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Discussion Starter #1
Guys, can the V8 be made to get a notable jump in mpg thru either cam swaps, tunes, headers, etc...

I'm looking at an H3T w/ a V8 but I really need some decent mpg. I don't mind spending say $2-3K if I could pick up some serious torque and say 3-4 mpg.

Is this possible?
 

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Just my opinion, but an H3T with a V8 and decent mileage aren't members of the same subset. Takes a lot of push-o-line to propel that brick through the air...........
 

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Just my opinion, but an H3T with a V8 and decent mileage aren't members of the same subset. Takes a lot of push-o-line to propel that brick through the air...........
:funnypost:

True, though. You might be able to get a few MPG better with an intake, exhaust, and a good tune.
 

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Just my opinion, but an H3T with a V8 and decent mileage aren't members of the same subset. Takes a lot of push-o-line to propel that brick through the air...........
That's a 5000lb. Brick,I was going to get one until I saw that weight! 14-18mpg say all the tests and it would take 600hp just to run decent!
 

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Discussion Starter #6
I'm just getting desperate for a new truck while waiting for the new Canyon. There is a good deal on one of these down the street. But I can't deal with that sort of mileage so the wait continues. Thanks!

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Discussion Starter #9
one of GMs most ugly vehicle ever 'designed'...

resale value of a used shoe.
I don't know what they cost new but 5 years old they are still going for 30 plus thousand dollars.

I think they look fantastic. But I can't deal with a big heavy vehicle and no fuel economy. I'm waiting for my new canyon diesel.

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Most LSx engines benefit from better air flow and a tune. It is not uncommon to see a well tuned LS1 with headers and LS6 intake only gain a couple (1-3) MPGs over stock, assuming the driver can keep their foot out of it.

Another area to address is the rear gears. 4.10s are crap for MPGs, so you could look into a gear swap to 3.73s or even 3.42s. That would help quite a bit for highway MPGs. It would cause a larger drop to towing MPGs though, as you're losing the low end grunt the 4.10s provide.

The most radical option is to upgrade the transmission to the 6L80E. I know it is pricey, especially if it only nets you another 1-3 MPGs, but combine that with the air flow mods and a good tune, and I wouldn't see it impossible to bump those things up to about 23 MPG highway (depending on your driving habits). I've read a few people who have done this on a TBSS and it was good for 2-3 MPGs on average. Still a big price tag for the minimal savings in fuel costs (truck still got only 20 MPG highway and the conversion cost about $5-6K).
 

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Discussion Starter #12
Most LSx engines benefit from better air flow and a tune. It is not uncommon to see a well tuned LS1 with headers and LS6 intake only gain a couple (1-3) MPGs over stock, assuming the driver can keep their foot out of it.

Another area to address is the rear gears. 4.10s are crap for MPGs, so you could look into a gear swap to 3.73s or even 3.42s. That would help quite a bit for highway MPGs. It would cause a larger drop to towing MPGs though, as you're losing the low end grunt the 4.10s provide.

The most radical option is to upgrade the transmission to the 6L80E. I know it is pricey, especially if it only nets you another 1-3 MPGs, but combine that with the air flow mods and a good tune, and I wouldn't see it impossible to bump those things up to about 23 MPG highway (depending on your driving habits). I've read a few people who have done this on a TBSS and it was good for 2-3 MPGs on average. Still a big price tag for the minimal savings in fuel costs (truck still got only 20 MPG highway and the conversion cost about $5-6K).
Did all hummer H3s come with 4.10s?



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Did all hummer H3s come with 4.10s?



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I think they did because of their weight, but I'm not 100% on that. If there were another option, it would be the 3.73s. I know the Colorado/Canyon could be had with 3.73s in V8 trim (same V8, same platform), so it is possible.

EDIT - A quick search found a post on Hummer forums saying all V8 H3s/H3Ts came with 4.10 gears.
 
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