like the topic asks

 

Untouched Ls1 heads will drop compression and shroud the valves on a 5.3, they flow about the same.

From smokemup.com

Stock 5.3 heads
Chamber 61.15 cc 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 LS1 heads
Chamber 66.67 cc 0.100 0.200 0.300 0.400 0.500 0.550 0.600
Intake 200 cc 67 122 178 215 219 223 227
Exhaust 70 cc 52 97 133 156 170 176 180
Valve Diameter Intake 2.00"
Valve Diameter Exhaust 1.55"

 

what about stock ls6 heads? do they flow more, and what do you mean by shrouding the valves? For the price of used ls6 heads on ebay ($500-$800), what can you find for just as good of a deal?

 

Stock LS6 heads do flow more, but will also reduce compression because they have a 65cc chamber.

By shrouding the valves I mean that LS1 and LS6 heads were designed with 2.00" intake valves to be used on engines with 3.90" bores. Putting them on a 3.78" bore 5.3 will put the edge of the intake valve close to the edge of the bore and hurt airflow.

If you want heads, the ones I had WCCH do for me are 5.3 heads that outflow stock LS6s, and are also milled to raise compression. Pricing is very resonable. Give Richard a call he'll hook you up.

 

so in the long run what could it do for me? im still learning about the compression and etc...

 

Not sure what you mean by this...... But lower compression will cost power on a N/A motor. A lot of FI guys run lower than stock compression so they can run higher boost levels with less fear of detonation.

It all depends on your goals and future plans for the truck.

 

if i got the heads worked on could i get the compression set higher or???

 

I think that you are better off starting with a set of 5.3 heads to port, as I posted above, they flow the same as a LS1 head, but have a smaller chamber.

Take my heads for example, they were ported which increased the chamber from 61cc to 65cc. From there, they were milled .045 which reduced the chamber size to 58cc, which when used with a .009 thinner head gasket than stock, will raise my compression from 9.5:1 to 10:1. If I wanted more compression, I could swap out the stock dished 5.3 pistons for stock flat top 4.8 pistons, but at that point I'd rather just build a 408.

 

I recently had my stock 5.3L heads reworked by Richard@WCCH. They did a great job and put larger valves (1.95/1.57), ported the bowl area, and milled 0.025". I ended up with 57.2cc combustion chambers (stock on mine was 62cc). I used stock heads gaskets, but believe my compression ratio is better than 10:1 now. I'm going to re-dyno hopefully this Friday and will post the results. I'm really happy with the results just from my street tuning and these heads. The Tahoe really hauls a@@ now.

Best,
Stan

 

these are the plans i plan on doing: get the heads, have a valve job done, p&p, and go from there. im limited on what i can do right now cause tranny and posi may let go soon, and i dont have time to tear apart the motor im just doing little things here and there.