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GJF GJF is offline
Slantnose from HELL
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Join Date: Dec 2004
Posts: 810
Velocity is a BIG factor here. If the core of the IC is too restrictive (velocity/air flow). Then the IC ability to flow air from a larger turbo will bottleneck and hurt performance. Having increased flow capability (velocity/air flow) will allow more power, IF, the current IC can't flow the cfm the turbo is rated for.

Example you have a air cleaner rated for 750cfm, and turbo rated for 900 cfm and a IC rated for 850cfm.

The air cleaner is choking the turbo, and then the IC is bottle necking the flow capability of the turbo. Here you have 2 negatives.

The IC is not going to change responsiveness of the engine even if it is a crappy little inefficient unit. It will only suffer as far as velocity on the top end.

Adding a larger IC is only going to benefit mid range and top end which relates directly to air flow (velocity through the IC).

Having a bigger IC WILL drop intake air temperatures, that are generated from the turbo. By lowering the temps from the turbo using a IC will help longevity of the engine by reducing thermal loads on the pistons, rings, valves and guides.

The only way to increase low end response is to raise static compression.

When these cars came out, in all reality, they were crude as far as tuning goes. They had 7.5:1 compression, fixed ignition timing with vacuum advance assist (very limited).

It was thought, that having low compression would allow for more boost and reduce risk of detonation. In all reality it was partially true but the low compression causes poor low speed drivability, poor transition onto boost, poor low speed fuel economy and massive lag.

The main limiting factor early tuning had was lack of ignition timing control. The complete control of timing allows for more compression, which improves performance at all RPM levels.
87 911 Carrera platform
Twin Garrett's, Big Valve, Xtreme Cylinder Heads, JB Racing cylinders and machine work, custom JE pistons, GT2 EVO cams, GT3 oil pump, modified 3.2L intake, 80mm TB, custom Intercooler, equal length headers, DFI, KEP Stage 2 custom twin disc, G50 custom gear set, LSD, Tilton trans pump, Fluidyne cooler
Old 05-28-2014, 04:22 AM
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