Fred - Injuneer

[soCalTA]

Fred,

I went to your site and saw that you have the LT intake and heads. How much would you say a ready-to-go stock set should go for? Also may I ask why you went that route rather than AFR or other type of LT4 heads?

Thanks,

Jorge

[Injuneer]

The LT4 heads cost about $1,200 from GM in stock trim, fully assembled (can't buy them any other way). The LT4 intake is about $200, I think. To get them ported can run as high as $1,800 for the heads and $350 for the intake. Check Lingenfelter or CNC Cylinder Heads for pricing.

The shop that built my engine has a huge catalog of flow data on virtually any LT1/LT4 heads they have ever been able to get their hands on. If a car comes into their shop, the heads get flowed, even if only for their data bank. They even flowed the Dominion 32-valve heads for GM High-Tech Performance magazine. Same bench, same opeerator, same conditions.

The AFR's simply did not stack up to the other heads. The LTx AFR heads are simply Gen 1 SBC heads, with extra metal added to reduce the combustion chamber volume to the LTx volume. That puts the plug in a "hole" and the shop feels that's the reason the heads don't work as well as they should. This is typical of many aftermarket heads. They can't afford to develop a totally new LTx head, because of the limited volume, so they cobble up a Gen 1 head.

A buddy of mine had what was, for 2 years, the quickest 4th Gen on the planet.... and over the course of the 5 years that he built his 30th SS convertible from a brand new stocker to a 1,125HP thumper, he tried the AFR heads and rejected them, because they did not help, and in fact hurt compared to the Lingenfelter LTx heads he used.... first the LPE LT1 CNC heads, and later the LPE LT4 CNC heads. For the 1,125HP setup, he was using Canfield LT4 heads (no longer produced), but they had at least $5K of work in them, including relocating the valves.

The shop catalog indicated (at the time I bought my heads) that the LPE and GTP heads were by far the best flowing they had tested. I was the first person to bring them the CNC Cylinder Heads LT4's and when flowed with the intake in place, they outflowed anything the shop had tested in the intake side (except the Dominions). They actually used what they learned from the CNC heads to tweek my buddy's LPE heads. But the CNC heads totally sucked on the exhuast side, and CNC suddenly refused to even talk to me or the shop about the problems with the heads, so I would suggest that you stay far away from CNC.

The shop was later asked to build a 1,000+HP clone of my buddy's engine (with his approval), and the got a set of updated LT4's directly from LPE, and they flowed even better than the earlier LPE heads.

The AFR's are probably the only thing avialable for all out race cars, with the 225cc runners, but those will not be a "street friendly" head on anything other than a huge 400+ cubic inch stroker.

Just some rambling observations.......

[soCalTA]

Thank you so much for taking the time to give me such a great answer. So basically you took the GM LT4 heads and intake and had them ported/polished to match your particular application?

Thanks again.

Jorge

[4THGEN Z]

Hmmmm...the LPE site has nothing on LTx heads anymore....we are becoming extinct.

[TraceZ]

Hmmmm...the LPE site has nothing on LTx heads anymore....we are becoming extinct.

Sure it does. I was just looking at them this morning. $1850.00 for them to CNC your cores, LT1 or LT4, same price.

[fastTa]

I ordered my LT4 heads and intake manifold from Combination Motorsports. I had them ported to their "Stage 3". Cost was $3,023 for the heads with 2.00"/1.60" valves with all Titanium components and Comp dual springs. I had a LT4 intake manifold also ported by them to match the heads for roughly $400 (includes price of new intake manifold). The heads flowed 309CFM @ .600". I later had the heads ported a little more but 309 is not too shabby for a stage 3 LT4 casting.

I would also steer clear from the AFR's. They are just not a good head for a street/strip application. The plug being in the hole and the other design inconsistencies make them less than desirable. A well ported LT4 head will significantly outperform an AFR head.

[4THGEN Z]

Sure it does. I was just looking at them this morning. $1850.00 for them to CNC your cores, LT1 or LT4, same price.

Yeah previously I just did a search for LT1 and 4 and nothing but I looked under "store" and there they were.... If only I had more $$