Yukonjackgt

iTrader: (1)

I was looking for a set of 243s when I found these 823s cheap. I was told they were better than the 243s but I don't know anything about them. So any opinions or info or experience with them would be great.

Tootall

iTrader: (79)

you have to get the L92 truck or L76 car intake to run them ,. . . . they're a square port

Yukonjackgt

iTrader: (1)

I was wanting to swap them onto my 04 HD with a cam swap. Will the L92 / 6.2 intake be a direct replacement ? I was told my stock intake would work ,but I want to make sure before tearing anything down.

Coban

iTrader: (14)

This is wrong, it will not work. Cathedral Port versus rectangular.

The l92 intake is not a direct swap either, but its not extremely difficult.

2manycars

iTrader: (7)

Nice thing about the 823's too is a 2cc smaller chamber so should raise your compression like .15-.23 not a bad little side affect. One thing to think about too with an aftermarket cam, a huge intake valve, and flatops is PTV clearence. Not sure what type of releifs LQ9's have. Also when you order a cam make sure you tell them that you have L92 heads as they will give you a cam that is spec'ed out differently than for a cathedral port head. They may also shed some light on any PTV issues that may arise.

Yukonjackgt

iTrader: (1)

Picked em up just hope its worth it over the 243s . Ill do more research if anything. I know I can get my money back and get some 243s.

SweetS10V8

iTrader: (4)

I have a set of L92/LS3 heads on my LQ9. I love them, although I had Lingenfelter CNC them for me.

LQ9s have true flat tops with no reliefs. I had mine milled .030 and had very little PTV with my aftermarket cam. ALWAYS check PTV whenever you change cams, or goto a head with a HUGE valve like this one.

GMCtrk

iTrader: (27)

I thought it has been shown that the PTV issues with the L92s are related to the exhaust valve and not the intake valve. Was this the case when you checked your PTV? I find it interesting that your cam has large exhaust duration but is small on the intake side. It's promising though that you were able to mill the heads that much and still fit that cam in with flat top LQ9.

SweetS10V8

iTrader: (4)

PTV depend son your camshafts valve events. the exhaust vavle thing your talking aobut most likely stems from a thread showing why an L92 heads wont work on a 3.900 bore. The pic showed the exhaust vavle hitting the cylinder wall.

I had some PTV issues and had to change cams. Although I seem to be one of the few with PTV issues. Others have had CNC jobs and milled, yet could fit bigger cams. I couldnt.

I tried a Comp LSR 223/231 and had .045"-.050" on the intake. I backed out to the 219 and had around .075".

The large exhaust duration is because its an L92 specific camshaft. Comp has cathedral port cams and L92/LS3 port cams. My cam but for cathedral ports would be a 219/227 instead.

GMCtrk

iTrader: (27)

Once you get those LS3 heads ported and get the intake and exhaust flow rates more balanced like cathedral heads, I dont see why a huge exhaust duration is needed. It seems that a more traditional cam would work well.

I've got an Lq9 with ported 317s and a 222/226 cam, it pulls well, but it's hardly enough. I'm wanting to switch to the LS3 heads, the issue is I want a big cam. My current cam is way too tame, just like stock basically, drives like stock. I want something in the 230s duration, but how/if that can even work with flat top LQ9 pistons I do no know.