First off, yes i searched a bit for some answers here. I was out of the LS1 game for a few years and a lot has changed. I know a lot of guys are going with the 5.3 LS style motor as well as the LQ4/LQ9 Iron blocks.

Simple questions.......

Do all the LS style heads fit all 3 style blocks? Direct bolt on? I see guys using the ported LS1 heads on the LS blocks as well as the LQ9. Then I saw the 5.3 heads and they are going on stock LS motors.

I'm assuming they are all the same mold, correct me if I am wrong. And what's the difference. The SS I just sold had regular 99 casting heads ported by GTP, my next car I am buying has a set of the 5.3 PRC heads on it on a stock bottom end LS1 motor.

Give me the run down if you can, and don't yell too badly if I just missed a page on this somewhere. Thanks!

 

Yes. They all interchange. The difference in the blocks is more or less the bore. LQ4/9 are 4" bore, LS1 is 3.898, 5.3L is 3.78".

The differences in the heads are chamber design and cc size along with the runners.

The 6L heads are essentially LS6 heads with a 72cc chamber. LS6 are 64cc.

The 5.3L heads are essentially the LS1 heads, but with a 62cc Chamber or thereabouts, and the LS1 is 66cc.

There are multiple castings of each type of head.

The LS6/6L heads provide better flow out of the box. All of the heads come in at different chamber cc, so that provides a few different starting points to help get your compression where you want it.

Most with 5.7s choose to go either ported 5.3 to help raise the compression over say a ported LS1 or ported LS6 to raise compression and increase flow even more.

 

Yes all gen III/IV heads can be physically bolted to any gen III/IV block.

There may be some incompatibility with the bore size (eg. putting an LS3 head on an LS1 block or an LS7 head on an LS2 block) but besides that they all have the same bolt patern and can be bolted to any block.

 

cant stand bashers who take the time to say use the search button when with that time they could help a fella out....anyway....

4.8, 5.3, 5.7 and 6.0 heads will interchange. newer 6.0 and 6.2 rectangular port heads 0821, 0823, 5364 will not due to requiring at least a 6.0 4 inch bore because of the big 2.159 intake valve.

however, 4.8 and 5.3 862 and 706 heads (except 243s and 799s) have smaller stock intake valves of 1.89 compared to the 5.7 241, 243, 799, 853 and 6.0 317 heads which all have a stock intake valve size of 2.00.

the 862 and 706 heads have roughly 61cc chambers stock. the 241 and 853s have roughly 66cc chambers stock. the 243 and 799s have roughly 65cc chambers stock. the 317s have roughly 71cc chambers stock. the rectangular 0821, 0823, and 5364 have roughly 70cc chambers stock.

the rectangular port 0821, 0823, and 5364 heads use 8 standard rockers and 8 offset rockers.

in your case being ls1 motors came with 241 or 853 heads with 66cc stock chambers and they have replaced with prc 5.3s which have roughly 61cc stock chambers (unless they have been milled or the chamber reworked), you are looking at a nice bump in compression and flow since they also have now bigger valves, 2.02s.

i would ask the guy you buying the car from for as much info on heads, if milled or chambers reworked, if he has the tsp prc paperwork for them with specs, etc, to give you a better idea of what youre getting which i doubt will be great but even better to exactly know what youre working with.

hope i answered your ?. feel free to pm me or text me with any other ?s.

good luck with your new project and GOD Bless, Rob (956) 802-7700

 

one more thing....ls1s with tsp prc 5.3s heads love the tsp magic stick 3 cam....for max effort....some in the 10s with those and a few other goodies of course....

 

You guys all rock. Thank you very much.

 

The seller does have the paperwork for the Texas speed PRC stage 2.5- 5.3 heads. I will give those a good look over. I appreciate it. Small specs from some of the mods on the car I am getting....

PRC 5.3l stg 2.5 heads
227/231 113+4 pat g cam
Fast 92 intake and TB

 

I have those exact heads, and for what they cost I absolutely love them! Very nice budget head IMO!

 

NICE!

The SS I just sold but had the whole motor set up for Nitrous, and in the end not what I wanted to do. It had the solid rods, Nitrous pistons, High compression, etc etc. It was an amazing car, but I let her go to a good home.

Found me a nice ride with great mods for an amazing price. Can't wait to go get it Saturday

 

Awesome man! Keep us posted

 

1 more point to be aware of is the early heads had a notch about 1.25"/.625" on the inner edge btween 2 of the comb chambers and if You put the wrong type of head gasket under Them They'll leak coolant and the job will need 2 be done again . I believe the 97's, 98's & 99's but I'm sure 1 of You knows 4 sure.