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Outside-the-Box Power Options

zebra

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115
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cold & windy
From what all I've been able to find over the last year, I think I realize how few our options are... but why not just ask anyway?

My wife's got an 09 5speed non-Adventure. Still stock-ish with the exception of a resonator delete, Gibson cat-back, Hurst shifter, and 34" Coopers (285/75-17). She uses it as a daily driver with some occasional mountain trail riding every few weeks. After driving my built 5.3 Sierra for 14yrs followed by my current 6.7 Cummins, we both agree the LLR 5cyl is anemic at best for this truck's size (especially at our elevation: 3400'-6500') & have spent the last year looking into the best ways to get some more oomph out of it.

Our original plan when we bought it was to swap in a lightly-cammed LH8 5.3 since I've been tinkering with vehicles for 20+yrs & did my own v6 -> 5.3 swap in the GMC... but the more I dug into it highlighted it'd still be too much headache & money to be worth jumping through all the hoops required to make it work with the AR5 (and no other transmissions work). I've read through all the threads here & on hummerforum - particularly regarding the two trucks that were successful in doing it.

Being plenty familiar with forced induction, I then looked into blowers & turbo kits: all of which seem to have went the way of the Dodo on account of being serial engine killers (though it's unclear whether people were greedy with the boost or the engines really are that finicky considering the truck's weight).

Not to be deterred - I even pondered the LL8 straight 6 (same engine + one cylinder)... and saw a total of one less-than-impressive, half-finished swap that didn't fully convince me of its validity due to the 4200's length & custom parts/electronics it'd still require.

All that said: are we seriously stuck with the generic "intake, exhaust, tune" blandness to get more from these awesome trucks? It looks like the OTTP header might still be available; the rest seem to be out of production. And before anyone starts with the "just trade it for an Alpha" rhetoric... automatic transmission simply won't cut it - even for her.

Thanks for any additional insight y'all have.
 

Gpcalero

Well-Known Member
Messages
234
Location
SW Florida
Well... start with the rest of the bolt ons first. If that doesn't satisfy your want, then you could always manual tranny swap an alpha. There's a guy on here that has done it before.

Other than that, it's probably not worth pumping up a 5-cylinder because of the cost. I doubt anybody makes cams for them. If you rebuilt the engine with higher compression, that would help but would it be worth it? hmmm meh.
 

amrg

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I agree with manual swapping an Alpha

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cbetts

NERD!!!
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3,182
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Rancho Palos Verdes, CA
I went down this rabbit hole myself for a while. I loved having a manual transmission. I was able to find a few donor trucks back east that had the V8/Manual/4x4 magic combo that could carry over. They are few and far in between. Since I had a 2006 model, I would need to keep the donor in 2006-2007 or would need to perform the rewire like 06H3 did with his swap. I also looked into forced induction but feared that the Atlas engine would not be able to handle it for long.
 

650Hawk

Well-Known Member
Messages
480
Location
SoCal
Stuffing a V8 into an I5 H3 is, as you have found, difficult and expensive. Hummer didn't just add the 5.3 into the existing H3 platform; there was significantly more to it than that. They actually redesigned the firewall to narrow the distance between it and the dash to get a couple more inches of space in order to fit the 5.3. The front frame rails were also modified, a new oil pan was developed, a cast iron front diff to handle the additional torque, and a new steering system was added. New engine mounts were created (of course), and unique front suspension springs and shocks were introduced to hold the weight...

IMO, you would be better off simply keeping an eye out for an Alpha.
 
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zebra

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115
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cold & windy
i appreciate that suggestion, but swapping an auto for a manual is worse than swapping an i5 for a v8 and still leaves the same frankenstein adapter problems... while also having to change the center console, gauge cluster, and brake/clutch pedals; add hydraulics; reprogram the BCM; and probably screwing up cruise control & hill assist.

Has anyone looked into the older GM 4.2 V6, as found in the mid '90s S15 Jimmys/S10 Blazers? It should be short enough, and no wider that the 5.3 its based on.
for v6s, i believe you're thinking of the 4.3 that was based on the SBC 350 (a GenI engine) as opposed to the 5.3 (GenIII). both will easily fit in the engine bay.
either way, the 09s are based on GenIV architecture, which is much more than a plug & play job with non-LS engines to get everything working like stock.

Stuffing a V8 into an I5 H3 is, as you have found, difficult and expensive. Hummer didn't just add the 5.3 into the existing H3 platform; there was significantly more to it than that. They actually redesigned the firewall to narrow the distance between it and the dash to get a couple more inches of space in order to fit the 5.3. The front frame rails were also modified, a new oil pan was developed, a cast iron front diff to handle the additional torque, and a new steering system was added. New engine mounts were created (of course), and unique front suspension springs and shocks were introduced to hold the weight...

IMO, you would be better off simply keeping an eye out for an Alpha.
yeah, i know the LH8 & LH9 were specific to the mid-size truck platform. as for H3 structural modifications, i believe the 08+ or 09+ models all had them (too expensive to make two different bodies for a low-volume vehicle), so using factory components to set a v8 under the hood is the easy part... it's physically mating it to the trans & tricking a ECM into not looking for a TCM that complicates matters & drives the budget beyond what's worth the hassle.

for reference, the 5.3 swap in my 99 GMC was as simple as pulling the 4.3 out, swapping the engine mounts, using some braided hose to adapt the fuel lines to the rail, changing the engine harness/computer, and using a v8 clutch. everything bolted right up, worked like stock, and almost looked like a factory job. not the case with H3s.

the problem with using one of the real truck transmissions is the fact that the shifters all mount in the wrong place to feasibly work with, they have 32spline outputs, and they use the SBC/BBC/LS bellhousing bolt pattern.
 
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zebra

Well-Known Member
Messages
115
Location
cold & windy
and we just ain't tuned it yet on account of wanting to solidify our plans first (otherwise, it's a waste of money/time).
otherwise, a header's all that'd be left... if it was really even worth it.

that said, i know y'all tout PCM of NC around here... do they do live scan tunes or just the generic canned guess? and what kinds of real gains have y'all seen from them?
i ask because Blackbear's been tuning my stuff for over 10yrs and doing a great job with his datalogging tunes... he just ain't done that many H3s (especially stick-shift Atlas models).
 

amrg

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The headers isnt much an improvement in an H3, unless you regularly shift above 4500 rpms.
Most people here dont, me included. Torque down low is what we would need, not hp high up. Keep in minf headers will get rid of one of the cats, causing emission and sound issues

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Jeff V.

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123
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Kansas City, MO
This might be of interest to you.

https://www.topspeed.com/cars/car-n...-engine-gm-s-42-liter-atlas-i-6-ar174949.html
http://www.trucktrend.com/truck-reviews/163-0208-2002-chevrolet-trailblazer-twin-turbo

GM built a prototype twin turbo 4.2L for the Trailblazer SS before they decided to go with the V8. You might be able to carry some of that knowledge over to the 3.7L.

As an alternative, downsize to an EcoTec turbo 4 from the Solstice GXP. They used the same AR5 transmission we have, and seem to have a pretty good aftermarket.
 

Happy Hummer

Well-Known Member
Messages
1,301
Location
Wisconsin
The new baby diesel in a box swap would work very nicely. They already provide adapters for manual trans and it has all its own stand alone system.

In case you are unfamiliar with the 2.5r just look it up. New motor mounts, different manual trans and bob's your uncle.
 
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06 H3

a.k.a. "The Jackal"
Messages
9,350
Location
Meridian, ID
I’d just swap a 5.3,6.0,6.2 into it and keep the manual trans. It has been done before. Easiest and most reliable route IMO, your truck is already setup for the manual.
 

cbetts

NERD!!!
Messages
3,182
Location
Rancho Palos Verdes, CA
I’d just swap a 5.3,6.0,6.2 into it and keep the manual trans. It has been done before. Easiest and most reliable route IMO, your truck is already setup for the manual.

Not quite that easy. The donor needs to have a matching computer with the right code for a manual transmission. As far as bolting the components under the hood, no problem. Getting the engine to cooperate with the the manual trans, problem.

I found shops in LA that could do the work. I just couldn't handle the $20K price tag to get it done.
 

amrg

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On a 06 Id think a GEN 3 V8 will work nicely with the computers. Tuning is easy, wiring can be done.
I saw on fb the other day a SBC on an H3. Looks nice and simple, and cheap

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Gpcalero

Well-Known Member
Messages
234
Location
SW Florida
The headers isnt much an improvement in an H3, unless you regularly shift above 4500 rpms.
Most people here dont, me included. Torque down low is what we would need, not hp high up. Keep in mind headers will get rid of one of the cats, causing emission and sound issues

Sent from my SM-G960F using Tapatalk

Shorty headers help retain torque down low where we need it in these trucks.

You already know what I'm going to go with :wink:
 

zebra

Well-Known Member
Messages
115
Location
cold & windy
i think a lot of folks are missing our overarching goal: we're looking to get more power/efficiency from the truck without breaking the bank.
if it wouldn't cost $5000-6000 to v8 swap a $14000 truck, that's the route we'd go.
if building a 3-5psi turbo setup wouldn't cost the same $4000 that an engine-popping 9psi kit would run, that might be worth it to not deal with the electrical woes of a v8 swap.

either way, this transmission ain't made to take a whole lot more input torque anyway, so either of those options would have to be driven responsibly & capped around 300-350lbft regardless of their power potential - especially considering it looks like the stock 08+ H3 clutch is already the strongest one made (compared to the early H3 & all colorado/canyon models with no aftermarket beef-ups).

that said, i was more interested in whether there were other mods worth trying (e.g., a better-flowing intake manifold, bigger throttle body [if that's actually even a restriction], etc.) because i don't see much mentioned on here other than deleting the intake tube resonator & changing the muffler. looks like nobody makes a new cam set (or even just an intake-side).

The headers isnt much an improvement in an H3, unless you regularly shift above 4500 rpms.
Most people here dont, me included. Torque down low is what we would need, not hp high up. Keep in minf headers will get rid of one of the cats, causing emission and sound issues

Sent from my SM-G960F using Tapatalk
which is why i questioned the real value of a header over the stock manifold. thanks for the sanity check.
losing one or both of the cats ain't a bother... we're emissions exempt for being stationed out of state, so none of our other vehicles have cats either.
but while we'll wind it up to 4 or 5000 up an on-ramp or driving up big hills with a 55-60 speed limit, we typically don't turn it that fast.

This might be of interest to you.

https://www.topspeed.com/cars/car-n...-engine-gm-s-42-liter-atlas-i-6-ar174949.html
http://www.trucktrend.com/truck-reviews/163-0208-2002-chevrolet-trailblazer-twin-turbo

GM built a prototype twin turbo 4.2L for the Trailblazer SS before they decided to go with the V8. You might be able to carry some of that knowledge over to the 3.7L.

As an alternative, downsize to an EcoTec turbo 4 from the Solstice GXP. They used the same AR5 transmission we have, and seem to have a pretty good aftermarket.
hmm... yeah, i'd forgotten about that little science project. too bad it'd also take an engine rebuild to make it a viable option... which defeats the point of cost-effective mods.
as for the GXP swap: we need a broader low torque curve (especially when not in boost), which is exactly the opposite of what you get when taking an underpowered 5000lb truck & reducing displacement (at least when comparing two similarly-built gas engines).

The new baby diesel in a box swap would work very nicely. They already provide adapters for manual trans and it has all its own stand alone system.

In case you are unfamiliar with the 2.5r just look it up. New motor mounts, different manual trans and bob's your uncle.
i'd have to look up what trans it uses & whether it works in these trucks... nothing i've seen other people try over the last year's reading has.

Buick V6 turbo from an 80s Grand National. Compact, gobs of torque, injected, works with a manual trans.
while that old 3.8 was quite an impressive engine, see my "old engine to new electronics compatibility" comment from last night & cbetts' comment below

Not quite that easy. The donor needs to have a matching computer with the right code for a manual transmission. As far as bolting the components under the hood, no problem. Getting the engine to cooperate with the the manual trans, problem.

I found shops in LA that could do the work. I just couldn't handle the $20K price tag to get it done.
checks. we've already played the "put $40k worth of mods into a <$20k car" game... while it's been my childhood dream weekend cruiser/track car build (making it worth it), we don't drive it every day & ain't in a spot to have two dogs in that fight.

and after talking to Mark at PCMofNC this morning, he confirmed a lot of what we've been chatting about here.
 

zebra

Well-Known Member
Messages
115
Location
cold & windy
On a 06 Id think a GEN 3 V8 will work nicely with the computers. Tuning is easy, wiring can be done.
I saw on fb the other day a SBC on an H3. Looks nice and simple, and cheap

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should on an 06... probably 07s, too.
ours is an 09 - which matters because starting in 08, the engine control module in automatics required communication with a separate transmission control module for everything to work the right way.

Shorty headers help retain torque down low where we need it in these trucks.

You already know what I'm going to go with :wink:
GenIII+ LS exhaust manifolds already flow about the same as a shorty.
i wasn't sure about the one on an Atlas engine.
 
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Jeff V.

Well-Known Member
Messages
123
Location
Kansas City, MO
Not quite that easy. The donor needs to have a matching computer with the right code for a manual transmission. As far as bolting the components under the hood, no problem. Getting the engine to cooperate with the the manual trans, problem.

I found shops in LA that could do the work. I just couldn't handle the $20K price tag to get it done.

I'm not 100% sure on this, but I think you can use the software from a manual trans 06-07 CTS-V. It uses the same E67 ECM as the H3, and used the class 2 data bus for most of its body communications. You might need a slightly older E67 part number to get the right hardware and operating system compatibility, but it's still an E67. Need to use a gen IV V8 though.

E67 ECM
AR5 to LS bell housing adapter
CTS-V operating system
Gen IV V8
Custom non-supercharged tune. Might just be able to swap appropriate tables over from your donor V8.
 
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cbetts

NERD!!!
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3,182
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Rancho Palos Verdes, CA
That is clever! Too bad I sold my H3 back in January.

I am going through a similar scenario with my Subaru Crosstrek. Thinking about dropping a WRX or STi engine swap. Fortunately, Subarus are like legos and a lot of things are compatible.


I'm not 100% sure on this, but I think you can use the software from a manual trans 06-07 CTS-V. It uses the same E67 ECM as the H3, and used the class 2 data bus for most of its body communications. You might need a slightly older E67 part number to get the right hardware and operating system compatibility, but it's still an E67. Need to use a gen IV V8 though.

E67 ECM
AR5 to LS bell housing adapter
CTS-V operating system
Gen IV V8
Custom non-supercharged tune. Might just be able to swap appropriate tables over from your donor V8.
 

Jeff V.

Well-Known Member
Messages
123
Location
Kansas City, MO
You might even be able to do a reconfig on the existing E67. I just don't know enough about what tables and options are compatible across different years.
 

BC backroader

Member
Messages
21
Location
Abbotsford, B.C.
Yes, I meant the 4.3, and you're correct, of course, it was based on the 350. I had an S15 4dr in '93, so it's been a while since since I was familiar with it. My 76 year old memory is getting a bit fuzzy on details from that far back ;-)
 

zebra

Well-Known Member
Messages
115
Location
cold & windy
I'm not 100% sure on this, but I think you can use the software from a manual trans 06-07 CTS-V. It uses the same E67 ECM as the H3, and used the class 2 data bus for most of its body communications. You might need a slightly older E67 part number to get the right hardware and operating system compatibility, but it's still an E67. Need to use a gen IV V8 though.

E67 ECM
AR5 to LS bell housing adapter
CTS-V operating system
Gen IV V8
Custom non-supercharged tune. Might just be able to swap appropriate tables over from your donor V8.
hmm... didn't realize the Gen1 CTSs changed to the E67 (thought they stuck with the 0411), but doggone - you could be onto something because they never mated to an auto.
might just leave the GenIII (LS2) to GenIV (LH8) crank reluctor converter & the trans adapter... which I believe Novak might still could make.
the tune would be custom anyway, but even the stock caddy file would be a decent starting point because those were just a N/A 6.0 LS2 (Gen2 cars with the LSA were the first blower models).

Yes, I meant the 4.3, and you're correct, of course, it was based on the 350. I had an S15 4dr in '93, so it's been a while since since I was familiar with it. My 76 year old memory is getting a bit fuzzy on details from that far back ;-)
don't sweat it ;) i only remembered that off-hand because my last truck started a 4.3, and after i spun a rod bearing, i heavily weighed the differences between a Vortec 350 (easier / cheaper / more direct swap / unique for the body style) or still using factory parts to do a 5.3 LS conversion (more powerful / more efficient / more expensive). even then, the entire LS swap was ~$2000. can't find an LH8 for that nowadays (and it's only been 10yrs since i did my truck).
 
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