2.9L to 3.7L on a ‘08

2631 Views 4 Replies 3 Participants Last post by nullptr, Sep 18, 2020

08InSeafoamGreen

Discussion Starter · Sep 18, 2020

Very soon I might be needing a new engine in my 08 extended cab, and was wondering if I can go from a weak 2.9 to the more bulletproof 3.7 for a little more towing and off-road power. The truck is a special edition WT model produced for the US Forest Service, and so I feel like a truck that came from the woods should be better in the woods. How much different are these motors, from one another? Are the electrical systems compatible?

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nullptr

· #2 · Sep 18, 2020

The 3.7 is an ok motor, but if your going to go to the trouble of a swap, why not 5.3? It'll be easier to find parts for and I don't believe there is a big real world difference in gas mileage. As for difficulty, it may actually be easier to swap due to better aftermarket support and the fact that it's a more common swap.

I've owned both, a 2011 3.7 and 2012 5.3, the 3.7 didn't really impress.

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08InSeafoamGreen

Discussion Starter · #3 · Sep 18, 2020

nullptr said:
The 3.7 is an ok motor, but if your going to go to the trouble of a swap, why not 5.3? It'll be easier to find parts for and I don't believe there is a big real world difference in gas mileage. As for difficulty, it may actually be easier to swap due to better aftermarket support and the fact that it's a more common swap.

I've owned both, a 2011 3.7 and 2012 5.3, the 3.7 didn't really impress.

Mostly price. Is the 5.3 diesel or a V6? I think my main concern is the difference in electrical monitoring between a 08 and a 12.

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NewColy

· #4 · Sep 18, 2020 (Edited)

for overall simplicity and time, i'd consider just replacing it with another 2.9L and get an 89/93 mail order tune if its a 2wd model. that would put the HP very close to a stock 3.7L. Check out the google search results for 3.7L and 5.3L swaps, the good news is the all the engines from 2008-2012 have the same electrical system, but the 3.7's and 5.3's will have more sensors, hence you will need those harnesses and connectors etc...

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nullptr

· #5 · Sep 18, 2020

08InSeafoamGreen said:
Mostly price. Is the 5.3 diesel or a V6? I think my main concern is the difference in electrical monitoring between a 08 and a 12.

5.3L is a V8 gas engine, GM uses it in a ton of vehicles, including later years of the 1st generation Colorado, and it's pretty cheap to find at junk yards with decent miles on it. Probably easier to find than the 5-cylinder, which was only used in the Colorado and Hummer.

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