4.8 heads

[qwikz28]

a guy on ls1tech is selling a set of ported and polished 4.8 truck heads. they are milled out a bit and flow pretty well. my question is what are the advantages of running these heads over a set of 6.0 heads or ported ls1 heads. i dont understand why anyone would use smaller heads. is there some advantage i dont know about. the price is pretty damn good. thanks

[badzracing]

Smaller chambers.....more compression!!!

[jims69camaro]

it's all about flow. smaller chambers and ports can create a very strong vortex that helps with scavenging. kind of the like difference between running in the dead of summer with 90% relative humidity and running in the winter in 30* weather.

http://hotrod.com/techarticles/48778/

http://chevyhiperformance.com/techarticles/41598/ - just about every head on the market is tested and the numbers are posted here

[foff667]

higher compression=more powa but they would need to be heavily ported to do you any good. Were they on like a 4.8 or 5.3 truck that HE had? Or did he buy them for his fbody or something & now he's selling them? Or link me & I can probably tell you if they are worth it or not.

[badzracing]

4.8/5.3 heads flow pretty damn good in stock form. Certainly enough for a n/a bolt on ls1.

[foff667]

yeah but dont they have undersized valves? I remember reading in gmhtp that a good amount of porting needs to be done to even get them to flow what standard ls1 heads do. :shrug:

[qwikz28]

http://www.ls1tech.com/forums/showthread.php?t=423000&page=1&pp=20

what do you guys think? i never realized how engine illiterate i am. :(

[foff667]

:shrug: one way or the other your talking $900 for a set of heads I've never heard of, with stock ls6 valves 2.00/1.55. My opinion with ls1's has changed though...personally if i couldve done it again I wouldve just gone cam only. You'll save yourself a good chunk of money in the long run & can still muster some great results with the stock heads. But thats me.