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AFR vs Vortec vs ?

Greg Ducato

Greg Ducato

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My 1989 62K mile 5.7 TBI Burb has been smoking during start up for some time now and is getting progressively worse, now even smoking badly after idling for a few minutes. I can just change the seals but it seems like an awful lot of work for no improvement beyond the smoking situation.

I'm thinking this may be a good time for a head upgrade and top end makeover. I have a "small" roller cam ( stock LT1 Z28), Eddy TBI intake, ported throttle body and some Thorley tri-y's I have been saving for a build, my problem is I am not convinced of the best head for the job.

There is no doubt the Vortec is a good head, but it will require a dedicated intake, plumbing of the EGR and some other minor changes. Add in the dedicated rockers and you are looking at $1k or more in expense. I don't want to go back with a stock TBI head at this point, there is virtually nothing to gain with it that I'm aware of.

The AFR 180CC head looks pretty good to me, nice flow, proper CC for retaining compression ratio, lighter weight and the ability to use all my gathered top end parts, plus it will be enough if I want to go to a 383 short block down the road. These are about $1500 a pair, which is strong but you get what you pay for I'm telling myself.

There are other heads on the market in cast iron and aluminum, can anyone share some personal experience on any of this, pros and cons, things to watch out for or consider etc.

Thanks!
 
The TBI will be your most limiting factor so I wouldn't spend a bunch of money on heads for a TBI engine. If you want your engine lighter some edelbrock heads would be considerably cheaper. If you want to get rid of the TBI then Dart or Brodix would make the most power. AFR is over rated in my opinion, they are in a lot of mags and advertisements, but if you go to the racetrack not many people run them that actually measure the speed of their car.

I do like the fact that you picked some that aren't too large for the TBI engine, but even with 180 cc heads in AFR or edelbrock the TBI will limit the power more than the heads already, especially since the cam has to stay small.
 
Thank you for your input sir, There is a big part of me that wants to remove the TBI and run a well built Q-jet but that seems like going backwards even though there would be good power gains and probably no real loss in MPG. I have a set of AFR 195's on the 383 in my Caprice and have used them on a few Ford builds in the past and they have always done a good job for me.
 
Don't take it the wrong way, AFR is a good quality head and a good brand, you definitely won't not like them. But when it comes to raw performance others can outperform them, and I don't think they are the best bang for the buck either.

If you remove the TBI I would go with another EFI like FAST, Holley, BS3, etc. I agree, going back to a carb is a step back in driveability, especially on inclines and changing altitudes that can happen with an offroad vehicle. But it may not be worth the cost depending on how you use the vehicle. Maybe just keep the upgrades mild?

Whatever you do don't go with one of those overseas heads that are cheap, because they will cost you more in the long run.
 
Even just a nice reworked set of L98 heads would be an improvement over what you have.

Martin
 
A buddy of mine in college put together a 350 TBI for his 1991 Camaro RS to replace his 305 TBI. He started with a 350 core out of a early 90's truck. I cleaned all the pistons for him, he honed the cylinders, reringed the block, drilled the holes to make a factory roller setup work (I think he used an LT1 cam too, but I can't remember for sure). He then had a set of slightly worked L98 heads, a Holley TBI intake, and Holley throttle body. Threw on a set of headers, and ran it. With a stock tune on street tires, it ran 14.0.

Not super impressive, but it was a nice running engine (that cost him next to nothing, all used parts), that ran much stronger than the 305 that was in it.

Martin
 
folkenheath said:
Don't take it the wrong way, AFR is a good quality head and a good brand, you definitely won't not like them. But when it comes to raw performance others can outperform them, and I don't think they are the best bang for the buck either.

If you remove the TBI I would go with another EFI like FAST, Holley, BS3, etc. I agree, going back to a carb is a step back in driveability, especially on inclines and changing altitudes that can happen with an offroad vehicle. But it may not be worth the cost depending on how you use the vehicle. Maybe just keep the upgrades mild?

Whatever you do don't go with one of those overseas heads that are cheap, because they will cost you more in the long run.
Click to expand...

No offense taken I appreciate your experience and comments:waytogo:
 
82355 said:
A buddy of mine in college put together a 350 TBI for his 1991 Camaro RS to replace his 305 TBI. He started with a 350 core out of a early 90's truck. I cleaned all the pistons for him, he honed the cylinders, reringed the block, drilled the holes to make a factory roller setup work (I think he used an LT1 cam too, but I can't remember for sure). He then had a set of slightly worked L98 heads, a Holley TBI intake, and Holley throttle body. Threw on a set of headers, and ran it. With a stock tune on street tires, it ran 14.0.

Not super impressive, but it was a nice running engine (that cost him next to nothing, all used parts), that ran much stronger than the 305 that was in it.

Martin
Click to expand...

I have thought about those heads but I am worried about header clearance with the angle plugs these use
 
I doubt you would have clearance issues with truck headers, but if you already have the headers you just need some heads to check it on the bench.

I bought a set of used aluminum ZZ4 heads once for $500 with the rockers and valve covers included from a friend that really takes care of his stuff off of a running driving engine. (maybe I paid too much) Then they had broken inner spring dampeners when I got them home and took them apart to lap the valves. By the time I bought all new dual valve springs, etc, I was only a couple hundred bucks from brand new RPM heads. Then I put them together and blew a head gasket, turns out the head deck wasn't flat by .005" so I had to replace the head gaskets and deck the heads at that point. And I didn't even replace the guides or get a valve job (hand port and hand lap). So , used can be a great deal if you know the exact condition. Or it can cost you a lot more time and the same amount of money as a new set if minor hidden things pop up. I am not saying don't go used, it my be the best solution for this application. I am just saying be careful what you buy. The good thing about them is they raise your compression because the chamber is so small.
 
Is an LS-swap completely out of the question?

I know you have parts, but realistically, dumping the money into one of the gen1's vs LS swap is somewhat swimming against the tide. I'm sure an LS swap will be exponentially more expensive, but what is a 5.3 LS swap worth over a TBI setup, 100HP, with no mods?

In regards to "gen1" heads, these http://www.summitracing.com/parts/drt-127121/overview/make/chevrolet or these http://www.summitracing.com/parts/tfs-30410005-m64/overview/make/chevrolet would seem to be pretty cost effective and have the major benefits of the Vortecs, being the combustion chamber. Of course, need to have the right intake bolt pattern, think both of those are the "first" style intake bolt pattern. If buying new, should not be an issue to get the proper bolt pattern as-sold.

As mentioned, probably need to look at what sort of CFM the SBC throttle body (~525CFM?) will run and what RPM that will get you to, and where you want to make power.

As you mention, the Vortecs make running EGR a real pain, the springs are weak, press in studs, require new rockers, and the specific intake is another expense.
 
Thanks for the tip on the Dart heads. I am not a fan of the LS engine in full sized trucks. I own a 2014 Tahoe Z-71 with the latest 5.3 and it fails to impress with torque or fuel economy. I have owned two 2500 series single cab 4x4's with the 6.0 and they also were flaccid performers in the low end and returned poor MPG. I mostly operate this truck at low rpm where the Gen1 makes good torque numbers by comparison. The LS is a good solution for some but I'm not convinced it is my cup of tea. I do like the tuneability and injection system of the LS though!
 
If you dump the '747 ECM and go with a later TBI ECM, there is a lot more "tuneability" to be had.

If the LS' are out, they are out. So many people say they are impressive that I wasn't one to question it...IIRC, the LS MPG and power isn't particularly impressive when compared to some of the last Gen1's that came out, but I just figured I was missing something.

Are you under any emissions constraints? You might seriously consider a TPI swap if low end is your concern. Look at the later ('90-92) TPI numbers, and see how that sits with you. They do everything right for low end power, and personally based on my setup, offers stellar performance with no penalty in economy. I don't think you will see any MPG differences vs. TBI, but felt power is pretty significant.

The plus to TPI now is that it's "old news". They used to run $500, now I'm seeing complete (base to ECM) TPI setups in the $200 range.

Vs. any of the new stuff its pretty antiquated, but it is the system that should have been installed in trucks. GM would have had no competition had the trucks got TPI starting in 1985.

Edit: Martin beat me to it. :)
 
I like the idea of the TPI and am very interested in PMA4x4's build of his TPI engine, I'm told they have lots of torque, I will certainly be converting my computer no matter what induction set up I end up with. My truck does not require an emissions inspection in Texas due to being 25 years old (bonus!)
 
I never understood why GM didn't offer them as an option in trucks.

Martin
 
Because they were cheap bastards that had lost touch with their customers? lol

If there is a problem with TPI, it's that it really even chokes a stout 350, and larger displacement becomes a real challenge, at which point you might as well not waste money on it, there are better options. But if you are happy with near-stock performance (maybe a few tweaks, all with low end in mind) then I think it's a great solution.

Should be darn easy to swap MAP TBI over to MAP TPI.
 
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