Generation III Internal Engine 1997-2006 LS1 | LS6
Sponsored by:
Sponsored by:

862/706 vs 243

Thread Tools
 
Search this Thread
 
Old 10-14-2017, 10:27 AM
  #1  
Registered User
Thread Starter
 
Loganglenn's Avatar
 
Join Date: Oct 2017
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
Default 862/706 vs 243

I know stock vs stock the 243 is the superior head but my engine came with 706 non crack-tec heads and I'd like to use them if I could. My question is what performs better, a stock 243 or a professionally hand ported 862/706 because for the price of 243s I could have my 706s hand ported and flowed by a well known drag racer/engine builder in my area. I also know that I'm going to want to mill the 243s if I get them because my set up is a 5.3 with 4.8 flat tops and I want to stay around 10.5-1. Are 243s just such a superior head vs the 706 or could the 706 out perform the 243 with alittle work?
Old 10-14-2017, 10:32 AM
  #2  
TECH Senior Member
iTrader: (2)
 
HCI2000SS's Avatar
 
Join Date: Aug 2012
Location: Howell & Fenton MI
Posts: 11,145
Likes: 0
Received 15 Likes on 15 Posts
Default

With some work the 862/706 head will easily out perform the stock 243 head. I run PRC 5.3 (862) heads and for the price I'm very happy with their performance
The following users liked this post:
cookseyb (09-13-2019)
Old 10-14-2017, 10:33 AM
  #3  
TECH Senior Member
 
G Atsma's Avatar
 
Join Date: Jun 2016
Location: Central Cal.
Posts: 20,878
Received 3,022 Likes on 2,353 Posts
Default

Look for 799's as they are identical, and came on every 5.3 truck engine since about '07. Prices should not be too bad, as common as they are. I'm surprised 243's haven't come down more in light of this.
Old 10-16-2017, 02:23 AM
  #4  
TECH Enthusiast
iTrader: (1)
 
07NBSChevy's Avatar
 
Join Date: Apr 2013
Location: Las Vegas, Nevada
Posts: 607
Likes: 0
Received 5 Likes on 5 Posts
Default

799 and 243 heads were used on all 2007.5-2013 4.8 and 5.3, as well as previous years but on certain ones.

Some Pick-A-Part/Pick-N-Pull Yards have great prices on parts. My local yard sells aluminum non-overhead cam heads for $44.00 ea. with a $10 Core. I can get a set of 243/799 heads any day of the week down there for $120 out the door without cores and $100 with cores. So if you would rather spend your money on 243 heads, check your local junkyard first.

In Stock Form, the Cathedral Port 243/799 are the best flowing GM Production heads for Sub 4.00" Bores in a N/A Setup, at least in my opinion. Above 4.00" Bores, 6.0L+, it can vary depending on your setup.
Old 11-29-2017, 08:44 PM
  #5  
TECH Veteran
iTrader: (2)
 
wannafbody's Avatar
 
Join Date: Apr 2006
Location: Pittsburgh
Posts: 4,614
Received 801 Likes on 611 Posts

Default

I just saw a dyno video in which in stock form the 706 head beat stock 799 heads by 2 hp. But if you plan on getting them ported, I think the 799/243 head is a better choice since they have larger valves stock and can fit 2.02 valves.
Old 11-30-2017, 06:48 AM
  #6  
KCS
Moderator
iTrader: (20)
 
KCS's Avatar
 
Join Date: Mar 2005
Location: Conroe, TX
Posts: 8,848
Received 307 Likes on 207 Posts

Default

Apparently 706>243>241>317...

Factory Head Dyno Test
Old 11-30-2017, 07:42 AM
  #7  
12 Second Club
iTrader: (4)
 
fastlt1's Avatar
 
Join Date: Sep 2005
Posts: 1,502
Received 18 Likes on 9 Posts

Default

I'd say hp gain was bump in compression not flow
Old 11-30-2017, 08:20 AM
  #8  
KCS
Moderator
iTrader: (20)
 
KCS's Avatar
 
Join Date: Mar 2005
Location: Conroe, TX
Posts: 8,848
Received 307 Likes on 207 Posts

Default

Originally Posted by fastlt1
I'd say hp gain was bump in compression not flow
Agreed. Makes a good case against shopping for heads on flow numbers alone though. The OP has a similar application so it's certainly applicable to his situation.
Old 11-30-2017, 08:32 AM
  #9  
TECH Senior Member
iTrader: (2)
 
HCI2000SS's Avatar
 
Join Date: Aug 2012
Location: Howell & Fenton MI
Posts: 11,145
Likes: 0
Received 15 Likes on 15 Posts
Default

Very interesting. I didn't realize the 706 head was stronger out of the box like that. I assume the same can be said for the 862 casting as well?
Old 11-30-2017, 07:40 PM
  #10  
TECH Veteran
iTrader: (2)
 
wannafbody's Avatar
 
Join Date: Apr 2006
Location: Pittsburgh
Posts: 4,614
Received 801 Likes on 611 Posts

Default

706/862 casting are the same spec.
Old 11-30-2017, 08:07 PM
  #11  
TECH Veteran
iTrader: (40)
 
00pooterSS's Avatar
 
Join Date: Mar 2008
Location: Dallas
Posts: 4,916
Received 523 Likes on 372 Posts

Default

Originally Posted by Loganglenn
I know stock vs stock the 243 is the superior head but my engine came with 706 non crack-tec heads and I'd like to use them if I could. My question is what performs better, a stock 243 or a professionally hand ported 862/706 because for the price of 243s I could have my 706s hand ported and flowed by a well known drag racer/engine builder in my area. I also know that I'm going to want to mill the 243s if I get them because my set up is a 5.3 with 4.8 flat tops and I want to stay around 10.5-1. Are 243s just such a superior head vs the 706 or could the 706 out perform the 243 with alittle work?
Yours ported will do better. Sounds like the dude is charging 400-500 ish? If so I need his info.

Originally Posted by 07NBSChevy
799 and 243 heads were used on all 2007.5-2013 4.8 and 5.3, as well as previous years but on certain ones.

Some Pick-A-Part/Pick-N-Pull Yards have great prices on parts. My local yard sells aluminum non-overhead cam heads for $44.00 ea. with a $10 Core. I can get a set of 243/799 heads any day of the week down there for $120 out the door without cores and $100 with cores. So if you would rather spend your money on 243 heads, check your local junkyard first.

In Stock Form, the Cathedral Port 243/799 are the best flowing GM Production heads for Sub 4.00" Bores in a N/A Setup, at least in my opinion. Above 4.00" Bores, 6.0L+, it can vary depending on your setup.
Name of the yard?
Old 11-30-2017, 08:19 PM
  #12  
12 Second Club
iTrader: (4)
 
fastlt1's Avatar
 
Join Date: Sep 2005
Posts: 1,502
Received 18 Likes on 9 Posts

Default

Originally Posted by HCI2000SS
With some work the 862/706 head will easily out perform the stock 243 head. I run PRC 5.3 (862) heads and for the price I'm very happy with their performance
Why did you go prc 5.3 vs prc 243
Old 11-30-2017, 09:45 PM
  #13  
TECH Senior Member
iTrader: (2)
 
HCI2000SS's Avatar
 
Join Date: Aug 2012
Location: Howell & Fenton MI
Posts: 11,145
Likes: 0
Received 15 Likes on 15 Posts
Default

Originally Posted by fastlt1
Why did you go prc 5.3 vs prc 243
Car came with the 5.3 heads when I bought it
Old 12-01-2017, 01:25 PM
  #14  
On The Tree
 
Joe69z28's Avatar
 
Join Date: Oct 2011
Location: Dirty South
Posts: 102
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by KCS
Apparently 706>243>241>317...

Factory Head Dyno Test
I'm not ready to crown the 706 as king yet but in stock form it's hard to beat. If this was a 3.9 bore we would not even be talking about which is best. But this test does tell Alot about how important chamber size , shape, and valve size play. First the 317 has a huge disadvantage with it's wide chamber underhang and cc volume.The 241 has pretty good chamber width , but IMHO the 2" is a bit big on the smaller bore. If you look at the L83 , GM went to a 1.93" which probably is better match for the bore.
Old 12-04-2017, 08:33 AM
  #15  
9 Second Club
 
uraloser2me2's Avatar
 
Join Date: Dec 2015
Posts: 143
Likes: 0
Received 2 Likes on 2 Posts
Default

I ran 10.78@128 with ported and milled 706 heads on a 5.3 with 12.2 compression on e85. Car weighs 2950 with me in it.
The following users liked this post:
64post (09-06-2019)
Old 12-05-2017, 03:48 PM
  #16  
Teching In
iTrader: (1)
 
ben42391's Avatar
 
Join Date: Dec 2017
Posts: 15
Likes: 0
Received 0 Likes on 0 Posts
Default

if it is a 5.3 use the 243 heads
Old 12-05-2017, 06:10 PM
  #17  
TECH Fanatic
iTrader: (12)
 
Cwarta's Avatar
 
Join Date: May 2012
Location: Elm Creek, NE
Posts: 1,796
Received 57 Likes on 47 Posts

Default

After seeing Richards head shootout, I called my machinest. $400 gets my 862’s intake valve seats machined to accept the stock ls1 valves, and a 7 angle valve job. 11:1 unmilled on my ls1. That’s what’s I’m doing.
Old 09-05-2019, 08:51 AM
  #18  
Teching In
 
Dave12's Avatar
 
Join Date: Jul 2019
Posts: 18
Received 0 Likes on 0 Posts
Default

Originally Posted by uraloser2me2
I ran 10.78@128 with ported and milled 706 heads on a 5.3 with 12.2 compression on e85. Car weighs 2950 with me in it.
Did you run Stock bottom end? Cant decide on milled 243s or 706s. Have stock 5.3
Old 09-05-2019, 09:44 PM
  #19  
TECH Veteran
iTrader: (2)
 
wannafbody's Avatar
 
Join Date: Apr 2006
Location: Pittsburgh
Posts: 4,614
Received 801 Likes on 611 Posts

Default

Flip a coin. Either will work and once ported there is only going to be a couple hp difference between them with a moderately sized cam.
Old 09-12-2019, 08:49 PM
  #20  
TECH Resident
 
Fast355's Avatar
 
Join Date: Oct 2006
Location: Euless, TX
Posts: 900
Received 132 Likes on 113 Posts

Default

Originally Posted by Dave12
Did you run Stock bottom end? Cant decide on milled 243s or 706s. Have stock 5.3
Lloyd Elliot Ported/Milled 862s with 2.00" intake valves on my LQ4 6.0L. Could not be happier.


Quick Reply: 862/706 vs 243



All times are GMT -5. The time now is 04:04 PM.