1BADHD

I was browsing Ebay for a set of heads. I had seen this before, but never asked about it. I seen two sets of 6.0 heads on Ebay, one iron, one aluminum. They look the same except for the exhaust ports......on the iron they are round (also seen some aluminum 6.0 with round) and the other set have a sorta D-shape port.

Iron round ports


Aluminum D ports.

So.......is there any difference in performance between the two?

Yelo

As far as I know there is NO difference in performance between the Alumnum "O" port, Aluminum "D" port and Iron "O" port heads....all the research I have done and the experianced people I have discussed this with have led me to understand that the runners and chambers are the SAME in ALL THREE HEADS, the ONLY differences are in the actual port shape (and if you are worried about it the "O" port heads CAN be opened up to the "D" port shape)

*On a side topic....coming from someone who OWNS Iron heads* I have talked to ALOT of VERY knowledgeable people about this and ALL of them have suggested that I stick with the Iron heads I have and have them gone over to clean up the runners, chambers, and ports a little...EVERY shop I have spoken to (including cmotorsports) has recognized the benefits of the Aluminum heads but the power potential and reliability of the Iron heads outweighs ANY benefit the Aluminum heads have

BigTex

iTrader: (16)

I disagree with the iron head being better than the aluminum statement.

The D shaped aluminum heads have port designs similar to the LS6 head. The iron heads are similar in design to the plain LS1 head and 4.8/5.3 head. The LS6 head flow better than any other LSx head in stock form, followed by the 6L D shaped aluminum head. I know that stock LS6 heads are good for at least 15hp over stock LS1 heads.

I've hand ported a set of 5.3 heads and a set of D exhaust 6 liter heads, and I can tell you for sure that the 6 liter head has different runner characteristics than the other round exhaust truck head.

Yelo

RELIABILITY was supposed to be the key word on that statement BigTex...the aluminum heads DO have the potential to make more power but the Iron heads will outlive them by a long shot (especially if you live in a VERY HOT climate and are prone to overheating while towing trailers up 6000ft passes)

It was explained to me that the 6.0 "O" heads and 6.0 "D" heads had the SAME runner shape with the only difference being the actual port opening....which is VERY different from the runners on the 4.8/5.3 heads

Also...NO-ONE currently has dyno numbers to prove that the different 6.0 heads make different power levels that I have seen....and a few VERY reputable companies (Scoggin Dickey, Cmotorsports, Henderson Chevrolet) suggested that I stick with the Iron heads because $800 for nothing but a 50lb weight reduction seemed kinda silly to them and in stock form they will make EXACTLY the SAME power (according to them...I haven't swapped heads to find out)

I think the Iron heads were given a bad rap after the Aluminum heads came out because they were heavier.....but if you look back at all the muscle cars of the 60's, 70's, and EVEN the 80's MOST of them had Iron heads because they were cheaper to produce and iron is easy to cast into complex shapes

I'm not trying to start a Iron vs. Aluminum war....I'm just relaying what has been told to me

Ryan23silverado

iTrader: (1)

Yes, there is a difference between the LQ4 and LQ9 heads. The LQ4 is not a "D" shaped exhaust port -the LQ9 is. D ports generally flow better than "O" ports.

1BADHD

So they are not the same casting number? Thought they were all "317's". Which are on my truck?

Thought the LQ4 and LQ9 differences were tuning, cam and exhaust......first I ever heard about heads.

Yelo

I also thought all 6.0 Aluminum heads were "317"'s...I have never found a reference that states there is a difference between the LQ4 and LQ9 heads, the only differences I am aware of are the compression ratio, and the tuning (and the cam after '00)

BigTex

iTrader: (16)

Oh God, not this again.

In that book that came out about LS1/LS6 motors by Chris Endres, he made a small reference to the LQ9 head being a better head than the LQ4 head. He said it was a 035 casting. BUT, my LQ9 motor has 317 heads. The heads I had off of an LQ9 Escalade were 317 heads. I've never seen an 035 head, and I've looked at every Silv SS and Escalade I could get my head in. That being said, Patriot Performance says their LS6 type heads they are porting are 035 casting, so I guess they do exist.

I still think the aluminum D heads flow better than the iron O heads. I could see the iron head having a thicker stronger deck, but you wouldn't need that unless you are really putting down some big HP numbers.

1BADHD

Sorry.......I was just curious.

BigTex

iTrader: (16)

No problem.

The difference in the LQ4 and LQ9 is the pistons. Same heads, same cam. Maybe a little tune difference. The LQ9 has higher compression due to the pistons (10:1).