Suggestions for 450-500HP build
Apr 30, 2026 | 09:00 AM
#11
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I don’t have an lq9 I have an lq4
You have a 6.0 block. The same block was used for both 6.0 engines. One of the main differences between those engines was the pistons. If you put flat-top pistons in it, you now have a LQ9 bottom end.
I don’t need a converter because my truck has an NV4500.
Apr 30, 2026 | 09:03 AM
#12
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Apr 30, 2026 | 09:23 AM
#14
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https://www.google.com/search?q=lq4+vs+lq9 FWIW
Note also, that the LS2 is a flat-top 6.0 w 243/799 heads. So, what you're building is REALLY a LS2 long block, optimized for a truck..
Note also, that the LS2 is a flat-top 6.0 w 243/799 heads. So, what you're building is REALLY a LS2 long block, optimized for a truck.
.
Apr 30, 2026 | 02:33 PM
#15
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From: Ohio, Georgia, Nevada, Texas
OP,
We’re going to start with some basics to put the combo into perspective.
An LQ4 from the factory is around 300-330 hp and 360-370 ft. lbs. They use 317 71cc heads and a 6.7cc dished piston, which puts them around 9.4:1 compression with a .051" head gasket.
If you’ve got the Wiseco WIS-PTS523AS pistons, those are a -4cc dome. That bumps you up to roughly 10.7:1 with the stock 71cc heads. The 1.335" compression height also puts the piston about .004" out of the hole, which helps power but makes the combo more sensitive to cam, fuel, and a proper custom tune, especially under load.
Because of that, we’d pass on the 799 or 243 heads. Dropping to a 65cc chamber would push you up into the 11.5 to 11.7:1 range, which is pretty aggressive for a tow rig.
As a general guideline for trucks that tow, around 10:1 is fine on 87. By 10.5:1, you’re into 91 to 93 under load unless you’re planning to pull timing. At 10.7:1, this is definitely a premium fuel combo when towing.
The Comp 54-412-11 you’re looking at is 212/218 on a 114+2 with 265/271 advertised. That puts intake closing around 64.5* ABDC. With your compression, that works out to roughly 8.5:1 dynamic, assuming about 1,000 ft elevation. That’s what helps make the 10.7:1 static number manageable. It’s not lowering compression, it just gives you more margin on 93 under load when paired with a proper custom tune.
That’s also why this cam makes sense. It keeps drivability and torque, but has enough seat timing to help control cylinder pressure.
We like the Comp 54-412-11 here knowing what we know now. We would still consider the SUM-8719R1 as it offers very similar performance and drivability, just with slightly shorter seat timing, at a better value. Pairing that with our budget-friendly SUM-174002 LS6 style beehive springs makes for a solid, cost effective cam and spring combo. We would take the SUM-8728R1 out of the equation at this point, as it would push dynamic compression too high for your application.
One thing we would steer you away from is trying to lug it in 4th or especially 5th up hills under load. That’s where heat and cylinder pressure spike, and where detonation shows up first. Even with the cam helping, you’re better off letting it come up in RPM and downshifting when needed to keep it in a safer range.
Also worth noting, altitude and terrain matter here. There’s a big difference between Midwest hills and long mountain pulls out west. If you could provide more info on what kind of hills you’re dealing with and your typical elevation, that would help fine-tune the recommendation.
We’re going to start with some basics to put the combo into perspective.
An LQ4 from the factory is around 300-330 hp and 360-370 ft. lbs. They use 317 71cc heads and a 6.7cc dished piston, which puts them around 9.4:1 compression with a .051" head gasket.
If you’ve got the Wiseco WIS-PTS523AS pistons, those are a -4cc dome. That bumps you up to roughly 10.7:1 with the stock 71cc heads. The 1.335" compression height also puts the piston about .004" out of the hole, which helps power but makes the combo more sensitive to cam, fuel, and a proper custom tune, especially under load.
Because of that, we’d pass on the 799 or 243 heads. Dropping to a 65cc chamber would push you up into the 11.5 to 11.7:1 range, which is pretty aggressive for a tow rig.
As a general guideline for trucks that tow, around 10:1 is fine on 87. By 10.5:1, you’re into 91 to 93 under load unless you’re planning to pull timing. At 10.7:1, this is definitely a premium fuel combo when towing.
The Comp 54-412-11 you’re looking at is 212/218 on a 114+2 with 265/271 advertised. That puts intake closing around 64.5* ABDC. With your compression, that works out to roughly 8.5:1 dynamic, assuming about 1,000 ft elevation. That’s what helps make the 10.7:1 static number manageable. It’s not lowering compression, it just gives you more margin on 93 under load when paired with a proper custom tune.
That’s also why this cam makes sense. It keeps drivability and torque, but has enough seat timing to help control cylinder pressure.
We like the Comp 54-412-11 here knowing what we know now. We would still consider the SUM-8719R1 as it offers very similar performance and drivability, just with slightly shorter seat timing, at a better value. Pairing that with our budget-friendly SUM-174002 LS6 style beehive springs makes for a solid, cost effective cam and spring combo. We would take the SUM-8728R1 out of the equation at this point, as it would push dynamic compression too high for your application.
One thing we would steer you away from is trying to lug it in 4th or especially 5th up hills under load. That’s where heat and cylinder pressure spike, and where detonation shows up first. Even with the cam helping, you’re better off letting it come up in RPM and downshifting when needed to keep it in a safer range.
Also worth noting, altitude and terrain matter here. There’s a big difference between Midwest hills and long mountain pulls out west. If you could provide more info on what kind of hills you’re dealing with and your typical elevation, that would help fine-tune the recommendation.
Last edited by Summitracing; May 1, 2026 at 10:36 AM.
Apr 30, 2026 | 11:06 PM
#16
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Joined: Aug 2023
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OP,
We’re going to start with some basics to put the combo into perspective.
An LQ4 from the factory is around 300-330 hp and 360-370 ft. lbs. They use 317 71cc heads and a 6.7cc dished piston, which puts them around 9.4:1 compression with a .051" head gasket.
If you’ve got the Wiseco WIS-PTS523AS pistons, those are a 4.030" (.030" over) -4cc dome. That bumps you up to roughly 10.8 to 10.9:1 with the stock 71cc heads. The 1.335" compression height also puts the piston about .004" out of the hole, which helps power but makes the combo more sensitive to cam, fuel, and a proper custom tune, especially under load.
Because of that, we’d pass on the 799 or 243 heads. Dropping to a 65cc chamber would push you up into the 11.5 to 11.7:1 range, which is pretty aggressive for a tow rig.
As a general guideline for trucks that tow, around 10:1 is fine on 87. By 10.5:1, you’re into 91 to 93 under load unless you’re planning to pull timing. At 10.8:1, this is definitely a premium fuel combo when towing.
The Comp 54-412-11 you’re looking at is 212/218 on a 114+2 with 265/271 advertised. That puts intake closing around 64.5* ABDC. With your compression, that works out to roughly 8.6:1 dynamic, assuming about 1,000 ft elevation. That’s what helps make the 10.8:1 static number manageable. It’s not lowering compression, it just gives you more margin on 93 under load when paired with a proper custom tune.
That’s also why this cam makes sense. It keeps drivability and torque, but has enough seat timing to help control cylinder pressure.
We like the Comp 54-412-11 here knowing what we know now. We would still consider the SUM-8719R1 as it offers very similar performance and drivability, just with slightly shorter seat timing, at a better value. Pairing that with our budget-friendly SUM-174002 LS6 style beehive springs makes for a solid, cost effective cam and spring combo. We would take the SUM-8728R1 out of the equation at this point, as it would push dynamic compression too high for your application.
One thing we would steer you away from is trying to lug it in 4th or especially 5th up hills under load. That’s where heat and cylinder pressure spike, and where detonation shows up first. Even with the cam helping, you’re better off letting it come up in RPM and downshifting when needed to keep it in a safer range.
Also worth noting, altitude and terrain matter here. There’s a big difference between Midwest hills and long mountain pulls out west. If you could provide more info on what kind of hills you’re dealing with and your typical elevation, that would help fine-tune the recommendation.
We’re going to start with some basics to put the combo into perspective.
An LQ4 from the factory is around 300-330 hp and 360-370 ft. lbs. They use 317 71cc heads and a 6.7cc dished piston, which puts them around 9.4:1 compression with a .051" head gasket.
If you’ve got the Wiseco WIS-PTS523AS pistons, those are a 4.030" (.030" over) -4cc dome. That bumps you up to roughly 10.8 to 10.9:1 with the stock 71cc heads. The 1.335" compression height also puts the piston about .004" out of the hole, which helps power but makes the combo more sensitive to cam, fuel, and a proper custom tune, especially under load.
Because of that, we’d pass on the 799 or 243 heads. Dropping to a 65cc chamber would push you up into the 11.5 to 11.7:1 range, which is pretty aggressive for a tow rig.
As a general guideline for trucks that tow, around 10:1 is fine on 87. By 10.5:1, you’re into 91 to 93 under load unless you’re planning to pull timing. At 10.8:1, this is definitely a premium fuel combo when towing.
The Comp 54-412-11 you’re looking at is 212/218 on a 114+2 with 265/271 advertised. That puts intake closing around 64.5* ABDC. With your compression, that works out to roughly 8.6:1 dynamic, assuming about 1,000 ft elevation. That’s what helps make the 10.8:1 static number manageable. It’s not lowering compression, it just gives you more margin on 93 under load when paired with a proper custom tune.
That’s also why this cam makes sense. It keeps drivability and torque, but has enough seat timing to help control cylinder pressure.
We like the Comp 54-412-11 here knowing what we know now. We would still consider the SUM-8719R1 as it offers very similar performance and drivability, just with slightly shorter seat timing, at a better value. Pairing that with our budget-friendly SUM-174002 LS6 style beehive springs makes for a solid, cost effective cam and spring combo. We would take the SUM-8728R1 out of the equation at this point, as it would push dynamic compression too high for your application.
One thing we would steer you away from is trying to lug it in 4th or especially 5th up hills under load. That’s where heat and cylinder pressure spike, and where detonation shows up first. Even with the cam helping, you’re better off letting it come up in RPM and downshifting when needed to keep it in a safer range.
Also worth noting, altitude and terrain matter here. There’s a big difference between Midwest hills and long mountain pulls out west. If you could provide more info on what kind of hills you’re dealing with and your typical elevation, that would help fine-tune the recommendation.
May 1, 2026 | 10:33 AM
#17
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Joined: Oct 2020
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From: DFW
May 1, 2026 | 10:38 AM
#18
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Joined: Jan 2008
Posts: 465
Likes: 250
From: Ohio, Georgia, Nevada, Texas
OP,
Good catch on the pistons. We went back and double checked and realized we were looking at the PTS523A3 .030" over version instead of the PTS523AS standard bore piston. We’ve also updated post 15 to reflect that.
With the correct piston, still being a -4cc dome and about .004" out of the hole, you’re right around 10.7:1 static compression with the 71cc heads and a .051" gasket.
Regarding fuel, with that compression, we’d recommend 93 any time the truck is under load or towing. For normal unloaded driving at your 1800 to 2000 ft elevation, you may be able to get away with less, but that’s going to depend heavily on the tune. A proper custom tune is what really keeps this combo safe and consistent.
At your elevation, dynamic compression works out to roughly 8.5:1 with the Comp cam and about 8.6:1 with our 8719R1. Since this is already a 93-under-load combo, that small difference doesn’t really change anything from a fuel standpoint.
On the cam question, our Summit cam isn’t necessarily better, just a more budget-friendly option in the same range. The slight bump in lift and slightly earlier intake closing on the 8719R1 should help the low-end and midrange a bit, which fits how you’re using the truck. Pairing that with the 174002 LS6-style beehive springs makes for a solid, cost-effective cam and spring combo. The Comp 54-412-11 is still a good option, so you’re not going wrong either way.
As for how you’re using it, pulling in that 2000 to 2500 rpm range on lighter loads is perfectly fine. That’s not really what we’re concerned about. It’s the heavier load, low rpm, high gear situations where heat and cylinder pressure build quickly. That’s where detonation will show up first, so don’t be afraid to let it come up in rpm and downshift when needed.
On the intake side, we’d stick with a truck-style intake for what you’re doing. The LS6 intake can pick up some power up top, but it tends to give up some low and midrange torque, which isn’t ideal for a tow rig. If you were looking to upgrade, a later truck intake like a TBSS or NNBS style would be a better fit while keeping the torque where you need it.
With your elevation and the fact that those longer mountain pulls only happen a few times a year, this combo should be manageable with 93 under load and a proper custom tune.
Good catch on the pistons. We went back and double checked and realized we were looking at the PTS523A3 .030" over version instead of the PTS523AS standard bore piston. We’ve also updated post 15 to reflect that.
With the correct piston, still being a -4cc dome and about .004" out of the hole, you’re right around 10.7:1 static compression with the 71cc heads and a .051" gasket.
Regarding fuel, with that compression, we’d recommend 93 any time the truck is under load or towing. For normal unloaded driving at your 1800 to 2000 ft elevation, you may be able to get away with less, but that’s going to depend heavily on the tune. A proper custom tune is what really keeps this combo safe and consistent.
At your elevation, dynamic compression works out to roughly 8.5:1 with the Comp cam and about 8.6:1 with our 8719R1. Since this is already a 93-under-load combo, that small difference doesn’t really change anything from a fuel standpoint.
On the cam question, our Summit cam isn’t necessarily better, just a more budget-friendly option in the same range. The slight bump in lift and slightly earlier intake closing on the 8719R1 should help the low-end and midrange a bit, which fits how you’re using the truck. Pairing that with the 174002 LS6-style beehive springs makes for a solid, cost-effective cam and spring combo. The Comp 54-412-11 is still a good option, so you’re not going wrong either way.
As for how you’re using it, pulling in that 2000 to 2500 rpm range on lighter loads is perfectly fine. That’s not really what we’re concerned about. It’s the heavier load, low rpm, high gear situations where heat and cylinder pressure build quickly. That’s where detonation will show up first, so don’t be afraid to let it come up in rpm and downshift when needed.
On the intake side, we’d stick with a truck-style intake for what you’re doing. The LS6 intake can pick up some power up top, but it tends to give up some low and midrange torque, which isn’t ideal for a tow rig. If you were looking to upgrade, a later truck intake like a TBSS or NNBS style would be a better fit while keeping the torque where you need it.
With your elevation and the fact that those longer mountain pulls only happen a few times a year, this combo should be manageable with 93 under load and a proper custom tune.
Last edited by Summitracing; May 1, 2026 at 11:46 AM.
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