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Location:
central coast NSW
Registered:
November 2004
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Re: 4age bigport fabricated shortened intake manifold
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Tue, 24 May 2005 07:12
 
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I would agree with Ben.
With the stock bigport manifold, each runner out of the plenum splits into 2 smaller cicular runners (thats 2 per cylinder) which mate up with the TVIS plate. TVIS operates a butterfly in one of each of these pairs of circular intakes per cylinder. The remaining intakes (without the butterflies) are un-obstructed.
For an atmo engine, adding a TVIS plate to your setup may well choke flow too much. On the flip side, running with that manifold may well see some laggy throttle response to the large cross section of each runner (ie low intake velocity >> poor volumetric efficiency at low rpm). With a stock 4ag setup you would lose torque and perhaps gain a little peak power. You would need extensive head modifications to make use of the flow available from that manifold, and the extra power achievable will be at the top end of the rev range.
I have no experience with turbo's but I think your manifold is much better suited to this application, like Ben says. It should work better without a TVIS plate because less restriction equals less work for your turbine to do.
Forced induction is not all about boost pressures, the principle is still to get a greater volume of air into the motor. For example, with a TVIS plate, you would register higher manifold boost pressures, but most likely would be flowing less cfm of air into the engine than without the TVIS running a lower boost pressure. Further, less pressure equals less heat generation, we all know thats a plus.
Jeez that's almost an essay, didn't mean to preach. Just my opinion.
Did you make this manifold or is it for sale somewhere?
Scott
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