2.5, 2.75, or 3” Exhaust for new 95-97 Wit’s End Turbo? (1 Viewer)

HDJdreams

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The exhaust on my 97 is shot. Especially where the pipe goes over the crossmember by the rear axle, that has pounded itself almost flat after the exhaust mounts wore out. (Mounts have been repaired)

When @NLXTACY turbo arrives :clap:, I will need a new exhaust. I was hoping to use @OTRAMM SS work of art, but I can’t give up the 2nd cat. :crybaby:

So is there any other quality, quiet, high clearance and high flow systems currently for 95-97s? I just need 2 cats and the O2 sensors in about the factory location.

Or does anyone have a recommendation for a good exhaust shop near Provo/Orem?

Does anyone have a recommendation for a QUIET high flow 2.5” muffler? (I once had to get a “turbo” muffler to get the car through inspection ($150 vs $800 quote). It was awful, replaced it a few months later when I found a more economical OEM style muffler.
 
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Why don’t you just find a reputable exhaust shop near you? A guy local to me made a custom y pipe for me so the exhaust is inside the frame, no cats, and I have 2 30” flowmasters on it. Came out great.
 

HDJdreams

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Title Edit: since the consensus seems to have built locally, I tweaked the thread title.

What’s the best pipe size for Turbo back exhaust @NLXTACY @scottryana and other 1FZ turbo owners (? @LandCruiserPhil )?

I THINK it’s 2.5”. This was debated somewhere in the 120 pages of Joey’s thread. I THINK the actual turbo owners/designers recommended 2.5” but there’s SO MUCH speculation and chit chat in that thread, hard to find needles in the haystack.

Has anyone with a forced induction 1FZ went bigger, like 2.75 or 3” AND regretted it? I.e., do I lose anything by using 2.75? Or even 3”? (Other than routing issues).

Cost should nearly be the same. My logic is go to the largest diameter I can use effectively if (when) the turbo system gets upgraded. (Intercooler at a minimum)

So @scottryana and @NLXTACY what say you?
 
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On a turbo car you usually want the most free flowing exhaust possible. It helps relieve the back pressure on the turbo and allows for a quicker spool and/or more boost. BUT since there isn’t going to be any fuel or ignition changes with the turbo kit I have been recommending that people stay with the stock sized exhaust with something that approximates the stock back pressure so that they don’t experience any issues with the turbo setup. If you do go to a 3” free flow exhaust just be aware that you will have to check your boost levels and AFR’s since it will be possible you could see higher boost than expected.
 
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I have 3" SS for my 5.9 6BT, my only regret is that it isn't 4"...

Anyways, 3" will fit under an 80 series fine, if your gonna spend the money do it once and be happy, the better the flow past the turbo, the more pressure differential, the quicker/easier it is to spool it up.

It's an apples to oranges comparison (I know) but when I added about 4 feet to the exhaust to take it from the rear axle to the rear of the truck I noticed a difference in the turbo spooling up not as quick and the thing sounds different.

A turbo does knock the exhaust sound a bit, and adds its own sound to the mix of things too, but with a turbo a restrictive exhaust has a larger effect on performance than a normally aspirated power plant in my experience.
 
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A couple of years ago near the end of my first round of “reviving the wife’s 80” I built a 2.5” SS exhaust leaving room for cats if I ever was to move to a state that requires them.

I built it with elbows and scrap I have saved from my work where we build liquid bottling fillers and rinsers.

It took a lot of trying, marking and taking the parts back to work to tack, take back home, and back to work for final welding.

I routed the exhaust up over the frame where the early 80s went and used a full 2.5 in and out SS truck muffler from my local NAPA. I think it’s a Walker, but I’ll check with my store manager when I get back to life next week.

I made my own three-bolt flanges based on common exhaust gaskets.

Once I get back to re-reinstalling the engine I will finish routing the exhaust further back towards the rear bumper.

For anyone not in my line of work who would like to find similar scrap stuff find a local dairy service that has piles of the stuff laying outside their shop. Nice smooth bends. It only requires a decent TIG setup and argon to purge the inside of the tubing.
 
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mudgudgeon

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IMG_20170430_124037.jpg


4" into 3" I built for turbo HZJ105 to run inside the frame rail from front to rear
(Frame and drive train is more or less the same as 80 series)

I used 6x9x18 full flow 3" magnaflow behind the t-case, and a 6x16 full flow 3" muffler at the rear.
The result, a free flowing exhaust that is very quiet. You still hear the turbo noise, but no drone.
The turbo cuts out a lot of exhaust noise by blending the individual pulses

Takes a bit of careful work to get 3" pipe past the t-case, and over the frame at the rear diff, but is achievable.
 

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