Given the choice (meaning you have the funds) for a stock-cubed motor, would you opt to spend the extra $$ for a set of ported LS6 heads (243 casting) over a set of ported LS1 heads (241 casting)?

I ask because, well, I have an option to pick up a set of lightly-used '03 LS6 heads (complete, ready to bolt-on), and I am contemplating using these for cores and getting a ported LS6 set. Or, the other more economical option would be to just purchase ported LS1 heads, use my LS1 stockers as cores, and completely forget about using the LS6 heads (stock and/or ported).

With that said, here's my mods & what I use my car for... '02 Firehawk, M6, stock LS6 intake, '02 LS6 Cam, StainlessWorks longtube headers w/ RT high-flow cats, P/P TB, ASP pulley, custom PCM tuned, and a few other minor bolt-ons (stock MAF). Stock 346ci displacement, and it'll stay that way. No turbo/SC are in the long-term plans.

I *rarely* go to the 1/4-mile track (never gone yet with the Hawk). I want a fully street-friendly setup, no "quirks", as I am building the car for (street) power. With the addition of the heads, I can also forsee another cam-swap to one that is a bit bigger but still friendly for stockish-idle quality & behavior. I will gladly give up HP for better all-around driveability & behavior, as this car needs to both cruise nicely at 75mph and also sit for long-periods in 0-20mph stop-and-go rush hour traffic. Hence, a big lopey cam is completely out of the question. (Would then going with a extremely high-flowing head be a waste of $$?) I would like to raise the CR a bit, and prefer low/midrange torque over high-rpm HP.

What sort of flow and HP benefits does a S1/S2 LS6 head have over a S1/S2 LS1 head?

Any help is appreciated. The 'search' isn't turning up much helpful information; at least, not yet....

 

Well, theortically, with the Mods you have and a good tune, you would be close to, if not better than a Z06 in perfomance with the LS6 heads.

Just a thought.
Paul

 

your demands are the same as mine as far as what the car is used for...(pretty close)
and if i were you id just go with TSP race style stage 2 5.3 heads... there a cnc head with hand polishing! get them with a 10.8:1 CR, dual springs, Ti retainers, Hardend pushrods, ARP bolts etc...
and if you want low end more than top end id say get a COMP 216/218 535? lift 114

they have great deals on H/C combos

 

I picked up a set of complete 5000mile LS6 heads for $850 ... of this, I got back $300 for used valve train and valvecovers. Then I put in 918 springs, oversize valves and titanium retainers. Race valve job and opening up the valve inserts and milling cost $300 (they also assembled). I did some basic porting work to clean up the runners.

With my small 222/224 cam I got 400rwhp. Go for the LS6 heads every time. It also gives you some room to move if you want more power (ie. stgII or stroker)

 

Seriously for a street car only, its not really worth the added expense for LS6 cores, IMO. The power increase due to flow over a ported LS1 set is marginal on a 346 motor. If I were going to do new heads, I'd start with a set of 5.3s just for the added compression. You can easily get 10.8:1 with them with minimal milling.

 

For stock cubic inch, ported LS1/5.3 heads are the best choice for your application.

 

Thanks for the replies - curious though. If I drop on an unported LS6-head, using the LS6 cam, I should see about a 20-25 rwhp (peak) gain over the stock LS1 head, correct?

Using the LS6-cam (for now), I'm trying to figure out the bang vs buck 25hp @ $800 = $32/hp. Ported LS1 head ~40 hp (??) @ $1500 = $38/hp.

I totally appreciate the replies.....

 

Is there any flow difference between a stock LS1, say '99 head, and a 5.3 head?

Off topic question... If you are building a motor, don't you just get your compression through the pistons (well, most of it anyways)? So you want 11.1 compression, and you are building a motor, you would buy pistons that are made to get 11.1, not a regular stock style piston and them get the heads milled or whatever to get your desired compression?

I am not an expert on this, so I this is just what I have gathered from seeing engine's being put together, the correct way is through the piston, etc, not the head, correct?

 

Either way works. It is just you have more choices when building the complete motor and the bad thing about milling heads is you can only go so much before you run into intake runner problems and clearance issues on the TB and water pump. With 5.3 you can mill more if you need to but not needed because they already have smaller Combustion chambers ETC...Hope that clears some things up for you. I am not an expert either just know a few things I am sure you already knew some if not all of what I said.

 

You didnt plan on replacing pistons right? 5.3L heads will slightly outflow LS1 heads with the same valve size, but its by a small amount. Your choice on whether you want ported LS1 vs. stock LS6 is your choice...I'd go ported LS1s, but I'd also step up to a slightly larger cam to also take advantage of the higher flow capabilities. If you're going to stay with the LS6 cam, I'd just save money and pick up the LS6ers. A cam with some more overlap and more advance will help the midrange power tremendously.

 

A recent article in Hot Rod confirms what Scott is thinking . . . achieve your desired compression as much through pistons as possible rather than the heads, and generally you will see more power ( that's assuming the stock-type heads are great to start with, as ours are ).

- Dug

 

That's what I though Dug, this is especially the way to go for blower guys, the pistons are the way to get that low compression ratio.

 

They are refering to the sqwench area or something of that nature. Supposed to help reduce detination ETC... And that is where some of the extra power comes from but that is a grey area cause some cars run better than others ETC... And cost is a huge factor in how you raise or lower your compression for most people. If your going for a build up though I agree the pistons are the way to do it but not the only way. JMO.

 

Ya, if you aren't ready to dig into the engine, I would agree. If you are I would get as much as possible through pistons. To save money go with off-the-shelf pistons as close as you can and get the rest through heads, etc.

 

No offense guys, but please don't hijack my thread. None of this has anything to do with my original questions. I appreciate the help, but please stay on-topic.

 

Sorry dude! Back on track . . .

- Dug

 

Same here, easy to do, I appologize