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Desirable INTAKE/EXHAUST Port and Valve Sizes?

Ok, I'll admit it, these threads about Kremer and RUF cars and Porsche porn made me hit the books published in the 70-80s. From my research I'm questioning accepted wisdom regarding desireable intake and exhaust port and valve sizes on these 30 plus year old engines.
Considerations:
1) Yes, the street TURBO uses X and Y sizes but these were driven by emissions, fuel ecomony, part throttle response and CIS system AT a specific (low 260-300HP) horsepower level.
2) Factory racing TURBO engines have larger intake ports BUT more importantly they have huge exhaust ports. Before you say they would have no response on the street reread Bruce Anderson's book. Several 962s were adapted to the street in the late 80s. They were responsive and VERY powerful.
3) I stopped by a local P-car engine builder, 36 years at it. He has flow bench, fixed dyno and has been porting and flow benching for years. He says he's porting 930s and getting 75HP for the effort. He didn't elaborate (obvious, he wants to get paid for his work) but mentioned EXHAUST.
Ok, what do you guys know based on actual back to back testing. What has been done, this looks like uncharted territory.
This has an point, I have a Superflow 110 flow bench and I'd like to start doing some testing.

Last edited by copbait73; 02-17-2008 at 02:20 PM..
Old 02-16-2008, 01:34 PM
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Quote:
Originally Posted by copbait73 View Post
Ok, I'll admit it, these threads about Kremer and RUF cars and Porsche porn made me hit the books published in the 70-80s. From my research I'm questioning accepted wisdom regarding desireable intake and exhaust port and valve sizes on these 30 plus year old engines.
Considerations:
1) Yes, the street TURBO uses X and Y sizes but these were driven by emissions, fuel ecomony, part throttle response and CIS system AT a specific (low 260-300HP) horsepower level.
2) Factory racing TURBO engines have larger intake ports and valves BUT more importantly they have huge exhaust valves and ports. Before you say they would have no response on the street reread Bruce Anderson's book. Several 962s were adapted to the street in the late 80s. They were responsive and VERY powerful.
3) I stopped by a local P-car engine builder, 36 years at it. He has flow bench, fixed dyno and has been porting and flow benching for years. He says he's porting 930s and getting 75HP for the effort. He didn't elaborate (obvious, he wants to get paid for his work) but mentioned EXHAUST.
Ok, what do you guys know based on actual back to back testing. What has been done, this looks like uncharted territory.
This has an point, I have a Superflow 110 flow bench and I'd like to start doing some testing.
We measured the ports on a current rebuild with twin plugged heads It has been increased by 4mm intake and 6mm exhaust with correspondingly larger valves with titanium hardware. The builder with many years of porsche engine expierence ( recently did a factory 935 ) said with the cam profile we are using, it should have more torque than HP.These guys do not elaborate much. I think some of the 962 heads had even larger valves and exhaust ports at 41mm. I live in WI so let me know what you are doing with your equipment.
Old 02-17-2008, 12:48 PM
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Originally Posted by voitureltd View Post
We measured the ports on a current rebuild with twin plugged heads It has been increased by 4mm intake and 6mm exhaust with correspondingly larger valves with titanium hardware. The builder with many years of porsche engine expierence ( recently did a factory 935 ) said with the cam profile we are using, it should have more torque than HP.These guys do not elaborate much. I think some of the 962 heads had even larger valves and exhaust ports at 41mm. I live in WI so let me know what you are doing with your equipment.
Ops forgot to put photo of the recipient of the motor. Not a street car so maybe you wanted different info for your testing destination.


Last edited by voitureltd; 02-17-2008 at 01:26 PM..
Old 02-17-2008, 12:54 PM
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One more thing, better to use the early racing twin plug heads that uses the smaller spark plugs for larger porting and valve seats.
Old 02-17-2008, 01:25 PM
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Thank you,
Can you get the valve sizes? He's blown out the exhaust ports. Heads are now
36MM intake (vs tiny 32MM) and exhaust 40MM (vs tiny 34MM).
Here is the comparison from Bruce's book:
Valve sizes are the same for the street TURBO and racing TURBO, Intake 49MM, exhaust 41.5MM (thats a nice starting point) but the street turbo has 9MM smaller intake ports and 7MM smaller exhaust ports. What you measured sounds extreme (and it is in comparison to street) however they are still less than the all out racer TURBO's ports.
Goran, have you experienced "ported" street TURBO motors?

Last edited by copbait73; 02-17-2008 at 01:45 PM..
Old 02-17-2008, 01:35 PM
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Quote:
Originally Posted by voitureltd View Post
Ops forgot to put photo of the recipient of the motor. Not a street car so maybe you wanted different info for your testing destination.

Not really, an uncorked extreme HP street TURBO motor may feel weaker at the onset of it's climb to a much higher HP, but the absolute torque output should be equal or higher.
For me it's academic as I'm starting with a 964 base and the ceramic port liners don't lend themselves to porting the exhaust. However, my N.A. 964 has 6MM larger exhaust ports than the 964 3.6L turbo so I'm set. I'll open up the intake ports to match the 993.
One thing that jumps out in my comparisons is the 993TT stops all this choked port stuff so draw you own conclusions of CIS.
Twin plugging may be needed to pump power with FLOW vs VELOCITY but I have this sneaky suspicion most of this is about emissions/CIS.

Last edited by copbait73; 02-17-2008 at 02:21 PM..
Old 02-17-2008, 02:09 PM
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I think the 41.5 and up porting in the all out highly competitive racing motors used specialy forged heads ( some watercooled ) that when on the market for sale seem to be into the 5+ figure range. I like to drive fast but not that much need for that exta % of power vs cost. You can get lots of HP for not that much but the last 100 or so hp gets real pricey.
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Quote:
Originally Posted by voitureltd View Post
I think the 41.5 and up porting in the all out highly competitive racing motors used specialy forged heads ( some watercooled ) that when on the market for sale seem to be into the 5+ figure range. I like to drive fast but not that much need for that exta % of power vs cost. You can get lots of HP for not that much but the last 100 or so hp gets real pricey.
Oh, I'm not proposing that extreme be applied. I'm somewhat fishing here for anyone who knows what RUF and other tuners applied when they ported these engines. The idea being to use street, non-racing heads.
The stock 3.2L N.A. motor has the same size valves but 8MM larger intake and 4MM larger exhaust ports.
Old 02-17-2008, 03:30 PM
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Oh, I'm not proposing that extreme be applied. I'm somewhat fishing here for anyone who knows what RUF and other tuners applied when they ported these engines. The idea being to use street, non-racing heads.
The stock 3.2L N.A. motor has the same size valves but 8MM larger intake and 4MM larger exhaust ports.
The Porsche race cars were putting out 750 plus hp and were expected to last,in some cases for 24 hours of non stop abuse. Now the video on Porsche Porn of getting over 1000 hp for a few sec,min is believable along with that much power for a 1/4 mile. However to get a season of use of around 700hp and torque are nearing max. I'm shooting for 550-600 and hoping for longevity of intermittent use of adjustable boost to get over 600hp on occasion with this car.

Old 02-17-2008, 05:29 PM
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Ok, I've still not learned any specifics on 930 porting. With the hope of resurrecting this subject go to this site that claims 627HP on CIS.
http://www.spezialmotorer.com/
Crazy site, you need to scroll to the right and click on PROJECTS then drop down to 930CIS.
The supplied pictures show PORTING of the exhaust and intake. Anybody out there know this shop, or others, and what sizes they are using?
Goran, are you out there and have input?
Old 02-20-2008, 11:47 AM
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Two words:

SC heads.
__________________
- Craig 3.4L, SC heads, 964 cams, B&B headers, K27 HF ZC turbo, Ruf IC. WUR & RPM switch, IA fuel head, Zork, G50/50 5 speed. 438 RWHP / 413 RWTQ -
"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 02-20-2008, 05:54 PM
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Originally Posted by Craig 930 RS View Post
Two words:

SC heads.
Thanks, have you reason to think there is any loss in drivabilty or response?
What is your exhaust primary tube size?
Collector tube size?
Old 02-21-2008, 05:48 PM
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Copbait, I'll have the heads off a RUF RCT hopefully by the end of the weekend. It's a 3.6 964 single turbo conversion. I am very anxious to see what port/valve sizes it has. Also curious to measure the valve lift at TDC overlap. I'll share the details when I get them.
Old 02-21-2008, 06:06 PM
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Copbait, I'll have the heads off a RUF RCT hopefully by the end of the weekend. It's a 3.6 964 single turbo conversion. I am very anxious to see what port/valve sizes it has. Also curious to measure the valve lift at TDC overlap. I'll share the details when I get them.
Great, thanks Mike. I'd like to start a file as we pull this stuff together.
Old 02-21-2008, 06:10 PM
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Sounds cool. It's not my car but I've got some seat time. It's an incredible package. Only makes 365 rwhp at 11psi but it's sooo smoooth. I wish I could datalog the entire motronic map somehow...
Old 02-21-2008, 06:23 PM
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Quote:
Originally Posted by Craig 930 RS
Two words:

SC heads.

Thanks, have you reason to think there is any loss in drivabilty or response?
What is your exhaust primary tube size?
Collector tube size?
-------------------
No reason whatsoever. Comparing identical engine builds to mine, same dyno, only difference
being the SC heads - SC heads overcome the tiny port/small valve issue 930s have.
Must use the early SC heads with large ports -
__________________
- Craig 3.4L, SC heads, 964 cams, B&B headers, K27 HF ZC turbo, Ruf IC. WUR & RPM switch, IA fuel head, Zork, G50/50 5 speed. 438 RWHP / 413 RWTQ -
"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 02-21-2008, 07:43 PM
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