Recently aquired my 2000 blazer 4x4, it has the 4.3 and im finding that it's just not enough motor for all the fun i want to have. been tossing around a few ideas and after visitting other posts on here im finding that my questions/options are fairly common so here it goes again (sorry).... Would it be better idea to mod my 4.3, swap in a 5.3, or go right for the 5.7 vortec?! if i was going to go with the 5.7 (which im thinkin to be an awesome idea) what is the difference between the 2 bolt and 4 bolt versions of this motor?! ( im sure im just still quite a mechanical newb and not understanding all the ins and outs like this). Also understand that this task would quite pricey and difficult but i do hav help so im just trying to get as much input as possible before making a choice and makin moves to get it done. Im also fairly certain that the V8 options will be alot tougher on my fuel economy so if i went with a V8 option would i benefit from a tuner or any other add ons that might help recover some MPGs?!

 

the 4.3 is a pretty good motor in the blazer. sounds odd coming from someone who did a v8 swap...lol but they do run really well. could be an issue with your current setup.

2 bolt is simply 2 bolts holding main bearing cap, 4 bolt..tada, 4 bolts holding it on. which version depends on how much power you want to make.

If you have money 5.3 hands down. more power, lighter, runs cooler, better mpgs but it is the harder swap to do. 5.7 isnt a hard swap at all. fuel mileage in mine is slightly better then the 4.3. cooling is a factor and of course its heavier. someone whose done it and kept torsion bars will know if theres an issue more then i do.

this is just general there is tons of info to go along with it, as well what you should and shouldnt do.

 

so if performance upgrades r in my future plans i should probably go on with the 5.7 in a 4 bolt set up... slightly easier swap then the 5.3 but not as good mpg gain... have u changed to a bigger fuel tank to go with ur larger motor or just runnin the factory 14gal? im sure that would also help things atleast to avoin multiple fill ups... eventually i would like to turn this into a tuff off roader, but at the moment the means only provide for daily driver and small upgrades as i go along so im trying to MPG conscience.

 

If you have any concern on mpgs, 2 bolt vs 4bolt is non issue. your talking close to 500 horsepower before the concern is there. If your going to put that kind of money to push that much horsepower your back to 5.3 or even ls1. which is a helluva lot better base.

im using factory tank. like i said, mpg is slightly better then my tired 4.3 that came out, so it isnt really any concern to go to a bigger tank.

 

This kinda sparks my interest as I too want to do a motor swap eventually why would a 5.3 or a ls1 be that much better of a base than a 350? I was thinking about a 383 stroker. Gas mileage isn't really a concern i'm just thinking about performance.

 

well i know LS1 would b awesome option, but isnt that a bit of a pricey option?! the power potential with that would b rediculous i think, but how well would that work in a 4x4 situation? im guessin it would b just as good as a drag car rite? more power means better performance? mite be able 2 get one cheaper out of an old/wrecked WS6 firechicken tho!! swap would probly b a nightmare tho

 

got a '96 silverado with a vortec 454 in it... MPGs would be horrible but i wonder if it would fit in my rig?! that sorta motor would quite incredable i think!!! prolly too big a motor tho with out super intensive and expensive modding!

 

Once you start building up an engine, everything goes out the window. ...lol

stock motor
5.3 As a better base, id say technology. smaller displacement = lighter. puts out more horespower, comparable torque. 5.7 has a little advantage torque wise, it makes torque lower in rpms then the 5.3 does and mpg. and then gm replaced the 5.7 with a 5.3. sometimes i wander what the hell theyre thinkin but, i bet the engineers at gm are smarter then i am...lol both can be built up though. id still lean towards the newer motor.

454, hell ya u can make it fit, but only reason would be to tow, and hell why stop at 454, go diesel.

 

I don't think you can fit a big block without cutting and / or modifying fender wells and the firewall...

 

with the 5.3 or 5.7 options would i need new trans? right now im assuming i have a 4speed auto... shifts on collumn i not too fond of but u get used to it i guess... or would i want to just pollish up what i've got already? wasnt sure if it would match back up or handle the added demands of a V8.