Anyone looked into using the LQ9/LQ4 6.0L heads for supercharging?
11-18-2003 | 06:00 PM
#22
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Originally Posted by BigTex
There is no physical difference in the LQ9 / LQ4 head. I have an LQ9 motor in my Silverado SS, and it has heads with casting number 317. The 317 heads also come on Escalades, Denali, HD trucks, etc... All the newer (01+) 6 liter heads have 71 cc chambers and the D shaped exhaust ports similar to the LS6 head.
The difference in compression on these motors comes from the piston, not the head: flat top hypereutectic on the LQ9 VS cast dished on the LQ4. Several months back, Chris Endres wrote an article for GMHTP (also in his book, but the article came out first) saying the 035 head was preferred over the 317 6 liter head in the FI community due to its 9.4:1 CR. He didn't take into account the CR was different due to the piston, not the head, so the article was misleading at best.
Dont pay a premium for the 035 head, its the same as the 317 head.
The difference in compression on these motors comes from the piston, not the head: flat top hypereutectic on the LQ9 VS cast dished on the LQ4. Several months back, Chris Endres wrote an article for GMHTP (also in his book, but the article came out first) saying the 035 head was preferred over the 317 6 liter head in the FI community due to its 9.4:1 CR. He didn't take into account the CR was different due to the piston, not the head, so the article was misleading at best.
Dont pay a premium for the 035 head, its the same as the 317 head.
11-18-2003 | 09:15 PM
#23
Originally Posted by MYTURBOT/A
So do the stock 6.0 heads flow better then the stock ls1, or is the only advantage the comp. drop?
11-19-2003 | 07:20 AM
#24
Originally Posted by MYTURBOT/A
So do the stock 6.0 heads flow better then the stock ls1, or is the only advantage the comp. drop?
comparable to the ls6 heads.
im pushing past 58lbs/min of air at 10lbs of boost, with just the exhasut sides midley ported.
11-19-2003 | 02:10 PM
#25
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Originally Posted by BigTex
There is no physical difference in the LQ9 / LQ4 head. I have an LQ9 motor in my Silverado SS, and it has heads with casting number 317. The 317 heads also come on Escalades, Denali, HD trucks, etc... All the newer (01+) 6 liter heads have 71 cc chambers and the D shaped exhaust ports similar to the LS6 head.
So the point is that this is not correct... maybe (
). Please refer to post #6 in th following thread:http://www.ls1.com/forums/showthread...hreadid=376535
I purchased the 317 casting from Shaun, and I would truly like to think they are the same as the 035s, as I had previously thought. But in the big three, a part number change NEVER, NEVER happens without a engineering change notification and that means a different part. What else can I say?
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Caddy always gets the cool stuff 
11-19-2003 | 04:17 PM
#28
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Why would GM have to different versions of the same LQ9 motor?? That doesnt make sense, there is some bad info floating around talking about those heads being on the LQ9s and it isnt true.
Also I think it was Big Tex, He worked on an EXT and it had 317 heads on it as well
Also I think it was Big Tex, He worked on an EXT and it had 317 heads on it as well
11-19-2003 | 04:37 PM
#30
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I think the lq4 and lq9 heads are exactly the same. there is no evidence other then the part numbers that says other wise. The port volumes are the same, combustion chamber CCs are the same, same D shaped exhaust ports. Can`t find any flow charts that show both lq4 and lq9. I think that the pre 01 lq4 iron heads were differant then the lq9 so people just assumed that when they went aluminum they were still differant, when in reality all they did was take the lq9 heads and slap a new part # on them and called them the new and improved aluminum version lq4 head.
11-19-2003 | 05:50 PM
#31
[QUOTE=Pro Stock John]I have the older 6.0 heads that were 70/71 cc's stock.
Mine are around 69cc's now. I did the 6.0's for two reasons:
-higher cc
-better flowing heads at higher lift than ls1/5.3's
[QUOTE]
what year were your heads John?
the older 2000 and older were iron, i hope your heads arnt iron.
i got the 6.0 heads off a 2001 truck, they cc'ed to 69cc's (both heads)
did you have your heads cc'd?
wonder if theres that much difference in tolerance for gm for one head to have 69cc's and another 71cc's
i also think the lq4 and lq9 heads are the same.
Mine are around 69cc's now. I did the 6.0's for two reasons:
-higher cc
-better flowing heads at higher lift than ls1/5.3's
[QUOTE]
what year were your heads John?
the older 2000 and older were iron, i hope your heads arnt iron.
i got the 6.0 heads off a 2001 truck, they cc'ed to 69cc's (both heads)
did you have your heads cc'd?
wonder if theres that much difference in tolerance for gm for one head to have 69cc's and another 71cc's
i also think the lq4 and lq9 heads are the same.
11-20-2003 | 06:42 AM
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Originally Posted by MYTURBOT/A
... when in reality all they did was take the lq9 heads and slap a new part # on them and called them the new and improved aluminum version lq4 head.
Big Tex: I hope that post is wrong, too. (It IS LS1.com, after all), but I still see no real conclusive proof that it is, in fact, wrong. I would be convinced if someone could identify the change that created the new number (though it still could be that there were more than one change that happened simultaneously). Or... Bone stock flow numbers on the two part numbers, at the same time, on the same flow bench. Now THAT would do it!
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10-24-2010 | 03:33 AM
#34
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Here's a chart for engine block and head casting numbers. The LQ4 and 9 had the same heads.
http://chevythunder.com/LS1%20components.htm
http://chevythunder.com/LS1%20components.htm
read the dates of the posts in the thread
10-27-2010 | 05:19 PM
#37
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Here's a chart for engine block and head casting numbers. The LQ4 and 9 had the same heads.
http://chevythunder.com/LS1%20components.htm
http://chevythunder.com/LS1%20components.htm
