I just picked up a set of Absolute Speed 5.3L Heads that I hope to use on my LQ4 build.

Heads have 2.02/1.57 valves.

Flow Chart I got with them says:

Lift: intake exhaust
200 141 114
300 202 158
400 255 197
500 293 214
600 313 227

28inches H20
3.9 inch bore.

Main reason I got these where:
a) they where cheap
b) will bump my compresion up from 9.4 to 10.4:1
c) seems to flow as well as the TSP LS6 budget heads

Are these going to perform as good on my LQ4 as they do on a LS1?

I'm looking at cams now somewhere in the 224-230 range. Trying for 400rwhp and some nice low end torque.

 

What is the chamber size ??...I think CR will be closer to 10.8:1 if the stock size chamber is used.

 

Not 100% sure on the true chamber size. I plan to clean them up and try to measure them.
Stock is 61.15 cc I believe.
Based on that I got 10.83:1 using a .040 gasket and 10.47 using .054 gasket.
I will try the .040 gasket if I have clearance with what ever cam I end up with.

On a side note: How can I measure the combustion chambers? I've heard of using a syringe with water. How accurate would this be? Am I better of having a shop do it for me?

 

I wonder what those numbers would be on a 4" bore like the lq4

 

I would only guess they would flow a small percentage better...

Any draw back to using the 5.3L head on a 6.0L?
Piston/Valve clearance issues?

Biggest cam I am even considering is a Futral F13 (230"/232" .595"/.585" 112LSA) or a TSP Torquer 2 (232/234 .595/.598 112LSA).

 

In stock form the 4.8/5.3 head has smaller valves than the 6.0 heads (1.89/1.55 vs. 2.00/1.55)....trying to get a 6.0 to breath through that size intake valve is pointless. After a good P&P/valve job the 5.3 head is a great, it'll net you a higher compression than is capable from a 6.0 head and still flows really well

 

The only drawback I see aside from p/v issues are the fact that a 5.3 head is made for a smaller bore but the ls1 guys dont seem to have any problems with that causing hot spots. I think youve got a great combo there.

The lq4 has the dished pistons right?

Me personnaly Id be shooting for 11:1 and if need be a slightly smaller cam I think the added compression shows gains across the rpm range where sacrificing compression for cam just makes for better peak numbers and not neccesarilly better ET. I think your combo is gonna be alot of fun especially on the street.

 

Stout flow #s on the heads.... They will work great on the LQ4.... But like the others have said, make sure you verify your PtV clearance...!!!

 

224-228 range for the low end you are wantign while still running well up top. A 232-234 is going to cut that motors nuts off down low for torque. I run a 237/242 in my 418 and it gives me plenty of tq down low but I have over 50 more cubes then you too.

 

i run the tsp tv2 in my LQ9 right now im at 11.1CR but looking to bump it up some more. trying to be at 11.4 mimnum. this cam loves compression. as for not having power down low i dont see any side effect of having this cam. but im also a 3800stall with 410s.
i dont have any P/V issues with my setup i use 6.0 MLS gaskets with 243 heads