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Porting aftermarket heads

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Old Aug 20, 2022 | 06:34 AM
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Default Porting aftermarket heads

The AFR site lists their 260 Mongoose heads as;

"AFR’s 260cc LS3 “Mongoose” heads feature 100% CNC ported intake, exhaust and chambers".

Why do they not cast the head with optimum dimensions instead of porting after they are cast?
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Old Aug 20, 2022 | 09:48 AM
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With any casting there are almost always minor imperfections.
Having said that, it is now proving that as-cast can flow just about as well as CNC porting if the basic port shape is a winner to start with.

Last edited by G Atsma; Oct 5, 2024 at 08:50 PM.
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Old Aug 20, 2022 | 09:59 AM
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Originally Posted by SteveJewels
The AFR site lists their 260 Mongoose heads as;

"AFR’s 260cc LS3 “Mongoose” heads feature 100% CNC ported intake, exhaust and chambers".

Why do they not cast the head with optimum dimensions instead of porting after they are cast?
The tolerances on machining are far better than casting. You get far more consistent dimensions - I.e. less variability - piece to piece and even port to pet within the same piece.

Also, the texture left by tooling is beneficial to wet flow and atomization due to boundary layer effect.
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Old Aug 20, 2022 | 10:11 AM
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Originally Posted by Darth_V8r
The tolerances on machining are far better than casting. You get far more consistent dimensions - I.e. less variability - piece to piece and even port to pet within the same piece.

Also, the texture left by tooling is beneficial to wet flow and atomization due to boundary layer effect.
I was just going to say the same thing, on anything non DI surface finish makes a difference. How much difference is subjective but there is a reason people like Chad Speier uses a burr finish on some stuff..
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Old Aug 20, 2022 | 06:25 PM
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Originally Posted by 84ta406
I was just going to say the same thing, on anything non DI surface finish makes a difference. How much difference is subjective but there is a reason people like Chad Speier uses a burr finish on some stuff..
Yeah the stuff I've seen surprise people you'd never be able to sell because it looks like stir fried ***. But it flows like crazy. One day I'd like to get someone to finish my ports with a bent tool. Not kidding
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Old Aug 20, 2022 | 08:21 PM
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Originally Posted by 84ta406
I was just going to say the same thing, on anything non DI surface finish makes a difference. How much difference is subjective but there is a reason people like Chad Speier uses a burr finish on some stuff..
another 1 of my Uncles. I said A Common sense statement on the subject.

https://www.yellowbullet.com/threads...#post-73766694
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Old Aug 25, 2022 | 05:50 PM
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Appreciate the explanation. I have so much to learn.

I am looking at ported LSA for a build so this is very helpful.

Another question, what is "non DI surface finish"?

Thanks!
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Old Aug 25, 2022 | 05:54 PM
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Originally Posted by SteveJewels
Appreciate the explanation. I have so much to learn.

I am looking at ported LSA for a build so this is very helpful.

Another question, what is "non DI surface finish"?

Thanks!
It should read,

"on anything non DI, surface finish makes a difference."


The "DI" is referencing "Direct Injection"
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An engine is an air pump. The more air you ingest and expel, the more power you will make.

Boosted engine love large cylinder heads.
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Old Oct 5, 2024 | 08:08 PM
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I think some people were experimenting with dimpled ports, like a golf ball.
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Old Oct 6, 2024 | 05:05 AM
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Originally Posted by Mark O'Neal
An engine is an air pump. The more air you ingest and expel, the more power you will make.

Boosted engine love large cylinder heads.
I've had good success with smaller unported heads and running more boost pressure no issues with heat or anything and I get better throttle response off idle and lower rpms.
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