what do you guys think of a stock LS6 head swap onto the 5.3? they would have to be milled slightly to keep the compression up since the LS6 heads have about 3cc larger chamber. the LS6 heads do flow fairly well compared to the 5.3s, and surely they would be worth 20-25hp. there are a couple posts here and on tech where these could be had brand new for $700-725.

Stock 5.3 Heads
Chamber 61.15cc 0.100 0.200 0.300 0.400 0.500 0.550 0.600
Intake 200 cc 63 128 179 210 218 221 226
Exhaust 70 cc 54 93 121 145 163 168 174
Valve Diameter Intake 1.89"
Valve Diameter Exhaust 1.55"

Stock LS6 Heads
Chamber 64.45cc 0.100 0.200 0.300 0.400 0.500 0.550 0.600
Intake 210 cc 62 126 184 224 251 256 257
Exhaust 75 cc 57 108 143 163 176 180 183
Valve Diameter Intake 2.00"
Valve Diameter Exhaust 1.55"

 

One thing that worries me is the LS6 bore is 3.9'' as to our 3.79''. Smaller chambers seem to be fine on a larger bores but, the other way I'm not to sure about. I've talked to a few companies about this and their opinions varied.

Maybe someone knows for sure though.

 

Bump to the top.

 

I made a thread about this a few months back, I was told something about shrouding, appearently the valves are just to big for our motors...not to sure

 

I just tuned an 02 5.3L with LS6 heads and an ls1 cam.

The truck put more than 280 to the wheels, I think it was 284hp. I'll have to look at the dyno chart again to be sure.

The truck had exhaust and a couple other simple bolt ons so I'd say it's worth it.

It also put about 450tq to the ground with a 150shot.



good luck,


allen

 

i don't think the valves would be an issue really. we're only talking about an .055" increase in the radius going from the 1.89" to 2" intake valve. the combustion chamber setup from the differences in the 5.3 and ls6/ls2 bore sizes is my major concern. would i be setting myself up for quench/squish problems with this combo? what could some of the long term issues be with this combo?

Allen - thanks for the reply to my PM i sent you this weekend. i am in the convince "the one who shall be obeyed" mode right now. all will depend on how i play my cards, and so far it looks promising.

 

When doing something like this I think shrouding would become a problem. This being a partial blockage or restriction caused by an object in close proximity to the valve seat, IE cylinder wall. A 3.78" bore with a head designed for a 4" bore. Thus the valves will be close to the walls. Not really a great idea IMO. Yea your gonna mill the heads to get CR back. But you might not gain a whole lot. Bore size on the 5.3 really isnt big enough to take advantage of head like those of the LS6.

 

thx for all the info. i may be changing directions after getting a reply to a PM this morning and instead of making a head swap i may opt for a bore increase....

hopefully i will know something soon.

 

your saying 4" bore b/c of the 6L right? they also used those heads on the 5.7's that are 3.89". just wanted to throw that in. hope it works out for you okie...

 

hey blue, i mean swabby , what's up? the pic in your sig looks bad as hell! you have any video or sound bytes of your truck?