lq4 6.0 ideas for my motor

[scwyyz]

I bought an lq4 6.0. Plan on putting it in a 67. Chevy truck. The motor is an 03 model out of a chevy truck. Very low mileage. The guy that had it sold the pistons and the crank. Just wonder what I can do with this motor. Any ideas would be great. Im going to build but im just looking at all my options. Any ideas?

[Firebirdjones]

I bought an lq4 6.0. Plan on putting it in a 67. Chevy truck. The motor is an 03 model out of a chevy truck. Very low mileage. The guy that had it sold the pistons and the crank. Just wonder what I can do with this motor. Any ideas would be great. Im going to build but im just looking at all my options. Any ideas?

Hmm, without the rotating assembly to go with it, then it sounds like a perfect candidate for a stroker setup since you have to buy it anyway.
I'd make a 402/408 out of it.

[scwyyz]

If I made a 402/408 which piston would I use and if I bore it out how far can you go before you have cooling problems. This is the first new age motor I've ever messed with. I've been more old school. I figured I would try something new.

[Firebirdjones]

Well you're in luck. For your first new age engine you picked a good one to start with. You are ahead of the game with the cast iron block. They can be bored as far as .060. The aluminum blocks are lucky to be honed .005 before sleeving is required.

With that said, .030 is probably all that will be needed for your block and it still leaves room for another refresh down the road. With a 4" crank it gives you a 408.

If you got the heads with the engine, they are probably 317 castings. Patterned off the famed LS6 heads but with a larger 72cc combustion chamber.

The LQ4 originally had a dished piston to produce a 9.5 compression ratio with that 72cc head. What I would do since you are buying pistons is go with a flat top, which will give you just over 10:1 with that same head when you figure in the longer stroke. If buying heads you can bring that chamber volume down and easily bump compression to 11:1 or more. It's really what ever you wish it to be depending on your plans.

[scwyyz]

I think its the ls1 heads. What is the difference between the ls1 and the 317 heads

[My00Z28]

if its an lq4 it will probably have 317 heads unless the guy switched them...

[Firebirdjones]

317's were designed specifically for the 6.0 truck engines to keep the compression down with their 72cc combustion chambers.

You would see 853's, 241's, or 243's on an LS1 passenger car engine. They have a smaller 67cc combustion chamber.

[scwyyz]

They have 806 stamped on the front top corner

[My00Z28]

Well doesn't look like u have truck heads... It is an iron block correct?

[Firebirdjones]

Hmmm,,,,806?? The only cathedral truck heads in that era of engine were the 317's, 035's, for aluminum, and a sole cast iron piece with a number of 873, but those were only installed early in the 6.0 production (1999-2000). In 01 they went to an aluminum head.


I looked it up,,,806's are very early LS1 heads from 97-98. So they are a smaller 67cc chamber.

[scwyyz]

So why would some one put these heads on this motor is there any benefits

[scwyyz]

Yes its an iron block

[Firebirdjones]

So why would some one put these heads on this motor is there any benefits

Someone trying to bump the compression would be my first guess. Those heads would probably give you a 1/2 point bump or slightly more.

[scwyyz]

So if that's the case then if I use the 4" crank and the flat top pistons then will there be enough clearance between the pistons and the valves

[Firebirdjones]

Sure, even with a pretty decent sized camshaft there should be room. It's always something I prefer to check.

[scwyyz]

So why would some one put these heads on this motor is there any benefits

Someone trying to bump the compression would be my first guess. Those heads would probably give you a 1/2 point bump or slightly more.

Sorry I was meaning to say are the valves different I kind of worded that wrong. I figured that the compression would be more lol. My bad.

[Firebirdjones]

Nope, same valve size in all the cathedral port heads for LS1/LS6/LS2/LQ4. 2.00/1.55

[scwyyz]

Another question. Would it benefit if I change the intake out to an LS6 instead of the truck Intake. Now im guessing that the truck intake is for more torque and not as much horse power. If I go the route that you where saying and make it a 402/408 the which would you think would ne the better choice. I haven't check the gearing in the rear end yet but Im going to bolt a T56 to the back of it.

[Firebirdjones]

Another question. Would it benefit if I change the intake out to an LS6 instead of the truck Intake. Now im guessing that the truck intake is for more torque and not as much horse power. If I go the route that you where saying and make it a 402/408 the which would you think would ne the better choice. I haven't check the gearing in the rear end yet but Im going to bolt a T56 to the back of it.

Well since you are putting it in a 67 truck you could go either way, you have the room under hood so that's not an issue.

One thing that will make the decision for you is which accessory drive you use. They are different between the trucks and cars to work around either intake manifold.

The LS6 intake will definately make more HP if that's your goal. For me I would also consider the weight of the truck and the gear ratio you plan to run before making a decision.

I can tell you I did this swap in my 72 blazer recently and I stayed with the truck intake for a couple of reasons. I wanted the torque to move this big heavy truck around (not much gear either), plus it came equipped with the truck accessory drive setup anyway, and I wasn't about to swap all that around too.

[scwyyz]

Nope, same valve size in all the cathedral port heads for LS1/LS6/LS2/LQ4. 2.00/1.55

Ive got a set of heads off of a 4.8 and thought about using the valves for my heads but they are smaller. I thought all the valves in the cathedral port heads are the same