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> Cylinder head flow vs Intake valve size, Beyond my knowledge
lmcchesney
post Jul 21 2006, 07:32 AM
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I want to start off by stating I am not a experienced/knowledgable engine designer (IMG:style_emoticons/default/confused24.gif) and also want to thank Jake for the email alterting me to the discrepency (IMG:style_emoticons/default/burnout.gif) .
I have a 94mm x 78mm stroker crank with a Web 73 cam. P and P heads but it was suggested by the engine builder that I go with 48mm intake and 38mm exhaust. The builders are fairly known race engine builders for VW and others, but predominately in the short track circuit (outlaws, circuit, etc.)
I have been told that the 48mm intakes limit the rpm of the engine despite the builder stating that the engine is an 8,000 rpm engine build.
My questions are:
A larger intake valve would increase the volume of air flow or less resistance, so how does that decrease the potential rpms.
If as it seems to be a fact and I want/need a higher rpm engine, can it be adjusted for with a programable ECU like a megasquirt?
Or (IMG:style_emoticons/default/dead horse.gif) do I just need to rebuild the heads with smaller intake valves and what size is optimal?
Thanks,
Larry
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Randal
post Jul 21 2006, 07:49 AM
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QUOTE(lmcchesney @ Jul 21 2006, 06:32 AM) *

I want to start off by stating I am not a experienced/knowledgable engine designer (IMG:style_emoticons/default/confused24.gif) and also want to thank Jake for the email alterting me to the discrepency (IMG:style_emoticons/default/burnout.gif) .
I have a 94mm x 78mm stroker crank with a Web 73 cam. P and P heads but it was suggested by the engine builder that I go with 48mm intake and 38mm exhaust. The builders are fairly known race engine builders for VW and others, but predominately in the short track circuit (outlaws, circuit, etc.)
I have been told that the 48mm intakes limit the rpm of the engine despite the builder stating that the engine is an 8,000 rpm engine build.
My questions are:
A larger intake valve would increase the volume of air flow or less resistance, so how does that decrease the potential rpms.
If as it seems to be a fact and I want/need a higher rpm engine, can it be adjusted for with a programable ECU like a megasquirt?
Or (IMG:style_emoticons/default/dead horse.gif) do I just need to rebuild the heads with smaller intake valves and what size is optimal?
Thanks,
Larry



Get Jake to match your engine components for you. That is his business and he has done the dyno work to confirm his designs.

What I've learned during the process of having my engine built is that valve size isn't the "final" solution to making hp with our engines.

However cam design is and Jake can match a cam to match your heads.

And if you want to really go crazy Jake can get you heads that have huge velocity and flow.
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lmcchesney   Cylinder head flow vs Intake valve size   Jul 21 2006, 07:32 AM
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