Gen3 Gen4 LS Vortec heads info

[Marky Dissod]

My budget is my biggest problem. Living in a NYC apt is problem number 2.
My idea was - IS - to see if I can mix and match GM parts better than GM.
Hence, holy port heads a 6.2L.
Not crazy enough to try 862 / 706 heads on any 6.2L, but they'd be great on any 6.0L.
The 6.2L can get 243 / 799 holy port heads instead of the 862 / 706.

 

[Marky Dissod]

@swathdiver,
the other thing I noticed about TYF is an aversion to more assertive axle(s) gearing.
You said
"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."
The engine made the same power. The ground never got it, the tall heavy tires dissipated it.

Had a Caprice wagon.
Top speed with 2.56: 130MpH. Took so long, I got worried about the engine.
Literally long-dragged a cigarette and exhaled it all between 129MpH & 130MpH.
Top speed with 3.42: 140MpH. Wish I'd timed it -
did not take nearly as long to 140MpH, as 2.56 did to 130MpH. I got scared @ 140MpH and let up.

Very rough math suggests that that axle upgrade was worth 60 horses, and more than 60 ftlb.

But if I make an engine with enough low-end, 3.73 will be just barely enough axle gear.

 

[swathdiver]

is your VVT limited? Or did you disable VVT entirely?

No VVT on the 2009 5.3 LC9 engine. Stock VVT setup all around on the 2013 6.2 L9H.

 

[j91z28d1]

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.

I read an article forever ago in a car and driver mag, I believe it was. back when having magazines sent to your house was a thing.. very enjoyable thing too. anyways, the lt1 was meant to be gm's world beater. they thru everything at that engine. reverse cooling for high compression, the opti spark was said to have such fine resolution, it could change timing 1 deg for each individual cyl and remember that offset. the timing strategy was meant to be able to run max timing in each cyl, not just a over all timing. because the old sbc loved timing. the more you could get in it, the faster it went. Sadly it was the down fall too and the end of the small block. they basically started with a clean sheet for the ls. it works, but I still feel had they just went coil packs, and had the lt4 heads be the standard head across the board it might have survived. it definitely had the grunt and a whole different sound. maybe a aluminum block too haha


man, you're taking me back.. the tpi days, still under rated to me. probably should have been a truck engine instead of a sports car engine, I've always wanted to put a tpi intake on my 96 tahoe 5.7 but you just can't tune the 96&97 black box ecm. I had a z28 tpi 305 with a old slp cam, no real tuning, it was a 5 speed car and ran 13.8 at the track at the same time the car world was falling all over the 93 lt1's running 14.0s. we had so much fun running around town racing everyone one of them we could find. no one would ever believe it *** a little 305. it just hooked hard, rowed gears at 4500rpm and held them off. never let them know it was done at 110 and they just got rolling around then haha.

still got a 90 formula sitting in the garage just begging for some time. right now it's got a 406 with a decent cam, some old school trick flow heads and scored a super ram going on 30 years ago now. was said to he ported by Lingenfelter long before accel bought them out. it's still a 5 speed car, only cause I haven't driven it enough to break it. t56 shoved in a corner for when it goes. now that things got the tq, big tb and cable throttle so nothing slows it down. wack the throttle in the first 2 gears and it feels alive, like it's got a soul my ls3 c6 just doesn't have. sadly the ls3 car would probably beat it even when I'm done and get it tuned right. but what can ya do haha.

 

[Geotrash]

I read an article forever ago in a car and driver mag, I believe it was. back when having magazines sent to your house was a thing.. very enjoyable thing too. anyways, the lt1 was meant to be gm's world beater. they thru everything at that engine. reverse cooling for high compression, the opti spark was said to have such fine resolution, it could change timing 1 deg for each individual cyl and remember that offset. the timing strategy was meant to be able to run max timing in each cyl, not just a over all timing. because the old sbc loved timing. the more you could get in it, the faster it went. Sadly it was the down fall too and the end of the small block. they basically started with a clean sheet for the ls. it works, but I still feel had they just went coil packs, and had the lt4 heads be the standard head across the board it might have survived. it definitely had the grunt and a whole different sound. maybe a aluminum block too haha


man, you're taking me back.. the tpi days, still under rated to me. probably should have been a truck engine instead of a sports car engine, I've always wanted to put a tpi intake on my 96 tahoe 5.7 but you just can't tune the 96&97 black box ecm. I had a z28 tpi 305 with a old slp cam, no real tuning, it was a 5 speed car and ran 13.8 at the track at the same time the car world was falling all over the 93 lt1's running 14.0s. we had so much fun running around town racing everyone one of them we could find. no one would ever believe it *** a little 305. it just hooked hard, rowed gears at 4500rpm and held them off. never let them know it was done at 110 and they just got rolling around then haha.

still got a 90 formula sitting in the garage just begging for some time. right now it's got a 406 with a decent cam, some old school trick flow heads and scored a super ram going on 30 years ago now. was said to he ported by Lingenfelter long before accel bought them out. it's still a 5 speed car, only cause I haven't driven it enough to break it. t56 shoved in a corner for when it goes. now that things got the tq, big tb and cable throttle so nothing slows it down. wack the throttle in the first 2 gears and it feels alive, like it's got a soul my ls3 c6 just doesn't have. sadly the ls3 car would probably beat it even when I'm done and get it tuned right. but what can ya do haha.

I think they took the ol' SBC as far as they could for performance and efficiency. It wouldn't have survived the kind of power we're seeing right out of the factory with the LS and now LT engines. 6 bolt main caps vs 4, the main caps bolt through the skirted block, stronger crank, bigger cam diameter means more valve lift with less shock to the valvetrain, and this is all before we even talk about the heads.

What I like most is that GM blew away the conventional wisdom of the time which said that a 2-valve pushrod design could never make the kind of power that a 4-valve DOHC design could. And yet, here we are. Simpler design than DOHC means easier to work on and better durability. Timing chain stretch is killing DOHC engines every day with half the miles of an LS on them.

 

[j91z28d1]

it's kinda all relative, and in theory cause I only know really what a read.

there was a hybrid block for a while, that was said to be the best of both worlds, it was a Gen 1 sbc bottom end using ls heads. it was pricey back we people didn't buy expensive parts like today and iron. back then everyone wanted the aluminum ls1 for swaps but it was said in a perfect world that was the setup.


depending on who you follow, some like the cross bolt mains of the ls, others say it's a m8 bolt, it ain't doing anything but leak oil where a 4 bolt main with splayed style make the bolts pull from the main webbing of the block.


there is something to the valvetrain of a ls, as much as I hate that you gotta pull the heads to replace them, most engine builders I've read about say you can get a away with a hydraulic lifter in a ls way longer than a sbc. you wanna make any rpm with the old school stuff just go solid they say.

the Gen 2 lt4 head is pretty comparable flow numbers with the old ls1 stuff. I think it would have heald it's own. bottom end of both are plenty strong for bolt on hot rodding around. if you wanna make big power like say a turbo e85 build, both really should be built off a aftermarket block and rotating assembly. and then at that point you pop head gaskets in the ls every other pass.

the fastest stick shift car right now is a gen 1 in a 4th Gen camaro. it's all race car so it hardly matters, but does show that 5 head bolts are better than 4 at some point. that point probably isn't na thou.

i currently have 2 of each, and if I gotta pick one to work on, I'd much rather work on a gen1.

 

[Marky Dissod]

Gonna try to pull this back toward the original topic, if y'all don't mind ...

Long story, medium, when the day comes to replace my engine,
It already has 12559862 or 12561706 heads, duhr.

Scenario 1 (how GM should've done every 6.0L, damnt):
If my replacement / upgrade engine is a 6.0L, it'll get my old 5.3L heads.
With luck it's a Gen4 aluminum 6.0L, likely equal to or better than an LQ9.
My guess:
A Gen4 6.0L with 862 / 706 heads'll make less peak power at a lower RpM vs OE.
If the rest of the powerband moves back to the left, I'll be happy.
Is there a better GM OE cam than the LS2 cam for this concept engine?

Scenario 2 (more of a risk):
If my replacement is a 6.2L, it'll get 12564243 / 799 heads.
12559862 / 12561706 would exceed 11.1 to 1 compression.
I'M FULLY AWARE THIS ABSOLUTELY REQUIRES CUSTOM PCM TUNING.
My guess:
A 6.2L with 243 / 799 heads'll also make less peak power at a lower RpM vs OE.
If the rest of the powerband moves back to the left, I'll be even happier.

Don't forget I'll be using a 12200411, so NO VVT either.
(I think VVT helps rectangle heads at very low RpM.)

How crazy does the above seem, really?

 

[j91z28d1]

do you currently have a 5.3?

do they still make that 5.3 stroker kit? that might be the most cost effective way to get where you want? you can pick the compression you want when you're changing pistons.

 

[Marky Dissod]

L59, yes.
RANT
GM first pist me the L off by making a 4.3L L99 V8 out of a 5.7L LT1 V8, instead of using the 4.3L L35 V6.
Then GM made 4.8L & 5.3L Vortec engines out of 5.7L LS1s, and I developed a chronic tick.
For decades, GM upgraded the 350 V8 for 'vettes & F-cars.
(Every great GM 5.0L is outnumbered by 1000 5.0Ls that could've been better by .7 more litres.)
Then GM makes a pretty damn good 5.7L, and de-bores it for trucks?
And then de-strokes the 5.3L they already de-bored, instead of improving the 4.3L V6 like they did the small-block just a few years ago?
I could've saved GM BILLIONS by simply lowering the LS1's redline for use in trucks.
I dream of a world, where every 4.8L & 5.3L, is a 5.7L that just needs a better cam & valvetrain. Then I wake up.
ANYWAY
I've no intention of re-stroking anything to restore what GM de-bored.
Bore makes more power than stroke anyway.
I'll live with yanking a Gen4 crank to swap a 58x crank reluctor for a 24x.

Obviously scenario 1 is cheaper ...

 

[Marky Dissod]

Just finished this video from Richard Holdener.

Under 4000RpM, where most of our engines spend most of their time,
guess which heads performed best on a cam'd 6.0L?

706-862-895 heads outperformed 243-799 heads. In other words:
Gen3 holy heads outperformed Gen4 holy heads ...
243-799 heads outperformed 716-364-823-821 heads. Or:
Gen4 holy heads outperformed Gen4 rectangle heads ...
UNDER 4000RpM, which I care about far more than 4000-5500RpM.