Marky Dissod

It's 2024. I feel safe assuming y'all know way more about GM OE Gen3 & Gen 4 heads, intake manifolds, and cams than I do.
So much so, that I'll jump well ahead ...

When it's time to replace my '02 Tahoe Z71's L59, it's either a 6.0L, or a 6.2L. Every time I floor this engine, I die a lil inside.
(I know the 6.2L crank will need a 24x reluctor installed to work with a 12200411.)

Scenario 6.0L (almost seems too easy):
It'll get my 706-862 (895?) heads basically as is (maybe clean 'em up a wee lil bit?)
If I can't find an LS2 truck intake manifold, it gets mine then.
Which GM OE cam should go in this 6.0L for best throttle response / drivability / MpG UNDER 4500RpM?

Scenario 6.2L (clearly the more complicated option):
Either get my 706-862 heads with the same barely detectable improvements as before, or
for a wee lil bit less static comp, 243-799 heads.
Again, either LS2 truck intake, or mine.
Again, which GM OE cam in this 6.2L for best throttle response / drivability / MpG UNDER 4500RpM?
PCM tuning will be even more of a requirement for this engine, than for the 6.0L scenario.

Important note: NEITHER ENGINE WILL EVER SEE 5900RpM.
As is, despite a leadfoot, can't remember my last WOT 1Up2 shift, never WOT 2Up3 shifted.

Given no desire for a WOT UpShift over 5400RpM, do either or both of these scenarios make sense?

shakenfake

Welcome Marky

6.0: I would skip the 706/862s and find some 243 or 799s. The LS2 truck mani is nice but not needed. GM OE cam I would choose an LS6 probably.

6.2: I would get the 243/799s. I am not sure on the 6.2 what OE cam would be best. PCM tuning is 100% going to be a requirement for both.

Yes they make perfect sense.

Marky Dissod

'sup shakenfake.
Two reasons why I'd like to stick with the 706 / 862s, at least with a 6.0L:
Already have a pair, so they're FREE.
I'm much more interested in MpGs and quicker throttle response at daily-driving RpMs;
65cc chamber (243 / 799) vs 61cc camber (706 / 862) ... should I really be averse to a pinch more compression?

Although Dorman's LS2-truck intake manifold might eventually pay for itself in MpGs,
reusing my Vortec manifold would be a lot cheaper and much easier.

I actually hope that this Cheap@$$ 6.0L is NOT an original idea.

shakenfake

I’ve been down the 862 road and I would not do it again. The flow is just not there. We had another user on this site who had similar experiences. Compression is good, flow is better; Why not both? Fortunately those cylinder heads are cheap (not free admittedly…) and you could always mill them. You are going to need to machine shop your 862s anyway (recommended)

Intake manifold is certainly not worth it if looking for MPGs.


When I built my 6.0 I also did the cheap way. Looking back there are things I would have changed to make it better that would not have costed me a lot extra. at the time it would have pushed the build back but it would have been a better outcome.


Edit: Rethinking “Compression is good flow is better” that is obviously not always true. I think there are benefits from running both heads. In my experience I feel the engine falls off early. Maybe it is not early for you.
You may not be unhappy at all with the 862s but I do believe sometimes GM has the right idea with their product. Big engine needs good flow, the 317 execution was not so good.
Just my cents

Marky Dissod

What went wrong?
How early is early, then?

I totally get that the 706 / 862 heads will end the fun sooner than the 243 / 799.
When the day comes to replace the L59, if I have more money than I expected, I'll use 243 / 799 heads.

It's becoming more obvious that the 6.2L scenario will cost more in terms of time energy and money.
If there be devils in the details, I'm clearly not aware of enough of those details.
But the point is to think all these details out in advance - right?

smokinlmm

The juice isn’t worth the squeeze for a 6.2. They aren’t all they are made out to be either. The 6.0 is plenty capable of making efficient power just needs to be setup for it from drivetrain to gearing it all has to be in concert.

1redta

A 6.0 with 243 and 799 heads is fun!

silentbravo

iTrader: (1)

6.2L are like these unicorn engines that people put a high price tag on. 6.0L can be had much more reasonable and should do what you need just fine. The stock LQ4 or LQ9 cam is probably fine, it's already optimized by GM for truck use and under the curve torque. The "bigger" the cam you go, the farther out the power band goes and typically you are giving up low end power for high end.

Another thing to consider, will be your transmission. I'm not sure what condition it is in, but plan for a rebuild if it's coming up due as the 6.0L power and lead foot will help it die that much faster.

Marky Dissod

Starting to realize that, even if I had the money to make (effectively) a Gen3 6.2L, a 6.0L would be a far better bang for the buck. Nevermind that my 6.2L would be the weirdest salad of OE parts, to say the least.
Although I still want to finish that thought experiment, it may not ever be more than an idea.
4L60E with NP246(E?) xfer case, 3.73 axles now, hoping for 4.10 axles someday.Isn't a 6.0L w/ 243 / 799 heads an LS2 (depending on the cam)?
Although I basically agree, I have a SLIGHTLY different definition of fun.
How 'bout a 6.0L with 706 / 862 heads? I have slightly different goals than most.
This swap engine, like my L59, will NEVER HIT 5900RpM. MpG & quicker throttle response are more important to me than peak power.4L60E was rebuilt in '22 just before I bought it. If it needs replacing, lots of trans places in NYC no longer rebuild 4L60E, they just buy a pre-rebuilt one, install it, and send yours back as a core.
Anyway, I am definitely preparing for this eventuality.

And yea:
What GM OE cam would you select for a higher compression 6.0L with 706 / 862 heads that would never hit 5900RpM?

Marky Dissod

A GM OE LS2's compression ratio is 10.9:1 'cause it wears 243 / 799 heads.
What would an LS2's compression ratio be, wearing 706 / 862 heads?

If you were stuck with a WOT UpShift no higher than 5900RpM, what GM OE camshaft would you choose?
Would you choose the LS2 cam anyway? If not, which GM OE cam instead?

Basically, Scenario 6.0L is me trying to build a better LS2 ...