Ported Holley ls1 carb intake manifold

[Carnut1]

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Yes it is expensive. It looks well engineered. It unbolts to port or cnc port. The project is for a cathedral port engine with heads I developed. This is to see if it is worth a possible cnc intake manifold to match the cnc heads. Meaning if these prototypes dyno well they may get copied in the future. No guarantees and part of the reason I am making a thread is I could use some input since I am new to cathedral port design. Thanks, Charlie

[Carnut1]

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Stock it has good transitions. The casting is quite good. I don't see lots of low hanging fruit here.

[Carnut1]

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The parting line is close but not perfect. Plenum has a nice shape. I like the extended runner dividers and the shape of the leading edge.

[Carnut1]

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Not sure why this is reversed. Casting number.

[Carnut1]

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Aftermarket ls1 head ported, stock Holley intake, Holley 770 cfm truck avenger carb bolted to bench. I am quickly becoming an ls fan.


Bare head. Head intake and carb

.05 35.4. 35.4
.1. 68. 68
.15. 97.4. 97
.2. 129.7. 129.2
.25. 162.3. 159.6
.3. 193.6. 188.4
.35. 224.1. 215.8
.4. 255.1. 242
.5. 302.1. 281.6
.6. 325.6. 300.2
.7. 307.8. 287.6
.8. 310.9. 288.5

[jed]

What head casting number and valve size please and any other port sizing information that you might have.

[Carnut1]

What head casting number and valve size please and any other port sizing information that you might have.

Import casting many cnc guys are using, quality looks quite good. 2.02"/1.59" Newen valve job speced by me 45/45 seats to use out of the box valves no back cuts. Intake port right at 218 cc. Input welcome. Thanks, Charlie

[Elroy]

I would like to hear some details of the shortblock. Bore, stroke, ring end gaps, compression///so on and so forth. I assume you have finished it already. When is the projected dyno session, and what are the horsepower and torque goals?

[Carnut1]

I would like to hear some details of the shortblock. Bore, stroke, ring end gaps, compression///so on and so forth. I assume you have finished it already. When is the projected dyno session, and what are the horsepower and torque goals?

Shortblock being built by party I am doing work for. 6.0l block, internal goodies, 7000 rpm. And we will see! Think hot street mill not aimed at all out drag. Heads are ready to ship now I need to see what the intake needs if anything. Running engine by Nov. Thanks, Charlie

[Elroy]

That manifold looks much better than Holley's other single plane for cathedral LS in the pics. /////which is a piece of Chinese shit./// The 2 piece looks very much like a SV copy for the most part and appears to be a bargain price wise. Will you be speccing the cam and other details of the "internal goodies"?

[Carnut1]

That manifold looks much better than Holley's other single plane for cathedral LS in the pics. /////which is a piece of Chinese shit./// The 2 piece looks very much like a SV copy for the most part and appears to be a bargain price wise. Will you be speccing the cam and other details of the "internal goodies"?

It will be DV cos cam specced most likely. I am thinking 230-234 .6" .56" 109 lc we will see what the program comes up with.

[BobbyB]

Carnut,
"Newen valve job speced by me 45/45 seats to use out of the box valves no back cuts."

Why no back cuts?

[Carnut1]

Carnut,
"Newen valve job speced by me 45/45 seats to use out of the box valves no back cuts."

Why no back cuts?

Good question, On these I could kick up the low lift flow by a large margin with intake back cut. The ports worked better at higher lift by a few cfm without. These are aimed at a hot street application with a decent size cam so I wanted to keep the back flow reversion down. Also IF these ever get cnc and possibly sold I need to keep them simple to assemble. Just valves from the supplier. Thinking this way is new for me. Thanks, Charlie

[BobbyB]

Have any of you ever seen the backcut increase low lift flow but hurt overall performance because of reversion?

[Carnut1]

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5 bolts 2 shouldered hold the manifold together.