summit. Holley Stealth Ram
From what I've heard that thing pulls like crazy up top. I wonder if it gives you the feel on an LS1?
-Rippin

Chris Ja

I run a SuperRam with LPE heads and cam, 52mm TB, TES headers and a host of other mods. The car runs best when shifted at 6000 RPM's and has run 12.96 at 110MPH. That was before the supercharger install. With the right parts the engine will breath fine. It just takes some research, money and time.
The aftermarket has some good TBI systems that will flow over 900 CFM's. Don't let people make you think you can't make a TBI engine flow big numbers with aftermarket parts. My one friend Hot Rod Hawk has a 4th gen in the 9.9 with a aftermarket TBI system. Like I said it just takes alot of research and money. Hope this helps.

DanTheIROCMan

While we're on the subject of rpm/airflow, I wanted to put my $.02 in. I never realized just how much of a rpm wall there was in my IROC until I purchased my 99 Cobra. It seems that where my IROC leaves off, the Cobra takes over. The Cobra is all top end. I'll tell you, it was quite a shock when I first got on the Cobra, and was admittedly a little disappointed. Although the Cobra will clobber my IROC on the freeway, it's a different story around town.

It's kinda funny, I am now working on my Cobra to gain more torque down low, and will soon be working on my Camaro to gain some hp up top.

But since this is a Camaro board, I'll keep it on that subject. Will the suggestions in this post, such as the Holey System Max, reduce my low end torque? It seems like there is always a trade off, but I want to try and avoid any reduction in torque at all cost. It is highly addictive!!!

What RPM can the 350 block safely handle on stock internals?