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Old 12-05-2000, 10:17 PM   #1
Keiho
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Post Wastegate dumping to atmosphere?

Quick question here. What's the difference between dumping back into the exhaust system and to the atmosphere? (besides the obvious!) Any gains? Disadvantages?

I was told that dumping to atmosphere, you'd get a cool "fireshow" at night when the wastegate is open?
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Old 12-05-2000, 10:33 PM   #2
Imprezer
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Yes, it does look and sound cool plus it is good for better exhaust flowing. But, you get noise which others might not like, things can melt and it is illegal since you are bypassing the cat/cats. If you do it, make sure to route the dump tube away from anything that could melt/burn.
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Old 12-06-2000, 04:31 AM   #3
SteveS
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Here's a clip of someone dumping to atmosphere:
http://www.twingles.com/ideck/mpg/dregrowl.avi


MMmmmm. I like it, but I'm not sure it's very streetable. I have a friend who is now dumping to atmosphere in his 95 GSX though.

SteveS
www.lagging.com
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Old 12-06-2000, 05:21 AM   #4
bender
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hey keiho, you need a turbo first, man hehehe
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Old 12-06-2000, 10:07 AM   #5
Keiho
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What do you mean by not that streetable? Too loud? Bad driveability?
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Old 12-06-2000, 11:30 AM   #6
SteveS
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It's loud and quite obvious, especially on upgraded DSM's that are usually pushing a lot of boost and the turbo is capable of pushing more. You have to hope they don't notice it at inspection (visual). It's only obvious under boost conditions, though...

MattC is dumping to atmosphere in his RS. Dunno if anybody else is.

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Old 12-06-2000, 01:45 PM   #7
Keiho
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Emissions where I am, I don't believe they do a visual check, just the tailpipe sniffing on a 4wd dyno which means the car will be under load. Will a setup of wastegate dumping to atmosphere still pass then? There is a hi-flow cat in the exhaust system.
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Old 12-07-2000, 04:17 AM   #8
SteveS
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If they're checking emissions, then they might have some type of visual check. They might look for a catalytic converter, for instance, and notice this weird pipe that goes nowhere.

If they romp on your car enough to build boost, which can really only happen under load, then the dump tube would open. In an enclosed space they'll definitely notice your exhaust leak!

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Old 12-07-2000, 04:47 AM   #9
wac
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Keiho,

You might be lucky, because as you may already know, AirCare testing stations work by the book. They stick a sniffer in the exhaust pipe. Even if there's a leak somewhere upstream, the only readings that count are those at the tailpipe. Is that still the case? Or have they added a visual check now?

OTOH, if your high-flow cats aren't up to snuff, you may even fail AirCare. When are you getting the turbo? Good luck!

-WaC
Wayne

[This message has been edited by wac (edited December 07, 2000).]
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Old 12-07-2000, 09:09 AM   #10
Keiho
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wac - were you from Vancouver originally? I believe they still go by the book, that is a visual can't fail a person. I HOPE so anyway, I don't recall them doing any serious visual checks. All they look for I believe is the presence of a cat.

Turbo? Who said anything about me getting a turbo? I'm just curious that's all.
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Old 12-07-2000, 09:13 AM   #11
efoo
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i've got an open wastegate that dumps to atmosphere. and I'm going to get it routed back into the exhaust next week. it's just too darn loud - you're not just bypassing the cats, by the way, you're obviously bypassing the muffler!

Everyone within a block radius knows when i've reached maximum boost in my car. WaC can testify to that quite handily - he heard me build boost in parking garage and was complaining about my car for quite a while afterwards. For a race car it may be worth it and sound cool, but not for my street car.

-Edwin
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Old 12-07-2000, 09:41 AM   #12
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Maybe I'll take some pictures one day, see if its possible to reroute it back into the system.
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Old 12-07-2000, 10:02 AM   #13
Tim Prudence
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Why not weld a small muffler (like one of those "cherry bombs") on the dump tube. That would go a long way for inconspicuousness.
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Old 12-07-2000, 06:37 PM   #14
wac
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Let me tell ya, I sure don't miss photo-radar!

Edwin's wastegate sounds like someone blowing into a trumpet as hard as possible. Which results in a dissonant blare that's as loud as college football bands. Simply annoying, I must admit.

-WaC
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Old 12-07-2000, 07:56 PM   #15
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I don't find it nearly as annoying. Wayne, you have also heard my car. Is it as loud as Edwin's? I personally love the sound. It only gets annoying when I am on the highway. The only reason I am thinking of routing it back into the downpipe, is it might be screwing the reading off the O2 senor. I believe Edwin is seeing the same problem.

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Old 12-08-2000, 04:44 AM   #16
wac
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I only heard Matt's car at a Philly Region auto-x, and it isn't as loud and obnoxious as Edwin's. It could be that the course never allowed him to stay on the wastegate long enough? I never got on boost for more than 1-2 seconds at a time on that course (well, the car wasn't tuned properly either).

Also, I believe Matt has a Deltagate, while Edwin has a Tial.

-WaC
Wayne
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Old 12-08-2000, 06:33 AM   #17
efoo
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well, it doesn't matter... i'm having my wastegate rerouted back into the exhaust very soon. can't take it any more - under long periods of boost (like a 5th gear WOT TEC-II tuning run), I can barely hear my passenger screaming at me.

-Edwin
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Old 12-08-2000, 10:57 AM   #18
Keiho
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"The only reason I am thinking of routing it back into the downpipe, is it might be screwing the reading off the O2 senor. I believe Edwin is seeing the same problem."

Would throwing the reading off the O2 sensor be bad? What would happen? Could it be what might be throwing on my AT oil temp light? (I've got another post here on powertrain)
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Old 12-08-2000, 11:35 AM   #19
NateP
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Another advantage of the dumping the WG to atmosphere is that it gives the effect of having a larger exhaust system them you actually do. Let's say you have a 2.5" downpipe, high-flow cat, and cat-back. If you dump the WG gasses to atmosphere, that makes it so that less gasses have to go through the exhaust system, so the turbo will actually be able to push more air through the exhaust system since the WG gasses aren't being routed back in and taking up space.
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Old 12-08-2000, 11:54 AM   #20
Keiho
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Ah, never thought of it that way. Right now I'm still running the NA size 2.25" midpipe that opens to a 3" Blitz muffler.
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