Caswell

With complete LS6 heads going for just over $700 a piece unported and under $1000 each CNC ported, how come more guys aren't running them as opposed to ported LS1 heads? When you look at the cost of even stage 1 LS1 heads and factor in not having to supply cores when you buy new LS6 heads, doens't it make more sense to step up to LS6 heads? I thought the general consensus was that LS6 heads outflowed ported LS1 heads. TIA.

Country Boy

iTrader: (24)

Because you still have to pay an EXTRA $1400 to buy the LS6 heads. Everyone already has the LS1 head or can get 5.3 heads for ~$300. By the time you add it all up it gets really $$$$..

Buy or pay core charge for LS6 Heads $1400
Have them ported ~$2000 - $3000

Thats anywhere from $3400 - $4400

When you have the LS1 heads, you just pay for the porting.

Caswell

As I said in the original post, CNC ported LS6 heads can be had from GMPP dealers for less than $2000 a pair (SDPC listing for ported LS6 heads). The main drawback to those IMHO was that they mill the head down to an 11.2:1 comp ratio, too high for a street car. However, I've heard second hand that they can be ordered without the milling to keep the comp ratio down to stock LS6 specs.

Now, considering that MTI (for example) sells their stage 1 heads for $2000 + core, it seems like a set of GMPP ported LS6 heads would be a better buy. The only advantage I can think of for the ported LS1 heads are better valvetrain components, which could be taken care of by selling your LS1 heads and using the cash on some good springs and Ti retainers.

So my question really boils down to this: considering they're about the same price, wouldn't it be a better buy to get some ported LS6 heads than to ported LS1 heads? This isn't a flame of guys who've gone the ported LS1 route - I'm genuinely curious as someone who sees new heads off in the distant future.

<small>[ April 09, 2003, 07:46 AM: Message edited by: Caswell ]</small>

Slowhawk

iTrader: (12)

I bought the LS6 heads for $1200 a pair and had them ported/bigger valves and run 11.1-1 compression on pump gas with 28 degree's of timing <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Ended up costing less than $2400 all together.It was well worth the $$.Too bad most of the sponsors are charging too much for the port work nowadays <img border="0" title="" alt="[Frown]" src="gr_sad.gif" />

I8COBRA

iTrader: (56)

I dont think 11.2 CR is too high for street use. I'm running it so far with absolutely no problems.

Caswell

That's good to hear about 11+:1 comp ratios on pump gas... I guess I'm still stuck with my old man's notions of compression - 10:1 seems high enough to me!

Any more input on LS6 heads, ported or otherwise? It does seem to me like head porting charges are pretty ridiculous for GenIII's, so I was wondering if there was some magic that the GMPP heads couldn't touch.

Pro Stock John

iTrader: (34)

A set of ported LS6 heads should outflow LS1 heads by 25-30 cfm.

11.25:1 is fine for the street, remember you have aluminum heads and blocks, and they dissipate heat much better than the old skoll stuff we all played with ten years ago. My old 69 Z/28 was maybe 10.5:1 but pinged like a sumbitch on pump gas until I pulled the timing back.

Sell your stock heads for $300, and get the GM heads for $2000 shipped, and have some fun. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

robertbartsch

..when i ordered my LS6 heads from SDPC they would not ship/order un-milled units...

...consequently, I beleive I am now limited to a relatively low lift/duration cam.

Apparently, flycutting the pistons is a major issue and running extra thick head gaskets is not an ideal solution either...

I have posted several times requesting owners of these heads to indicate which cam they are using...

I assume there is not that many guys running these since the data is very spars... SDPC claims to sell 60 pairs a month, however!!!! If they really do, they must all go to racers since the board does not indicate they are widely used in street applications....just a hunch....

Pro Stock John

iTrader: (34)

At the end of the day, you are worrying about running say a .560 or .570 lift cam vs a .580 or .590 lift cam.

You match the lift to the cylinder headflow.

It's reccomended that folks stay at or below .570 lift with the GM LS6 CNC heads... That's not bad at all.

Zeta

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by robertbartsch:
[QBApparently, flycutting the pistons is a major issue and running extra thick head gaskets is not an ideal solution either...
[/QB]</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I agree with PSJ. Unless you intend to have the heads ported again, then you should stay with a smaller cam.

Also, reread the article that fireball started. I read it as the technique he was using was the problem.

How much HP are you needing anyway? 400 is there with a 220 cam and list of mods of course.

robertbartsch

Oh! I thought a .530 lift with these heads was about the max unless you flycut or used a thick gasket...

...are you saying these heads flow a bunch with a low lift cam and not to worry, or are you saying .560 lift is no problem so go ahead?

Thanks..

Pro Stock John

iTrader: (34)

Since you have not bought a cam yet, you might want to talk to Tom @ Speed Inc., Paul @ Thunder or Jayson @ MTI, and see what they come up with for you... The nice thing about partnering up with a big shop is that you get to find out what cam they would use with your heads, and they will speak from experience.

robertbartsch

Good advice; thanks...

...I'm located in the Northeast so it is (i) East Coast Dyno, (ii) Cartech or (iii) SLP...

Lingfelter who CNC'd the heads suggested the following GT2-3 cam:

207/220 duration at .050" .573/.580 lift 117.5.

Any thoughts here?

Thanks...

Pro Stock John

iTrader: (34)

That cam might peak a bit high do they install it advanced, or does it have advance ground in?

If they are reccomending that cam with those heads then they must feel comfortable that you won't have piston to valve problems right? Were you talking to Ed Potter?

muscratmauler

I'm running over 11.4 compression with a 224/228 .581/.588 112LSA XER cam
and have 29 degrees of timing, no KR on pump gas. So I would think it's not a problem at all

BigBake

Looking at the numbers a set of ported LS1 heads outflow ported LS6 heads to a certain lift and then LS6 heads run away. But where does your lift spend the majority of it's time? I am sure not at maximum lift, so is it really worth the extra $$$$ just for a small amount of CFM for a very brief time constant?
In fact this months issues of GMHTP had a nice article on gen 3 heads. Take a peak at that and you will understand.

Paul J.

I bought a set of new LS6 bare castings on Ebay for $500, added Ferrea 2.02 intakes, stock 1.55" exhausts, Ported and flow tested them myself, assembled with 918 springs and homemade titanium retainers all for about $900 total. My testing revealed the redesigned LS6 intake port worked very well with the LS6 intake, substantially better than the LS1 intake port. Swirl was way down compared with the LS1 port due probably to combustion chamber shape which will reduce part throttle power somewhat. The LS6 intake port really shines at higher lift, up to about .600". Check around, be patient, good deals on LS6 heads are out there.

Paul J.

LS1derfull

I also worked bare castings like Paul J and found same great results with LS6 intake. These heads are clearly better than LS1 design, keep port size in check and run proper cam and i think it cant be beat.

PurEvl

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by LS1derfull:
<strong> I also worked bare castings like Paul J and found same great results with LS6 intake. These heads are clearly better than LS1 design, keep port size in check and run proper cam and i think it cant be beat. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Bah my ls1 heads are withing 10 cfm. I am just jealous of course. <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />