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Standard and ported flowdata of Pre HE V12 heads
I ported these heads in a way so people can use them with std inlet manifolds and cams.
They have 25% flow increase at std valvelift, but supports cams up to 13mm in a good manner, I set them up so you get enough clerance between the Mobeck spring retainer and valvestem seal to avoid oil pumping through the seal with 13mm lift.
The ports are small enough to function good to std inlet manifolds, but the manifolds should be releiwed around the protruding injector boss for less cross cectional changes throught the runner.
196 CFM supports teoretically 600 HP with the correct tuning. These heads flow better than my GrA heads that produced 493HP with only 10.5mm valvelift and no headers,
Lovely work. What type are those valve stem seals please, and do you use them on both inlet and exhaust valves?
Valve stems are Coilisbro, witch is pretty good (friction and wear) against Pulse plasma nitride valvestems. https://www.columbiametals.com/files/products/130.pdf
In this matter I can shoose a incredibly good seal witch is teflon with spring support. This seal keep up for many years and dont go brittle and loose function due to age and heat.
But to be honest, I do a tiny trick to the real surface on the ones mounted on the exhaust side to have some lubrication there, but this way it is really nicely controlled. (good question Greg)
V12 Flow numbers
