Gen3 Gen4 LS Vortec heads info

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Marky Dissod

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Researched GM LS / Vortec heads. Ignored LS1 LQ4 & LQ9 heads, LS9 & LSA heads, LS7 heads.
Two types of holy heads ('holy' is shorter for 'cathedral' than anything else I could think of):

12559862 / 12561706!: . . '99-up 4.8L / 5.3L:
61.15cc combustion, 200cc holy in- port, 70cc oval ex- port, 1.890" in- valve, 1.550" ex- valve
These 'Gen3 holy heads' were eventually phased out, superseded by ...

12564243 / 799: . . '05-up 4.8L & 5.3L ... '01-up LS6 5.7L ... '05-up LS2 6.0L ... '08-'13 LFA / LZ1 6.0L hybrid:
64.45cc combustion, 210cc holy in- port, 75cc D- ex- port, 2.000" in- valve, 1.550" ex- valve
(Could these heads be an upgrade for 6.2L engines with talented custom tuning? Methinks YES.)

Two types of rectangle heads (don't say 'square'):

partnumber / partnumber: . . most 6.0L (10.4:1 or less) & 6.2L (10.5:1)
70cc combustion, 257cc rectangle in- port, 87cc D- ex- port, 2.165˝ in- valve, 1.590˝ ex- valve

partnumber / partnumber: . . LS3 (10.7:1) & L99 (10.4:1) 6.2L
68cc combustion, 257cc rectangle in- port, 87cc D- ex- port, 2.165˝ in- valve, 1.590˝ ex- valve
These heads seem a safe upgrade for the 6.2L Vortec engines.
 

j91z28d1

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upgrade might depend on what you're tyring to do. I doubt a Cathedral port on a 6.2 is going to make more hp up top. you might get more tq down low around town and pulling, maybe run 87 octane but the rec port head will be faster in a race on 6.2 engine?

there's a aftermarket head that might be worth mentioning. it's ls3 based head with ls7 raised intake ports, using ls7 intake and all. ls3 valvetrain. for about the price of dropping a old set of heads off to be cleaned up and refreshed.

again, depending on what you're after, I don't think these would be good low in tq heads since the truck intake would not fit it. only a short runner high rpm intake
 

strutaeng

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What about CFM airflow at a varying, given lift?

That will help you match the heads to the cam (actually, I think it's the other way around, but you get the idea.)

Aftermarket heads have even higher CFM.

More CFM = 'Mo Powah
 
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Marky Dissod

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... doubt a Cathedral port on a 6.2L is going to make more hp up top.
Might get more tq down low around town and pulling, maybe run 87 octane ... but the rec port head will be faster in a race on 6.2L.
Up top, as in, OVER 5000RpM? Rectangle heads, no doubt.
What about CFM airflow at a varying, given lift?
That will help you match the heads to the cam (actually, I think it's the other way around, but you get the idea.)
Aftermarket heads have even higher CFM.
More CFM = 'Mo Powah
Again, PEAK horsepowah thinking - also, forgetting about compression.

Been reading up on Richard Holdener. Does he huff nitrous or Jokergas before taking a pic?
Anyway, between reading his writings, and studying the above OE data carefully ...

Thinking ahead to my replacement engine here, to be ready if/when mine fails.
Closest I get to racing, is reacting to the light turned green before duh-slo-mol-lasses.
I floor it all too often like a jerk, yet it's been weeks since I last saw 5000RpM,
my last WOT 1Up2 shift was months ago, can't remember my last WOT 2Up3 shift.
Actively disinterested in any more peak RpMs than the L59 already has.

IFF I upgrade from my intake manifold (maybe? or not?), as similar to the LS2-TBSS intake as possible.
Forced to settle for another 5.3L, no iron - aluminum block with an LS2-TBSS-type intake manifold.
If 6.0L, aluminum preferred, hope I can still afford an LS2-TBSS-trucky intake?
If 6.2L, selling the rectangle heads should cover the cost of an LS2-TBSS-trucky.
Obviously no V4 mode horseschidt. Don't forget: no VVT either.

I'll be ecstatic to make 370 horses @ 5000RpM on 87 octane.
The REAL goal is to improve MpGs.
Only thing left to do is a short list of 3 or 4 or 5 no-V4 no-VVT cams -
leave that for another thread though.
 

swathdiver

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My 5.3 makes more torque down low than my 6.2s. If only for a few moments and then they rocket off into space! I too considered 243 heads for a 6.2 build but their heads flow so much better, you don't have to port/polish do bowl work until you are well over the 600 horses mark.

My 2013 6.2 Sierra puts down 372 horsepower to the rear wheels through the traps in the quarter mile. She's bone stock still.

Can't wait to see what BlackBear will unleash with a tune and raising the shift points past 5,800. The lifted 2012 keeps pulling like a freight train at 6,200 rpms.
 

j91z28d1

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OK.. long ramble warning.

so Richard Holdener...nothing wrong with the guy. I've seen this guy's articles from the 90s when businesses would throw parts at these magazines writers for the advertising. picture long nights in a dyno trying to make a combo work in a way to put their parts in a good light. and then show that combo.

so you got a new high flow head, well you don't bolt the heads on a stock engine to show a performance gain. you put the stock heads in a big cam, big displacement, high compression engine. make a pull, swap on high flow heads. make pull, numbers go up.. parts sell. it's not dishonest in anyway, but it is a tad misleading. you have a part that's marketing low end tq, you bolt it on a reverse combo.

so he's got all these saved engine dyno charts from different combos tested over the years. he picks a subject for tonight's live and then shows the charts that back up what tonights story line is. all very interesting and entertaining. I've watched a few myself.


but the part that's a bit dishonest in my opinion...we all thing we are learning something special but none of that pertains to your real world driving experience. he's got an engine on a dyno stand, free flowing well tuned for Scavenging exhaust, no accessory load, aftermarket stand alone ecm that's targeting best air/fuel ratio for power and timing. 100 octane fuel to remove the variable of knocking and wot from whatever power band he wants to show you.. either 3k to 7k or 2500 to 6k. he is open and tells you all of this but if you don't understand how that pertains to your vehicle and driving style. you are left with almost completely useless information. say your combo, and I think you're wanting what 90% of us want out of our daily driver.

your stock exhaust is unturned for scavenging, you have tons of accessories on the front, your stock ecm is targeting 14.7:1 air/fuel. (to lean for power) anytime it's not in power enrichment mode(PE usually to rich for best power to be safe on the street) piss water 87 octane. and you're never or hardly ever at wot max load at say 2k rpm, and definitely not running out to 6k often.

so as you can guess, you can take the engine off his dyno stand that seems like it would be perfect for your driving style, bolt it in the truck and never hit the perimeters used during his testing. it's just not really relevant.

in my opinion, the transmission tune, and if it's 4 speed, 6 speed or new 10 speed, along with axle gearing has more effect on what you're trying to get from your truck than even 40hp or 40tq moved into a different rpm band on your truck. what you're looking for is throttle pedal mapping. the feel of it being eager to run at 1/4 throttle. in that way something like a pedal commander and a good tranny tune would go further towards your goals than anything you're going to be able to build using different heads.


I drive lots of ford's, fleet junk. but one thing I believe they do much better than gm is the throttle mapping. they always feel like they want to go. they tune their trucks that way where even a gm car that has sport mode will need to be turned to sport to feel that way. this I believe what sells on a test drive and really what we all want from our mods if we aren't going to drag strip or lineing up next to our friends for a little grudge march.

as for what you're looking for, I believe gm built basically that combo. the LFA they stuck in the hybrids I would hope is the more efficient combo for daily driving, cause gotta have a little faith in gm engineers haha. it's a aluminum 6.0, so lighter and smaller bore works better in theory to control detonation, allowing for your lower octane 87 than a 6.2 bore. (this is said to be why gm loved the 305ci in the 90s smog era, small bore better mixture inside the cyl during compression stroke) the Cathedral Port heads for higher speed airflow in the intake port at lower rpm(better filling). they also raised the compression, but mainly because of the cam they went with. late intake closing, it bleeds off a low of compression at low rpm, say idle to 1500 for a cleaner charge from there up. you wouldn't want this cam, it would feel super lazy, but not 100% sure you could run 87 in it with a normal cam on that higher compression. they cover for the lack of off idle tq by using electric motors, but even then the throttle map in the hybrid is more loft down the road on a magic carpet (cvt tranny keeps it at that stead efficient rpm while mph increase too) than race from light to light but something like that with a normal cam and compression, might get you the best hard parts for 87 octane and 2000 rpm tq at lean part throttle a/f, but it will all be in the tuning of making the throttle mapping feel right and the tranny keep you in that band just right.


so yeah.. in the end, it's best to keep the combo you have and do the longevity mods to make it last 300k than anything else. that and vvt is your friend, try and keep that active even if you build something new. they don't really fail and it's free tq.
 
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Marky Dissod

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I'd love a more precise definition of 'down low'? Not to mention, how much more torque?!?!?!
Suffice to say, bet it's where most of our engines spend most of their time.
is your VVT limited? Or did you disable VVT entirely?

Hard redline ceiling no higher than 6000RpM, like any 5.3L.
Don't want / need the 6.0L to peak power past 5700RpM.
With a 6.2L, an even lower peak power RpM would be PREFERABLE.
Trying to make a slightly-higher compression, yet still truckier truck engine.
Need to find accurate LOW-lift flow numbers ...
 
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Marky Dissod

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My mistake, posting in the GMT900 subforum. See my sig.
Any mod who thinks this'd be better off in the GMT800 forum, feel free to move it.

But j91z28d1 has the idea. I'm accustomed to the mid '90s LT1.
Quick snappy throttle response from 10:1 compression w/ 87 octane.
Party's over by 5400RpM, which protects both engine and 4L60E.
I've also L98 memories, not quite as quick throttle response,
but even more low-end due to the TPI manifold.

Yes, I think 2 out of 3 of us would prefer more of the powerband sooner.
 

swathdiver

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I'd love a more precise definition of 'down low'? Not to mention, how much more torque?!?!?!
Suffice to say, bet it's where most of our engines spend most of their time.
is your VVT limited? Or did you disable VVT entirely?

Hard redline ceiling no higher than 6000RpM, like any 5.3L.
Don't want / need the 6.0L to peak power past 5700RpM.
With a 6.2L, an even lower peak power RpM would be PREFERABLE.
Trying to make a slightly-higher compression, yet still truckier truck engine.
Need to find accurate LOW-lift flow numbers ...
From idle to about 1300 rpms at WOT before my 6.2 exceeds my 5.3 torque and horsepower numbers. At 1,296 rpms they are both making 66 horsepower and 268 foot pounds of torque. I recorded this data from each truck with the Tech-2 and then extrapolated (filled in) the data between points in an excel spreadsheet.

6.2s love to rev with those 823 heads. You'd get more torque down low with 243/799s and up to your 5700 peak probably.

My 6.2 example is bone stock, my 5.3 has been tuned but still shifts at 5800.

It just occurred to me, when those 6.2 numbers were taken, she was still running on KO2s which sapped the engine of over 50 horsepower due to all the extra rotational weight of the heavier tires. Hmm!


My mistake, posting in the GMT900 subforum. See my sig.
Any mod who thinks this'd be better off in the GMT800 forum, feel free to move it.

But j91z28d1 has the idea. I'm accustomed to the mid '90s LT1.
Quick snappy throttle response from 10:1 compression w/ 87 octane.
Party's over by 5400RpM, which protects both engine and 4L60E.
I've also L98 memories, not quite as quick throttle response,
but even more low-end due to the TPI manifold.

Yes, I think 2 out of 3 of us would prefer more of the powerband sooner.

Me too, I miss the off the line torque of our older cars, when they were rated at like 235 horses and a hundred or more foot pounds of torque more and they were all out of breath by 5400 rpms. BUT, these LSs exceed them in power and efficiency in every way.
 

strutaeng

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How about a LS 383? Bore the 5.3 bore to LS1 bore diameter (I think?), 4" stroke crank, new pistons. No clearancing the block on the iron block version is what I've heard/read. I always hear the torque is pretty good on that combination. A stock 5.7 bore on an iron block is also an option.

I may decide to try to build one of those down the road, just for fun.

You'd have the low-end torque but if you wanted, but still have all the ponies under the skinny pedal, ready to be released.

I've wondered why the LS 5.7 was never installed on trucks in an iron block version, especially the heavier ones, but it's probably because they (GM) had the 6.0 under their sleeve.

Do you have a budget?
 

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