formula17

iTrader: (4)

Has anyone replaced the 2.16 intake valve on the LS3 head with a 2.20 like out of an LS7? Read somewhere about somebody contemplating it, But never heard anything else more about it.

Old SStroker

Why do you want to do that? Not being a smartass...it's a serious question.


Jon

Caveman

iTrader: (2)

Richard at WCCH said that they were working on head for LS3/L92 motors with 4.06- 4.08 bore that used a 2.20 intake valve. I had asked in a previous thread if anything could be done to fit an LS7 head on a 4.07 bore LS3 motor, he said that the intake valve could work but the exhaust valve on an LS7 will not clear the cylinder sleeve on a 4.07 bore. The new Mast 12*heads for LS3's look good but very expensive.

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iTrader: (4)

Ok that's where I read that. Yeah I was looking at doing the same thing putting LS7 heads on an LS3 block, That's why I read that post. Now that I found that won't work for sure I was interested in what Richard had said about putting the bigger intake valve in there and combination with a newer cnc program he said he was releasing, Could get LS7 power out of an LS3 head. I would assume the idea of putting in the bigger intake valve would be to increase flow therefor making a little more power?? I know these heads flow pretty well on the intake side already and the intakes out still don't seem to be able to keep up with the heads, But like everyone else I'm just looking for options to make a little more power. Wonder if it would be more beneficial on these heads to up the exhaust valve size?? I noticed the Mast heads have a 1.60 exhaust valve where stock LS3 heads have like 1.57 or 1.59?? Not sure if there is anything there to improve on, But it seems LS3's are weak on the exhaust side more then the intake.

Stang's Bane

iTrader: (22)

You can get more than enough air out of a 2.16 valve.

The exhaust side is no weaker than any ls head. Just in relation to the intake, it seems so.

formula17

iTrader: (4)

I'll play devils advocate here.....If that was the case then why do LS7 heads have a 2.20 intake valve??

Old SStroker

I'll guess: to feed a 4.125 bore 505 fwhp OEM engine with mild valve lift?

The flow dynamics of L92 (and LS7) heads may be different from what we are used to. Just enlarging the valve without doing corresponding work to the port probably is not a good idea. I don't doubt that Richard may make a larger intake valve work in the L92 head.

If you thought cathedral port LS heads confused some head people, y'all ain't seen nothing yet! I think we will see quite a few different approaches to making L92 heads work better than stock. From what I've seen so far, not all "reworked" L92 heads are an improvement. Some are of course.



Jon

Jontall

I know the Mast Motorsport LS3 head has a 2.20 intake valve:

511-204 "Bare Large Bore"
LS3 12 Degree 4.125"-4.200" Bore 6-Bolt CNC Cylinder Head
Utilizes the Gen IV LS7 valvetrain and valves, but accepts the LS3/L76 intake manifold.
Designed for any new Gen IV short-block with 4.125" bore or larger.
The 6-Bolt design is compatible with GM LSX and World LSX blocks.
Uses a 2.200" Intake Valve and 1.610" Exhaust Valve
Only cylinder head on the market to utilize LS7 valvetrain components and accept the LS3 intake manifold.

formula17

iTrader: (4)

"Uses a 2.165" Intake Valve and 1.600" Exhaust Valve"

Thats taken right from Mast's site. I really like those Mast Heads, expensive though.

Edit: Large bore Ls3 heads use a 2.20 intake 1.60 exhaust.

Stang's Bane

iTrader: (22)

I have seen that on the mast heads. I can't figure out why anyone would use that head over a ls7 style head. the intake manifolds for the ls7 heads are light years better for big HP production.

Jontall

Because they can be used on smaller bore motors, where the LS7 head can't.

formula17

iTrader: (4)

But why would anyone buy the large bore heads? I can understand the med bore or small bore. Also the large bore specs mean nothing to me in this situation as they wont fit on my 4.070" bore, So whatever size valves they have is irrelevant. So the medium bore head with the 2.165 intake and 1.60 exhaust is all that I can really use to compare with.

Camaros-n-Chevelles

iTrader: (3)

I am going to send my LS3 heads out to be rebuilt. The heads will be ported. Is it a good idea to have the 2.20 Intake Valves installed?

Jimbo1367

Just stick with stock LS3 intake valve UNLESS you are going all out.

KCS

iTrader: (20)

No, not really.

A.R. Shale Targa

iTrader: (2)

So bigger isn't better ?

JakeFusion

iTrader: (7)

The Frankenstein Stage 3 LS3 heads have 2.200" valves...

KCS

iTrader: (20)

Haha, well of course it is!!

The problem is that the LS3 valve spacing is larger than both the LS7 and LS6 heads, so the same valve configuration in an LS3 head is going to be closer to the bore wall and consequently more shrouded. If you have the bore big enough to fit say a 2.20"/1.60" valve combo, you're better off starting with an LS7 head.