2000NemeSS

iTrader: (2)

So.. I know 243 heads are off the zo6 and are sought after. But whats so special about them over my 2000 ls1 heads? Little more flow? If Im upgrading my valve springs and putting a 224-224 cam in it, what would I really gain by putting 243 heads on it?

Also whats the difference between 243s and 799s? Simple questions but I honestly have no definitive answer.

redtan

iTrader: (5)

They are a better design and flow more...so that's why.

With a cam, you can expect a good 25-30 rwhp gain with a set of 243s.

thunderstruck507

iTrader: (18)

They were an improved design with more flow and slightly more compression than ls1 heads.

They also offer more flow potential ported.

The 243/799 are the same casting design, the 799 are just rougher. (It's like comparing ls1 853 to 241).


Without any porting or milling, bolting on a set of 243/799 would likely get you ~15rwhp (+/- 5hp).

Tainted

iTrader: (9)

Nothing really. They are just a little better casting and flow better. They are just a popular budget head and stock casting to get ported along with the 5.3 heads.

jdhedman

iTrader: (31)

~flow~

ROCNDAV

iTrader: (100)

How much better are they compared to 241s?

need2speed94

I think the real reason LS1 guys like it so much is because you can find them for Dirt cheap, and they give marginal gains. And with CNC work they can be comparable to some more expensive aftermarket heads.

baxsom

iTrader: (6)

higher compression from smaller chambers, better intake and exhaust flow.
other than that they are the exact same. they are cast the same. nothing else is different. the 799 heads are basically 01 z06 heads with the solid valves.

KCS

iTrader: (20)

The ports are different.

Put the 853/241/706/862 heads next to the 243/799 and you'll notice the short turn is taller.

Tainted

iTrader: (9)

Between the two stock, maybe 15hp between them ported probably 25ish give or take

redtan

iTrader: (5)

You can gain a helluva lot more than 10hp from porting them depending on the cnc program.

badazz81z28

iTrader: (6)

Just to throw this out there, The #799s and the #243s are not really the same. They have the same design, but they are casted differently. Expect a rougher surface in the ports, slag, imperfections etc. They actually have been shown to flow less and make a few less poneys than the 243s in stock form. From my extensive searching, 243s are not what I would call "cheap". They seem to go for around $400-$600+ in stock used form. Plus you need to get springs for them. Thats asuming they dont need to be gone thorugh or rebuilt which is additonal $$$$. If you want to send them out to hey ported, thats about $1000 from AI. For that $$ you should have bought from Texas Speed or Patriot.

joecar

A few years ago GMPP was selling brand new LS6 243 heads (with hollow valves) for about $450 each ready-to-go (seats/valves/springs/retainers/keepers/seals).

See here for flow numbers: http://www.smokemup.com/tech/ls1.php

edit: I meant 2002-2004 LS6

badazz81z28

iTrader: (6)

Too bad they dont do that anymore. I did find those at Summit Racing, they are still listed but price is N/A and "not available"

ZeeOSix

That was a great deal. I heard you can't get them anywhere new anymore from any source ... don't know how true that is or not.

So are the 243 heads the only ones that used the hollow valve stems? Or did GM use 243 heads with solid valve stems on other engines beside the LS6?

badazz81z28

iTrader: (6)

You can get new heads from Advanced Induction for $750, but they have solid valves.

Only the LS6 Corvette Z06 got the hollow valve heads, I think the Caddy CTSV as well.

GTO LS2 engine had 243s with STD valves.

ZeeOSix

So when you see "243" heads, it doesn't automatically mean they have the hollow valves stems, but depends what vehicle they came from. Thanks for that info Badazz.

groundZ-28ERO

I got my 243's for free there off a buddies 03 zo6. I noticed a definite difference from bottom all the way too top end performance. I'm still on the stock cam

badazz81z28

iTrader: (6)

Thats right, Usually the yellow valve springs will let you know if they are Z06 heads, but as usual with the way people mod stuff these days, thats not a guarantee.

I Only know for certain the Z06 had the hollow/sodium filled valves. If it came off of a GTO, regular valves.

baxsom

iTrader: (6)

the 01 Z06 did not have the hollow/sodium valves. only 02+