I have 241 casting heads for my 02 z-28. WHat exactly does the casting number mean? Im thinking about ported ls6 heads or ported ls1 heads... Any real difference between the two? May be before porting, but what about after?

 

The 241 are the latest LS1 castings, which I believe started in 2001. They don't provide any major performance increase over the previous heads...maybe a few cfm and horsepower over previous castings.

The difference between the LS6 and LS1 quite significant.... less combustion chamber volume and bigger intake runners on the LS6, which lead to more power via more compression and more peak flow.

LS6 heads can be ported leagues beyond the LS1 stuff as well, but like anything else, it all depends on who ports them.

Mike

 

Thanks man.

 

That started in late 2000. I have them on mine.

The 241 are cast different and are supposedly worth a few more hp because of this.

 

I have a set of perimeter bolt 98 vette LS1 castings in the shop laying next to a set of 241 castings and they are the same heads in the ports and chambers. They will flow the same on the bench as well.

LS1 castings are LS1 castings, nothing real trick between any of them.

The small truck castings, 6.0L truck castings (317) and 243 (LS6,LS2 and new 5.3 trucks) are all different. The 243's being the best of the bunch.

Bret

 

You have flowed them?? Side by side?? There are minor changes from the 853 to the 241, what they are only GM knows. And of the '00 model year cars the ones with the 241s tend to run a little stronger than the rest. Mine was one of them

 

Yes I have flowed them and either way LS1 castings, reguardless of casting numbers or years are nothing special. Either way WHY care unless you are running a legal NHRA/IHRA stocker, put a head in there that has some short side and you will be much better off.

The differences are external the port cores are the same.

Bret

 

Not to jack, but I've been wondering this myself..

Does the casting # have anything to do w/ int/exh wall thickness? I've hear that a certain manufacturer take a certain casting and punches the head out to obtain optimum flow, but in turn the INT walls were literally PAPER thin! A couple people have dropped rocker studs/mounts due to head failure.. Smell what I'm steppin in? Or did I go off on a tangent?


Good stuff here... I'm going to throw it in my stickey..

 

No that's entirely possible. The easiest way to figure out wall thickness if the port core (inside) is the same is put the heads on a scale, usually the lighter one has thiner walls. Then you can get a spare head and cut it up to measure local thicknesses.

Looks like they are chasing flow bench numbers again.

 

Another bone-head question... Forgive me on this one.. I never understood the Casting #'s thing at ALL!

Is the Casting number relative to the different intake/exh port or CC design?? Such as the LS1 heads being slightly different and the LS6 heads being the slightly better flowing set? Such as the # referring to the style of heads?

*hides*

 

Hell if you don't know something you gotta ask... I had to ask a bunch of guys from Missouri what "gigin" frogs was before I knew.

Yes heads have a casting number on them that will have the last 3 or 4 numbers displayed on the head someplace. LS series heads has that on one end of the head right next to the valve cover rail.

LS1 heads are commonly 241 castings
LS6, LS2 and the 2007 5.3L trucks are 243
6.0L Iron Block truck motors are 317
4.8L and 5.3L truck motors are 853 (I think)

The L92, LS7 and C5R heads all have numbers as well but it's easier to just look at the rest of the head to tell what it is, but those all bo by a 4 digit number.

Bret

 

Hey Bret,

How about you get my motor out of your avator and call me? Ignoring me is not helping the situation.

 

For all practical purposes, the casting number is no more than a ID number for the mold used to make the head.

Re'

 

^^ Sweet! Thanx for the help!

[/THREAD JACK]

 

i have 243's on my '07 5.3, but ive heard that the valves are actually smaller than the 243's from the vette. is there any truth to it? it seems to me that there would be a different casting number if this was the case.