Single Turbo RX-7's Questions about all aspects of single turbo setups.

Engine bay noise... exhaust leak, or normal?

Old Nov 20, 2016 | 01:20 AM
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From: Japanabama
Engine bay noise... exhaust leak, or normal?

My engine is really loud. It almost sounds like I have an exhaust leak, but I wonder if it's normal for single turbo cars with:

1. wastegate dump pipes

2. tubular manifolds

3. no cats

4. loud racing exhaust

So is it normal for the exhaust pulses to be loud, or might I have an exhaust leak?
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Old Nov 20, 2016 | 02:32 AM
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My Turbo setup was so quiet you could hear the injectors clicking.
You got an exhaust leak my friend
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Old Nov 20, 2016 | 03:21 AM
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Did your wastegate have a dump pipe?
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Old Nov 20, 2016 | 07:08 AM
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Time to get the old listening tube out. A short length of fuel or heater hose jammed in your ear hole and used like a stethoscope and all will be apparent.
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Old Nov 20, 2016 | 07:22 AM
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the open dump wastegates only come into play when at boost. you probably have a leak, but you could also have an open exhaust so loud it makes you think it has a leak.... post pix
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Old Nov 20, 2016 | 07:28 AM
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I had actually considered doing that. Will try it with some vacuum hose as soon as my turbo oil hose gets fixed...again. That's what I get for letting my mechanic use the old fittings instead of buying a new hose from Greddy.
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Old Nov 20, 2016 | 10:58 AM
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When I did have an exhaust leak it was due to using the old Manifold to engine gasket..
It was like Pukka,pukka,pukka....
In a pinch I took a sheet of exhaust gasket material and doubled up on the gaskets there (stock metal gasket and coated metal stuff).It stopped the leak so effectively that I didn't go back and fix it correctly..lol..(besides you always have other things to do on these cars!)
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Old Nov 21, 2016 | 04:50 AM
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Very common for cars that are not street use, to develop exhaust leaks. Plugging the exhaust outlet and doing a smoke test is the best way to rectify them, rather than guessing location.
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Old Nov 21, 2016 | 05:14 AM
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From: Japanabama
Originally Posted by billyboy
Very common for cars that are not street use, to develop exhaust leaks. Plugging the exhaust outlet and doing a smoke test is the best way to rectify them, rather than guessing location.
Smoke test using what?
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Old Nov 21, 2016 | 01:05 PM
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Originally Posted by Valkyrie
Smoke test using what?
There's such a thing as a smoke test machine, assume they're over there too - although people have done, roll your own, DIY versions.

Basically, machine is connected to power and low pressure regulated air, a rubber cone is inserted in the end of the exhaust with a hose from the machine carrying said air with the generated smoke and presto, exhaust leaks are identified quickly and easily.
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Old Nov 21, 2016 | 06:45 PM
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Originally Posted by billyboy
There's such a thing as a smoke test machine, assume they're over there too - although people have done, roll your own, DIY versions.

Basically, machine is connected to power and low pressure regulated air, a rubber cone is inserted in the end of the exhaust with a hose from the machine carrying said air with the generated smoke and presto, exhaust leaks are identified quickly and easily.
That's what I thought. I don't have a compressor, though...
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Old Nov 21, 2016 | 07:31 PM
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Listening tube will pin point it well enough.
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Old Nov 21, 2016 | 07:45 PM
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California smoke test procedure:

step one: Take giant bong hit.
step two: blow it out around the exhaust mani while the car's running. If it doesn't look like its being blown back at you, jack the car up and see about that down pipe.

Repeat steps 1 and 2 until exhaust leak is found or you no longer care about it.
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Old Nov 22, 2016 | 03:31 AM
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Originally Posted by Natey
California smoke test procedure:

step one: Take giant bong hit.
step two: blow it out around the exhaust mani while the car's running. If it doesn't look like its being blown back at you, jack the car up and see about that down pipe.

Repeat steps 1 and 2 until exhaust leak is found or you no longer care about it.
I like your thinking..I think?...

makes me Think!...

Ok..thought!..what about using a E-SMOKE?..put the mouthpiece to a vacuum line?..It creates "smoke per say".

(also another thought: why do they call it a "Bong"?..when you get Buzzed after using it?)
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Old Nov 22, 2016 | 06:51 AM
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Originally Posted by misterstyx69
I like your thinking..I think?...

makes me Think!...

Ok..thought!..what about using a E-SMOKE?..put the mouthpiece to a vacuum line?..It creates "smoke per say".

(also another thought: why do they call it a "Bong"?..when you get Buzzed after using it?)
That ironically might the be best solution. And almost certainly cheaper than buying a professional smoke checker. It could also be used for vacuum leaks or even for drafts in your house...
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Old Nov 24, 2016 | 01:22 AM
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Seeing as how I've already done three track days with it like this, one more won't hurt, right?
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Old Nov 25, 2016 | 09:19 PM
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It turns out there was a big gap between my downpipe and midpipe. Guess I gotta go find a new gasket.
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Old Nov 26, 2016 | 01:29 AM
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I always find it handy to have Gasket material in my "box of tricks"..
I bought some exhaust gasket material and have made numerous pipe and manifold gaskets for these cars and saved..honestly,100's of dollars doing so.
My intake gaskets for my FC lower to FD upper were made by yours truly and that car was nuts!
Nothing beats paper and a ball peen hammer..lol!
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Old Nov 26, 2016 | 02:47 AM
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The front pipe and midpipe seem to be pretty badly aligned. But I still have some sort of exhaust leak somewhere else. Probably the manifold...
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Old Nov 27, 2016 | 12:22 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by Valkyrie
The front pipe and midpipe seem to be pretty badly aligned. But I still have some sort of exhaust leak somewhere else. Probably the manifold...
when i put my turbo car together it was louder than the P port, and when i took the fun exhaust off to put the stock one on to smog it, i took some 80 grit sandpaper to the flanges and found them to not be flat.

so once it passes smog shortly, i'm hoping the fun exhaust is much quieter, although it did drown out the diff, so it wasn't all bad
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Old Nov 27, 2016 | 07:44 PM
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I mean the flanges were at physically different angles. I had to jack up the front pipe a bit (probably a bad idea) to get them to match up. I will probably have to get the entire exhaust system reinstalled to fix the leaks and the tendency to leaky.

And get my rotten floor pan fixed while I'm at it...

One of the bolts was actually loose when I found the leak, so I'm hoping it was just a lack of torque that let the leak form.
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Old Dec 10, 2016 | 12:48 AM
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I take that back, MOST of the exhaust leak sound was from my intake manifold. The shitty ACV block-off plate I had made had come off.
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