Cam and head selection
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Teching In
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Cam and head selection I'm building a 6.0L LQ4 to go in a GN.
I am trying to pick heads and a cam - plus I have read the stickys!
My engine builder has a set of aluminium 862's that he rebuilt and added LS6 springs to for me...issue is I gave him the green light on them before I had honestly made up my mind on them. I believe these heads came on the 5.3's or 6.0 engines.
I am really kinda stuck with the 862's as he has done the work...so question is do I use them ?
I am aiming for a car with street manners - hoping for 450-500 HP. I am looking at the L92's with a GMPP HotCam. After some reading it looks like GMHTP has done this as have some other magazines and it proved great numbers. Should have done more research before I pulled the trigger!
If I stick with the 862's and HotCam how much HP/TQ will I be sacrificing? The 862's have much smaller valves and lower CFM of course....
I am trying to pick heads and a cam - plus I have read the stickys!
My engine builder has a set of aluminium 862's that he rebuilt and added LS6 springs to for me...issue is I gave him the green light on them before I had honestly made up my mind on them. I believe these heads came on the 5.3's or 6.0 engines.
I am really kinda stuck with the 862's as he has done the work...so question is do I use them ?
I am aiming for a car with street manners - hoping for 450-500 HP. I am looking at the L92's with a GMPP HotCam. After some reading it looks like GMHTP has done this as have some other magazines and it proved great numbers. Should have done more research before I pulled the trigger!
If I stick with the 862's and HotCam how much HP/TQ will I be sacrificing? The 862's have much smaller valves and lower CFM of course....
TECH Veteran
Joined: Sep 2014
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From: Mississippi
LQ4 means you need some compression If you going all motor. I would skip right past the 862 heads and go right to the L92/LS3 head for your power goals. Maybe if your budget I would get the heads milled to add a tad bit more compression. You mention running a gmpp cam. I would skip over a gmpp cam for either a tooley cam/tick cam.
With 225 intake duration that combo made 470rwhp.
I'm not go say the 862 heads can't make the power but you'll need a bigger cam which means less great street manners.....
With 225 intake duration that combo made 470rwhp.
I'm not go say the 862 heads can't make the power but you'll need a bigger cam which means less great street manners.....
Those hp goals flywheel or rear wheel?
If flywheel that is an 11second car that could need a rollbar if you make it work right.
If rwhp then it is 10s.
The rectangle port heads on a 4.00 bore are favored only when blindly looking at peak numbers and ignoring average output.
The 862s ported by some random local guy could be anything between amazing and paperweights and literally anything in between.
If flywheel that is an 11second car that could need a rollbar if you make it work right.
If rwhp then it is 10s.
The rectangle port heads on a 4.00 bore are favored only when blindly looking at peak numbers and ignoring average output.
The 862s ported by some random local guy could be anything between amazing and paperweights and literally anything in between.
Aren't the 862 chambers small...??? Like 61 cc or so ??
That would kick the 9.4compression up to around 10.85 with GM gaskets
I'd bet KCS could verify if the 5.3 seats can be machined out to 2"/1.55" valves. If not I'd still just port them and toss in one of Martin's (Tick) street heat stg.1 V2 cams and that thing will make great average torque....with the right exhaust and tune I'd bet 425 rear wheel or so.
IMO the LS3 heads belong on a larger bore/engine in order to develop faster port speed during low rpm driving.
That would kick the 9.4compression up to around 10.85 with GM gaskets
I'd bet KCS could verify if the 5.3 seats can be machined out to 2"/1.55" valves. If not I'd still just port them and toss in one of Martin's (Tick) street heat stg.1 V2 cams and that thing will make great average torque....with the right exhaust and tune I'd bet 425 rear wheel or so.
IMO the LS3 heads belong on a larger bore/engine in order to develop faster port speed during low rpm driving.
Thread Starter
Teching In
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Thanks for the reply guys.
I am running the 200 trans but its built. Lots of billet internals etc. I have a 2800 lock up converter and am still running the 3.42 rear end gear. My HP goals are rear wheel but I'm not a dreamer either. I'll be using an LS1 intake for now...but will likely move up to a FAST. Don't want to limit myself by picking poor heads / cam at this point...but the car must have decent street manners and isn't a daily driver.
The motor is not together yet and I'm at the point of cam selection. Im interested in the Tick cam...having a look now.
After doing some more searching - it appears the L92 heads only really matter +5,000 rpm. I'll be more interested in low end torque at this point.
I am running the 200 trans but its built. Lots of billet internals etc. I have a 2800 lock up converter and am still running the 3.42 rear end gear. My HP goals are rear wheel but I'm not a dreamer either. I'll be using an LS1 intake for now...but will likely move up to a FAST. Don't want to limit myself by picking poor heads / cam at this point...but the car must have decent street manners and isn't a daily driver.
The motor is not together yet and I'm at the point of cam selection. Im interested in the Tick cam...having a look now.
After doing some more searching - it appears the L92 heads only really matter +5,000 rpm. I'll be more interested in low end torque at this point.
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Verdad Gallardo Thread Starter
Teching In
Joined: Mar 2011
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How you mean a contradiction?
Not possible? What do you suggest...
Heres an old article - 6.0L LQ4 with a HotCam and LT headers - stock heads - 483 flywheel HP. Not bad.
http://www.hotrod.com/cars/project-v...4-short-block/
How much HP loss through drivetrain....a bit but still very respectable numbers at the wheels.
Not possible? What do you suggest...
Heres an old article - 6.0L LQ4 with a HotCam and LT headers - stock heads - 483 flywheel HP. Not bad.
http://www.hotrod.com/cars/project-v...4-short-block/
How much HP loss through drivetrain....a bit but still very respectable numbers at the wheels.
Last edited by HOTSIX; Jan 26, 2015 at 07:54 PM.
Aren't the 862 chambers small...??? Like 61 cc or so ??
That would kick the 9.4compression up to around 10.85 with GM gaskets
I'd bet KCS could verify if the 5.3 seats can be machined out to 2"/1.55" valves. If not I'd still just port them and toss in one of Martin's (Tick) street heat stg.1 V2 cams and that thing will make great average torque....with the right exhaust and tune I'd bet 425 rear wheel or so.
IMO the LS3 heads belong on a larger bore/engine in order to develop faster port speed during low rpm driving.
That would kick the 9.4compression up to around 10.85 with GM gaskets
I'd bet KCS could verify if the 5.3 seats can be machined out to 2"/1.55" valves. If not I'd still just port them and toss in one of Martin's (Tick) street heat stg.1 V2 cams and that thing will make great average torque....with the right exhaust and tune I'd bet 425 rear wheel or so.
IMO the LS3 heads belong on a larger bore/engine in order to develop faster port speed during low rpm driving.
Even with the stock 1.89" intake valves, I'd bet they'd still make more low and mid range power than a set of L92 heads. You're talking almost an entire point of compression between the two heads.
I'm building a 6.0L LQ4 to go in a GN.
I am trying to pick heads and a cam - plus I have read the stickys!
My engine builder has a set of aluminium 862's that he rebuilt and added LS6 springs to for me...issue is I gave him the green light on them before I had honestly made up my mind on them. I believe these heads came on the 5.3's or 6.0 engines.
I am really kinda stuck with the 862's as he has done the work...so question is do I use them ?
I am aiming for a car with street manners - hoping for 450-500 HP. I am looking at the L92's with a GMPP HotCam. After some reading it looks like GMHTP has done this as have some other magazines and it proved great numbers. Should have done more research before I pulled the trigger!
If I stick with the 862's and HotCam how much HP/TQ will I be sacrificing? The 862's have much smaller valves and lower CFM of course....
I am trying to pick heads and a cam - plus I have read the stickys!
My engine builder has a set of aluminium 862's that he rebuilt and added LS6 springs to for me...issue is I gave him the green light on them before I had honestly made up my mind on them. I believe these heads came on the 5.3's or 6.0 engines.
I am really kinda stuck with the 862's as he has done the work...so question is do I use them ?
I am aiming for a car with street manners - hoping for 450-500 HP. I am looking at the L92's with a GMPP HotCam. After some reading it looks like GMHTP has done this as have some other magazines and it proved great numbers. Should have done more research before I pulled the trigger!
If I stick with the 862's and HotCam how much HP/TQ will I be sacrificing? The 862's have much smaller valves and lower CFM of course....
Thanks for the reply guys.
I am running the 200 trans but its built. Lots of billet internals etc. I have a 2800 lock up converter and am still running the 3.42 rear end gear. My HP goals are rear wheel but I'm not a dreamer either. I'll be using an LS1 intake for now...but will likely move up to a FAST. Don't want to limit myself by picking poor heads / cam at this point...but the car must have decent street manners and isn't a daily driver.
The motor is not together yet and I'm at the point of cam selection. Im interested in the Tick cam...having a look now.
After doing some more searching - it appears the L92 heads only really matter +5,000 rpm. I'll be more interested in low end torque at this point.
I am running the 200 trans but its built. Lots of billet internals etc. I have a 2800 lock up converter and am still running the 3.42 rear end gear. My HP goals are rear wheel but I'm not a dreamer either. I'll be using an LS1 intake for now...but will likely move up to a FAST. Don't want to limit myself by picking poor heads / cam at this point...but the car must have decent street manners and isn't a daily driver.
The motor is not together yet and I'm at the point of cam selection. Im interested in the Tick cam...having a look now.
After doing some more searching - it appears the L92 heads only really matter +5,000 rpm. I'll be more interested in low end torque at this point.
Just make sure you choose the camshaft carefully and don't overcam it.
TECH Veteran
Joined: Sep 2014
Posts: 4,893
Likes: 706
From: Mississippi
I personally think you can be successful with either head..... only with one exception... the rectangle port head camshaft is VERY VERY CRITICAL. This is why you really see the LS3 combos being a hit or a miss.
Thread Starter
Teching In
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What are your thoughts on working over the 862 heads a li?
As KCS indicated - going 2.02 / 1.60 valves....what benefits will I see here and is it worth the cash?
Keeping in mind that this is a street car that will prob never see the track and is no DD.
As KCS indicated - going 2.02 / 1.60 valves....what benefits will I see here and is it worth the cash?
Keeping in mind that this is a street car that will prob never see the track and is no DD.
I did something pretty similar in my Trans Am with a set of 241 heads. I used 2.02"/1.60" valves, opened the throats to 90% of the valve diameter, blended it all in up to about the valve guide, and it made over 410whp before the clutch would let to at about 5000RPM.
