1995 FSC 4.3-- what size exhaust pipe to use

[My95Chevy4x4]

I will not have a cat, it will be straight pipe to a single in single out tip behind rear wheel

[SierraDan]

On a stock TBI 4.3, or even a Vortec 4.3 I say 2.5" single is a great setup, flows well enough for a V6 but small enough to keep velocity up. I suggest a turbo muffler if you want it fairly quiet or a Thrush Welded for more sound. I put a Thrush Welded on a friend's 97 C1500, went stock 2.75" pipe into a 2.5" in/out muffler and 2.5" pipe bent out in front of the axle, stock cat. It sounds real nice for a V6, not too loud but the stock cat is rattling so it's time for a new one, wonder if a highflow will make it too loud.

[UnderCover W/T]

why single exhaust? If you had to put in a new system, why wouldnt you go dual? I have a 4.3 L Vortec in my 98 and im trying to figure out the best setup. Whats wrong with what you have now?

[SierraDan]

Why not dual?

#1. It's a V6
#2. Single sounds just as good
#3. Single flows just as well
#4. Single is easier to make
#5. Single is cheaper, less piping used

Shall I continue?

[UnderCover W/T]

1) V6s can have dual exhaust
2) and sound good provided its done right
3) not necessarily
4)If your trying to keep it cheap and easy, then looks like it makes sense.
Really, though, whats your ultimate goal, here?
And what do you have on there now?
Please do...

[My95Chevy4x4]

right now I have a glasspack where the cat goes, and then it runs into a stock muffler then dumped and tucked in by the roll pan.

just looking for something that sounds better, thinking of getting everything cut out and run 2 1/2" pipe from the Y pipe back to a welded thrush then dumped in the same place

[bobfig]

here's my thread: http://www.fullsizechevy.com/forum/general-discussion/performance/exhaust/453289-just-finnishing-redoing-my-exhaust.html?daysprune=365

i got a 3" catback dumped over the axle with a pypes race pro muffler. i do have stock manifolds and cat on so if your nor going to run a muffler or cat then i would go 2.5" max on the pipeing. i would honestly like to hear what it would sound like with the pypes violator.

[silverado_lover]

1) V6s can have dual exhaust
2) and sound good provided its done right
3) not necessarily
4)If your trying to keep it cheap and easy, then looks like it makes sense.
Really, though, whats your ultimate goal, here?
And what do you have on there now?
Please do...

Dual would be a waste on a v6...what would be the point of dualing out a v6. Please don't say performance :lol:

[Hellga92]

Dual would be a waste on a v6...what would be the point of dualing out a v6. Please don't say performance :lol:

have to agree with him on that there is no reason to do that. 2.5 would be perfect any bigger and you back preasure would drop which would reasult in loosing power.

[Quyonmob]

2.5" straight piped.
3" with muffler and cat.

[Hellga92]

2.5" straight piped.
3" with muffler and cat.

Even with a muffler or cat 3" is still pretty big man i feel that you would loose more power with a bigger exhuast like 3" I had a 92 with a 4.3, ended up putting a 2.5 with a cherry bomb going all thw way back sounded pretty good

[SierraDan]

1) V6s can have dual exhaust
2) and sound good provided its done right
3) not necessarily
4)If your trying to keep it cheap and easy, then looks like it makes sense.
Really, though, whats your ultimate goal, here?
And what do you have on there now?
Please do...
1. Never said V6's can't have duals, I just said V6, implying duals belong on a V8.
2. I know that, I said as good, not better with single. In fact I think single does sound better since it's a smaller engine and they have a smoother tone through one pipe, not a deep enough rumble for two pipes.
3. Yes it does, it depends on the pipe size. Sure 3" duals outflow 3" single but it's not necessary. In some cases like 3" single outflows 2" duals (it does, have the former on my Sierra and latter on my Burban and the Sierra outflows it bigtime.

He wants a better sound for cheap. He's got it right, best bet is keeping as much of the pipe he already has while using the least amount of new possible so he's spending the least he can. I say 2.5" single, cheap highflow like a Thunderbolt to keep it legal and control sound more, and a Thrush Welded sounds like a great V6 setup to me. In some cases i'd use a turbo muffler on a V6 if I want it quiet but if you want to hear it, that's the way to go.

[bobfig]

Even with a muffler or cat 3" is still pretty big man i feel that you would loose more power with a bigger exhaust like 3" I had a 92 with a 4.3, ended up putting a 2.5 with a cherry bomb going all the way back sounded pretty good

i agree with ya but with my 3" i would say it helped better then the exhaust i had on before. i didn't seem to loose any low end but i did notice a good gain over 3500rpms. my thought on that is because the shop that did mine the first time used a 2.5" flowmaster into 2.25" pipe that exited before the wheel. that pipe was pressed bent so that is where i think was choking on the upper end of the power band.

[Quyonmob]

Even with a muffler or cat 3" is still pretty big man i feel that you would loose more power with a bigger exhuast like 3" I had a 92 with a 4.3, ended up putting a 2.5 with a cherry bomb going all thw way back sounded pretty good

What size was stock?

[bobfig]

What size was stock?

for my 97 stock is: 2 1/4" header to Y, 2 3/4" cat to muffler, 2 1/4" tail all of it was press bet so that restricts more in the bends.

[Hellga92]

for my 97 stock is: 2 1/4" header to Y, 2 3/4" cat to muffler, 2 1/4" tail all of it was press bet so that restricts more in the bends.

yeah if your going to bend it a lot you'll need bigger pipe to even it out. 2.5" would b perfect for what your looking for.

[My95Chevy4x4]

so i got it installed today. from the Y i got 2.5" all the way back to the thrush welded muffler, then the tailpipe runs all the way to the back of the truck and dumps at the corner of the roll pan. sounds good on the outside but crap on the inside. its to loud for me. what would the best way to get it a little quieter. glasspack back in or high flow cat?

[bobfig]

how far back is the muffler?

a cat would help quiet it down but my guess is its the drone from the muffler. 2 things that would help fight it is to have the muffler mounted 90º so the flattest part are facing side ways and to have it mounted farthest back as possible.


:nopics:

[My95Chevy4x4]

http://i56.tinypic.com/dvr7rk.jpg
http://i53.tinypic.com/v5dh0y.jpg

the muffler is about as far back as it can go

[Jameslleary]

May want to take into consideration the possibility that his o2 sensor may be located at the Y......if it is, duals not a good idea. That being said, maybe you could custom tune for the o2 to be located into the driver`s side exhaust. We have a local guy here with an 91 obs K1500 4.3 truck, and he has dual 2" from stock manifolds back, and that thing goes like a bat outta hell, and sounds nice with 2 12" case magnaflows. Only kicker is, that here in CA, he has to stick the stock exhaust back on every 2 years.

[bobfig]

well the only other option would be to trun the muffler 90º and see if that helps.

[My95Chevy4x4]

i think i am gonna order the thunderbolt high flow cat, hope that helps

[SierraDan]

May want to take into consideration the possibility that his o2 sensor may be located at the Y......if it is, duals not a good idea. That being said, maybe you could custom tune for the o2 to be located into the driver`s side exhaust. We have a local guy here with an 91 obs K1500 4.3 truck, and he has dual 2" from stock manifolds back, and that thing goes like a bat outta hell, and sounds nice with 2 12" case magnaflows. Only kicker is, that here in CA, he has to stick the stock exhaust back on every 2 years.
The 95 doesn't have an O2 sensor in the y-pipe, only 96+ OBD2 trucks have that. My 95 Sierra has no exhaust O2 sensor except just after the manifold, so it is in the y-pipe but before the merge.

The Thunderbolt should help, and yeah turn the muffler that'll help a bit. But what i'm willing to bet would get rid of the drone 100% is cut off that turndown. I'd say you need a more gradual turn like a mandrel bent 45, that'd get rid of it. My Suburban used to drone, I have stock exhaust but an 18" Mag sectioned in. I decided to cut the 90 degree bend off so the exhaust is hidden, I shopped it off just after the last hanger so all hangers are used so it's supported still, check it out:

http://www.supermotors.net/getfile/821706/fullsize/dscn2029.jpg

http://www.supermotors.net/getfile/821695/fullsize/dscn2026.jpg

Now it doesn't drone at all, just a low V8 rumble, twice as good.

[Jameslleary]

The 95 doesn't have an O2 sensor in the y-pipe, only 96+ OBD2 trucks have that. My 95 Sierra has no exhaust O2 sensor except just after the manifold, so it is in the y-pipe but before the merge.

The Thunderbolt should help, and yeah turn the muffler that'll help a bit. But what i'm willing to bet would get rid of the drone 100% is cut off that turndown. I'd say you need a more gradual turn like a mandrel bent 45, that'd get rid of it. My Suburban used to drone, I have stock exhaust but an 18" Mag sectioned in. I decided to cut the 90 degree bend off so the exhaust is hidden, I shopped it off just after the last hanger so all hangers are used so it's supported still, check it out:

http://www.supermotors.net/getfile/821706/fullsize/dscn2029.jpg

http://www.supermotors.net/getfile/821695/fullsize/dscn2026.jpg

Now it doesn't drone at all, just a low V8 rumble, twice as good.

Must be a Ca thing then, because most of the GMT400`s i climb under around here (89 to 95) have the o2 sensor in the collector, right after the merge. All of the 96+ obd2 trucks have a sensor for each bank, then 1 after the cat(5.0 and 4.3) then the 5.7s have 1 before and after each cat(2)

[Ghostyman25]

My 93 had one on the manifold but that was it. The 91 we put in my dads 4x4 had like 3 and a smog pump,i suspect it came from an original cali truck.