any truth to this info...???
Thread Starter
Staging Lane
Joined: May 2009
Posts: 54
Likes: 0
any truth to this info...??? I have a 99 ss m6.... I would like to do H/C/I.... as far as a head setup, if the following info is true, what are some opinions on getting a set of 243 heads and having them milled .030 to raise the compression? I plan on a h/c/i combo with a 150 shot. Thanks for any opinions fella's...
If I remember correctly the LS6 (243) stronger spings than the LS1 (241) -
Hands down the LS6 head flows better than the LS1 due to the runner volumes and the smaller combustion chambers!
LS6 heads are refined and improved LS1 heads, basically:
- Intake runner volume increased to 210cc vs. 200
- Exhaust runner volume increased to 75cc. vs 70
- Combustion chamber is smaller at 64.45 cc vs 66.67
- Compression ratio is higher at 10.5:1 vs. 10.1:1
- "D" shaped exhaust ports vs round
If you mill the deck on the LS6 head 0.030" you will get 11.1:1 compression.
Flow #'s (Stock heads @ 28") Head vs Lift
Head/.200/.300/.350/.400/.450/.500/.550/.600
LS1 / 137/ 187/ 207/ 223/ 228/ 237/ 242/ 243
LS6 / 156/ 204/ 225/ 243/ 257/ 268/ 275/ 278
In short smaller and more efficient combustion chamber allows quicker burn times, requires less ignition timing resulting in higher torque.
If I remember correctly the LS6 (243) stronger spings than the LS1 (241) -
Hands down the LS6 head flows better than the LS1 due to the runner volumes and the smaller combustion chambers!
LS6 heads are refined and improved LS1 heads, basically:
- Intake runner volume increased to 210cc vs. 200
- Exhaust runner volume increased to 75cc. vs 70
- Combustion chamber is smaller at 64.45 cc vs 66.67
- Compression ratio is higher at 10.5:1 vs. 10.1:1
- "D" shaped exhaust ports vs round
If you mill the deck on the LS6 head 0.030" you will get 11.1:1 compression.
Flow #'s (Stock heads @ 28") Head vs Lift
Head/.200/.300/.350/.400/.450/.500/.550/.600
LS1 / 137/ 187/ 207/ 223/ 228/ 237/ 242/ 243
LS6 / 156/ 204/ 225/ 243/ 257/ 268/ 275/ 278
In short smaller and more efficient combustion chamber allows quicker burn times, requires less ignition timing resulting in higher torque.
if you send the 243's out to a reputable company such as Advanced Inductions, they can make killer power. 450+ whp on the right combination of parts. In stock form, milled, and cleaned up 430whp should be about par with a decent cam in the 226-228 duration range.
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TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Correct. Another option is to send your stock heads to AI and get their 241 219cc CNC program. Then can keep stock valves, no milling and weld the chambers to reduce size and therefore you get close to stock clearance but with higher compression.
Stock bottom end 346?
What size chambers do you have? - cc's?
headgasket thickness?
How much did you mill your head?
If more than .060, did you run into any intake manifold fitment issues?
The most common reason for intake fitnemt issues is people not milling the intake face of the head like they are supposed to. Any amount milled off the deck surface should not cause intake fitnemt issues if the machine shop did the milling correctly.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
That is because Grr is not telling you the whole story.
Sure guy, not telling the whole story. Whatever man
Stock 346, .05 stock mls gasket
Pistons are out .008
Heads are 46.x cc
best guess is they are milled around .135-.140, do not remember what was taken off the first time. Calculated at 12.96:1
Dynamic compression is 9.65:1
Stock 346, .05 stock mls gasket
Pistons are out .008
Heads are 46.x cc
best guess is they are milled around .135-.140, do not remember what was taken off the first time. Calculated at 12.96:1
Dynamic compression is 9.65:1
