Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Custom Duratec UIM finished... other secrets too

Originally posted by TCobra50:

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looks pretty cool. one thing id have to question however is the airflow paths of the intake. maybe u could fill me in....im fairly sure if that was an N/A motor....it would be horrible for even air distribution to all cylinders.. if u think about the different paths the air has to take to each cylinder. now maybe in a pressurized intake you wouldnt see the same problem...however...its quite possible you would. another thing id like to question is the choice of runner length...why not shorter or longer? (i really dont know the pro/cons of either except that turbos tend to like shorter runners.)

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The main plenum of the intake will be, at minimum, half of the displacement of the cylinders it's feeding. Since he's got the banks divided with separate plenums, they each feed 1.5L of displacement, requiring .75L per plenum. He's fine there... the length of the ram tubes/LIM/head port length are most critical. You can find calculations online using the cam duration, RPM you want the intake tuned for, and pressurized or not to be able to find the port volume you're after. Boosted engines (this one will wear a Vortech SC, custom configuration of course) are much less critical.

If he wanted low end TQ, he could have built a 5.0L swap, which would have been much less costly because it's been done before by other people. David just likes to be his own kinda person... a trait common in XR owners in the first place.