454 Exhaust Suggestions Needed

[cLaWz]

What is everyone running exhaust wise for their 454's? I am almost to the point that I will be ready to fire up the truck after replacing head gaskets but I need to figure out exhaust before I can.

Right now the setup on the truck is as follows:

Dual exhaust, 2.5" pipe out of headers all the way back to glasspacks (look like old rusted cherrybombs) that dump under the bed before the rear axle.

The truck is LOUD, even in the cab. Highway driving is uncomfortable for extended periods of time. I was looking for info on how these were run from the factory and found conflicting info. Seems some came with dual exhausts, some with y's with a single exit.

Should I stick with the dual exhaust and just swap out for dual mufflers and extend the pipe out the back? How will a Cat' factor into all of this? Due to it being an 83 I do not have to be emission tested in Texas but I believe I still may have to pass the "visual" inspection. I obviously do not want to restrict the flow and cause issues but I also do not want an obnoxiously loud truck. Would prefer a subtle, deep, v8 rumble that sounds good but allows me to keep my hearing!

[78 Big10 454]

My Big 10 454 came with factory dual exhaust. The set-up consisted of 2.5 inch pipes off the exhaust manifolds wyed to a single Cat mounted on the passenger side that wyed off into two pipes and two mufflers. The exhaust pipes dumped behind the rear wheels. I swapped out the stock exhaust manifolds for a pair of CARB-approved Hedman headers. From there, I ran each exhaust pipe through its own Cat and muffler straight out to the rear. Still a bit too noisy for me with glasspacks. Although I have to have the truck's emissions tested every two years, I've never had a problem passing either the visual or performance part of the test. Hope this helps.

[truckfan]

funny you should bring this up.... i am in the process of re-doing mine. i just bought Summit Racing race mufflers (flowmasters knockoff) in 2 1/4".

My exhaust man says 454s need some back pressure, so he suggested 2 1/4. i ordered them today. he will do it as soon as they come in. my truck is a regular gas/no cat w/factory dual mufflers now. we'll install the Summits and new pipe from exhaust manifolds back and straight out the back. 2 1/4 all the way

[BigE77']

Ive got flowtech long tube headers and 2.5 that dump just before the rear, the only difference is I have flow's. Its still really loud but a little quieter than glass packs....If you take it all the way out the back it will be better plus you dont want to put a cat on if you dont have to

[cLaWz]

On the Cat issue I'm not entirely sure if it is going to be needed or not. Text from the emissions laws here in Texas.

Exhaust Emissions System Section:

If installed as original equipment by the manufacturer, the catalytic converter will be considered a part of the exhaust emission system on all 1984 and later model vehicles. It will be inspected as a part of the exhaust system on prior to 1984 model vehicles.

Exhaust System Section:

The catalytic converter will be considered as a part of the exhaust system on all vehicles prior to 1984 year model and will be inspected only visually (if present) for leakage. On 1984 and later model light truck and passenger vehicles, the catalytic converter will be checked for presence and leakage. Flexible tubing which meets the requirements listed below may be used anywhere in the exhaust system.

Truck originally had a 350 in it and has some of the other emissions systems so I am guessing it had a Cat originally. I am not sure how they are going to know that however unless it states it in the VIN information. Guess once I get it running I can take it and just see what happens before spending money on it since it's due anyway.

Thanks for the suggestions on everything else. The goal for my "fix it" build is to turn it into a daily driver and the exhaust is an issue with that. The drone these glasspacks have just really gets to me at highway speeds and is so loud it even drowns out the stereo and wind noise. I've never run open headers but they can't be much louder then this current setup. Right now I am looking at just getting 2 cheap Flowtech Raptors (or similiar) to replace the glasspacks and then extend the pipe out to the back. Would be the start of a new system to be completed at a later date. Budget is set right now just to get it up and running, and legal to drive.

Would an eventual dual system with a crossover pipe (H or X.. dunno yet, still learning this stuff!) in 2.5 work well for a 454 but still be a good setup for an eventual 350? And one other random question, anyone know where to pick up some plugs for the emissions tubes out of the headers? The pipework was falling apart when I tore down the motor to replace the headgaskets.

[S10Fan]

I just completed a 454 swap in my truck. Stock manifolds, 2 1/2" pipe, 3" Magnaflows, 2 1/2" pipe over the axle and straight out the back. True duals.

The Magnaflows sound way better with the 454 than they did on my 383 powered S-10.

[ghettoluxury]

Hooker headers to 2.5 true duals with no cats and 40 series flowmasters with turn downs

[cLaWz]

How loud is that setup if you don't mind me asking? Running what I believe to be stock headers but sounds essentially like what I'm going to end up with shortly.

[Contagious209]

I'm on the process of doing mine also. I am planning on hooker long tube headers with 2.5 piping to some mufflers which I Dnt know which to get

[ghettoluxury]

It's not bad for driving. Dont get me wrong but you can still tell it is a big block.

[SSC's76]

I have full length headers with a 2.5 dual system with glasspacks with H pipe. Now I had to cut the pipe infront of the axle when I installed the hitch. I had the exh straight out the back. Before the chop it was very quiet in the cab but sounded great to everyone else in the world. I keep saying Im going to fix it back to the way it was but just havent found time and the snow on the ground and the buick in car hole kinda prevent me from doing anything.

[BigE77']

Claws I might as well be in Austin also and I just had mine inspected one month ago in travis county and they didnt give me a single bit of grief about the cats. It might also depend on where you take it, two different shops might do two different things.

[Pyrotechnic]

I believe 84 and up requires visual inspection.

Sounds like you have a good setup. 2.5 is good size for a big block and over the axle and out the rear is best for directing the noise away from you, it just sounds like you need some different mufflers.

I would suggest swapping in a pair of turbo mufflers, or a pair of Flowmaster 50 series Delta Flow. I would also suggest adding a crossover pipe to help overall flow and scavenging, but mostly for fact that they take the edge off the exhaust note.

[Matt Man]

i have doug's long tube headers into a 2.5 inch pipe with no cats into flowmaster 50 series mufflers its very nice driving it around theres no drone but the exhaust is a little small i would go 3inch. when i redo mine it's going to get a 3 inch.

[cLaWz]

Originally Posted by BigE77'

Claws I might as well be in Austin also and I just had mine inspected one month ago in travis county and they didnt give me a single bit of grief about the cats. It might also depend on where you take it, two different shops might do two different things.

Oh yeah? Didn't check for the cat's or anything? Sounds like I may be in luck thanks for the heads up!

Sounds like Turbo mufflers and out the back is the way to go then with maybe a crossover pipe later.

thanks all

[dbmx66]

open headers

[LiveAnimals]

My 73 has LT headers, to a stainless Xpipe w/cut outs, to Flowmasters w/3" pipe to 4" chrome angled tips that dumps right over the rear end

[Devil'S Ride]

I run a set of hooker supercomp long tubes back to a 3.5" collecter into 3" pipe to a set of flowmaster 40's to a 3" turn down over the rear axle. Works great for me....but everything i own is neighborhood-window-rattling loud!

[BigE77']

Originally Posted by cLaWz

Oh yeah? Didn't check for the cat's or anything? Sounds like I may be in luck thanks for the heads up!

Sounds like Turbo mufflers and out the back is the way to go then with maybe a crossover pipe later.

thanks all

NP, I had a couple other things missing on my truck after I built the motor like the EGR valve and a heat tube that would have gone from the exhaust to the snorkle but now all that is gone. One place wouldnt pass me for that but didnt even look for the cats and the next place just said "Hell if I make you put it on I know your just going to take it back off when you get home so as far as Im concerned Its on there" I tiped him a 20 and its off to the races, thats why im saying if one place fails ya try another. If you need I can tell ya which one I went to.

[68 TT]

The pipe size depends upon how your engine is built.

If it is pretty much bone stock a 2-1/4" dual system will work best.

If it has headers, a mild cam and an aftermarket dual plane intake dual 2-1/2's will work better.

If it has a big cam, single plane intake, big valve heads and higher compression a dual 3" system is the way to go.

If it has a nasty cam, rectangular port heads, very high compression and large tube headers then a dual 3-1/2" system will work.

Going too big for your combination will lose power and efficiency just as bad as going too small.

Most street driven trucks with typical modifications will work great with a dual 2-1/2" system.

I ran 1-3/4" primary long tube headers reduced to 2-1/2" pipe into an X-pipe, Flowmaster 50 series SUV mufflers and Flowmaster mandrel bent tail pipes on my 67 C-10 with a 427 and it worked great, sounded fantastic and wasn't overly loud at idle. It was still plenty loud when you got on it though.

I am in the process of putting the same system onto my 78 K-20 but may not run the X-pipe for ground clearance reasons.

[cLaWz]

Originally Posted by BigE77'

NP, I had a couple other things missing on my truck after I built the motor like the EGR valve and a heat tube that would have gone from the exhaust to the snorkle but now all that is gone. One place wouldnt pass me for that but didnt even look for the cats and the next place just said "Hell if I make you put it on I know your just going to take it back off when you get home so as far as Im concerned Its on there" I tiped him a 20 and its off to the races, thats why im saying if one place fails ya try another. If you need I can tell ya which one I went to.

I may just have to hit ya up for the info. This truck has been a nightmare so far due to all the stuff that isn't done correctly. I have no idea where most of the emissions stuff would even be located (if its even there anymore.. see the pictures of the header tubes crimped off in my build thread , link is in my sig) Long road ahead of me with this truck. If the 12 hours I worked on it today doesn't tell ya anything, I'm loving it

[BigE77']

Originally Posted by cLaWz

I may just have to hit ya up for the info. This truck has been a nightmare so far due to all the stuff that isn't done correctly. I have no idea where most of the emissions stuff would even be located (if its even there anymore.. see the pictures of the header tubes crimped off in my build thread , link is in my sig) Long road ahead of me with this truck. If the 12 hours I worked on it today doesn't tell ya anything, I'm loving it

Nice looking truck man, I like the color scheme too bad about the wrinkly passanger side...Im not sure what intake you had on it but there will be an egr valve on the intake just at the base of the carb. mine is plated off. Also The heat tubes off the exhaust manifolds runs up to the stock snorkle or to the underside since you have it torn down it would be a perfect time to slap some headers on there and do away with that mess all togather. but if you have an aftermarket housing I guess your father inlaw decided to half ass crimp it off?? mabey its something else?? Im not too familiar with having it on both sides though???? The Insp place is pretty far south I dont know if your familiar with south austin but its down at the end of Manchaca where it dead ends into 1626 hang a left and its about a 1/4 mile down on the right just before the light at Twin Creeks I think its just called 1626 inspections....cool guy and thats all he does is inspections. Good luck and lemme know

[BLOWN73]

get some larger series spintech mufflers great sound control at idle and crusing but when you stomp it it sounds really nice

[ortega]

i was about too post this exact question? my 454 has 3in from the headers back with original 40s the whole exhaust came out of my blazer. the muffler is right under the cab with about a foot of pipe after that. way to loud. sounds like 2.5 is what most people have

[cLaWz]

Originally Posted by BigE77'

Nice looking truck man, I like the color scheme too bad about the wrinkly passanger side...Im not sure what intake you had on it but there will be an egr valve on the intake just at the base of the carb. mine is plated off. Also The heat tubes off the exhaust manifolds runs up to the stock snorkle or to the underside since you have it torn down it would be a perfect time to slap some headers on there and do away with that mess all togather. but if you have an aftermarket housing I guess your father inlaw decided to half ass crimp it off?? mabey its something else?? Im not too familiar with having it on both sides though???? The Insp place is pretty far south I dont know if your familiar with south austin but its down at the end of Manchaca where it dead ends into 1626 hang a left and its about a 1/4 mile down on the right just before the light at Twin Creeks I think its just called 1626 inspections....cool guy and thats all he does is inspections. Good luck and lemme know

Used to live in the area before moving to Cedar Park so I know exactly the place your talking about.

From the looks of it my EGR is plated off. Got some kind of flow restrictor setup (has a plate on a swivel that I guess opens or closes depending on vacuum pressure) on the passenger side header that has a vacuum connector to it as well. Guess it is more emissions stuff.

Anyone have a vacuum / emissions blueprint or diagram for these trucks?