243 headed lq9
01-15-2013, 06:00 PM
#12
FormerVendor
iTrader: (6)
Join Date: Nov 2004
Location: BERRIEN CENTER,MICHIGAN
Posts: 1,017
Likes: 0
Received 0 Likes
on
0 Posts
I'd go with the 243's. Nothing wrong at all with being up around 11:1 cr on an na setup, motor will feel nice and snappy. Plus if we are talking stock for stock 317 vs 243 from all of the flow numbers I have seen the 243's do flow better. It is no drastic amount between the two by any means but every little bit extra is nice. 
I have never first hand personally seen the two heads flow tested. My statement above is just based on some flow numbers I have seen posted a few places now.
However looking at your cam choice which I didn't realize you had listed with the 243's your DCR (Dynamic Compression Ratio) would surely be up there pretty high. In fact maybe even too high for just premium out of the pump.
I have never first hand personally seen the two heads flow tested. My statement above is just based on some flow numbers I have seen posted a few places now.
However looking at your cam choice which I didn't realize you had listed with the 243's your DCR (Dynamic Compression Ratio) would surely be up there pretty high. In fact maybe even too high for just premium out of the pump.
Last edited by KLUG'S SS; 01-15-2013 at 06:09 PM.
01-15-2013, 08:18 PM
#13
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Nov 2005
Posts: 391
Likes: 0
Received 0 Likes
on
0 Posts
Any idea what the dcr would be? The machine shop said they would true the surface, and install my PAC1218 springs and set them up for the .581 lift for $475. This would be on a factory ls2 mls headgasket. It would be dd and tuned on 93 pump gas. 200 miles a week.
01-15-2013, 09:09 PM
#15
FormerVendor
iTrader: (6)
Join Date: Nov 2004
Location: BERRIEN CENTER,MICHIGAN
Posts: 1,017
Likes: 0
Received 0 Likes
on
0 Posts
I see you are running a lower temp tstat and running strictly 93 octane, I mean you'd probably be "ok" but it won't like a bunch of timing that's for certain! Hahaha.
It'd be a torque monster with that setup.
It'd be a torque monster with that setup.
01-15-2013, 09:31 PM
#17
FormerVendor
iTrader: (6)
Join Date: Nov 2004
Location: BERRIEN CENTER,MICHIGAN
Posts: 1,017
Likes: 0
Received 0 Likes
on
0 Posts
With a good tune and run a step colder plugs like some TR6's yeah it could be safe. It is definitely pushing the envelope a bit in my personal opinion. I know their are definitely some guys out there that have run that high of a DCR even on a daily driver.
Would I personally run that DCR on my daily driver? No. That cam you've got is a great cam but just changing your cam up to something different if that was an option at all in your mind and you could definitely lower the DCR with a differently spec'd cam.
You could just go with the 317's and your 220 cam and have a static compression ratio of 10:1 and your DCR would still be a healthy 8.2 or so. Engine would still be torquey and fun to drive.
Would I personally run that DCR on my daily driver? No. That cam you've got is a great cam but just changing your cam up to something different if that was an option at all in your mind and you could definitely lower the DCR with a differently spec'd cam.
You could just go with the 317's and your 220 cam and have a static compression ratio of 10:1 and your DCR would still be a healthy 8.2 or so. Engine would still be torquey and fun to drive.
Last edited by KLUG'S SS; 01-15-2013 at 09:40 PM.
Will still be a good combination and make great power. Should be a nice flat torque curve with that setup!
01-16-2013, 09:43 AM
#20
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Nov 2005
Posts: 391
Likes: 0
Received 0 Likes
on
0 Posts
My buddy I'm getting the lq9 from had a core motor in the back of his shop with a set of 317's he is giving me when I buy the shortblock. I'm gonna have a valve job done, and bowls and exhaust ports cleaned up, milled .010 and my springs put on. Saved me some money not having to buy heads. I'll have this project completed in the next month or 2.