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

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Carnut1
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Sat Nov 11, 2017 1:08 pm

Doing it. Wider as well. Throat ratio change, valve angle change. Lots to change and retest.
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by jarmoyp » Sat Nov 11, 2017 4:45 pm

Carnut1 wrote:
Tue Nov 07, 2017 8:52 pm
8v vw stock counter flow 7th cfm.jpgvw 8v stock vs. 7th porting and flow tests.
1.496" intake valve? I have never seen so much intake flow from a VW head, almost 190 cfm/28"

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

Post by Carnut1 » Sat Nov 11, 2017 5:00 pm

jarmoyp wrote:
Sat Nov 11, 2017 4:45 pm
Carnut1 wrote:
Tue Nov 07, 2017 8:52 pm
8v vw stock counter flow 7th cfm.jpgvw 8v stock vs. 7th porting and flow tests.
1.496" intake valve? I have never seen so much intake flow from a VW head, almost 190 cfm/28"
1.57" intake valve. Cut #7 was the best I have done as far as flow so far.
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Morgo » Sat Nov 11, 2017 6:10 pm

Well;with the stock valve it's about 100 cfm at 10".
Anyone claiming more is just bullshitting.Maybe 103 if worked hard.
The valve is what it is and can't flow more than it can.
"when uncomptent order unwilling to do unnecsessary the probablity of failure is high"

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

Post by Carnut1 » Sat Nov 11, 2017 7:36 pm

Morgo wrote:
Sat Nov 11, 2017 6:10 pm
Well;with the stock valve it's about 100 cfm at 10".
Anyone claiming more is just bullshitting.Maybe 103 if worked hard.
The valve is what it is and can't flow more than it can.
Stock port and valve flowed 143 cfm on my bench.
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Smoke ring » Sat Nov 11, 2017 8:37 pm

100 cfm at 10 inches depression converted to 28 inches depression is 167 cfm.

Charlie's original stock flow of 143 cfm would equate to 85 cfm at 10 inches depression.

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

Post by naukkis79 » Sun Nov 12, 2017 3:00 am

4vpc wrote:
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?
We want to turn flow to flow past SSR part of valve, what you supposed to SSR will do exact opposite.

For better SSR turn flow that port entry has to be raised, both floor and roof.

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

Post by Carnut1 » Sun Nov 12, 2017 10:36 am

1110171234.jpg
VW 8v intake port. One of the higher flowing intakes so far. I always find it interesting to blow the chips through a port as I am grinding to "see" the direction of the air as it leaves the bowl. Stock these VW heads have fairly low swirl and small quench pads. Since the lift and rpm will be limited I need to keep this in mind and how it will change torque production. Should I try to increase the swirl? Should I forget the swirl and go for max airflow? At this point I am working on max airflow while limiting port csa to have higher port energy filling the cylinder. Now if I can do this AND increase swirl I feel lower rpm torque production will help this design com up on cam faster and have a wider usable torque band while using less fuel. Input welcome. Thanks, Charlie
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Sun Nov 12, 2017 2:46 pm

1112171440d.jpg
Add .435" flowball to add 4 cfm @ .4" lift. From 169 to 173 cfm. This was a new port that I put effort into keeping the bowl a bit smaller and ssr as high and narrow as possible.
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Wed Nov 15, 2017 4:33 pm

Resized_20171114_182739.jpeg[/attachment]
Resized_20171114_182739.jpeg
Top port #3 ssr deep cut bottom same port with radical widening and shape change. Bottom caused higher airspeed across ssr but no real increase in mass cfm. The wider ssr did not have airflow increase with .435" flowball next to guide. Seems back of the intake bowl does little on these heads
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Mon Nov 20, 2017 7:17 pm

cylinderheadarticle1.jpg[/attachment]
cylinderheadarticle1.jpg
Doing a bit of reaserch on vw 8v high performance I found this old DV story. This is actually a bit older engine with smaller valves. The flowbench numbers are 25 " water. What is really interesting is DV's opinion on burr fininsh many many years ago! Worth a read. Thanks, Charlie
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Mon Nov 20, 2017 7:22 pm

]cylinderheadarticle3.jpg[/attachment]
cylinderheadarticle3.jpg
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Carnut1 » Mon Nov 20, 2017 7:23 pm

cylinderheadarticle5.jpg
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by mag2555 » Tue Nov 21, 2017 6:34 am

There is nothing much you can do with a Exh port short turn like that!

If you stuck with having to run the same size valve then your resigned to making the most of the low lift flow that you can and max out the port bias to gain what high lift flow you can.

If your able to stuff in bigger seats to run a larger valve that would allow you to port out the Throat to gain a taller short turn and you would have a far better chance of having your cake and eating it too!

In regards to port reshaping it's pretty easy to use this diagram and see how the size of the Throat your working with and the heads valve inclination angle can guide you as to what needs to be done , or can be done within the limits of the port wall thickness your dealing with!
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Re: Porting the VW/Audi 8v head with port energy discussion

Post by Frankshaft » Tue Nov 21, 2017 9:29 am

Try D-porting the floor at the short turn transition. Once you start moving air thru that round port, it can be necessary to gain the area needed, and will help the air turn, and should help flow and keep the port from stalling. Obviously start off conservative.

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