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JohnJL JohnJL is offline
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Join Date: Jan 2005
Location: Toronto, Ontario
Posts: 4,728
Thanks, yes I'm planning on using the 3.0 CIS runners to hold the new injectors in position. I agree that the Porsche engineers knew what they were doing, but it is clear that at the time of manufacture, they were having to compromise significantly to meet US emission laws. I am not similarly constrained.

I've looked closely at the port sizes on the Porsche engines with similar set-ups and for markets where the emission laws weren't so constrictive (thanks to Wayne's book!) and at similar displacements and CRs, they went up to 40MM or more. So given the lesser constraints on my setup and the improved fuel & air supply I can provide the engine with, I'm thinking that 38/38 is close to where I want to be in the balance of torque/hp/rpm range.

I don't have access to other porsche engines and intakes to compare the other setups, particularly the RS and SCRS intake manifold-to-port fit. Would appreciate other's views, measurements and pics.

My pics wouldn't be very interesting right now...just a bunch of stock CIS runners...

Also, any comments on the downside of using thick-walled silicon hose as an intake runner material? Would it work to use larger-ID hose in the same approximate shape as the aluminum runners to achieve greater airflow? Would the flexibility of the runner material be detrimental somehow?

2007 911 Turbo - Not a toy
1985 911 Cab - Wife's toy
1982 911 3.2 Indiash Rot Track Supercharged track toy
1978 911 3.0 Lichtbau toy "Gretchen"
1971 911 Targa S backroad toy
Old 08-07-2005, 03:43 PM
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