LQ9 243/799 vs 821/823 heads?
01-23-2013, 03:55 PM
#1
LQ9 243/799 vs 821/823 heads? I sort of asked this question in the wrong forum. I posted a question about my LQ9 build but placed it in Internal Engine forum by accident (noob!).
Anyways, I'm looking for recommendations for new heads, and I'm trying to keep this budget friendly. I just picked up an complete LQ9 along with a GTO T56, which will be going into my '67 Camaro. It will not be a daily driver, but I'd still like to keep it streetable. I'm looking for the best bang for the buck here. Number wise, I'd like to be in the 400-450 rwhp. The more the better.
It looks like the 243/799 heads flow the same as my 317's, but pick up some compression with the smaller chambers, where as the 821/823 heads flow better, but keep the compression about the same. I'm less worried about peak numbers, and would rather have more under the curve. But I'd also like to be able to shut my friends up with their 911's, Audi S5's, etc.
I'll be running a Vic Jr. intake (either cathedral or rectangular port depending on the heads) with an Accufab 4150. I'll look for cam suggestions later.
What's the best stock head for my setup? Thanks guys.
Anyways, I'm looking for recommendations for new heads, and I'm trying to keep this budget friendly. I just picked up an complete LQ9 along with a GTO T56, which will be going into my '67 Camaro. It will not be a daily driver, but I'd still like to keep it streetable. I'm looking for the best bang for the buck here. Number wise, I'd like to be in the 400-450 rwhp. The more the better.
It looks like the 243/799 heads flow the same as my 317's, but pick up some compression with the smaller chambers, where as the 821/823 heads flow better, but keep the compression about the same. I'm less worried about peak numbers, and would rather have more under the curve. But I'd also like to be able to shut my friends up with their 911's, Audi S5's, etc.
I'll be running a Vic Jr. intake (either cathedral or rectangular port depending on the heads) with an Accufab 4150. I'll look for cam suggestions later.
What's the best stock head for my setup? Thanks guys.
01-23-2013, 05:35 PM
#3
I was looking at stock casting, low mile or new takeoff's.
I have priced out some of the ported 5.3 stage 2.5 TSP's, and haven't ruled them out. But for $500-600 I can pick up the stock heads new or like new. Just weighing my options here. Thanks.
I have priced out some of the ported 5.3 stage 2.5 TSP's, and haven't ruled them out. But for $500-600 I can pick up the stock heads new or like new. Just weighing my options here. Thanks.
01-24-2013, 02:08 AM
#4
You can mill the ls3 heads to have more compression. But you also need to factor in the cost of rockers to the ls3 heads. Also, if you're sticking with the true 4 inch bore, it will shroud the larger intake valves of the ls3 heads.
For your goal, I would just keep your 317's and have them milled a little to raise the compression and put a good cam in it to match the intake and compression.
Also, if you don't have the heads off, make sure you have an lq9 and not an lq4. The only difference is the pistons.
For your goal, I would just keep your 317's and have them milled a little to raise the compression and put a good cam in it to match the intake and compression.
Also, if you don't have the heads off, make sure you have an lq9 and not an lq4. The only difference is the pistons.
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01-24-2013, 09:15 AM
#9
Point I'm trying to make is if you put an LQ4 in an Escalade you'd have to reprogram (tune) the computer and all to compensate for the lack of compression. I know. I have one. An 04 to be exact.
Maybe I should rephrase my comment to say "IF THE MOTOR WAS NEVER SWAPPED"
Perhaps I should also add in there "Ensure the Escalade was all-wheel-drive or it will have a 5.3"
Maybe I should rephrase my comment to say "IF THE MOTOR WAS NEVER SWAPPED"
Perhaps I should also add in there "Ensure the Escalade was all-wheel-drive or it will have a 5.3"
01-24-2013, 01:58 PM
#12
Point I'm trying to make is if you put an LQ4 in an Escalade you'd have to reprogram (tune) the computer and all to compensate for the lack of compression. I know. I have one. An 04 to be exact.
Maybe I should rephrase my comment to say "IF THE MOTOR WAS NEVER SWAPPED"
Perhaps I should also add in there "Ensure the Escalade was all-wheel-drive or it will have a 5.3"
Maybe I should rephrase my comment to say "IF THE MOTOR WAS NEVER SWAPPED"
Perhaps I should also add in there "Ensure the Escalade was all-wheel-drive or it will have a 5.3"
Seriously, they put 5.3's in some? I have NEVER heard that.
Does anyone have flow #'s for stock 823's? I have not found any, and would like to know where these things fit in real world #'s. Thanks
01-24-2013, 02:52 PM
#14
01-25-2013, 10:22 PM
#15
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"budget friendly" you said.
okay, if an lq9 with flat tops, (not lq4 with dished)...you can mill the 317s .030 and still be able to put in a big cam and have close to 11:1 cr. you can add some cometics .040 head gaskets to increase cr slightly more and help with detonation. i would recommend a flowtech streetsweeper high torque cam (ssht), 228-232, 611-600, 111+3. will work great with stock heads carb, and have that muscle car lope. you can get some 60 grit sand paper and hand port the heads smoothing all rough edges on intake and exhaust ports, and finish off with 1000 grit. every lil bit helps.
so figure cost of milling heads, cometic gaskets, cam kit (cam, ls7 lifters, springs, pushrods) and sandpaper. cant get more budget friendly than that and make close to 450hp or more....
okay, if an lq9 with flat tops, (not lq4 with dished)...you can mill the 317s .030 and still be able to put in a big cam and have close to 11:1 cr. you can add some cometics .040 head gaskets to increase cr slightly more and help with detonation. i would recommend a flowtech streetsweeper high torque cam (ssht), 228-232, 611-600, 111+3. will work great with stock heads carb, and have that muscle car lope. you can get some 60 grit sand paper and hand port the heads smoothing all rough edges on intake and exhaust ports, and finish off with 1000 grit. every lil bit helps.
so figure cost of milling heads, cometic gaskets, cam kit (cam, ls7 lifters, springs, pushrods) and sandpaper. cant get more budget friendly than that and make close to 450hp or more....
01-26-2013, 05:50 PM
#17
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67 Rally, im doing the same thing as you are. I am in the process of putting an lq4 with ls3 heads into my 69 camaro. Engine is being built right now. With the ls3 heads you have major potential for more power. I bought lq9 flat tops and new rings and sent it out to help with compression. Machine shop told me my block was out of round and i need to bore
to the next size up. So if you find out you have an lq4 and need flat tops and brand new rings PM me.
Anyways i think the ls3 heads are your best bet. I bought them for really cheap and found ana ls3 intake manifold complete with injectors for $200. I picked up cometic .040 head gaskets and texas speed 231/236 cam. With this set up i am told i will make between 450 and 480 rear wheel hp with a t56
to the next size up. So if you find out you have an lq4 and need flat tops and brand new rings PM me.
Anyways i think the ls3 heads are your best bet. I bought them for really cheap and found ana ls3 intake manifold complete with injectors for $200. I picked up cometic .040 head gaskets and texas speed 231/236 cam. With this set up i am told i will make between 450 and 480 rear wheel hp with a t56
01-26-2013, 07:26 PM
#18
67 Rally, im doing the same thing as you are. I am in the process of putting an lq4 with ls3 heads into my 69 camaro. Engine is being built right now. With the ls3 heads you have major potential for more power. I bought lq9 flat tops and new rings and sent it out to help with compression. Machine shop told me my block was out of round and i need to bore
to the next size up. So if you find out you have an lq4 and need flat tops and brand new rings PM me.
Anyways i think the ls3 heads are your best bet. I bought them for really cheap and found ana ls3 intake manifold complete with injectors for $200. I picked up cometic .040 head gaskets and texas speed 231/236 cam. With this set up i am told i will make between 450 and 480 rear wheel hp with a t56
to the next size up. So if you find out you have an lq4 and need flat tops and brand new rings PM me.
Anyways i think the ls3 heads are your best bet. I bought them for really cheap and found ana ls3 intake manifold complete with injectors for $200. I picked up cometic .040 head gaskets and texas speed 231/236 cam. With this set up i am told i will make between 450 and 480 rear wheel hp with a t56
450+ at the rear wheel will be a lot of fun!
07-24-2015, 07:49 AM
#19
That's funny, I just found my old thread while searching for something else.
I did this swap a couple years ago, so this is just as an update, I went with a set of 243 heads, just milled them enough to clean them up and had them Stage 2 ported by Total Engine Ariflow. Had a cam spec'd by Martin @ Tick Performance. The engine dyno'd at 458/410 on a Mustang Dyno by Slowhawk. It was still making power, but they had to shut the dyno down early because of driveline angle vibrations, which have since been resolved:
I did this swap a couple years ago, so this is just as an update, I went with a set of 243 heads, just milled them enough to clean them up and had them Stage 2 ported by Total Engine Ariflow. Had a cam spec'd by Martin @ Tick Performance. The engine dyno'd at 458/410 on a Mustang Dyno by Slowhawk. It was still making power, but they had to shut the dyno down early because of driveline angle vibrations, which have since been resolved:
