Head advice for LQ4
10-08-2008, 11:28 AM
#1
Teching In
Thread Starter
iTrader: (2)
Join Date: Jan 2008
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
Head advice for LQ4 I've done some searching, haven't been able to find what I wanted. I'm doing a mild LQ4 6.0 build for my Jeep. It'll see street time, high speed dunes, and rockcrawling, so I need strong power throughout the RPM range.
Bottom end will be stock with the exception of upgraded rod bolts.
Top end will have 1.7 roller rockers, upgraded pushrods, new head gasket, stock LS1 intake setup(for budgetary reasons), new head gaskets, ARP head bolts, upgraded valve springs, and I've settled on a cam in the TR224 range. I need help deciding on head choice. And a custom tune of course.
I’m looking right now at picking up a set of 853 heads milled .006” with PRC dual valve springs and a TSP 224R cam. I know the stock 317 heads flow really well but I’d like to up the compression for more power. The idea of milling them heavily isn’t very appealing to me. I can get the 853 heads with the upgraded valvesprings for about what the springs alone cost. 853s and 317s have the same valve sizes so that’s not a concern. I understand that the 317s flow a bit better than the 853s, but is the difference big enough to negate the power I’d be gaining from the increased compression?
I also have a fresh set of 862s sitting in the garage but I figure the smaller valves and decreased flow would really be hurting me there. Or would that be a good choice even with the smaller valves?
Any advice on those 3 head choices would be much appreciated. I may go to something like ported LS6 heads in the future, but for now I need to keep it cheap with one of those 3 options. Which will give me the best results for all around performance, not necessarily racing?
Bottom end will be stock with the exception of upgraded rod bolts.
Top end will have 1.7 roller rockers, upgraded pushrods, new head gasket, stock LS1 intake setup(for budgetary reasons), new head gaskets, ARP head bolts, upgraded valve springs, and I've settled on a cam in the TR224 range. I need help deciding on head choice. And a custom tune of course.
I’m looking right now at picking up a set of 853 heads milled .006” with PRC dual valve springs and a TSP 224R cam. I know the stock 317 heads flow really well but I’d like to up the compression for more power. The idea of milling them heavily isn’t very appealing to me. I can get the 853 heads with the upgraded valvesprings for about what the springs alone cost. 853s and 317s have the same valve sizes so that’s not a concern. I understand that the 317s flow a bit better than the 853s, but is the difference big enough to negate the power I’d be gaining from the increased compression?
I also have a fresh set of 862s sitting in the garage but I figure the smaller valves and decreased flow would really be hurting me there. Or would that be a good choice even with the smaller valves?
Any advice on those 3 head choices would be much appreciated. I may go to something like ported LS6 heads in the future, but for now I need to keep it cheap with one of those 3 options. Which will give me the best results for all around performance, not necessarily racing?
10-08-2008, 02:37 PM
#2
ive got an lq4 with 317 heads and a 224/230 cam. im going with some ls6 heads to up my compression and still have it flow well. i just need to wait for all the heads to go on sale during christmas. ive been seriously looking at these: http://www.texas-speed.com/shop/item...d=134&catid=40
10-08-2008, 04:05 PM
#3
Teching In
Thread Starter
iTrader: (2)
Join Date: Jan 2008
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
That's nice but it really doesn't answer my question about which of the 3 that I listed would work the best. A set of $1000+ heads is NOT in the cards for me right now, I want to know what will give me the best results on a budget.
10-08-2008, 05:02 PM
#4
What is your budget? You can find 243 heads for $500 off of LS6 and LS2 equipped cars. The 243 heads are the same as the 317, the 243 had 64cc chambers, where as the 317 had 72cc chambers. That mean going from 317 to 243 gets you from 9.5:1 to near 10.2:1.
Without flow numbers for those ported heads, you might be losing performance if they were not ported properly or evenly.
Without flow numbers for those ported heads, you might be losing performance if they were not ported properly or evenly.
10-08-2008, 05:27 PM
#5
Teching In
Thread Starter
iTrader: (2)
Join Date: Jan 2008
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
I know the 243s are good but that's not the route I'm going right now. The only 3 options at this point are those that I already listed, 2 of which I have already, and the 3rd already have upgraded valve springs. When it comes time to upgrade I'll get some good ported ones but I'm not ready to spend $500 on a marginal upgrade that I'll want to upgrade again later.
I just want to know what will perform best on an LQ4: stock 317s, stock 862s, or very lightly milled 853s.
I just want to know what will perform best on an LQ4: stock 317s, stock 862s, or very lightly milled 853s.
Trending Topics
10-14-2008, 10:04 PM
#11
Honestly man, I dont know about the valves sizes. Judging by the work that is done to the car already... I would assume they are not the smaller 862's. I know they have "yellow" springs and CNC'd ported by Ligenfelter. Also a very nice hand port job after I got to see after installing my FAST 92/92. They are great looking heads, but I have no flow number's or CC numbers.
Car made 409 RWTQ and 373RWHP before 92/92 install.
Car made 409 RWTQ and 373RWHP before 92/92 install.
10-15-2008, 08:04 AM
#14
TECH Enthusiast
iTrader: (28)
Join Date: Apr 2008
Location: Grayson, KY 41143
Posts: 593
Likes: 0
Received 0 Likes
on
0 Posts
I am gonna run a P&P set of 862's on my LQ4..Should put the compression right up where you want it in the 11-1 range with a .51 gasket "don't quote me on that number" I am thinking very seriously about installing larger intake valves in mine you can go up to a 2.04 without problems on the stock seats if you have the stock 317s steal the intakes out of them and get them installed in your 862's the sell the castings to pay for the machine work. That is my plan, and honestly without any issue of shrouding with the smaller intake valve on the bigger bore cylinder you may not even notice it in the power band of the engine I have heard that smaller intake valves make for more bottom end torque I am sure that would be of use to you in the rocks and trails..Hope this helps you out a bit.
