ItalianZ28Stallion


were did you get the cam from and how does it perform ?? bet it sound sweet :-)
is that in your stock ls1 longblock??
any hp #
and what other performance mods do you have ??
and would the 243 heads bolt up with out any problems ??

 

pretty sure the 243's allow you to port them a little better without them getting too thin around the rocker arm bosses

 

you can always get the 853s ported, i had lloyd elliot port my 853 heads off my 99 t/a sometime in 2002, and they flowed 317 intake at .600, and 229 eshaust at .600. this was using stock valves, no valve job. car made 385 hp before, and fiqured about 425 hp after. and all was done for $500

 

I just bought a complete 2007 LS4 with transmission harness, intakes and all with 12k for $499. They also come with 243 heads. They are on impalla ss and monte carlo ss 5.3ls. Theres another one form the same seller for $499 too on ebay.

 

I just bought a 08 GMC Sierra 5.3/4l60e dropout and it came with 243 heads...

 

yep..we did two 2008 silverado cam swaps ..and both had 243 heads ...with ls6 springs

 

well The 04 GTO ls1 is kinda a ls6/ls1 hybrid only major hp difference that im aware of is the 243's and cam size possibly compression is better on ls6 and the 04 gto does have the ls6 intake as well. so a pair of 243's on stock 04 gto could give you up to 40-50 hp more at the crank

 

the LS2 also has a 4" bore,as opposed to the LS1s 3.898 bore..
346ci for the LS1,364ci for the LS2..
and the 243 is a better head,even when both are ported..the 243 has a more efficient combustion chamber and a better short side radius on the intake port..that's why,IMO,you see other variants of the LS platform using them in OEM applications..
how much better is an ongoing debate,it all depends on what your goals are and how much money you want to spend..

 

241 heads can flow good when ported by someone good. My 241's flow 339 @ .650 lift and 217 @ .650 lift and make over 500rwhp N/A. Just wanted to throw that in there in the mix

 

So don't keep us in suspense........

Who is your porter????

 

Obviously, your car runs damn good but I would like to know what your heads flow at .200,.300.400 lift. The big numbers look good but the mid lift numbers are where its at.

 

Which one of those heads would be good for lowering the compession on a stock cube 5.7, that would be getting a rear mount turbo. I have a friend that is looking for the truck head that would be the best deal to lower his compression. I have heard talk about it in the past, but not sure what casting he should be looking for, or if a cnc version was available already assembled, from Patriot or SD. The lightweight valves on the larger chamber heads would be a sweet setup, for the budget minded.

 

The heads you are referring to are the 317 casting used on 6.0L truck engines. They flow essentially the same as the 243 LS2/LS6 heads, and have larger 72cc combustion chambers. These do not come with the hollow valves (that I have seen) but you could add them on your own.

 

So let's talk numbers then.... What are the flow rates on the 241 vs 243 at various lifts - stock of course... Cuz like was said, flow rates change from porter to porter - for the good or bad. Not everyone knows how to correctly port a head and those that don't, typically make the flow worse.

 

www.advancedinduction.com they are a sponsor on here!

 

I am swapping my 5.3 for a 408 in my wife's 06 Trail Blazer. It is nonEXT and 4x4. It, to my suprise, has 243's.

 

As stated, many factors weigh on the quality of the porting. Though the LSx heads do lend themselves rather well to additional porting, and do not require one to be an expert, veteran head guru to make some gains with the stock castings (trying not to turn this into a head-porting tutorial thread).
Something to keep in mind is the runner volumes and what kind of an engine you want to end up with (cubic inches, RPM range, efficiency vs. power, etc.).
The 243s start out as a 210cc intake runner (as do the 317s, I believe), while most of the other LS1/4.8/5.3 heads start out as 200cc intake runners. Again, depending on the extensiveness of the porting (and/or increases in valve size), you can expect to end up with a 225cc-240cc intake runner when porting the 243s. This is fine for the guys who have bigger cams, more cubic inches, or higher operating RPMs. But for a tame street engine, mild daily driver with a small cam'd stock-ish shortblock, a guy might want to start with some 853s/241s and end up with potentially smaller runner volumes for slightly more efficiency and more low speed response on the street. Kinda like choosing AFR's 205 instead of their 225 version.
'Give or take' 10 cc's may not 'make or break' your engine combo, so starting with unported 243s is certainly a cheap way to gain some useable power. You just don't want to jump into the biggest, most heavily ported heads you can find. Of course, if one does not have thousands to spend on heads, any budget ported head may be preferable to bone-stock, within reason-- obviously (in the pursuit of affordable power, we will usually accept loosing some efficiency without pitching a fit). Just be aware of the volumes, so you can decide if the additional CFMs are worthwhile and useable in your situation (or if you plan to 'grow' your combo in the near future).

 

I did not port mine. these are 241's i might be having 2nd thoughts about that but here is a pic mine with 2.02/1.60 valves installed I'm in the process of building my 383. is my engine not going to receive enough air flow due to not porting the heads or will the oversize valve compensate for that?

 

The only way to know for sure is to take a few valves out and have a look for your self. Since the seats were replaced for the larger valves, you must have had a valve job done. Check the quality of work where the machine cutting meets the uncut casting. If they have already been blended or make a reasonably smooth transition, you will likely be fine. If not, you have room for improvement with some careful bowl work.

In all the posts I have seen here, the biggest improvements to stock castings comes from a quality valve job and porting the areas around the seat and the guides.

 

The GTO 243 heads do not have the light weight 02/04 LS6 valves.Also,the cam in the Goat has .525 lift (same as 01 LS6) the valve spring are only good for .540 lift.Sorry to say this,but the LS2 intake is a real dog...some poor engineering by GM.