MechMan1

iTrader: (5)

I am planning a LS3 build and I had a set of heads I was looking into but now I am not so sure. I was looking a t the Chevy Performance CNC heads but now I am not so sure. I started thinking maybe I should just pickup a pair of stock heads and have them ported and milled but then I thought maybe I should just go big and get a set of something from a company like Frankenstein. I am am keeping it stock cubes and looking to be around 500-550 crank HP. Not married to the number just something i am shooting for. No boost at least not for the foreseeable future. I just am looking for the best heads for my application with the possibility to grow. Any help would be appreciated. Thank you.

64post

iTrader: (5)

Lots of choices there, just how much of your engine build budget can you spend on heads? MMS LS3’s 260+5cc might be the tip of the spear. If your limited then ported 821 or 823’s. I’m a diy hard head so I ported my 823’s on one LS3 and bought AFR 260’s for the other.

onebadbowtie86

iTrader: (13)

I run the chevy performance cnc ls3 heads, they work great, they have the hollow stem intake valves as well which is a plus.

spanks13

iTrader: (5)

Ported ls3’s on such a mild build won’t be worth it at all. They already flow well enough there are better places to spend money.

GM sells a 525hp Ls3 with just a cam swap and it’s not even a great cam selection compared to what the aftermarket is doing.

MechMan1

iTrader: (5)

My build budget is pretty nebulous. I have been collecting parts here and there so I am a lot already. I have the cash for the block and rotating assembly so I am just throwing what I can into savings. I have been saving and continuing to save. I won't be starting this project for a bit so I can save up more for good heads.

MechMan1

iTrader: (5)

It may be mild now but I will be building this with room to grow.

spanks13

iTrader: (5)

Stock LS3 heads are really quite good up to ~600 hp I guess is what I was trying to say. I have stock ls3's on my 402 and I'm definitely in the 580-600 flywheel horsepower range.

AFR260's and the FED M311 both seem like good choices these days. FED ported LS3's are really quite a big port. Working really good on a 415 drag engine that only runs above 6000. Couldn't tell you what they'd be like on a street engine at lower rpm.

My buddy had CNC ported GM LS3's on his engine with a stage 2 sized cam and made decent power, but I don't really think they did anything too significant for him in that build.

Darth_V8r

iTrader: (4)

+1 to not porting the stock heads at your power level. Stock ls3 heads flow great already. Sometimes porting kills the port velocity and makes it run worse.

Do a good VJ. Cam in the high 220s. Rod modded intake. Headers. 550 bhp. Boom.

If you really think you would want more I would do afr 260 unless you plan to rpm in which case bigger ports like the 311 make sense.

64post

iTrader: (5)

just removing lumps and pumps, blending the bowl is an actual improvement for any level build, a mild port job, not removing a bunch of material and definitely not making the cross section bigger, there’s good gains in airflow there for a little time without adding much volume or slowing column velocity, just removing restrictions. It is worthwhile being that increased air flow is added power, I’ll take ported heads over cam.

Tuskyz28

I personally think even a mild port job can hurt the intake/exhaust relationship worse than what it already is...

G Atsma

If that mild port increases or changes the cross section, then yeah. But if it is a bowl blend and top drawer valve job, plus getting rid of casting hiccups, then it should be OK. I don't even call all that a port job. It's just rectifying a few defects....

Bspeck82

500-550 crank just use stock ls3 heads and intake with a valve job and maybe mill for compression depending on the rest of the build.

Tuskyz28

I wouldn't waste my money on a cnc port job. Here is a link where LS3 motors are making over 550 plus horses with a cam only swap..

http://www.superchevy.com/how-to/eng...tick-boomerang

KW Baraka

iTrader: (7)

Excellent article in that it also speaks to cam duration's impact on piston-to-valve clearance!

KW