C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Inside an LT1 intake

Old 02-06-2019, 12:22 PM
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Default Inside an LT1 intake

Boredom kicked in awhile back so this got cut open

Runners measure 3 inches, note the twist. (roof of heads do also)
EGR passages in floor of runners (small holes), behind TB
Cyl 8 has no radius on back wall ; cyls 3, 7, 4 & 8 have a little more width to them, guessing its tougher for the air to make that turn relying on the divider wall rather than a nice radius-

See how far it can be taken short of being paper thin or welding (using some shape not a big gaping hole)
-When theres time

These have a lot of potential & can move lots of air.

Last edited by cuisinartvette; 02-06-2019 at 05:43 PM.
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Old 02-06-2019, 09:48 PM
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Good stuff man. Thanks for sharing
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Old 02-07-2019, 10:07 AM
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The LT4 cars didn't use EGR from the factory. I wonder if the LT4 intake has the EGR holes.
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Old 02-07-2019, 12:19 PM
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Couldnt find pics to see if the runners have the holes in them. Dont think the rear of the intake has the same ones (LT4)
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Old 02-07-2019, 08:10 PM
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The holes at the runners are used by the IAC also. The IAC dumps into the small passages. If it didn't use the passages, at idle the front cylinders would run lean and the rear cylinders would run rich. The air comes in the front, of the intake and goes for the closest vacuum source, cylinders 1 and 2. The aftermarket minirams have this issue. Some of the aftermarket throttle bodies have a gaping hole at the IAC and will cause an LT1 to have this problem. I think the BBK and holley TBs were good.

If I remember correctly, the GM RAMJET intake uses a LS1 style throttle body with the IAC up top. The IAC passages run through the top of the manifold.
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Old 02-07-2019, 10:22 PM
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Thank you for sharing this. There's a lot to think about given the things you have noted and the pictures provided!
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