Wh ls1 heads

[big jace]

Just wounderin if any1 can ansa a question for me
I've been told the heads on wh statos are smaller
ported then say Ss heads from factory?

Any1 know if this is true? Should I replace my heads
with Ss ones 4 better flow b4 I do a maffless tune??

[GenReaper]

241 heads are smaller, 243 heads are the go.

Requires new ARP head bolts as they are different lengths.
Also new rocker covers if you have perimiter bolt patterns and switch them to centre bolt covers and also swap out coil packs and brackets.

[soop]

Will putting 243 heads on an internally standard LS1 achieve anything?

[Pub247]

I'm sure it would with a tune and a few other basic mods your VE would be increased and you'd gain some power and possibly better Fuel ecionomy depending on tune

[HRT 666]

Im not sure on the combustion chamber size on the 243 heads and what it would do to comp ratio (raise or lower it) maybe someone in the know can help us out here? I know the 243 flow a little better. Even on my stroker I stuck with the 241 and got them stage 2 cnc ported and they worked out killa.
With heads its all about keeping the air speed high dont look for peak cfm numbers.

[soop]

I've heard that the 243 heads don't fit the 3.9" bore of the LS1 properly.
I know 308 heads go on 253's and the discrepancy between the 4" 308 and the 3.6" bore of the 253 would be worse. I know apples and oranges...

[HRT 666]

My advice for a stock motor would be keep the 241 head as it has smaller ports and will keep the air speed at lower rpm and make better torque.

[soop]

Yeah I would anyway, just curious really.

I wouldn't even bother porting them for mild engine. After pulling the manifold of, they're some of the sexiest factory heads I've ever seen.

[Vt_vic]

arent the 243 the l98 heads?

[big jace]

Ok, thanks for the advice ppl, but last question is
should I put different heads on my wh Stato? It's goin
in forthe tune in 4 days so, if I male the change it's gona
need to be this wknd

[soop]

If its otherwise standard, no.

[SirNemesis]

Fair bit of crazy info here. 243 heads will bolt straight onto an LS1 (3.9" bore). These are LS2 standard heads and will perform better, but probably not good enough to justify the effort involved. L76/L98 (L92) heads will not bolt onto a 3.9" bore (5364 casting number). That isn't whats being discussed here, but where the confusion has come from.

[soop]

Fair enough, I didn't spread it as gospel. Just bought it up as I'd heard something along those lines to begin with.

[bortous]

the 243 heads fit on ls1 and do flow more but you need to get them ported etc and increase the compression and you will notice a massive difference.
From about 225CFM at the intake it will shoot up to about 320CFM which is huge. Still flows less than a stock l92 head but power wise not a big difference.

[soop]

Seems to be completely unnecessary on a mild LS1.