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Potential of stock TBI heads?

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kp texan

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I've got an '88 K5 with a completely stock TBI engine, except for the exhaust system. Due to very leaky valve guide seals, I'd like to either pull the heads and have some work done on them or replace them with a set of aftermarket ones in order to give me a little more hp over stock. What kind of potential do the stock TBI heads have as far as porting and new valve sizes go? How would they flow as compared to a set of cast iron Dart heads or world product heads? New heads will cost me atleast $1000 so I'm looking to save a little cash here and especially since I don't need to make crazy hp or anything. With the stock engine being 210 hp at the crank, I'd like to maybe make around 285 streetable, reliable, hp (I realize this will require probably a mild cam, throttle body, and chip). Do you guys have any suggestions for me?

Thanks,

Wes
 
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I'd get a set of vortec heads. You can buy them new for around $260 ea. By the time you have your stock heads reworked you'd probably be looking at a couple of hundred bucks each. Vortec heads would be much better. Just my .02.
 
Yeah but by the time I add the TBI Vortec intake and needed exhaust manifold the price would most likely be higher wouldn't it?
 
I see that AFR is working on some new heads called "Eliminator", but not sure of anything other than they should be fantastic heads.

Maybe check AFR's site and see what they say.

Vortec heads really add a lot of hassle to a "stock" TBI swap, but if you don't care about EGR, you could do a carbed Vortec intake with an adapter for a lot cheaper than the GMPP TBI EGR intake. I don't really see any downside to this, but if you have visual emissions inspection, obviously it won't work.

Vortecs also don't come with a lot of stuff the aftermarket heads do (good valve springs, screw in studs, etc) plus they require new rockers.
 
while we`re on the topic, my heads are worn, and possibly have damaged valve guides, and definitely need new seals....so which heads would be best to get, with it being mostly a dd with very occasional offroad use?
 
Yeah the key here for me is cost. I'm by no means cheap but for the horsepower that I would like to make, I'd like to do it in the most economical manner.

Thanks,

Wes
 
What do you guys think of the World Products heads? I'm running s/r torquers right now and I'm not to sure on the quality... They sure had cheap valve seals, I replaced those with good ones.
 
I thought I recalled atleast one person on here saying that the stock TBI heads could be ported and polished quite nicely? Also, when looking for a set of aftermarket heads, which specs do I need to look for in order for them to fit my stock TBI properly (combustion chamber size, intake/exhaust runner, etc). Also, I know many recommend the Dart iron eagle heads but it looks like a set of trick flow aluminum heads are about the same price. I also thought that aluminum heads are a little better for performance engines but are they not recommended on here because of durability? Thanks so much for the help.

-Wes
 
You make power in the heads. (well, for me anyways, that really is the bread and butter. An engine is a system, but the heads will net you some serious gains, and without good heads, any of the other mods are tempered) If you want to spend money on any one component for an engine, my vote is heads.

I'm not quite clear whether they are the same company or not, but RHS (Racing Head Service) and Pro-Topline are two companies to look at their offerings. Pro-topline heads could be had for quite cheap, and appeared to be equivalent to the Vortecs, but built with better components. You *could* at one time find their heads online brand new for about $500/pr.

Look at cost this way. Vortecs will essentially net you 40HP more than the heads you are running now, with no other mods. With absolutely no penalty in driveability, getting that much HP in one modification would be darn near impossible, especially for the cost.
 
dyeager535 said:
You make power in the heads. (well, for me anyways, that really is the bread and butter. An engine is a system, but the heads will net you some serious gains, and without good heads, any of the other mods are tempered) If you want to spend money on any one component for an engine, my vote is heads.

I'm not quite clear whether they are the same company or not, but RHS (Racing Head Service) and Pro-Topline are two companies to look at their offerings. Pro-topline heads could be had for quite cheap, and appeared to be equivalent to the Vortecs, but built with better components. You *could* at one time find their heads online brand new for about $500/pr.

Look at cost this way. Vortecs will essentially net you 40HP more than the heads you are running now, with no other mods. With absolutely no penalty in driveability, getting that much HP in one modification would be darn near impossible, especially for the cost.
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Pro topline went under and now it's RHS. I second Dorians words on the vortecs. No way I would spend time with porting and bowl work on tbi era heads.
 
Yes, you can do work on the stock TBI heads. I'll tell you right now, all the gains achieved from doing that STILL can't get you the vastly superior Vortec chamber.

For a "normal" truck application I'd be looking at the low end of the head flow numbers...180's or 195's max.

Combustion chamber is up to you, but that's one place where you start running into differences between all the heads. 64CC and 72CC are the two "stock" sizes, yet you will find aftermarkets around those numbers, but not exactly the same in some cases. Chamber size affects your compression ratio, which will start you thinking about what fuel ou want to end up running. With a set of Vortecs or Aluminum heads, 9.2:1 compression or a bit higher should be doable with 87 octane gas.

Aluminum heads vs. iron is pretty much a wash. Aluminum is lighter, but it sheds heat faster. Heat makes power, so the aluminum heads, all else being equal, make less power than irons. Increase the compression over iron (again possible because aluminum sheds heat faster) and you end up getting into the same power numbers as iron...but now with less weight. Not a huge factor for our trucks, but every bit helps if you ask me.

I've never heard anything about strength issues...GM started using them way back in the '60's, and now they are pretty much the norm.
 
kp texan said:
Yeah but by the time I add the TBI Vortec intake and needed exhaust manifold the price would most likely be higher wouldn't it?
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The vortecs require a different intake and different valve covers (both much better designs than the previous generation) but they use the same exhaust manifolds. If you are looking for power, an aftermarket intake is certainly not a bad idea either. My vote is for vortecs :waytogo:
 
Sorry, I meant to say exhaust manifolds. I thought I remember hearing that I had to run a vortec exhaust manifold on one side for the egr or air system? As for the TBI intake manifold that will fit vortec heads, what is the most economical choice there?

Thanks,

Wes
 
You'll need Vortec exhaust manifold to run EGR, or plumb it from headers if you go that route. TBI gets the exhaust gas for EGR from the crossover in the intake, Vortec heads/intakes don't have that crossover.

Again, not sure anyone but GMPP is selling the TBI Vortec intake manifold, but you might check on Edelbrock. There is apparently a factory application for the TBI Vortec intake, but it's gotta be real rare in wrecking yards. It was posted on thirdgen.org what vehicle it was. As I recall, it was a van of some sort.
 
vortec said:
i recommend a set of 305ho heads. i just might know a guy willing to sell a decent pair.:wink1:
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don't mislead the guy like that. 305 heads are piece of ****.


I agree completely with Dyeager. You would pay more, or put more of your own time into TBi heads than they are worth just to make them STILL worse than stock Vortec heads. Don't bother IMO. The ramps in the intak ports of the TBI heads would take a while to clean up to actually create RPM flow. If you REALLY want power, run the stock heads for a bit and save money to put some Vortec heads on.

The driver side Vortec manifold has an EGR port for the EGR tube, if you eliminate the EGR system there is NO need for the Vortec manifold. However IMO just based on their appearance I bet stock Vortec manifolds flow better than the older stock Chevy manifolds. Just looking at them they simply look a little straight in flow design.
 
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