cv67

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.

1993C4LT1

Good stuff man. Thanks for sharing

MatthewMiller

The LT4 cars didn't use EGR from the factory. I wonder if the LT4 intake has the EGR holes.

cv67

https://www.corvetteforum.com/forums...ine-build.html

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)

LT1_383

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.

mazdaverx7

Thank you for sharing this. There's a lot to think about given the things you have noted and the pictures provided!

cv67

Fun stuff. Been laid up again due to yet (another) head injury, was hoping to have a few ports finished by now. WIll update as I can..

This will be taken to its limit short of welding. Once the top is stitched back on it will be polished and wind up on (hopefully) someones track car.

Or better yet hide the seam and give it a nice fresh cast as stock look.

MatthewMiller

Not sure if you're talking about the intake here or your head. But seriously, I hope you get better quickly!

cv67

Both! lol

Tom400CFI

Cool pics....thanks for sharing. I've always thought that if you made the plenum bigger, you'd cut velocity past 1,2,3&4, reducing that front/rear mix problem. Now that you've chopped the top, I wonder if you could make a "super ram" type, big box plenum for it?

Sorry to hear about the head...get well soon.

drcook

Or just to speculate, a dual plane type of arrangement. If you had an uber expensive flow bench that could measure the flow at all 8 ports at the same time, an optimum arrangement could be setup since it is now a multi piece component, instead of one designed for manufacturing efficiency and cost containment.

I second the motion about "get well soon".