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How do I build my exhaust?

Discussion in '1992-Present Chevy & GMC models' started by Shorts, Jan 2, 2002.

  1. Shorts

    Shorts 1/2 ton status

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    i have 2 flowmaster 50 series delta flow mufflers sitting in my garage. the inlet and outlet inner diameter are 2.25"
    i've got a '94 350 - one, maybe both of the mufflers are going on the truck, but i'm not sure how i wanna get the system done. i do not want to lose any low end on this deal. dual tailpipes aren't necessary, but, since i'm messin' with the exhaust, i might as well. i also do not want to spend a whole lot on getting the stuff installed. i know that extra tailpipes will be the costly items in this(since i have the mufflers).

    i've run over several options:

    1) install one muffler in the factory spot (cheapest/easiest)

    2) install Y pipe after cat, then both mufflers, and 2.25" exhaust pipe out each muffler (seems kinda pointless/useless)

    3) install one muffler after cat, then a Y pipe, then 2.25" exhaust pipes (maybe, yes?)


    <font color=blue>Shorts</font color=blue>

    '94 K1500
     
  2. 95 Silverado

    95 Silverado 1/2 ton status

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    the problem I see with the 1st and 3rd option is the small 2.25 inch muffler, running the system through one 2.25 inch muffler seems restrictive, to use your mufflers I would run the "Y" after the cat and use the dual mufflers and pipes. To use a single muffler I would use a 3 inch then run the dual tail pipes or a single 3 inch tailpipe. I have a friend who has an exhaust shop, he has tried several different variations and that is what he has found to work best.

    '95 Chevy Silverado 1500
    5.7 V8-NV4500- 3.73 rears
    See My Toys: <a target="_blank" href=http://community.webshots.com/user/wdb172454>http://community.webshots.com/user/wdb172454</a>
     
  3. Shorts

    Shorts 1/2 ton status

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    yeah, that seems to be the thing i'm running into, 2.25" being small for a single.

    i know a single 3" will outflow dual 2.25", but i've got the mufflers already, so i figured i'd make them work.

    you think Y, the dual mufflers would work alright?





    <font color=blue>Shorts</font color=blue>

    '94 K1500
     
  4. HarryH3

    HarryH3 1 ton status Author

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    Your cheapest solution is probably to sell the 2 mufflers that you have to someone that wants duals and then buy a single 3 inch for your truck.

    I just put a Flowmaster cat-back system on my wife's '94 Suburban. $230 for the whole system and it installed very easily! I was impressed with how well it fit and it's 3 inches all the way back. It has a nice mellow rumble now. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  5. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I would love to run a single myself. However, that cross under pipe makes me want duels. Without a skid (taking out an additional 1.5-2" clearance) that thing is just asking to be bashed. I'm running a single now just because I had scraps laying around to throw it on but, I'll eventually (probably after crushing it) put the right ends on my duals (were for the diesel) and bolt them to the 350. Only problem is that it is very tight on the passenger side between the frame and tcase. That is where the fuel lines (and brake lines) run and it just to close for my comfort. I'll be re-routing these down the outside (top) of the frame rail when I go to duels. Just something to think about...

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Oops! Meant to reply to Shorts. Sorry...

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  7. 95 Silverado

    95 Silverado 1/2 ton status

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    I would say the "Y" into the dual mufflers would work out alright performance wise, but I tend to agree with Harry on the cost issue, till it's all said and done considering the extra pipe work involved it may actually cost more in the end.

    '95 Chevy Silverado 1500
    5.7 V8-NV4500- 3.73 rears
    See My Toys: <a target="_blank" href=http://community.webshots.com/user/wdb172454>http://community.webshots.com/user/wdb172454</a>
     
  8. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Sorry, my previous reply was totally brain dead (or rather I was when I made it). I forgot that you are dealing with an IFS and Cat, making my post totally irrelevant. Oh well, good luck.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  9. Shorts

    Shorts 1/2 ton status

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    hey that's alright [​IMG] i got a new idea though...

    the 2.25" inlet and outlet are my trouble here... why not just get those expanded???

    i referenced my flowmaster catalog for dimensions - the body of the mufflers are the same size, no matter the inlet/outlet size (of course, the body size varies with different models/series). the rate of flow would be the same through the muffler body, right? so all i need to do is expand the inlet/outlet.....yes?? no????


    .....make the mufflers work...make the mufflers work....make the mufflers work.... [​IMG]


    <font color=blue>Shorts</font color=blue>

    '94 K1500
     
  10. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    LOL! I've gotten into that mindset before too. "Make it work, make it work, &lt;I keep chanting to myself&gt; YOU WILL WORK #@$# [​IMG]". LOL! That's basically what it took for me to get the fuel system together in my TBI conversion. Just give up on an ideal solutions and "MAKE IT WORK"! [​IMG]

    You could have the little stub pipes stretched out at any exhaust shop (or use the manual tool yourself). However, I expect that the 3" muffler has a 3" opening into the body and that a 2.25 would have a 2.25 opening. Even if you stretch the pipe, the opening would still restrict flow and cause turbulence and back pressure. Perhaps more than a 2.25 exhaust? I don't know if the chant will work out this time. [​IMG] While you might "make it work", I don't know if you are going to get optimum results. Good luck.

    Oh, and about the extra "Y" (crossing under) after the cat. I wouldn't want that on a 4x4. To me, that is just another place to crush the exhaust if you can't route it up and well out of the way.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.<P ID="edit"><FONT class="small">Edited by BadDog on 01/04/02 10:13 AM.</FONT></P>
     
  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I suggest you consider another option. Straight pipe it after the cat.

    It's going to sound like crap with the cat and a muffler--hardly loud enough to tell you have flowmasters, especially with 2.25" pipe and 3 chamber delta flows.

    Sell your mufflers, cut your exhaust off right after the cat, put a y pipe there, and run 2 1/2" dual tailpipes out from there. The old bead type cats are quite restrictive as far as sound and believe me, it won't be that loud. You will be very happy with the sound as well...it sounds absolutely awesome.

    If you're stuck with the mufflers you have, hack the cat off and run 2 1/4 in. true duals with those mufflers....but honestly I think you'll like the sound of cat back straight pipes much better, it's emissions legal, and less restrictive.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  12. Sparky87k5

    Sparky87k5 1/2 ton status

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    Gotta second what HarryH3 said about the single 3" Flowmaster setup. I installed one on an 88 Sub I used to have and it was easy, a clean fit and sounded great. Cost me about $240 shipped to my door. I added a dual 3" chromed tipped resonator for anther $38. Ended up being a real nice sounding system. Installed the same on my present 87 K5 too.

    87 K5, 427BBC,D60 &amp; 14BFF, NV4500, NP208, TSM disc's,
     
  13. Shorts

    Shorts 1/2 ton status

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    well, as much as i hate to do it, i'm thinking i'll sell the mufflers and work on finishing my lift kit right now. i still need the wheels and tires too.

    besides, they're not doing me any good sitting in the garage.

    ohh..did i mention that i just got an emergency loan for school and that will need to be paid in full by april??????? [​IMG] at least i just got my chrome rear bumper sold and shipped off [​IMG] a front driveshaft and a 2 front shocks might be on the chopping block soon too...not to mention a crated rebuildable 350...

    <font color=blue>Shorts</font color=blue>

    '94 K1500
     
  14. k20

    k20 3/4 ton status

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    hey, anybody got flowmaster 40 series on a fairly stock 350? preferable with dual exhaust and headers, but anyway, how does it sound? good? too loud? what? thanks (with 3" pipes if possible)
     
  15. 55Willy

    55Willy 3/4 ton status

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    My 79 Jimmy has a fairly stock 350 and it has headers and true duals..with 2.5 2 camber flows running all the way back. It really brought that thing to life..it sounds sweet. The more built the motor the better the flows will sound. BTW, IMHO the 3" duals on a stock 350 is over kill. I wouldn't run 3" unless you had a big block. I was going to run 3" on my car and desided against it.

    <font color=red>Life is like a mud hole:</font color=red><font color=blue>
    When the S#!T gets deep, you have to keep moving and friends can always pull you out</font color=blue>
    55 Willy's
     
  16. 84_Chevy_K10

    84_Chevy_K10 Banned

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    With a tailpipe it's not going to be that loud at all.

    I guess everyone's opinion of loud is different, but I honestly don't think any truck with a cat is loud, unless it's a newer truck (the bead type converter trucks are all quiet).

    My friend's truck, a '93, came with Flowmasters after the cat. It honestly wasn't any louder than stock. He cut the cat off, made a piece of pipe for it, and now it sounds really good.

    I told him to cut the muffler off. I think it'd have sounded better with the cat and no muffler instead of no cat and flowmaster muffler.

    I have never heard any 350 with dual 3" exhaust though. That's a lot of pipe, very expensive, and will cost you some torque. If I could afford it, I'd probably have 3" straight pipes. I'd bet it'd be really deep toned and not too loud.

    A muffled 3" dual exhaust on a stock 350 would be very quiet.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  17. k20

    k20 3/4 ton status

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    im plannin (when cash comes around) put on a set of headers, dual cats, dual 40 series flowmasters, and 3" pipes turned out in front of the rear wheels. the engine is stock now, after i get my lift on, and the interior done, is when the engine starts gettin its buildup. So it wouldnt be stock for 2 terribly long.
     
  18. 84_Chevy_K10

    84_Chevy_K10 Banned

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    That's way to much pipe for any truck 350. 2 1/2" is better. Just put 3" tips on it if you wan the look. 2 1/2 is much cheaper too.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     

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