4.3L HP upgrades

[Schurkey]

Sell the V-6 truck, buy one with an engine in it.

There is nothing economical you can do to get more power UNLESS there's something actually wrong with the truck causing an unusual lack of power. So verify fuel pressure, perform all the tune-up services. Make sure the brakes don't drag.

You could invest in cam, compression, aftermarket parts of various sorts...and in the end a 5.7 will leave it for dead. A V-6 is a turd, and there's not a thing you can do to change that without a bale of money.

 

[HeavyAsAChevy]

What year is the truck? If it's a '96+ you can get a mail order tune from Black Bear Performance, PCM4Less, Nelson Performance, Wester's Garage etc.

My red '97 has the 4.3L. It's bone stock inside but I've done some small bolt on upgrades over the years. Without dumping a whole ton of money, I'd say a good exhaust setup and a tune would be the way to go. I'm running Pacesetter shorty headers (don't buy these) with a Magnaflow Y-pipe/cat and a Gibson single 3" cat-back system, and a tune from Black Bear Performance. I did the exhaust before the tune and it did seem to make a difference, but after the tune I was pretty impressed. It's definitely not as fast as a V8 but it's a lot peppier than it was from the factory now. Or at least it was, before I 4L80E swapped it.

All that said... I have an LQ4 sitting on an engine stand for whenever the V6 gets tired, or I finally decide I want the truck to actually be fast.

What headers would you suggest?

 

[kennythewelder]

What headers would you suggest?

I have a set of summit racing shorty's on my 97 5.7L. I have other summit parts on the truck as well. I have always been happy with Summit brand products. Grate price, and quality is good too. My be pacesetter who make them for Summit, IDK for sure. We hen I hadn't 4.3, I was working offshore on the oil drilling rigs. At one point, I was work at a dock, 3 hours from home. ( Working 2 weeks, and off 2 weeks). So I'm about 1 hour away from the dock when I need to make a U turn to change HWYs . I nail the truck, and it takes off, but before it shifts out of 1st, I hear a boom. Then the truck gets loud, but really takes off. I blew up the OE muffler. I could not believe the difference in power. I ended up putting a flowmaster on, but knowing what I know now, I would have done a free flowing muffler like magna flow or something. The flow master was not quite as good as the busted muffler, but a lot better than the OE muffler was. In time I also gutted my cat. I keep that truck for 10 years. I sold it to a coworker when the trans blew. This was long after I did the exhaust. He put a trans in it as soon as he got it. He asked me soon after that, what I had done to the truck. I said, what do you mean. He said, man that truck runs. When you hit 80, it's like it catches another gear. Well that just the torque converter going into full lock up at WOT. Everyone always talks about HP, but there is more to it than just that. My WT had 342 gears and I was running 275/60-15 tires. That's a decent combo for the HWY. My 97 has 373 and an Eaton truetrac and also has 275/60-15 tires. Your gear ratio needs to be in the rite range for the tires you have. The 4.3 never had the power my 97- 5.7 has. If your running 33s or a bigger tire, then yes, the truck will be slow. The 4.3 will never be what a V-8 is, but there is only 10 HP difference in the 4.3 and the 5.0. I liked my WT 4.3 when I had it. It was a grate truck and gave some decent MPGs. My 5.7 will run circles around the 4.3 I had, but I get about 10 MPGs in town too. As mentioned, if you want real power, then yes do a LS or 383 stroker swap, but you can get the 4.3 to be a good little truck with half way decent power.

 

[df2x4]

What headers would you suggest?

Anything but the Pacesetter shorties. They may be fine for V8 trucks, but the 4.3 models have incorrectly machined flanges that require pretty significant cutting to clear the coolant temp sensor. I reached out to Pacesetter about this issue and they basically told me to go kick rocks.

I've heard good things about JBA.

 

[HeavyAsAChevy]

My main issue with exhaust is making sure it’s not too loud. Since I’m still living with my parents due to my age, and my dad doesn’t like it when it’s really loud. I would like it to flow better, I can tell even when I unbolt just the oe muffler that it helps. It’s just sooo loud. Would a free flowing muffler be that loud?

 

[kennythewelder]

My main issue with exhaust is making sure it’s not too loud. Since I’m still living with my parents due to my age, and my dad doesn’t like it when it’s really loud. I would like it to flow better, I can tell even when I unbolt just the oe muffler that it helps. It’s just sooo loud. Would a free flowing muffler be that loud?

No, but it won't be as quite as the OE muffler ether. The lounger the muffler, the more quite it will be. I am running 2 old school glass packs on my 5.7. they are 24" long. My truck is not loud, until I nail the gas. Then you can hear it with no problem. The flow master I had on my 4.3 wasn't real loud ether. If you run the exhaust out of the back of the truck, it will be more quiet than say turn downs under the truck. You could also do a single out in the passenger side, behind the rear tire. That won't be to loud ether. Honestly, I was very happy with the flowmaster I had on my 4.3, but a flowmaster is somewhat restrictive. Glass packs are dirt cheap. Like $35 or $40 for a steel glass pack. Mine are Thrush brand. If you go that route, some glasspacks are directional, and some are not. Mine are not. The OE cat will also help it to not be to loud.

 

[L31MaxExpress]

I have a set of summit racing shorty's on my 97 5.7L. I have other summit parts on the truck as well. I have always been happy with Summit brand products. Grate price, and quality is good too. My be pacesetter who make them for Summit, IDK for sure. We hen I hadn't 4.3, I was working offshore on the oil drilling rigs. At one point, I was work at a dock, 3 hours from home. ( Working 2 weeks, and off 2 weeks). So I'm about 1 hour away from the dock when I need to make a U turn to change HWYs . I nail the truck, and it takes off, but before it shifts out of 1st, I hear a boom. Then the truck gets loud, but really takes off. I blew up the OE muffler. I could not believe the difference in power. I ended up putting a flowmaster on, but knowing what I know now, I would have done a free flowing muffler like magna flow or something. The flow master was not quite as good as the busted muffler, but a lot better than the OE muffler was. In time I also gutted my cat. I keep that truck for 10 years. I sold it to a coworker when the trans blew. This was long after I did the exhaust. He put a trans in it as soon as he got it. He asked me soon after that, what I had done to the truck. I said, what do you mean. He said, man that truck runs. When you hit 80, it's like it catches another gear. Well that just the torque converter going into full lock up at WOT. Everyone always talks about HP, but there is more to it than just that. My WT had 342 gears and I was running 275/60-15 tires. That's a decent combo for the HWY. My 97 has 373 and an Eaton truetrac and also has 275/60-15 tires. Your gear ratio needs to be in the rite range for the tires you have. The 4.3 never had the power my 97- 5.7 has. If your running 33s or a bigger tire, then yes, the truck will be slow. The 4.3 will never be what a V-8 is, but there is only 10 HP difference in the 4.3 and the 5.0. I liked my WT 4.3 when I had it. It was a grate truck and gave some decent MPGs. My 5.7 will run circles around the 4.3 I had, but I get about 10 MPGs in town too. As mentioned, if you want real power, then yes do a LS or 383 stroker swap, but you can get the 4.3 to be a good little truck with half way decent power.

Stock for stock there is a 40 hp difference between the 4.3 and 305 and only a 15-25 hp difference 305-350. Comparing power ratings of the various years of Vortecs.

 

[kennythewelder]

Stock for stock there is a 40 hp difference between the 4.3 and 305 and only a 15-25 hp difference 305-350. Comparing power ratings of the various years of Vortecs.

I was remembering what my 93 4.3 had. Here are the specs. As for a 305, you couldn't give me one. They didn't call it a 3-0-slow for nothing. The 4.3 uses the same internals as a 5.7 does, for the most part anyway.

 

[LC2NLS6]

I had a TBI 4.3 in my 88 Sierra single cab long bed 2wd 5 speed stick. I put in the entire edelbrock performer catalog on it, cam, headers, single 3 inch exh no cat, intake manifold, holley 670 tbi, chip, k&n, roller rockers, 3.73 gears, new clutch, rebuild the 4.3 too. Guess what, it was still dog slow, Barely into the 16's in the 1/4 mile. I solved that by in 2000 buying a 87 Turbo T and then 2001 a brand new C5 Zo6. I no longer was going to suffer with slow transportation once I graduated college and got a job to pay for my hp addiction.

 

[Erik the Awful]

Sell the V-6 truck, buy one with an engine in it.

There is nothing economical you can do to get more power UNLESS there's something actually wrong with the truck causing an unusual lack of power. So verify fuel pressure, perform all the tune-up services. Make sure the brakes don't drag.

Yup. I'll spell it out for you. Performance parts are more expensive for the 4.3 than for a 5.7, and you get diminished returns for that money. You're putting a diamond in a goat's butt. The ONLY reason to hop up a 4.3 is if you can't fit a 350 in its place. Small block Chevys can be had for free - ask your buddies who are all hot for an LS motor. I bought a hurt 4-bolt main 350 for $100 and my friend threw in another 2-bolt 350 for free. I ended up giving the 2-bolt away for free to clear space in my garage. If someone tries to gift you a 305, kick 'em in the junk. If a 350 is available, there's no reason to spend money on a 305. If a 350's not available, wait five minutes.

If you can tolerate the lack of power, the 4.3's a great way to save with fuel economy. Like Schurkey said above, tune that turd up! If you get that 4.3 running good, it won't be a slouch. From there, work on weight reduction. Put better tunes in it so that you are comfortable cruising slower. Clean that interior and make it look like a show car so that your romantic interests are willing to ride along.

Upgrading the exhaust is one area where you can upgrade a 4.3, and it will pay off if you ever swap a 350 in. Stick with the stock manifolds on the 4.3, but upgrade the rest to what you would want to run with your dream 350. You don't need the backpressure and you'll be future proof for upgrades.