Porting the VW/Audi 8v head with port energy discussion

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cjperformance
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by cjperformance » Thu Nov 09, 2017 3:31 pm

Carnut1 wrote:
Thu Nov 09, 2017 12:23 pm
I started using anti reversion techniques on my engines back in the 90's and have always had good luck. As in running a bigger cam than usually advised from cam coaches of the day with better than most street manners with come up on cam right now power. I think using AR on this build will really help. Thanks, Charlie
Charlie, i totally agree that ar stuff works. Its just a 2 edged sword(in my opinion) if you have to make any particular component less suitable for the combo/use just to achieve ar somewhere.
In the case you had shown, i would opt for the smaller more responsive pipe over more ar. Jmo
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Erland Cox » Thu Nov 09, 2017 7:25 pm

I just saw this thread. Watch out on the head with intake and exhaust on the same side.
There is nothing to port between the intake and exhaust port.
The walls there are very, very thin.

Erland

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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Thu Nov 09, 2017 7:30 pm

Erland Cox wrote:
Thu Nov 09, 2017 7:25 pm
I just saw this thread. Watch out on the head with intake and exhaust on the same side.
There is nothing to port between the intake and exhaust port.
The walls there are very, very thin.

Erland
Thanks, Erland. Good thing I have extra heads! I will be making sprinklers out of the first few ports and the cut em up.
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Erland Cox » Thu Nov 09, 2017 7:43 pm

I have done that so I thougt I should warn you.

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Re: Porting the VW/Audi 8v head with port energy discussion

Post by peejay » Thu Nov 09, 2017 7:52 pm

Huh. Wonder if the 5 cylinder version is different. I ported a 10v head's intake ports "round" before.

No idea if I accidentally made a colander, I went to get the deck cleaned up (switching to MLS gasket) and was told it was .017" high in the middle. Oops. And this for an engine I want to do everything possible to get compression OUT. So that head's sitting on a shelf gathering dust, might use it to mock up turbo manifolds, but it's one of those things where I spent so much time on it with no reward yet that I emotionally can't just scrap it.

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Re: Porting the VW/Audi 8v head with port energy discussion

Post by digger » Fri Nov 10, 2017 5:54 am

cjperformance wrote:
Thu Nov 09, 2017 3:31 pm
Carnut1 wrote:
Thu Nov 09, 2017 12:23 pm
I started using anti reversion techniques on my engines back in the 90's and have always had good luck. As in running a bigger cam than usually advised from cam coaches of the day with better than most street manners with come up on cam right now power. I think using AR on this build will really help. Thanks, Charlie
Charlie, i totally agree that ar stuff works. Its just a 2 edged sword(in my opinion) if you have to make any particular component less suitable for the combo/use just to achieve ar somewhere.
In the case you had shown, i would opt for the smaller more responsive pipe over more ar. Jmo
Cheers
My comment was more along the lines of even if the pipe isn't too large surely there are always gains downstairs. yeah I dont agree with making things a bit too big to make topend and bandaid the rest

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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Fri Nov 10, 2017 8:19 am

1109171714.jpg
1st port 8th cut. The bowl was thick enough so after some Pitot work I decided to take a deep cut from the sides of the bowl a bit off the roof and widen the ssr a bit to change the airspeed profile in the bowl. As strange as airflow can be I got a big boost in flow from .05" right to .4" lift on the intake. The flow at .5" was exactly the same, I feel that the csa from flange to new curves feeding the bowl are too small and fast. The same treatment on the exhaust caused a loss across the lift range.
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Fri Nov 10, 2017 10:48 am

1110171044.jpg
Quickie sharpie curve of intake makes me think raising the flange and adding csa to the 1st half of the port will help feed the bowl. Input welcome. Thanks, Charlie
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Fri Nov 10, 2017 11:05 am

1110171059.jpg
Sharpie curve of 8th exhaust cut. The larger bowl here flowed less than the 7th cut. These are tall but narrow ports. High airspeed on top, slower on floor. One spot about an inch from ssr apex shows zero airspeed from stock to 8th cut! Just too sharp a turn. Input welcome. Thanks, Charlie
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Smoke ring » Fri Nov 10, 2017 1:51 pm

Carnut1 wrote:
Fri Nov 10, 2017 10:48 am
1110171044.jpgQuickie sharpie curve of intake makes me think raising the flange and adding csa to the 1st half of the port will help feed the bowl. Input welcome. Thanks, Charlie
Seems like a good idea to me. Nice work here Charlie

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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Fri Nov 10, 2017 2:41 pm

Smoke, you would think increasing the csa and dropping the airspeed a bit would help but it looks like it increased airspeed across the ssr and dropped cfm at all lift points. Thing is giving me a headache.
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Smoke ring » Fri Nov 10, 2017 4:02 pm

Well, maybe it's time to get the clay out and do the exact opposite and see if the ssr does better at .500 to see if you're moving more air than the ssr can hold currently? Is it possible the flow at .500 is about maxed out for the valve size?

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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Fri Nov 10, 2017 4:20 pm

1110171521.jpg
Smoke, I decided to take a break from the intake and try an experiment on the exhaust. Since it is such a flat port I thought it was interesting the designers used a tulip style valve. So I did some work to a spare 8mm valve and ground it as flat as possibel to see if flow across the bowl increases port flow. VW makes some hard valves! The carbide was losing teeth like nobody's business so I did what I could and reflow. A small gain down low and just lagged behind at every other lift. I was also wondering what shape the aftermarket valves come in. Ok, a loser. Next up 7mm guides and 7mm valves. Thanks, Charlie. I know I didn't answer your question. Scattered!
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Sat Nov 11, 2017 11:57 am

[attachment=0]1111170946.jpg[/attachment
"Well if you didn't make a hole I would think you weren't trying hard enough!" Taking a good look at the crossflow VW head shows the port progression they used to get improved flow and better performance. The counterflows are a challenge. Thanks, Charlie
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by 4vpc » Sat Nov 11, 2017 1:03 pm

Why not simply round off the short side to give a better radius and blend the bit on the roof just before the guide?
Disadvantages of a better SSR?
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