http://www.gmgoodwrench.com/perfpart...on=ce&cat=9274

Thought that was cool! Wonder why they weren't testing a TPI 350 HO lol

There's an oxymoron in there somewhere....

Might have had something to do with the fact that the identical same long block made 245 HP in a Vette with TPI on it (except that the cam was optimized for TPI), as compared to 308 HP in a Camaro with a Q-Jet.

What I meant was, why build a q-jet motor when the TPI was doing so well?

I think RB83L69's point was that the TPI (350) wasn't doing so well. As an induction system for the 305 it was doing alright. My question is why didn't gm build a q-jet 350 when the TPI was limiting the motor's output. Course I've fixed that with mine.

The masses feared the extreme power of the HO motor so the program was shut down.

It most likely had to do with emissions is my guess.

Because GM's Corvette guys wanted to use TPI, and GM wouldn't want an upstart F-body raping the Corvette in a straight line like that.

That'd be like Ford having a Mustang kick the GT40's ***.

Ummm, yeah...

ZZ4 + TPI = 245 HP (siince that makes exactly a stock Corvette L98)
ZZ4 + Q-Jet = 308 HP (the package in question)

You do the math.

But that has nothing to do with why it was discontnued. I'm pretty sure the reason was poor sales. Most people looking to do a swap of that kind aren't going to be starting out with a BONE STOCK L69 or LG4 Camaro, and spending $5000 for a "kit" like that. It was too much money for what it was.

I doubt it had anything to do with the Corvette department "being afraid" of it.

another tpi vs carb kinda lol carbs suck cause gas milage thats it imo

I'd guess it was a combination of dollars and emissions. Figure GM spent millions developing the tuned port intake, trying to get some punch in the 305 with the poor cam and heads required to pass smog requirements, sure going to use it on something. With that 116 degree cam lobe separation on the L98, it was a decent setup I guess. Hard to beat a carb for power though. Looking at the L98, it should be pretty easy to get 300HP out of it I'd think.

ya and Tpi is a tourqe monster and that makes the cars feel faster thats why people think their 3rd gens with tpi are faster than they really are

Yea, I was just screwing around when I said that

That motor has nothing to do with a TPI or a 305 HO or whatever. It was a GMPP 350 crate motor package designed to put a little life into the wheezing 4bbl 305 cars. So to compare it to a TPI is senseless. I'm sure GM could have come up with a high horsepower TPI crate motor, but they didnt need as much help!

And for all you freaks who cringe at the thought of GM using the term "HO" to refer to a TPI motor, Pontiac called the 305 TPI the "305 TPI HO motor" in all its sales literature. (as if it really means jack shyte) And if you think about it, isnt it really a HO compared to the lesser 305's that preceeded it? (that ones for you RB)

Really!!!

Evidently you don't realize that the heads are the same casting (113) as the Vette L98? Or that it has the same piston configuration, maybe even the same piston part #, as the Vette L98? At its core, it's the same motor!!! All that's different, is the cam (which isn't even all that much different .... 208° intake .050" duration vs 203° to 207° depending on year); and the fact that one has TPI, while the other has an induction system that allows it to make power.

It's always amusing watching people try to apologize for why TPI cars are so slow and underpowered.

So, one more time, and this time we'll use the other name for that long block:

Vette L98 long block + TPI, in Vette chassis= 245 HP
Vette L98 long block + computerized Qjet, in F chassis = 308 HP

Why is this so hard to accept? It's just facts and numbers. Numbers don't lie. Facts are real. You (or I) can't twist them around to make them anything other than what they are. And the facts say, it's real simple: you take that motor and put TPI and manifolds & exhaust on it, it gives 245 HP; you take it and put a stock, emissions-legal Q-Jet on it and the same manifolds & exhaust, it makes 308 HP; you put a Holley 4-barrel and headers on it, it makes 345 HP. End of argument.

Yeah, the whole "HO" thing has gotten blown rather out of proportion; things like Pontiac calling a TPI motor that, pretty much have relegated it to the status of buzzword.... along with "Vette", "police interceptor", "Vortec", etc. etc. etc. Just look at all the ebay ads for "Vortec rockers" and "Vortec cams" and similar stupidity. Basically, it means nothing, it's merely something that's supposed to sound a bit romantic and inspire people to come off the hip quicker and larger for whatever it is. Kind of reminds me of the "Charger R/T" of the mid-70s, that had a slant 6 in it. All stickers and buzzwords, no substance.

sorry if this question is stupid, or if i'm missing something big here, but your telling me that if i just swap on a carb instead of my TPI on my L98 from my 88 iroc, i'll jump from 230 hp(or w/e) to 300?(i already have a full exaust)??????

i'm not laughing at you or saying this isn't true, i just had no idea this much of a gain was possible just from a carb. wow.

lol, if i'm missing something big, tell me. i probably am.

True about the TPI, but the throttle responce is what I love! And the bottom end torque. I'll never go back to my L69!

Though all mods and such really suck with a computer controlled car

It's not so much that that gain is possible with a carb as that much gain is possible without TPI.

That should be a sticky

lol

so why don't more people just throw a carb on it? if that much can be gained just from that.

To at least partly answer the question, not everyone wants to (or is able to) modify their car, or is willing to sacrifice fuel economy or emissions, or wants to lose the low RPM performance of the TPI.

It's not the carb that makes the power, it's the increased breathing potential gained by removing the restrictive TPI system. The same gains can be had with a different FI induction system.

Don't forget to include "hemi" in that list.

You can also have good results with a fully modded LTR TPI, a better cam and whatever else they did, gears, trans, exhaust, etc. I won't argue that stock TPI could use work to flow better. Yeah, carburetors are the easiest and usually cheapest way to make power, but they also don't have the certain advantages of EFI/TPI or other aftermarket systems. I like the both of them but I like EFI more.

TPI was designed for a 305 yes, but on the L98 it kept right up with it's competition and was more fun to drive around town with the TQ. It might not have dominated everything on the street like the LS1, but it was definetly good for the time and is still really nice to drive today. 350 TPI's were one of the fastest cars seen on the streets since the early 70's when they came out. If Third Gens were light like Corvettes or as a low optioned LX 5.0 is, it would have been pretty dominating with that 245HP/345TQ, more than F*rd could offer then. They should have been given manuals also. Better yet, if TPI was redesigned by GM for the 350 like the First Injection EFI, (this should have been the 350's TPI) forget about it! The long runner setups are great, they just need to be able to flow, 5.0's and LS engines are all long runner. Where's the LT1's almost non-existant runner design now? Are G92 L98's/low 14's that far from stock Auto new M*stangs and 04 GTO's? Not really, as those cars usually average high 13's and this is 20 years after the L98 was introduced. I think alot of people also tend to forget way too often that even mid 14's was enough to take out alot of 60's/70's musclecars, which have a rep of being really fast, when actually the really fast cars were few. There are new and advanced things out, but TPI deserves more credit/admiration. Some people give it and some don't, but that's just their opinion. There are people that just refuse to look at the good side of something unless it runs 12's or has 450HP stock I guess.

My point wasn't that the crate motor and the TPI small block didnt share some features, of course they do, they're both smallblock Chevys, my point was that why compare the two performance wise? Thats like comparing a Ramjet and an LS1. OF course the Ramjet makes more hp. Thats its purpose. And its no surprise the 350 HO makes more hp than a 305 or 350 TPI. That GM 350 HO replacement motor was made specifically to replace the LG4 while retaining its carb, electronics, and manifolds. It was way easier than going TPI...if you could afford it. I remember how bad the LG4s ran..I had an 85 TA with one. Reliable but slow.

And although there is come commonality between the 350 HO and the 350 TPI(both being Chevy smallblocks), I find it hard to believe the only difference comes down to the carb and intake. But since I lost my GMPP catalogue, I'll take your word for it.

And please RB stop the madness with your TPI sucks rant. You're embarassing yourself. Anyone who knows anything about these cars, knows that the 305 TPI consistently made MORE hp and MORE torque than the L69(1986 being the exception). The G92 5.0 5spd TPI and the 5.7 TPI are the fastest factory 3rdgens(pace car and Firehawk aside). Period. End of argument.

Torque is the name of the game. As far at the TPI unit having good low end torque but not enough peak power, that doesnt really become an issue anymore once a good set of runners, headers, exhaust, and a good ignition box are installed. And aside from the runners, arent those the most common mods that every 3rd genner does anyway? ...regardless of their type of induction? With those mods, my car pulls nicely to 5800 and STILL has a strong low end.

Can we take up a collection for RB? He's suffering from the worst case of TPI Envy I've ever seen.

At peak, yes. Across the board I wouldn't be so sure.

That's pretty good!!!

Actually though, they'll be serving ice cream in Hell long before I go looking for ways to spend that much money and trouble to slow my car down that much. And for that matter, if I ever happen to buy a car that has it, and I want to make it faster, it won't be long for the world; although I wouldn't be just hacking it off and slapping a carb on it, in all likelihood. I have nothing against FI in general, having worked on quite a few vehicles with it, and I understand it quite well (well enough to understand better than alot of people why TPI is so inferior); I'll just use some other form of it. In fact I happen to have just such a thing laying around at the moment, just waiting for the right opportunity.

I remember when these first came out. They were emission legal upgrades to fight off the Mustang which was killing the F-Body back then. I think Hot Rod or Car Craft installed one of these into an 87 RS and ran those times. It was expensive and for what you got, not worth it. That's why they stopped selling them.

The reason the TPI wasn't included was nobody made anything for it at that time. Bigger runners were coming but nobody had them as far as I know.

It's only been in the last year or two that they've stopped offering the 350 HO kit in the GMPP catalog, after stock ran out on some of the component parts.

Not worth it is right. You could just buy an L98 F-Body, do a few upgrades and run 13.8's that way instead.

BTW, was the 350 H.O. engine in that whole thing almost the same as the 350 H.O. crate engine that GM still sells? If it is, it's definetly not like an L98 with a 4BBL on top of it, at all. They also try to say it's a ZZ4 in that link too, don't know what that's about.

This was pre any ZZx combo. It was just an emission legal combo to work only on LG4 and L69 cars that gave a pretty modest increase.

But it wasn't worth it. My 84 HO 5spd Z28 was running 13.9 back when it came out. And on the cheap

The engine in that kit was the same thing as the ZZ3/ZZ4. In fact, for the last few years of its existence, it was the ZZ4, aka Vette L98 except with a slightly bigger cam.

It was not the same as the "HO" engine being offered now, which has Vortec heads and some kind of "peanut" cam. It had the 113 casting aluminum heads (the Vette L98 aluminum ones) and the ZZ4 cam.

In essence, it was the ZZx motor, with a kit of surrounding support parts; air cleaner, exhaust system, jet & PROM kit, and a few other little goodies. At its heart though, it was the ZZx motor.

Too bad "HO" has become a worthless buzzword. Just because 2 motors are advertised as "350 HO" doesn't mean they're the same thing; it just means they're both being marketed the same way to the same target market. "New!" "Improved!" "37% better throttle response!" "Tastes great! and just look at that shine!"