You've probably been ask this a lot But:
I'm an old school Carb and dist. guy and I have a friend that wants me to help him with a 2003 ZR2 blazer 4.3.
I was doing some searching (Jegs and the web) looks like the turbo/superchargers give the most HP, but I don't think he's going to want to go more than $1500-$2000. I was thinking Jet Performance Programmer, K&N, some sort of exhaust up grade. Maybe later a Throttle Bodies and/MAF.
Then there is always N2O, I run it on my V8 with a wet system, can these be run as a dry system like they use on the Mustangs for around 75-100 HP.
So you guys have been working on 4.3's. "Whats my most Bang for the Buck?"
Thanks for any Help.

 

You can go with headers and a full exhaust consisting of a high flow catalytic converter (2003 may be iffy on the choice of cats though). You can install a free flowing intake, but the MAF is good for over 350HP which I don't think you can attain with a budget of $1500-$2000. The throttle body can be modified for pretty much nothing by removing part of the baffle on the underside of the throttle plate. You will find a half moon shaped baffle under the throttle plate that is around 5/8" tall. I dremelled mine completely off on my old Bravada, but ended up having problems with the distribution of the EGR gasses in the intake causing some issues with uneven AFR as determined by reading the plugs. I would not cut it down to any less than a 1/4". This basically will increase throttle tip in response, but showed no real WOT gains when I compared my before and after PCM scans on runs to 60mph.

As far as PCM programming goes, Jet, Hypertech, etc tuners are good, but if you do a bunch of other modifications, you can get better results from a custom tune from places like PCMforLESS.com detailing to them what changes you have made and what you want out of the tune.

Nitrous is always an option especially when the budget doesn't allow for more radical changes. A wet kit can be used if you remove the shrader valve on the fuel supply line and connect up a -4AN feed line to the fuel solenoid. If you go wet, I would recommend a progressive controller as to not just bust up the drivetrain. There are some folks here that have dabbled in nitrous on these trucks that know more than I do.

Still staying under the budget, you may want to look into a different cam and possibly higher ratio rocker arms. All modifications and a custom tune should provide you with a good increase in power.

 

Thanks Kyle, I may be able to talk him into a little more money once we get started.
Hey, I'm also a Volunteer Fire Fighter.

 

It will be close to stay within budget with this option, but remember, that compression and flow = power. You can do bolt-ons to free up some HP, like headers/exhaust, intake, RRs, etc. if you're looking at serious horsepower, you can do a heads and cam job. mill and port the heads for better flow/compression, and match them with an appropriate cam to maximize the power within the RPM range. JUSTheads/cam work will fit into the $1500-$2000, so that's an option to really gain some performance. but if that's not enough, you can always get nitrous along withthem and have your cam made specifically for a shot of nitrous, then a good tune along with it. there are so many possibilities. basically, there are4 options with this price range: A)spend a little money here and a little there (that will eventually add up to roughly $1000) to do manyminor bolt ons, which are easy to install and increase HP a somewhat decent amount for a DD. this method is extremely easy and requires minimal work, but for not nearly as much power. B)dump all the available money out (all $2000) forthis huge, singlejob (H/C/I) and really pump out some serious power. this will increase the power the most and it will be consistant. C)spend around $700 for nitrous and all the accessories for a good 150shot that lasts only a few, short sprints (but good enough to kill a mustang). you'll need to continuously refill the bottle though. and D)spend most of that money and slap on a super/turbocharger for a few PSI of boost. i'm unsure of how much boost pressure these 4.3L can handle, but a good estimation is 20HP per 1PSI of boost. It's all really a matter of personal preference... If it makes any difference, i once knew a guy with a suburban running mid 12sec passes with nothing but a huge shot of nitrous. however, once he got on the street, he got beat by a civic because he ran out of nitrous... lol. good luck with the decision!

 

stock motor and tranny you're pretty safe running 6psi which is approximately 80 horse at the crank

 

That is true, 02vortech is running 7psi I believe with a stock motor and trans!!!

 

last i checked he was running 11 psi and stuff was blowing up. i think superchargers are better than turbos for these trucks anyway. it takes advantage of the fact that these trucks were built really torquey. they're not high speed racers, more for light to light, if you choose to take your truck in that direction.