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Port and Polish by Comiittee thread (Cool pics throughout)

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Port and Polish by Comiittee thread (Cool pics throughout)

 
Old 07-18-2018, 03:34 AM
  #451  
Strosek Ultra
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From many head porting tests I have found the best intake runner center line angle for a "straight shot" to the valves to be 22.5 degrees. This is for the S4 cylinder head.
The stock intake port taper, roof angle 19 degrees, floor angle 26 degrees.
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Old 07-18-2018, 03:46 AM
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Does this mean you are back onto the 928 head development project???
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Old 07-18-2018, 04:00 AM
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Originally Posted by slate blue View Post
Does this mean you are back onto the 928 head development project???
Greg, I am always there but first I have to finish the BMW Alpina V8 engine (pictures), then fix the old Volvo (starter and starter gear), replace the cylinder head on the BMW 635CSI. Well the list goes on.
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Old 07-18-2018, 04:05 AM
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I can see a lot of work just there Ake, it seems to take forever this type of work.
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Old 07-18-2018, 04:22 AM
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My heads are getting a bit more welding, that is for the purpose of raising the roof without getting too thin. I also may have found the custom cylinder head hardware. Its been hard to find the correct valve springs. The springs have to be of the best quality and of beehive design. I need the small end of the spring with retainer to go inside the hydraulic tappet. I also need around 0.650" max lift at least on the intake side. I'm going to spec the spring at 300 pounds per inch of compression. This is exactly the same as the Porsche 997 GT3 spring. The weights are roughly the same despite the intake valve being much larger (because its titanium) The differences are the Porsche uses a steel retainer and duel spring. The other differences are, my lift is quite different, 12.7 mm vs 16.5 mm. However if I have this right, your formula doesn't consider lift to be an issue. I can't comment on the acceleration of the cams either. Yes in the dark there. However I probably don't need the same amount of revs as the GT3. I think the red line on the GT3 was around 8,500 rpm but I am ready to be corrected.
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