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- Gold
- Posts: 64
- Joined: Mon Sep 30, 2013 4:31 am
- Location: Gaborone Botswana
Re: Cool Alfa 2.5 V6 12V CNC head porting video
Milling porn
Now i saw at the end a weird golf ball effect along what i think is the exhaust port. what is that from and what for? is it to increase back pressure reduce it? make the flow more turbulent? it got me curious

Now i saw at the end a weird golf ball effect along what i think is the exhaust port. what is that from and what for? is it to increase back pressure reduce it? make the flow more turbulent? it got me curious

'83 GTV6 stock with Wildcat exhaust system
Re: Cool Alfa 2.5 V6 12V CNC head porting video
Botswanaalfa you are correct in the term golf ball effect. But that is the inlet port. The dimpling is to reduce friction of the air as it passes the walls of the port. Just like a golf ball! Aerodynamically a golf ball will fly further due to less drag because of the dimples. Commonly used with CNC porting but very hard to reproduce by hand accurately. Gives more control of the air as it enters the port.
Re: Cool Alfa 2.5 V6 12V CNC head porting video
Just looking at the machine do the precision work gives you a bit of a high 

Re: Cool Alfa 2.5 V6 12V CNC head porting video
I always love seeing CNC porting. Especially as any sort of actual hand porting is a cr@p job to have to do.................
But those exhaust ports look huge and way too big for the ehaust valves.

But those exhaust ports look huge and way too big for the ehaust valves.
- Giuliettaevo2
- Verde
- Posts: 792
- Joined: Sun May 08, 2005 11:56 pm
- Location: Netherlands
Re: Cool Alfa 2.5 V6 12V CNC head porting video
Some before and after flowbench figures would be nice..
If it only looks nice it would be a shame.
What about the rest of the intake system? Would that also receive the golf ball treatement?
If it only looks nice it would be a shame.
What about the rest of the intake system? Would that also receive the golf ball treatement?
Drive it like you stole it...
- Maurizio
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- Joined: Wed Dec 01, 2004 4:49 am
- Location: the Netherlands, 153.1km from the N'ring :-)
Re: Cool Alfa 2.5 V6 12V CNC head porting video
If you look at euro bmw "m" heads they have cnc milled ports and combustion chambers from factory. 

Last edited by Maurizio on Fri Jun 24, 2016 1:07 pm, edited 1 time in total.
Banned.. ?
Daily donky.. ==> BMW 325d 
E36M3 (3.0) Ringtool
==> definitely BANNED!
AR 75 TS Ringtool '90, AR Spider 2000 veloce '79


E36M3 (3.0) Ringtool

AR 75 TS Ringtool '90, AR Spider 2000 veloce '79
Re: Cool Alfa 2.5 V6 12V CNC head porting video
Carb head for GTV 3.0 ?
Re: Cool Alfa 2.5 V6 12V CNC head porting video
I'm warning you Maurizio, if you highlight one more virture of the B*W and their superior engineering you will be banned 

- Maurizio
- Verde
- Posts: 680
- Joined: Wed Dec 01, 2004 4:49 am
- Location: the Netherlands, 153.1km from the N'ring :-)
Re: Cool Alfa 2.5 V6 12V CNC head porting video
oooh not again, just got my access back75evo wrote:I'm warning you Maurizio, if you highlight one more virture of the B*W and their superior engineering you will be banned


ps don't fear the superior engineering (=marketing), there are also a lot of issue's and there is room for improvement...

Banned.. ?
Daily donky.. ==> BMW 325d 
E36M3 (3.0) Ringtool
==> definitely BANNED!
AR 75 TS Ringtool '90, AR Spider 2000 veloce '79


E36M3 (3.0) Ringtool

AR 75 TS Ringtool '90, AR Spider 2000 veloce '79
Re: Cool Alfa 2.5 V6 12V CNC head porting video
Apparently a 2.5 head, so Alfa 6 maybe?KevinR wrote:Carb head for GTV 3.0 ?