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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.
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.
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.
Last edited by Tom400CFI; Apr 7, 2019 at 11:09 PM.
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.
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.
Inside an LT1 intake
