ur better off sticking with the i5 if you hunt on here its been talked over very well before maybe some one can link it for you

 

I don't see how the 4.3 would be an upgrade over the 3.5. It has more torque but less power. I can't see fuel economy being any better.

 

our blazer had the 4.3., it was 2dr, 4wd on 31"s, much lighter than my truck and had no power what so ever, 14mpgs city, 16mpgs highway if you baby it. inless it was a newer v6 from a camao or something i dont hardly any v6 swaps being worth it. the lil I5's do pretty good

 

My friend had a 2002 4x4 Blazer (also on 31's with 3.73 gears, and 4L60E so same transmission ratios as well) with the 4.3, and my heavier crew cab Z71 4x4 Canyon was faster and got better mileage (both vehicles were stock when he still had his Blazer). If you want economy you could always try for a 4bt cummins swap. You can build them for power, but you can also build them with economy in mind, or leave it stock as it still would do alright.

 

Yeah just stick with your 3.5L cuz I had a 2005 blazer stock 4.3 and it sucked on power

 

The 4.3 is a down grade period.

My buddy has an 03 blazer, 4.3, auto, 3.42s, 2wd............he gets a stagger 17.5mpg. My truck is a CC with a 3.5 and I can smoke him all day long.

 

Just remember, the only reason your truck has an I5 is because the I6 4.2L trailblazer engine didn't fit. Otherwise it's the same engine minus 1 cyl.

If you want to put in a V6 as previously stated, find a 2010 Camaro V6 with the 3.8L engine and you can get almost the same power as a 1998 Camaro LS1 with the same fuel economy.

 

i guess ill just stick with the 3.5... its an ok motor...i hear that a tune will open it up some, so we will see.

thank you.

 

ya and if you still need more you can swap in an 07 3.7

 

A tune will really wake it up. So will a more freely flowing exhaust (factory muffler is HUGE and restrictive), the MBRP exhaust made almost as much of a difference as the tune did on my 3.5.

If your truck has the 3.42 rear axle you could always swap it out fo one with 3.73's (find a rear axle out of a wrecked truck and swap the whole thing over...could also get one with the locker if you don't already have it). Regearing will make more of a difference than a tune or exhaust, etc.

 

truck is a 2005 ls, zq8, 5 speed. the factory muffler is already gone, was when i picked the truck up, used...its got a flowmaster on it. i have a 3 chamber magnaflow i want to put on it its a single in dual out, and have it dump behind the rear axle. i havent really done much to the truck, just lowered it, thats it.

 

Go check your glovebox sticker for your RPO codes (they're printed on it alphabetically).

Gearing codes are GU6 (3.42), GT5 (4.10), and GT4 (3.73).

I don't believe 4.10's were available on non-Z71 trucks (narrower rear axle). 3.73's would wake your truck up a lot and probably wouldn't have much effect on your gas mileage (assuming you have the more common 3.42's (for 2wd trucks...I think 3.42's were only an option on 2wd Z71 trucks)).

 

i have the GU6 3.42 gears and the G80 witch should be the lsd.

 

It's a locker rather than a limited slip. On your truck the locker was an option (standard on Z71 trucks). A 3.73 (GT4) rearend with the locker would definitely help your acceleration. Depending on where you are you could likely find one for $200-300. If you can change something like that yourself it'll be your best bang for buck option. That said I do still highly recommend a tune.

 

if i do the gears im think im just going to do the rear disk swap too.

 

If you want a set of 3.73's i have a set in my storage unit that was in my rear. Has around 40-50k on it. Pay shipping and their yours.

 

That is a good deal!! :thumbup:

 

thanks, but i think im just going to hold off with this for now.

 

ya i swaped out my rear to a 373 locker my old one is a 373 non locker

 

gutting the precat is free and supposed to gain about 10hp. idk how thorough inspections are where your at. mine has no cats or muffler. also if you think about an axle swap, i just did a dana 44 out of an isuzu rodeo. mine is 4.30 gears, you could put in 3.73s, or some come factory with 4.10s, and have disc brakes. pretty cheap swap

 

I have a set of lightly used 3.73 if our interested

 

I have a 2004 z71 ls colorado with the 3.5, m neighbor has a 4.3 v6 out of same era silverado but its got a big carb and cam on it, makes around 300 horse i think, could i get that in my colorado?

 

You can get the engine for free? If you rip out all the electronics, swap bell housing/input shaft, fab up something to make it shift right (assuming you have 4L60e), make some custom motor mounts as well as mounts for all engine accessories, go for it. Make sure you take lots of pics!

Otherwise, easier to LS swap.

 

I was wondering the same. I come across Canyons with bad engines for great deals. I have a surplus of good 4.3l engines. Great reliable engines just wondering if they would fit and what alterations to the motor mounts are needed.