H3 Ls376/480

I thought I would start with this, its a work in progress.
This video is created by the ppl doing the conversion.

https://youtu.be/4RGSYqH6AT0

Nice!


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Now that's a healthy sounding H3!!!

Not the normal h3 engine noise.

Sounds great.

Little update:

Finally drove the truck today, it was parked awaiting new intake piping and silicone hoses (had to order from the states and took just under 3 weeks to arrive)

I programmed the truck using hptuners, file was sent by pcmofnc (I provided them the crate engine base tune and they adapted it on the h3). The truck starts good, idles fine. Kept it idling for 4 hours before I drove it, no CEL.

Driving impressions:
break in procedure states to drive 30 miles at varying loads, not exceeded 4000 rpm. After 30 miles, do 6-8 50% throttle in gear up to 4000K and 2 WOT up to 4000K. The 50% throttle in third gear the truck pulls hard.
Did the WOT from a standstill and honestly with the 3000K stall converter, I felt like the truck jumped and twisted (totally unexpected) while the tires were screaming and my first reaction was to remove my foot off the pedal!!! Definetly will need two firm hands on the steering wheel and a strong heart! Ill probably not try much of those (or maybe not)

I got a CEL eventually and I will need to get the scanner to see what it is (suspect the trannny as with the new stall the car feels like its slipping alot which is totally expected). I did upgrade to a 40K cooler and driving around in slow streets the trans temp didnt go above 160. More testing will be needed.

As for the sound, I had the first cats replaced with MF HI flows and the second ones removed (the original ones were done for and had to be changed). The drone is loud, really loud. No way the cops won't pull me over and its too loud for daily driving so im looking at getting a muffler installed where the resonator originally is (mine is removed due to the gmperformance exhaust). Looking at borla vs magnaflow. I dont want to hurt performance but I need to have it quieter than this.

neat.

Idle video:

https://youtu.be/cfLtWDAT8sQ

So I thought I would update here,

The cooling on my truck was marginal at best esp with a/c and the hot summers. I would find my truck hitting the 235* easily in 120* ambients and that kept me very nervous.

Since I was using a car manifold, a clutch fan wont work. The car manifold sits 4" lower and the part where the intake goes into the throttle body interferes with the fan. The only way to fit a clutch fan would be to use a spacer but then Im using a dual core griffin radiator and there is no clearance.

Swapping to a truck manifold will do the job but then I may have to swap in truck fuel rails and obviously have to do a tune on the truck. Didnt want to do that and plus it looks ugly! But yeah mainly I didnt want to go that route (at first)



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So I started testing different efan setups. It was mainly a trial error kinda thing. Although I had a dual core griffin radiator with 1.25" cores netting a 2.65" thick radiator, the face of the radiator is too small for 500 hp.
For comparison, the H3 has a 22.5" radiator, a silverado with a 5.3 has 28" wide radiator while a 6.2 variant has a 32" radiator.

So to get the H3 cool, i needed a good radiator fan to utilize the best out of my situation.

I started with a jeep hemi 2 speed radiator fan. Due to clearance issues, ot was mounted directly to the core and covered 70% of the radiator.



That didnt work


So i added a 16" pusher fan to help. That wasnt enough either.

So I went on the vette forums to see what those people do. I ended up getting a dual High output spal fan setup. At the time nothing aftermarket could put more power than those. Each fan would pull 70 amps at startup and 35 running. They worked, but marginally and that was due to the fact they were also installed directly to the core. There was less than 0.3" clearance to the engine pulleys. They were super loud and the on/off was very hard on the system.

So what to do, There was no room To upgrade the pullers. I went and upgraded the pusher.

Installed a corvette c7 puller fan as my pusher. Its a brushless fan, variable speed 0 to 100%, has soft start and can be controlled by the pcm to whatever speed I want depending on temps and ac pressure.
It is also 600 watt brushless. This makes it equivelant to 800 watts of conventional brushed fan. Thats over 1 hp, and its used to cool a C7


To fit it I had to space out the radiator support and trim some of the body cross member where the support bolts up.



With this setup, my running temps moved from 235* to 220*. Thats an improvement, but not enough. I ran that setup 2 summers until eventually, technology, or knowledge, caught up.

My final step was removing my dual fan setup amd installing a camaro ss/ cadillac ats turbo fan. Its 850 watt brushless (equivelant to 1200 watts brushed, stronger than 3 of the most powerful brushed fans in the market) and comes with a shroud that covers the entire radiator.
By the entire radiator, I dont mean just the core, but the whole thing!
I had to trim abit but it fits


End result, the engine now idles at 205* on the hottest summer days (120* ambients) with a/c. The fact that the fan is bigger than the radiator and the shroud has flaps that open to airflow means it doesnt block airflow through the radiator at highway speeds but temps seem to stabilize at 215* at 70 mph.

Awesome! Got a part #? I haven’t had overheating issues yet with my 6.2 but who knows, I might when it gets hot

The pusher is ac delco 1581914 - $ 187 on rockauto. You will need to trim the shroud to the original fan housing.

The puller fan is ac delco 1581927- $ 252 on rockauto

Both fans can be run directly from the E67 ecu using a single line. The fans connect directly to power and use a low voltage signal line from the ECU to control their speed.

Otherwise you can buy a temperature sensor (spal or aftermarket) depending on what temp you want and it will run the fan from 30% up to 100% (with soft start) but you wont have ac pressure control

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Thank you! Any V8 swap (H3 or not) can be difficult to cool. Thank you for your well documented trial and error.

Very cool, I’m curious if the clutch fan is better or worse then the ATS turbo fan? I have a 6.2 with the truck intake so I can fit the clutch fan...I haven’t had problems yet, as it’s only been 50-60 out, but once temps rise I’m curious if I’ll have issues.

99% the clutch fan with a shroud should work perfectly. The cadillac fan is really powerful and can pull serious air but if it aint broke why fix it?
Fyi, the tbss came with the 6.0 LS2, a truck intake and a clutch fan although it was a performance vehicle, and the main reason according to GM was that no electric fan kept it cool at the time. Technology did improve drastically, brushless fans are the norm now (they are 30% more efficieny than the regular fans) and they are more powerful (to cool 600+ hp stock vehicles). Even the silverados now run dual brushless bosch fans.
The ats turbo/camaro ss fan is brushless and 850 watts, equivelant to 1200 watts of brushed fan ( thats 1.6 hp just for a fan ).

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5gn-h3t said:

Thank you! Any V8 swap (H3 or not) can be difficult to cool. Thank you for your well documented trial and error.

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I thought I would put this here so others can benefit from this. I was treading into new territory and would hope someone else can find this useful for them instead of figuring it out for themselves

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Yea, I won’t change it unless I have an issue. I’m just curious what kind of CFM numbers it will pull compared to a fan clutch

According to spal specs, the 500 watt fan pulls 2400 so the 850 watt should be abit over 4000. Now those are real test numbers, and unlike brushed fans, those numbers dont drop alot when there is a restriction infront of the fan (like a radiator & condensor)
As for a clutch fan cfm, I havent found any real test data and mostly just internet talk but no facts.
But since moving clutch to electric gains you 5 hp at peak rpm, then the clutch fan will be stronger at that rpm than an electric (even if you factor in big losses in efficiency)

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Yep, clutch fan from what I understand will ALWAYS move more air then an electric fan but since it’s RPM driven I’d like to imagine that at speeds under 20-30 mph the e fan could potentially move more air. Any speeds above that the natural air flow is doing more anyways.

A regular duty clutch fan will do 60% to 70% of the waterpump speed when engaged. A severe duty will reach 90%.
Since the water pump is overdriven by 30%, this endsup meaning a regular duty clutch fan spins at the same rpm as the engine. Since it depends on engine rpm, you can go as low as 600 rpms (idle) or as high as 6K (max rpm). The fan itself is a 18" blade.

The cadillac/camaro ss has a 19" blade, should spin around 3500 rpms at max speed, which is irrelevant to engine rpm!

So i guess anything above 3500 rpm the clutch fan will be better. 8-9K cfm at 6000 rpm shouldnt be unrealistic then for it!

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06 H3 said:

Yep, clutch fan from what I understand will ALWAYS move more air then an electric fan but since it’s RPM driven I’d like to imagine that at speeds under 20-30 mph the e fan could potentially move more air. Any speeds above that the natural air flow is doing more anyways.

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Btw, i thought that the fan should be off at highway speeds but behind my 40K trans cooler, ac condensor and 2.65" thick griffin radiator, i noticed that running the efan at highway speeds does lower the running temps no matter what ambients Im at. I tried it at 120* and at 70*.
The pcm does switch off the fan above 45 mph which is why I decided to run the puller fan independantly using its own sensor plugged into the passenger side head. Worst case the airflaps in the shroud will open up if I reach a speed where the puller endsup obstructing flow and bypass it altogether
The pusher fan on the other hand is pcm controlled and goes off above 44 mph as it endsup impeding airflow!

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So no overheating no matter how hard your on it in 120 degree Fahrenheit and A/C on?

I honestly havent offroaded this truck in the summer so I cant tell but driving around town and on the highway on my 3200 rpm stall the truck runs at 208* with a/c and drops to 205* at idle (the fan would probably be running at 50% speed since I use a 195* - 215* variable speed sensor). The fan actually starts at 200* and hits max speed at 220*
But keep in mind I have a griffin dual core radiator. A stock radiator may be a different setup.

FYI, I had recommended using this fan to someone on the colorado forums with a supercharged 6.0 Liter. He also is using a griffin dual core radiator and he has tested his in the dunes for a week. He may provide you with more info if you want

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Hello again amrg, I am Oscar from Spain, running a 2006 H3 3.5 automatic,

Right now I am deciding to switch to a efan setup, is not a simple question because here the Temps in the south of Spain reach sometimes 40ºC or even more...I usually g to sahara desert in Maroc where temps could be even higher under hard driving conditions (high rpm in dunes, a lot of temperature outside, ac on...etc)

I think that the best solution for me and my aplication is the Puller fan that you recomend from a Chevrolet camaro ss, so the questions are:

-With my actual aplication consider adding the Puller Efan that you suggested...Would the alternator from my 2006 3.5 i5 control that? Is only a 120 amp alternator, I think
-How to wire that fan to my Setup? I prefer maybe the external sensor setup over the PCM controling the fan
-How much power can I expect from that setup? In 355nation forums people talk about 10hp increase in Dyno, I am searching for Hp right now, but reliable too (I know people will suggest: ey! take a v8 over the 3.5, but this H3 is with me from 2007, a lot of miles with me, always very very realiable and there are a lot of things done to this with my hands. The Hummer can take almost everything, is incredible, better than any other brand that go with me to desert.)

Right now I am running a 3.5 i5 with Volant CAI 155356 adapted, Ported Throttle body and Supersparkz spring delete in Coils, Guted manifold, deleted muffler (straight pipe in that part) PCM tune from PCMof Nc.....and of course Fox 2.0 performance series shocks (that was the best mod by far), Alpha cv axles, Outfitter design steering rack kit and DIY differential bushings kit. Moog greaseable U joints, Moog reinforced links of stabilizer bar and bushing. 40000 Tru-Cool trans cooler (in desert driving under hard throttle and faster speed, take temps in 180ºF, perfect for my use and abuse)...

My next mods list is the EFAN setup (trying to liberate 10-12 hp from the engine and better mpg (more miles of range in desert drivings) and a Exhaust Header from JTR (the shortly style). Right now my engine is producing 260 hp at the crankcase with my calculations, I hope to reach the 280 hp with these mods.

Is amazing how powerful the engine is now, is super strong and a lot more torque from it. I hope that you can help me with the next mod Amrg (efan)

I will post more news from my Hummer in a new thread in these days. Very cool the stickers that i have!

Thanks

I dont have numbers BUT pcmofnc claims 10 hp on an I5 and 15 hp on a V8

Before I persuade you into this, keep in mind the following:

1. A clutch fan is claimed to pull 10K cfm at max speed (approx 3K engine rpm) on trail blazer. At idle it is claimed ti do around 2000 cfm

2. The camaro ss is rated 850 watts so at a alternator voltage of 13v thats 65 amps (80 amp fuse). No cfm data published but claimed 5000 cfm. (Spal rating cfm not ebay marketing)

3. The V8 alternator is rated 145 amps when COLD and at 1800 engine rpms. At idle (550 rpm) with a warmed up condition (hot) expect it to push 90 amps. This leaves you little room to run other electrical items (fuel pump, ac, lights, engine electricals, etc...). If the I5 is 120 amps, then expect it to push 75-80 amps at idle

Now for running it, the sensor runs the fan independently and lets you add an over ride switch. You can select from 3 different temp ranges (69-80, 81-92, 93-104) Our summers here are 50c. Yesterday it was 46, had ac fan speed on 3 and idling, switched the fan to full speed and it dropped my temp to 90c. On the highway it would reach 103c but when i was running a 5.3 and clutch fan i was hitting the same temps.

If you plan to run ac, you will need to get a large condensor fan to get air flowing and cool the condensor when the puller fan isnt running (cold engine)