I’m finally ready to rebuild my 2003 Blazer LS 4WD. I’m looking to replace the engine, transmission, exhaust, etc.. I’d really like to turn it into a high performance beast (still street legal) as much as I can.
For the transmission I was looking at picking one up from PerfomaBuilt.
Any recommendations where to find a high performance 4.3L long block engine?
I am very open to any suggestions or other recommendations to include with a new engine and transmission.

 

What exactly are your goals with it?

Seeing as its a 4x4, but wanting to upgrade it but keep it street legal, like offroading or street queen?

Personally would do more a Solid Axle swap, if keeping 4.3 and have better offroad capabilities, than worrying about a stout engine... If keeping it more 'street' I would do a V8 swap. Vortec V8 (SBCs) are easy to come by, or LS swap, but engine swaps can get expensive quick (ask me how I know!)

 

I would be driving it to work 2-3 times a week and doing some off-roading with it when I go camping. So stay with a 4.3L v6?
It currently has about 183,000 miles on it and the transmission is definitely starting to go. I absolutely want to hold on to it as it has some sentimental value to it.
My dad was a mechanic in the Air Force and made a career out of it. I bought this truck new and him and a friend he served with always helped me maintain it. My dad has since passed but his friend is still around and has a nice shop to work out of. He always tells me that he would help whenever I wanted to start my rebuild.

 

Also, how much extra is involved in swapping over to the 5.3L v8?

 

Depends how involved you wanna get.

4x4 harder for LS swaps than 2wd, so only one company I know of makes mounts, or you make your own.

current performance can make plug n play harness so all factory gauges work, or you can go holley terminator for ecu but is $2500 alone for that.

oil pan is a big issue for 4x4 due to front dif, milodon and canton do make swap pans, but are pricey at $7-800 for just oil pan stuff (you can also modify a factory alu pan if you have the fab skills.

can get away with stock rad far as I know, but best to inset it into the rad for clearance (adding 2 more cylinders so space between engine in rad is much tighter.

i am currently working on doing an LS swap (but going awd) and my budget is 20-25,000$… things get real pricey when you start doing performance mods…

 

Maybe I stick with the 4.3. Where would be a good site to shop around for a crate 4.3?

 

Are there any issues trying to use the LV3 4.3 that’s used 2011 Silverado 1500? Looks like those put out more HP, around 285.