What Specs for Ported/Polished Heads?
Thread Starter
Melting Slicks
Joined: Nov 2003
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From: In front!
What Specs for Ported/Polished Heads?
Hello. I was curious as to what the Specs are for ported heads. Basically, how much do companies actually port the heads based on what stage you are wanting? EX: What specifications does Cartek use for their Stage 2X port? Thanks:cheers:
Drifting
Joined: Jul 2003
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From: Annandale VA
Re: What Specs for Ported/Polished Heads? (Y2KRoadster)
Every head porter is different. The basic "specs" are the base casting (LS1, LS6, 5.3, etc), port volume, combustion chamber volume, and valve sizes. Also, some heads are milled .030" to .040" to raise the compression ratio.
Stage 1 heads usually have stock-sized valves, CNC'd runners, & stock combustion chambers. Stage "1x" may have swirl-polished and/or lightweight valves. Stage 2 heads usually have oversized valves, and some hand porting and combustion chamber work. Stage 3 heads usually have the largest valves possible, and are often only suitable for large displacement engines.
Every vendor's terminology can be different. Larger ports are not always beneficial, nor larger valves. Very few porters actually polish the combustion chambers, as it can actually cause the A/F mix to bead on the shiny surface.
Your best bet is to pick a few reputable vendors, examine their offerings, compare them to your other mods and performance goals, and then decide. AFR, Absolute, GTP, MTI, TEA and several others all make excellent products.
Stage 1 heads usually have stock-sized valves, CNC'd runners, & stock combustion chambers. Stage "1x" may have swirl-polished and/or lightweight valves. Stage 2 heads usually have oversized valves, and some hand porting and combustion chamber work. Stage 3 heads usually have the largest valves possible, and are often only suitable for large displacement engines.
Every vendor's terminology can be different. Larger ports are not always beneficial, nor larger valves. Very few porters actually polish the combustion chambers, as it can actually cause the A/F mix to bead on the shiny surface.
Your best bet is to pick a few reputable vendors, examine their offerings, compare them to your other mods and performance goals, and then decide. AFR, Absolute, GTP, MTI, TEA and several others all make excellent products.
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 2,213
Likes: 135
From: In front!
Re: What Specs for Ported/Polished Heads? (Y2KRoadster)
Oh ok. HOw about the actual porting though. If I were to use, say, 2.05 intake and 1.60 exhaust valves; approximately how much would I have to port the actual chamber that the valve sits in. Again, thanks for the help! :cheers:
Drifting
Joined: Jul 2003
Posts: 1,796
Likes: 1
From: Annandale VA
Re: What Specs for Ported/Polished Heads? (Y2KRoadster)
I'm not sure how big a valve you can use with the stock seats. That's one reason why the Stage 3 heads are more expensive --- extra machining to allow the oversize valves.
However, those big valves are shrouded in a stock displacement engine. They really only work well if the engine has been bored.
Talk to your vendor of choice. They will be glad to explain the differences between their various offerings, and make a recommendation for your needs.
Just remember --- bigger is not always better.
However, those big valves are shrouded in a stock displacement engine. They really only work well if the engine has been bored.
Talk to your vendor of choice. They will be glad to explain the differences between their various offerings, and make a recommendation for your needs.
Just remember --- bigger is not always better.
