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H3 End of warranty celebrations

amrg

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A truck intake makes more tq down low but at the expense of hp at higher rpm (but with a 6.2 its not a deal breaker)
A car intake doesnt let you use a clutch fan while a truck intake would allow you to use the HUMMER engine covers!

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jakesz28

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I have seen truck intakes make more power all the way thru the rpm range. Both torque and hp, especially the square port 4 bolt flange throttle body ones. ;)
 

amrg

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TBH the cost of a pullout engine here is as much as a 0 miles GM crate engine + shipping & tax from the states and im talking the one with a GM hot cam too!
For the H3, a 6.0 or a 6.2 is more than enough to make a 4.10 geared truck with 35s feel like a toy. Im upping to 37s next fall and I hope that makes it well mannered in 1st gear!

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jakesz28

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If engines are that valuable there maybe we should ship you some. I bought three 5.3L engines for $750. Then sold 2 for $1000 each so I could finish a swap. That swap I figured I only had about $300 out of the pocket when done. LOL
 

amrg

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Decided to upgrade my alternator to a high output unit.

My truck has been converted to efans and after driving for a while in extreme hot weather with a/c my coolant temps would increase at idle to 230* and I noticed my voltage would drop to high 11s too.
Since efans are rated at 13.2 volts I thought the voltage drop is causing them to run slower causing the increase in coolant temps. I have 100 amps additional load from the 3 efans alone and the stock 145 amp rated alternator won't cut it at idle.

Went with an E series 250 amp alternator from mechman. Instal was very straight forward, simply remove the drive belt, disconnect battery terminals, unplug the alt connector, unbolt the positive cable on the back of the alternator and remove the two alternator bolts and swap in the new alternator.

First impressions was a big increase in voltage at idle to almost 16 volts but was going up/down between 15.3 to 15.6. Stock was 14.1 to 14.3.

The efans were running much stronger than normal (they were much noisier than normal) and If I have all fans on + ac full blast and 40" LED bar on at the same time the LED bar would be fully lit with voltage abovr 13.5 (previously the LED bar would only have enuff juice to light up just 20" plus voltage would be in the low to mid 11s)

I also got a big 3 kit (OFC) so will see how it improves on the alternator esp at full load. I read on the tbss forums that the Big 3 improves alot on the factory wiring so hopefully the H3 is no different. Obviously trucks with heavy electrical loads will benefit from this more than stock setups.
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amrg

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Upgraded the battery positive and ground wires as recommended for the high output alternator.
Bought the big 3 kit but mechman recomends for 2005+ GM trucks wiring only the positive on alternator to positive at battery, ground from battery to alternator bracket. I could add battery ground to frame but it may or may not mess with the way the pcm monitors battery voltage and charging.
The kit comes with all needed screw in terminals plus fuse and its easy to do. I think there is enough wiring for two H3s
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JPaul

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That's kind of a weird setup. I get what they are going for, but it could create a ground loop for one (which is bad and can cause weird electrical issues), and second that is actually creating the exact problem you say they are trying to avoid with bypassing the current sensor GM uses on the negative cables to the battery. ALL negative wires to the battery should run through the current sensor so the the PCM can monitor charge and discharge performance/usage. There are a few ground wires that go from the block to the battery, frame, and body i think, the larger one goes from the bottom of the block up to the battery if I recall correctly, and is what provides the path from the alternator to the battery. The smaller ground wire from the negative battery terminal goes to the fender and several other grounds mount to the fender right there as well.

Adding another cable from the alternator directly to the battery for negative and bypassing the current sensor means the PCM no longer really knows how much current is going through the system. The current is going to take the path of least resistance and most of it will go through the larger, lower resistance cable. Some will still go through the smaller OEM cable, but not enough for the computer to really know what is going on. This affects both charge and discharge current.

It would be better to replace the OEM cable completely and run the larger cable through the sensor. Then run another cable from the block to the frame in place of the existing cable (which I am pretty sure is the OEM setup as there isn't anything going from the battery to the frame as far as I am aware). You always want to replace an existing ground cable instead of adding another in addition to the existing one, so that you avoid the possibility of introducing a ground loop.

Frankly it concerns me that they are making these recommendations as it doesn't sound to me like they really know what they are doing. I'm not an electrical engineer, but I know enough about electricity and electronics and battery chemistry to question their understanding of any of it. The suggestion to run a negative cable directly from the alternator bracket to the battery negative is a bad idea on these trucks, the voltage being well past 15v when ambient is well above freezing is a recipe for boiling the battery acid/water mixture away, and the other problem you might have with those higher voltages is while many, if not all of the sensors and electronic components should be tolerant of the higher voltages, it's possible that the levels might be over some of their thresholds and could cause them to either be damaged, destroyed, shorten their service life drastically, or just not work quite right, and looking at the cable and terminals they seem to be using for the cable kit looks like they're just using cheap welding wire cable and screw down terminals.

Welding cable is fine and all but don't expect the insulation to last very long, it's not really meant for the heat and chemicals you find in the typical engine bay. The problem with the terminals is they do not make a gas tight connection between the terminal and cable, so you'll see poor connectivity there compared to a properly crimped terminal, and at those amps the alternator can produce it can cause excessive heating and resistance at the terminal.

I really hope it all works out for you, and I am not questioning your judgment as this kind of stuff is beyond the understanding and knowledge of the vast majority of vehicle owners and is easy to misunderstand. I just don't want to see you drop all this money and start burning through batteries and/or having other weird issues crop up because of it. The guys at mechman just sound like nothing more than hacks that figured out how to screw with the internal regulators on OEM units and rewind the coils to produce more amps and mess with the voltages coming out of them and are preying on all the guys that want more power regardless of the cost. I'd be interested to see what the output looks like on an oscilloscope compared to an OEM unit. I wouldnt be surprised if the waveform was garbage.

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amrg

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You are right on the part that the wires should run through the sensor. It was an oversight mechman pointed out and I was correcting last night. I just never saw anybody mention it before that I missed it.
According to mechman (and basically what you said), the ecu needs to know the current passing through that sensor in order to control the altetnator output. They said the pcm has different voltage settings, and I saw from the tbss forums a table of different voltage outputs at percieved current loads. I don't know if the same table applies to our trucks but we do share the same ecu (e67)
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amrg

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Since the last update, I finally managed to nail the efan setup for my truck (which took a while and some money). The coolant temps now run 210 after a long idle with ac max and 115* weather and around 215* on the highway. Compared to a stock alpha in the same weather same results.

So the fan I got was from a camaro ss, running from an independant fan. Its 850 watts (1.2 hp), 20" and brushless which is more efficient than conventional fans by 30%. It needed some modding as the fan with its shroud are as big as the entire radiator (core & end tanks)

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I also added a 15" corvette c7 fan rated at 600 watts as a pusher. Brushless and runs directly from the ecu.

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Main important thing about those fans was that they soft start and ramp up speed depending on how much they are needed so you dont endup shocking the electrical system at startup or over taxing it by running it more than it should be.

More info on the whole trail & error process here:

http://www.hummer4x4offroad.com/forum/showthread.php?p=229143
 

amrg

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After 7 years and 110K miles my current set of tires were finally worn out (mostly dry out too) and needed to be replaced badly. I guess after 7 years I got used to the look of the 35s and wanted to get 37s this time and have them installed on my 4.5" b.s wheels (I got those in prep to get a lift kit back in 2015 but rancho had the kits cancelled so I had those in storage all this time).
Now for anyone reading, 37s will fit with a 1" daystar bodylift (some trimming required). With aftermarket wheels with negative offset (-12 for me), you will run into having to trim the fender flares and the fenders as well to run them. Since I wanted to keep the flares (the yearly inspection will give me trouble if tires stick out more than 1" from the fenders and I can get into liability if my truck throws rocks onto other vehicles) and I didnt want to trim the fenders and repaint. So I ended up replacing my daystar 1" body lift with a generic 2" kit I boughy myself. It was straight forward for my case and having an efan setup meant I didnt need to fabricate a new shroud or have the radiator dropped.

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Photos of the gaps

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2" body lift thread here:

http://www.hummer4x4offroad.com/forum/showthread.php?p=231451

Now one thing I may add, a 2.5" body lift is probably possible. Even a 3" but expect to at least need to extend the top rad hose and add a steering shaft extension (you can find em online for approx 200). Installing the body lift pucks (3") will be tricky for 2 of the mounts due to lack of space to get them through
 

amrg

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Another update, modded the rock sliders by cutting the mounts off and welding an extension. Had them raised 2" and outwards 1". Looks better that way
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amrg

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Then had the bush gaurd mounts cut and rewelded to match thr H3 grille lines
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amrg

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Did a front differential drop, used 1.25" height 2" diameter body mounts as the spacer and taller bolts. For the rear I had custom brackets bolted to drop the CM 1". Better angles on the halfshafts now although I had problems while im only at 23" hub center to fender (torn boots)
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amrg

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One of front brake lines ruptured going down the road, so ended up replacing both sides upfront. Will do the rears later
I my ac compressor clutch went out a week earlier and since an ac compressor costs $50 more than an ac clutch, I ordered a new compressor. Then a condensor, then expansion valves and before I realised I had an entire ac system replaced (minus the evaporator)
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amrg

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My last update was on the tune part of my H3. It was mostly trans related, shift points and TC lockup/unlockup points. I had my 1-2, 2-3,3-4 shift points extended, esp the 3-4. Driving around town with a 3K stall my trans would shift to 4th at 40mph and I end up cruising the streets at 3K rpm (coz of the stall). It would only lock once I hit 50 mph and my rpms would be too low for my setup with the cam and 37s (1400 rpms). I also had my 4-3 downshift programmed so I downshift earlier.
So now It holds 3rd at part throttle up to 60 mph which makes it so much better to drive, and I programmed 3rd gear lockup which puts me at 2000 rpm crusing at 50mph (as opposed to crusing at 3K in 4th gear). I also noticed a 20* drop in trans temps inside the city due to locking up in 3rd and 10* highway.

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Sennin

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My last update was on the tune part of my H3. It was mostly trans related, shift points and TC lockup/unlockup points. I had my 1-2, 2-3,3-4 shift points extended, esp the 3-4. Driving around town with a 3K stall my trans would shift to 4th at 40mph and I end up cruising the streets at 3K rpm (coz of the stall). It would only lock once I hit 50 mph and my rpms would be too low for my setup with the cam and 37s (1400 rpms). I also had my 4-3 downshift programmed so I downshift earlier.
So now It holds 3rd at part throttle up to 60 mph which makes it so much better to drive, and I programmed 3rd gear lockup which puts me at 2000 rpm crusing at 50mph (as opposed to crusing at 3K in 4th gear). I also noticed a 20* drop in trans temps inside the city due to locking up in 3rd and 10* highway.

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Great Stuff, I have only done my speedo correction when I installed the 37's. As I had already played with the shift points and running 35's. Recently acquired an off-road trailer that's much lighter than my Caravan that I refused to tow with the H. This coming weekend is a long weekend for us this side, then I will be tow testing to see how she tows with the 37's and the Rancho at 1600m (5300ft) above sea level. Already thinking of changing my 3-4 shifts and lockup parameters to something close to what you have done
 

Iwillnc

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Don’t you have an Alpha?

I know everyone always says when you do a gear swap to at least go up 2 steps to make it worth while. But I found the 4.10 to 4.56 swap on my H2 to be a tremendous improvement in drivability on the highway, towing, and generally getting out of the way of it’s own weight.
 

amrg

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Great Stuff, I have only done my speedo correction when I installed the 37's. As I had already played with the shift points and running 35's. Recently acquired an off-road trailer that's much lighter than my Caravan that I refused to tow with the H. This coming weekend is a long weekend for us this side, then I will be tow testing to see how she tows with the 37's and the Rancho at 1600m (5300ft) above sea level. Already thinking of changing my 3-4 shifts and lockup parameters to something close to what you have done
I would highly recommend that, the 3rd gear to over drive split is substantial and you will definitly find a difference. You can test it by manually putting the trans into 3rd, the GM programming will then let the trans lockup in 3rd and stay locked up.

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amrg

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Don’t you have an Alpha?

I know everyone always says when you do a gear swap to at least go up 2 steps to make it worth while. But I found the 4.10 to 4.56 swap on my H2 to be a tremendous improvement in drivability on the highway, towing, and generally getting out of the way of it’s own weight.
Yes and a cammed 6.2 actually, but my intake manifold and cam setup is more high rpm oriented and with 4.10 gearing, 37s and the 4spd my rpms are too low for my engines powerband. I am planning to swap my rear and front axles once I find a donor vehicle with 4.56 gears (Its hard to find a front cast iron axle with 4.56 over here) and regearing is out due to no shop being available to do it!

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amrg

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My junkyard axles are ready to be installed next week hopefully. I found a parted out H3 without engine/trans/tcase with relatively low mileage (compare to mine) and bought it for $150. The axles have 75K miles and zero rust, were behind an I5 on 32s, mine has 120K miles now and I ran 35s on it for 80K so Im hoping they didnt recieve the sort of stress my axles did.
Unfortunately the front is an aluminim case, will settle for that for now. There are no adv pack H3s in Qatar so a CI front diff isnt't an option. I am planning to do a part time 2WD tcase mod in the future and that will diffenetly increase the longevity of the front diff and CVs.
I had them primed and painted, 1 primer, 3 black coats and 2 rust protection coats. Now it matches how the underbody looks like on my truck. Will difinetly reuse my brakes on this
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amrg

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I got the axles installed over the weekend. Front and rear. Ive driven it alot since and I have to say the difference is alot. 2nd gear, 3rd and 4th are extremely noticeably quicker. Its something id recommend all Alpha owners do.


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