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Engine Swap

USMC_TOP

Well-Known Member
Messages
491
Location
Muir Michigan
Would you have any major mods to perform to swap out a 2006 l5 3.5 engine with a 2010 i5 3.7 ? Does it need the PCM swapped as well? Are they the same size externally? Did anything change under the hood or drive tran wise from 06 to 10? Would it be worth it? I'm sure the 3.7 has more HP and I'm guessing better fuel Eco just being 4 years newer. Just wondering because I'm buying a used engine for my daughters 2001 VW Passat for $1800 free shipping with a 3 year warranty so I looked up my 06 3.5 and the latest Hummer l5 engine. I don't need a engine; yet, the price for the 06 3.5 is like 2k and the 3.7 2010 is 2700.
 

SolidusJ

Well-Known Member
Messages
2,028
Location
FT. Carson, CO
On the 355 someone went to 3.5 to 3.7 and it didn't seem like it really did anything. Now I'm thinking of dumping a LS1 into my T and believe it or not it's for fuel economy! I would say anything worth doing is worth over doing right? I want to say that the year when the 5.3 was put in the firewall was pushed in 1" for the V8 but I'm sure you could make it happen.

http://www.355nation.net/forum/engine-swaps/43667-3-7-engine-swap-complete.html
 

USMC_TOP

Well-Known Member
Messages
491
Location
Muir Michigan
I just looked it up on Motortrend at it seems the 2007 and 2008 3.7 engines have the most HP =242 vrs my 2006 =220. I thought I read something about drive shafts needing to be changed with a bunch of other stuff as well if we wanna go to a V8
 

Chocflip201

In the Rocky Mountains
Messages
585
Location
Utah
Not sure on the swap, but when I was buying my H3 I test drove several 3.5's and several 3.7's and consistently the 3.7 had a huge "seat of the pants feel" of having way more power, enough so that I completely ruled out any H3 with the 3.5L.

The Alphas were out of my price range of what I wanted to pay, so needless to say I have a 3.7 and am very happy with it. But I also have the adventure package so I believe I have 4.56 axle gears, which help.
 

digglesworth

Well-Known Member
Messages
1,789
Location
illinois
I plan on doing this when my motor is old and worn out. Just hope I can get my hands on an 07 3.7 and I should have the t-case swapped for a 4:1 by then. Couldn't you keep your pcm and just have it tuned by pcmofnc. You'll probably have to do the case relearn and all that but it could be an option if the engine doesn't come with a pcm....
 

USMC_TOP

Well-Known Member
Messages
491
Location
Muir Michigan
I found a company called South West Engines. They seem to have every used engine on the planet. They offer a 3 year warranty on their engines parts and labor(don't know how they can offer the labor like that) free shipping In the US. I think I saw a 2007 Hummer H3 3.7 engine for just over 2k. They claim to go through them. Remove any sludge internally, steam clean external and ensure all gaskets and seals are gtg with a compression test. Only other option for a 3.5 to 3.7 swap I guess would be find a smashed 3.7 in a Colorado or a canyon. Doubt we can find a smashed 07 H3.........,,,,lol . My H3 I got a few months ago was totaled per the dealership I got it in Paris KY. When I got the title in the mail a few weeks ago guess what? Clean and clear! I have dumped at least 2k in it already. Had it in the body shop all day today aligning the entire front end, hood fenders, adjusting doors and body lines. Guy did a fantastic job! Pulled both fenders and found that the last cheese dick that did the body work was an idiot or just slapping it together to push out the door. They didn't do any rust preventive measures at all on the welded body parts and frame. My guy blasted everything sealed and painted it all correctly. Hood lines are now perfect as are the doors! They even took pictures for me through the process they did. They took the entire front end off the truck! I had missing body bolts all over the place too. This body shop that I have never used before spent over 8 hours on my truck doing all this for me and charged me for 3 hours of labor @ $46 a hour! Total bill today $138.00. I was like are you sure? I must be really living right! Great Body Shop on Ionia Michigan!
 

SolidusJ

Well-Known Member
Messages
2,028
Location
FT. Carson, CO
If you are going to do an engine swap, you have to go all in. Why limit yourself?


If I drop off my T with $10,000 would that be enough?!?!?!? :horns: The 4BT is what I really want to do but NO way I can pull off what you have done, LS1 simple as pie but not what I want. Only thing I would do is have the 4L80 trans.
 
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USMC_TOP

Well-Known Member
Messages
491
Location
Muir Michigan
To be honest I would be fine with a 3.7L. The 3.7 compared to a 3.5 may only be a 20 or 22 hp difference but you sure can feel it! The other problem is my 3.5 is running excellent and only has 82,000 miles on it now. I have read the horror stories about bad heads. some last some don't but so far mines doing great. Now I got to have my body guy straighten out The passenger side tow hook in the front because one of those are tweaked in order for my predator brush guard to fit properly. I think The last guy that had my Hummer hit a ****ing Oak tree. I have replaced like everything in the front end of that damn truck. But I still love driving it!
 

benlaud87

Well-Known Member
Messages
849
Location
Maryland
If I drop off my T with $10,000 would that be enough?!?!?!? :horns: The 4BT is what I really want to do but NO way I can pull off what you have done, LS1 simple as pie but not what I want. Only thing I would do is have the 4L80 trans.

Just swap bodies with one of the 1151s in the motor pool
 

CaseyS

Well-Known Member
Messages
755
Location
Louisiana
If I drop off my T with $10,000 would that be enough?!?!?!? :horns: The 4BT is what I really want to do but NO way I can pull off what you have done, LS1 simple as pie but not what I want. Only thing I would do is have the 4L80 trans.

With what I know now, $10K will cover all the parts and engine. It would not cover labor. You are only about 7 hours away, when do you want to drive up and start on it?

If you have an upgrade path laid out on the 4L80e with the factory engine, it will work with this swap as well. Anyone have that worked out yet?
 

SolidusJ

Well-Known Member
Messages
2,028
Location
FT. Carson, CO
With what I know now, $10K will cover all the parts and engine. It would not cover labor. You are only about 7 hours away, when do you want to drive up and start on it?

If you have an upgrade path laid out on the 4L80e with the factory engine, it will work with this swap as well. Anyone have that worked out yet?

Well I've been meaning to set up a meet with you when you got everything on you 3 worked out. Your work is out of this word and I'm already building up the cash for this job. :thumbs:
I want to start up my T and have that loud knocking diesel sound that I have grown to love. I know I'll be able to do the work my self but the harness, oil pan and mount I'll need from you.
 

CaseyS

Well-Known Member
Messages
755
Location
Louisiana
Sorry for the thread hijack. Is that price for a complete engine or just a long block?

Is it possible to rebuild a 3.5, just punch it out .100 over and use the 3.7 pistons? I know the 3.7 had slightly larger valves but at lower rpm's the displacement should still make a difference. Before I did my swap, I researched a good bit of stuff to try and rebuild the 3.5 and didn't find much of anything of use to add any power to it.
 

USMC_TOP

Well-Known Member
Messages
491
Location
Muir Michigan
My Marine Corps day's are over! Plus if a 0331 Machine gunner showed up at the motor pool I don't think I would of been able to sign one out.....................lol How to tell a Grunt from a driver? look at the soles of his boots!....................:)
 

USMC_TOP

Well-Known Member
Messages
491
Location
Muir Michigan
I pulled my daughters 2001 VW Passat on a car dolly 134 miles Saturday and the Hummer never missed a beat. I was impressed with how much towing muscle it had. Only thing I plan on towing with it is my Cam-Am Outlander Max XT 800r and a Kawasaki Brute Force 750 on trips to the Upper Peninsula of Michigan. Great times! Can't wait for Summer!
 

USMC_TOP

Well-Known Member
Messages
491
Location
Muir Michigan
When I do need an engine I will get a 2007 3.7 and have it installed by a pro! I'm 46 next month and 5 years from retirement. My big wrenching days are over! Time is one thing I don't have enough of...........I really like reading about all the Mod work you guy's are doing to these H3's! And thank you for all your advice! Great forum! Love my Hummer! I have yet to get a Hummer in a Hummer though.....................:(...........................lol
 
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