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GM Performance TBI Heads

BigCountryx

BigCountryx

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Well, I am of the opinion that stock TBI swirl port heads are some of the worst flowing heads that GM ever made. I can imagine that any heads like these would be an improvement for sure!

You could also consider a set of 87 - 92 L98 F-body (Camaro, Trans Am, GTA etc), or 87-92 Y-Body (Corvette) TPI 350 heads, they are one of the better flowing stock heads made by GM, and if you get them from a Y-body they are made out of aluminum. The 87+ heads are center bolt, and have the correct intake bolt pattern for the TBI intake.
 
Would these L98 heads or TPI heads your talking about be a direct bolt in for the TBI 350? I'm looking for something that will be a direct replacements, just flow a little better and give me a little more power. Probably gonna do a mild cam swap at the same time as well as TB mods and headers. I just don't want to start running into EGR issues and such. I Believe in the KISS (Keep It Simple Stupid) method most of the time. Thanks
 
If you get the heads I mentioned, they'll be a direct bolt up. Everything is exactly the same from the head bolts, to the valve covers :)

Make sure that you get a cam with a lobe seperation angle of at least 112 degrees, or your TBI will never run right afterwards.
 
Not to hijack but ive heard you can use a stock TPI cam in a tbi, and its supposed to be pretty good. Is there any truth to that? also are trucks are non roller cams right? and the TPI's are roller cam, so youd have to switch over to roller lifters?
 
Not all TPI are roller cams, infact, most of them wouldn't be...

I can imagine that a TPI cam would work fairly well with a TBI engine, as they'd have more lift etc, and are definitely EFI friendly.
 
Since all the car engines were roller from '87-on whether carb, tbi or TPI, I'd say most are roller cammed. That would leave '85 and 86 as the only non-roller cam TPI stuff.

If thirdgen's search was working, you could probably find all the comparative numbers, and results too. (from tbi to tpi cam swaps)
 
Also, Are the heads in the link that I provided just some L98 heads or some other GM heads that GMPP are marketing as High performance TBI heads?
 
i'll second the S/R Torquers for a mild TBI buildup, if you plan on using a stock intake. if not, L31 Vortecs are the way to go.
 
If all you are looking for is 285 HP your stock heads can support that.
Those GM TBI Performance heads are L98 heads. More for top end power than low end.
With a manifold, Mild computer frendly roller cam, 1.6:1 rockers, headers, you can make your 260- 280 hp goals. It is really not that hard to push a TBI motor over 300 HP with a little port work on the heads.
But
once you start adding a lot of flow with aftermarket heads/port work you are going to have to do some chip work.
If you stick with the stock heads the stock chip/ computer will be able to handle up to aprox 280 HP with an adjustable fuel pressure regulator and all the other TBI compontes in good working order.
If you are looking for ease of install stick with the TBI heads they are really not bad of a head for a truck. (Flame suit on)
 
Thunder said:
If all you are looking for is 285 HP your stock heads can support that.
Those GM TBI Performance heads are L98 heads. More for top end power than low end.
With a manifold, Mild computer frendly roller cam, 1.6:1 rockers, headers, you can make your 260- 280 hp goals. It is really not that hard to push a TBI motor over 300 HP with a little port work on the heads.
But
once you start adding a lot of flow with aftermarket heads/port work you are going to have to do some chip work.
If you stick with the stock heads the stock chip/ computer will be able to handle up to aprox 280 HP with an adjustable fuel pressure regulator and all the other TBI compontes in good working order.
If you are looking for ease of install stick with the TBI heads they are really not bad of a head for a truck. (Flame suit on)
Click to expand...

If I use the stock heads and manage to squeeze 275-280 HP out of this engine, where will my torque numbers be and at what RPM will it fall on it's face? Also, what cam would be a good match for the stockers.

BTW - I had a feeling that the Performance heads were L98's thanks.
 
With the stock heads expect them to fall on their face around 4500 RPM.
Good cams are Edelbrock 3702 or Crane 2020, or a 3030 if you want more midrange. Comp also has a mild computer frendly cam that works good in TBI. All these cams will work with a stock chip.
You should have an edelbrock or holley manifold to go with them. Also headers.
I would also use flat top pistons instead of the stock dished ones. flat tops will up the compression ratio to around 9:1. The stock chip can easily handle that and will make more power.
A bored 46 mm (600cfm) TB and an adjustable FPR running 14-15 PSI will top things off nicely. Should get your injectors rebuilt/cleaned/flow matched or get new ones.
Depending on the cam you will build all your torque in 2300 to 3000 range. The Crane 3030 will pull up to almost 4K
And HP will peak around 4000. Perfict power band for a heavy truck and fuel economy.
 
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