Exhaust system for 3B - straight pipe

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Hi guys,
So I had to re-do my exhaust (long story involving a hack job by a shop) and did 2.5" with a flex pipe stopping at the pass. wheel. Nice and short. Just for the fun of it, and since I had the parts I wanted to see how this would work with just a straight pipe, also because of the long weekend and everything I needed closed I did not have a glass pack. At idle it sounds like a Harley but once I give it some more it is way too loud, but I did notice a bit more power. I'll be buying a glass pack on Monday and installing it before the cops decide to give me a ticket. So if anyone ever wanted to know how a 3B sounds straight pipe - LOUD!, good but loud.
 
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I can second your assessment: when my exhaust separated on the freeway at the first junction due to rust about a year ago, I nearly lost a good pair of underwear. I limped to a muffler shop with everybody looking at me.

The turbos are supposed to quiet them to the point of being able to have that straight pipe alone.

B
 
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The turbo DOES quiet it down to the point of running without a muffler. My '82 BJ60 with an AXT turbo kit has been that way for the past 4-5 years and I have yet to be stopped due to sound. The FJ55 with the turbo'd 3B is also piped without a muffler and it too is quiet enough that way. I have run through AirCare stations with this configuration as well and I've never been hassled.
It has a nice throaty sound as well!!
 
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I don't have a turbo yet, I have to rebuild the Merc 300 turbo I got and install it. But for now I figured i might as well see what happens. I'll be buying a glass pack very quickly and installing it.
 
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Get the shop to make up a section of pipe the size of the glass pack with flanges and put flanges on the glass pack as well.
That way if you are hassled after you turbo you can always throw the glasspack back in for a re-inspection! It might save you a hassle later and it will make removing the glasspack when the turbo goes in easier.
 
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ran mine with a cherry bomb, being loud got old, but with a turbo you could probally get away with 3" straight exhaust all the way out. Theres a nissan turbo diesel in hervey bay with 3" straight pipe that apparently "whistles" at idle from the exhaust.
 

brownbear

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Crushers had a good point on here once about the 3" pipe....that it might not have enough pressure to keep water out. For that reason alone I am going to stick with 2.5 inch. So if at all possible if I am playing in a creek or seawater :lol: I have enough blow to keep the pipe clear............without the funny bong :) water purifier or whatever ............
 
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x2 on the atx with no muffler, not quite but reasonable. i was think of trying a muffler just to see, could save me some cash on stereo upgrades.
 

brownbear

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I hate noise. I had a new resonator installed on my Mercedes diesel and some pipe fixed. It has both a resonator and a muffler. Nice and quiet.

Not sure how I want to go with my exhaust. In about a month I am doing exhaust on my BJ60. Front to back, custom. I am going 2.5 inch and exiting in front or behind the drivers side back wheel. I'm a LHD so I want the exhaust exiting away from the sidewalk. Also it lets me see it while under load to see if I'm smoking any.
 
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Darryl, I like the sea water comment. As far as I know that lake had no salt. Once I get the turbo rebuilt I will redo the exhaust again, right now I only had time to make one out of parts from Crappy Tire and I hate their 90s. So once the turbo is in I will custom bend my own properly. As for exhaust ideas, I was never very happy with the clamp that attaches the exhaust to the engine (under the manifold), it kept vibrating off and then making an annoying noise. So this time I went off the flange with a 2" to 2.5" piece, to a flex pipe (proper with the wire mesh reinforcement) then to the 90s. This way it takes the stress off the manifold and flanges. I will stick with the set up of having it come out in front of the pass tire, less turns, less restriction, and not loosing any ground clearance. The original exhaust I ripped off on a trail because of that.
 
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i ran my 3B straightpiped barely past the front wheels when i first swapped it in. it was late and i was too tired to finish the exhaust. i only needed it to get me home, once, at at 2am.

what a heatscore, got pulled over twice in 16 km. engine braking down a long grade the second time scored me $440 in tickets! :doh:
 
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my '61 used to have two mufflers, one front small one and another at the back as big as a pillow almost. I had them both removed and it now has one small muffler, about 300mm x 150 and is as quiet as. the turbo certainly does take the sound out

cheers
gerard
 
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In my opinion - you hardly need a muffler with a 3B. I have been driving my BJ75 for 7 yrs with a straight through muffler. Its basically an expansion chamber with no baffles or anything.
My exhaust is 2.5" and the canister is 6" diameter and about 20" long. Its actually a race muffler made by dynomax.

There is no exhaust noise at all - more noise from the diesel rattle under the hood.
 
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So the glass pack is in, I picked up a unit from KMS (their auto dept) for $12, 19" long, 2.5" inside, 3.75" out. Low profile, purrs nicely and still can notice the extra power. At least now the cops won't harrass me.
 
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due to the fact that i want to go hunting this Autumn, i have had a DYNOMAX SUPER TURBO MUFFLER installed to what was previously a straight pipe. the result is a much quieter exhaust at the tip of tail pipe and no noticeable gain in egt's.

Dynomax :: Mufflers :: Super Turbo

Nice, I'll have to check that out for my BJ42 when I need pipe work. I forget the one I have on there now, but it is way too frappy. It is full time bikini top right now, and even with the pipe pointing out back it's too much some times for me. 2.5" following the stock routing, stock 3B (no turbo).

Aeroturbine 2525 on the BJ74, and HJ61, both 2.5": like that.

Had a 2.5" exhaust in Poo (13BT-BJ60) with no muffler at all, and it was not bad at all. The turbo certainly cuts much of the sound waves.
 
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sorry to bring up an old thread but I am soon to replace the exhaust on my BJ42 (3B turbo) and was hoping that cruiser_guy could tell me what size straight through pipe he had.... I'm happy for a nice growl from the exhaust. I'm sure it wont be anything like the volume I used to get with a high-flow system with no turbo...that thing was LOUD (it would set off car alarms as I drove by parked cars)
 

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