View Poll Results: Which one would you prefer if the Tahoe was yours?
Multiple Choice Poll. Voters: 12. You may not vote on this poll
862s vs 243s on an LQ4
#1
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862s vs 243s on an LQ4
The engine in question is the LQ4 in my Tahoe, unknown bottom end mileage but completely stock as far as I can tell besides a 224/228 113lsa .600/.600 cam. Plan to run it on 93 as a DD and maybe one day put a small amount of boost to it and try to squeak out 500whp.
Contestant one: 862 cut for 2" valves and have SS valves installed all around, with factory LQ4 gaskets it has right at about a 10.5:1 CR. These heads have been on the engine for about a year/20kmiles
Contestant two: 243s from an LS6 ported by Wilkes Performance with a 5 angle valve job and milled .010 which nets 10.4:1 CR with lq4 gaskets.
Both heads will run the same dual valve springs, CHE trunion rocker arms, ARP head bolts, and hardened pushrods.
Question 1: What kind of power difference would you expect to see?
Question 2: Which would you prefer with boost?
Question 3: Would you replace the unknown lifters while in there? If so with what?
Contestant one: 862 cut for 2" valves and have SS valves installed all around, with factory LQ4 gaskets it has right at about a 10.5:1 CR. These heads have been on the engine for about a year/20kmiles
Contestant two: 243s from an LS6 ported by Wilkes Performance with a 5 angle valve job and milled .010 which nets 10.4:1 CR with lq4 gaskets.
Both heads will run the same dual valve springs, CHE trunion rocker arms, ARP head bolts, and hardened pushrods.
Question 1: What kind of power difference would you expect to see?
Question 2: Which would you prefer with boost?
Question 3: Would you replace the unknown lifters while in there? If so with what?
#2
TECH Veteran
1. I think you should at least see 20+ from the 243s. I say that because looking at LS1 vs LS6 there was not a major difference between the two but they were rated at 350 and 450 respectively.
2. Can't really speak on boost personally but I don't think it would particularly matter.
3. Meh I guess so. If they are working I probably would not but if you want to then get something nice.
My vote is 243s
2. Can't really speak on boost personally but I don't think it would particularly matter.
3. Meh I guess so. If they are working I probably would not but if you want to then get something nice.
My vote is 243s
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#3
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1. I think you should at least see 20+ from the 243s. I say that because looking at LS1 vs LS6 there was not a major difference between the two but they were rated at 350 and 450 respectively.
2. Can't really speak on boost personally but I don't think it would particularly matter.
3. Meh I guess so. If they are working I probably would not but if you want to then get something nice.
My vote is 243s
2. Can't really speak on boost personally but I don't think it would particularly matter.
3. Meh I guess so. If they are working I probably would not but if you want to then get something nice.
My vote is 243s
One other big factor is that I have a 212/218 high lift cam on the shelf along with some single beehive springs, a CHE rocker set, and several size pushrods. If I pull the 862s they would make a good combo package to sell to someone and recoup some cost of the 243s.
#4
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Was under the impression you were swapping out no matter what, like pulling the heads and doing some more work to 862s or doing 243s
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dantheman1540 (07-23-2021)
#5
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Nope, the 862s already have the bigger valves and good valvetrain, I do have a lifter or 2 that make noise on cold starts occasionally that is annoying but no other signs of imminent failure and I cut filters every oil change at 5k. If I did want to pull the heads and swap lifters IDK what lifters are worth a damn anymore or in stock.
The 862s aren't a bad candidate for CNC porting just don't want to wait 6 months again for port work. Been waiting on these 243s since February. All the bad experiences I've had in the last 3 years with machine shops, in general, have made me want to just buy stuff from a catalog from now on.
The 862s aren't a bad candidate for CNC porting just don't want to wait 6 months again for port work. Been waiting on these 243s since February. All the bad experiences I've had in the last 3 years with machine shops, in general, have made me want to just buy stuff from a catalog from now on.
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dantheman1540 (07-23-2021)
#7
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Dude what? 5 months just for heads? I would've got my heads back within a week if it wasn't for my girlfriend's dad being retarded
If you are already getting the 243s I would just slap them on and rock them but that is just me.
Save them for another project maybe?
If you are already getting the 243s I would just slap them on and rock them but that is just me.
Save them for another project maybe?
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dantheman1540 (07-23-2021)
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#8
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#9
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I have absolutely no desire to put a cam bigger than this one in it.
It was a sorta odd deal, they were shipped from New Mexico to Alabama for the port work and when I called the shop they said 2-3week turnaround. Apparently, when you can't show up at the shop every week and bother them they take even longer. This is my 5th sorta bad experience with different shops.
#10
100% Redneck
After watching hours and hours of Holdeners dyno videos... boost is going to work well with either set of heads. RPM (boost or n/a) is flow related, you need more flow the higher RPM. The camshaft dictates RPM. So again small cam will not see high RPM whether in boost or n/a. Richard always says "all cams are boost cams" same as the heads. It's all where you want the power to peak and camshaft choice always dictates RPM range.
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