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Discussion Starter #1
ok so the turbo dumps out the side of the bike with a short pipe , so why cant i run it out the back through a set of cans , as a car of or truck runs through a muffler . im guessing its something so obvious im gonna feel dumb , but i dont know , i thought of gutting out the cans , and run it through the back for the look, and maybe so its not so obvious that im running a turbo , ideas ???????????????/
 

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Don't feel dumb. It's a good question, with a long, technical answer.

I've had a twin turbo 300ZX for years and this is a common question. The answer really depends on the design of the system, spring rate of the waste-gate, diameter of the exhaust, flow rate of the turbo, overall tuning and a metric shit-tonne of other variables.

Most turbos are setup to dump right into the exhaust pipe next to the turbine outlet, but this causes turbulence and slows the exhaust gas, effectively restricting flow. Your system vents to a short pipe to avoid that turbulence.

Race and performance systems usually have a "Y" pipe that separates the waste-gate from the exhaust turbine, reducing the turbulence. But, if the pipe is too long, you run into flow and back-pressure issues with the waste-gate...too short & you get turbulence again. When the "Y" is the right length and diameter, you get a venturi-effect that pulls the exhaust from the waste-gate and pushes it out through the tail pipe.

If you ran a pipe all the way to the back of the bike & a muffler, the waste-gate won't dump enough and pressure will build in the pipe faster than it can be released, robbing performance. You also run the risk of overboosting and causing performance problems (and potentially damaging the turbo) that you would see with a failed, always closed waste-gate.

Long story, short: unless you have the software and equipment to R&D a system, you're best leaving it as-is.
 

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Here's an example of the "Y" pipe for turbo on my Z. On the left side, at the bottom, you can see an "I" shaped block that separates the waste-gate from the turbine when it's bolted up to the turbo.



Here's a picture of the "I" shaped block sitting in between the waste-gate and turbine.

 

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You could leave the wastegate dumping to atmosphere(like it is right now I assume) and build an exhaust for the turbo exhaust side only. How my STi is setup. The wastegate dumps straight down to ground yet I have a 4" diamater downpipe that tapers to 3" right at the far flange of it. That bolts to the long midpipe which has the factory 02 sensor in it(my wideband sensor is in downpipe) and is actually 2 long sections bolted together for ease of removal/install instead of a 4ft 1pc 3" diamater pipe. Then at my car's rear axle is the 3" diamater tubing muffler.
That way, until wastegate opens, car is somewhat quiet since the turbo's exhaust flows through a high flow muffler. My WG spring pressure is a 19psi spring. So until I see 19psi or more it sounds like a normal loud turbo car.
But, once over 19psi the wastegate opens and those exhaust gases are expelled through a dump tube(about 1.5 feet long) and is LOUD as hell. There is still gasses going through muffler, but the excess above 19psi are going out the wastegate straight to atmosphere. Car goes from loud to REALLY REALLY REALLY FREAKIN LOUD.
Cool factor of being discreet below 19psi or whatever you set you WG spring pressure to. Needs to be tuned for what ever spring/springs you use. Once you are tuned on a turbo setup, you CAN NOT change anything at all. Even changing the muffler will alter your fuel trims so decide before getting tuned. But my set up is pretty common any more because there is power gained by not having the WG mix with regular exhaust because of terbulance like mentioned.
 

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On second thought, if you just want the look, you could always go the Honda-Civic-dual-muffler-method of useless exhaust cans...

Take a saw-z-all and cut your stock header pipe just in front of the lower mounting point, where it bolts to the bottom of the frame. Use that short end and attach it to your choice of slip-on and bolt it together. Now you'll have a pipe coming up out of the belly-pan, running to a muffler and it's purely decoration. Gut it for weight savings.
 

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Here is same car I have and same waste gate setup(external from exhaust)

Listen when the WG opens.
 

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On second thought, if you just want the look, you could always go the Honda-Civic-dual-muffler-method of useless exhaust cans...

Take a saw-z-all and cut your stock header pipe just in front of the lower mounting point, where it bolts to the bottom of the frame. Use that short end and attach it to your choice of slip-on and bolt it together. Now you'll have a pipe coming up out of the belly-pan, running to a muffler and it's purely decoration. Gut it for weight savings.
Not helpful to the guy man.

He can keep the waste gate venting to atmosphere for no turbulance/great power under high boost and have an exhaust system out the back or side of bike like a non turbo bike to keep it more quiet/stealthy, gain way more low/mid horsepower and TQ because his bike would now have some back pressure having some kind of a can on there. Plus with having a exhaust system, he can mount a wideband gauge to monitor AFR which is critical on boosted motors.
 

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On second thought, if you just want the look, you could always go the Honda-Civic-dual-muffler-method of useless exhaust cans...

Take a saw-z-all and cut your stock header pipe just in front of the lower mounting point, where it bolts to the bottom of the frame. Use that short end and attach it to your choice of slip-on and bolt it together. Now you'll have a pipe coming up out of the belly-pan, running to a muffler and it's purely decoration. Gut it for weight savings.
Took my slow tired ass a minute to actually picture this and yeah, that would wok. But I wouldn't gut the muffler and I would just keep the dump tube on the wastegate seperate.
 

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Not helpful to the guy man.

He can keep the waste gate venting to atmosphere for no turbulance/great power under high boost and have an exhaust system out the back or side of bike like a non turbo bike to keep it more quiet/stealthy, gain way more low/mid horsepower and TQ because his bike would now have some back pressure having some kind of a can on there. Plus with having a exhaust system, he can mount a wideband gauge to monitor AFR which is critical on boosted motors.
Agreed, on all counts. Just having some fun. :badteeth:
 

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But you are on right track though.

If he buys a pipe that he likes in stainless steel(not Ti because of how hard/expensive to weld) like a comp werkes which is cheap. Then takes bike, the comp werkes pipe to a custom exhaust shop(google for one in his area) and tell them to do what I said which is actually similar to what you were joking about.....Have the custom shop weld up a down pipe and mid pipe from turbo outlet to the comp werkes which everyone knows where that mounts on our bikes. Then have the waste gate's seperate dump tube either shortened to hid better or lengthened to run along under belly of bike to hide better. Keeping that wastegate dump SEPERATE from the actual exhaust and voila, he has what I paid a shit ton of money for. And for just a couple hundred bucks. $339 for the comp werkes pipe. another $50-$80 worth of 304 stainless exhaust piping, maybe $150 for labor too at the custom exh shop and he has a bad ass setup, a freakin external wastegate setup on a bike!!

I paid $700 for my entire wastegate setup. That included the Tial 44mm wastegate, dump tube, 19psi spring rate, uppipe(which is a jig welded custom for the STi). Then I had already paid the $1k for my turbo back exhaust( 4" downpipe diamater/ TXS catless race system w/RFL muffler).
He can do it on his bike for 15% of that cost!!!!!!! And would be sick as hell and NOBODY else would have that shit on any bike out there.
 

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Discussion Starter #13
thats perfect , i have access to stainless pipe and i can tig weld stainless myself , so i have to keep the waste gate seperate and just let it dump , man thanks guys , i think it would sound sick with a big blow off valve and the turbo exhaust ran out the back , my turbo kit is being built right now i have to wait for it to get here but im so friggin pumped its gonna be a nasty zx10r when its done , Im not gonna chop the bike all up i want it to look like a zx10 , i will post pics and vid of the bike as the turbo goes on and when i crack the throttle on it
 

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Discussion Starter #14
ok so what about the blow off valve ? any suggestions ? i want a loud blow off valve , i love the sound
 

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HKS super sequential BOV sounds the best to me and its definitely loud enough for everybody to hear. They're pretty expensive but you can buy a knock off super sequential on ebay for around $80. That's what i run on my 2jz and works well for me.
 

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Discussion Starter #16

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I hate you.....jk

like neverending, i have have an SRT-4 with the dump tube setup and love it. i kept telling myself i would not turbo my 10r but the more i see these turboed, the more im tempted.. bike looks good man
 

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Discussion Starter #18
thank you . believe me it took allot of work getting the bike done . unless you have access to a full mechanic shop dont attempt it . it was a pain in the a.. the whole way . but omg if you think a stock 10 is fast this will flat out make you think about how fragile life really is in essance it will scare the shit out of you
 

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Not helpful to the guy man.

He can keep the waste gate venting to atmosphere for no turbulance/great power under high boost and have an exhaust system out the back or side of bike like a non turbo bike to keep it more quiet/stealthy, gain way more low/mid horsepower and TQ because his bike would now have some back pressure having some kind of a can on there. Plus with having a exhaust system, he can mount a wideband gauge to monitor AFR which is critical on boosted motors.
I thought the turbo when not making boost was enough of an obstruction to the exhaust to work as full exhaust. With the limited room on a bike you can't feasible get a large enough diameter pipe to flow effiecently when making boost on the top end.

With the turbo mounted in the standard position wouldn't you have to make some pretty tight bends and sharp angles to get the exhaust back under the bike to run under the oil pan. Or you you would have a pipe hanging out of the fairings and running back but it would be a huge burn hazard and look pretty getto.
 

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A turbo muffles the exhaust note a little bit, but not the sound level overmuch. A snail with a dump pipe is pretty damn loud when it's wide open, though it is fairly mellow at idle.

I did my Concours with an internally gated turbo and a downpipe back to the factory exhaust location. It worked great, and it fit 99% under the fairings. You do have to be really careful with turbine sizing and down-pipe design, or bad things can happen. But it's very do-able and nice when done right.

That said, screamer pipes on high boost stuff are awesome. Juvenile, anti-social, loud, and just plain awesome. I help out a friend with an SRT-4 as well, and that thing sounds like all hell breaking loose at 25psi; wastegate venting, tires spinning, compressor noise, the great exhaust note it has... one of the most unique sounding cars I've ever been around. :)
 
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