LQ4 with LS3 intake and 823 heads

[KEWLKATDADY]

ok so I'm slowly getting my LS swap together.

6.0L LQ4 2005 DBW
823 heads
Aussie LS3 intake (I used this so the LQ4 MAP sensor plugs in)

Motor has 190K miles, going to have the bottom end gone through at the machine shop, stock bottom end re build.

823 heads will be P&P
Not sure on CAM...

I'm at point to where I need some advice.


I'm thinking aftermarket fuel rails, but which injectors?

What cam should be used. I'm wanting a STRONG truck hoping to get in the high 400's close to 500HP range naturally aspirated.

I want a truck to be able to driven comfortably, so I really don't want TOOO radical of a cam.


Next question is...
Flat top piston to raise the CR or factory replacement? Also, do I need to upgrade the connecting rods?

Thoughts?

[clinebarger]

If your having it rebuilt anyway.......LQ9 flat-tops, LQ9 Bushed/Floating Rods would be nice also. That should yield a little over 10:1 with 70cc heads.

Have you had the cylinders checked with a bore gauge?

[KEWLKATDADY]

I haven't opened the motor yet. I drove the truck it came out of and it didn't smoke at all. I expect the cylinders to be in good shape, but you never know until you crack things open. I'm thinking stock crank, h rods and flat pistons.

Originally Posted by clinebarger

If your having it rebuilt anyway.......LQ9 flat-tops, LQ9 Bushed/Floating Rods would be nice also. That should yield a little over 10:1 with 70cc heads.

Have you had the cylinders checked with a bore gauge?

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[clinebarger]

With a mild cam & therefore limited RPM capability, H-beam rods are a waste of money on a N/A 6.0L

[KEWLKATDADY]

Is an arp bolt upgrade on the rods enough? This motor will never get over 600hp.
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[BR3W CITY]

The rod bolts are worthwhile at any power level. Even though most people really NEVER see a failure, if your doing any performance stuff, its the best insurance you can get.

[KEWLKATDADY]

with a little more research, the 317 heads and 823's have the same size combustion chamber and really shouldn't effect the CR themselves.

So I'll definitely need flat top pistons to get the CR up into the mid 10's like I want it.

[BR3W CITY]

If your planning on taking the old stuff out anyway, then sure. Your other option would be to have the heads milled slightly if your already getting PnP work done to them. Going from the 9.6ish that the lq4 would have, its not hard to get into the 10's.

If you do choose a flattop, then keep in mind PtVC clearances with the head/cam/piston.
The 823 is an L92 heads so it already has improved flow over the 317. Just don't port it so much that you actually lose velocity and negatively effect valve lift.

Do you have a relationship with your machine shop? Avoid trusting your portwork to someone without seeing a portfolio or something. Too many machine shops offering "port work" which is just glorified gasket matching.

[KEWLKATDADY]

No I really don't, but I know Texas Speed is just a couple hours from me

I'm going to have the machine shop do a basic freshen up to the bottom end, clean up the block, rebalance crank, bearings, rods and pistons.

I'll install the cam and top end, check PTV clearance. I'm not going to deck the heads. So even with flat top pistons, I shouldn't have any clearance issues, but I do want to talk with Texas Speed about the correct CAM for this application.

tape and paint and jam it in.

<insert eye roll smiley> Things never go that smooth, but you get the picture.

[clinebarger]

As Brew stated....I would leave the heads alone, They already flow enough air for what your doing. You just don't have the displacement.