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Old 03-17-2009, 12:25 AM   #1 (permalink)
Driving the TurboWeasel
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Better Port-Matching?

On an upcoming maintenance, I have the chance to better match the ports in the lower intake manifold to the heads of my 3800 Series II (L36) powered LeSabre. The ports in the manifold as cast from the factory are terribly formed and much smaller than the ports in the heads. The goal would be to better match the port sizes. The manifold ports would still be smaller than the head ports, and better matching the shape of the ports in the heads.

Yay or nay?

2012 Chevrolet Cruze Eco 6MT
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Old 03-17-2009, 09:12 AM   #2 (permalink)
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yeay. no point in introducing restrictions on the intake. If the engine doesn't have to work as hard to pump air in, why make it?
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Old 03-17-2009, 09:35 AM   #3 (permalink)
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Nay. Unless the ports have some horrible flashing or something that creates an easily notable obstruction in them, the smaller port size is going to give better low rpm torque. Since we drive at lower rpms more often this leads to better FE. At low rpm, the small ports are not going to create a restriction at all.
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Old 03-17-2009, 02:03 PM   #4 (permalink)
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Thanks! One less thing to worry about when the top of the motor is ripped off.
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Old 03-18-2009, 03:22 AM   #5 (permalink)
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It would only make a difference with the throttle wide open. So, anybody out there with a CVT and an open-loop override, and probably Fiat's Multi-Lift valve system, don't be put off the idea of improving the intake manifold. It's a good idea.

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