To Dump or not to Dump, that is the question. - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 02-18-2009, 11:25 AM   #1
Senior Member
Thread Starter
iTrader: (4)
 
Join Date: Oct 2006
Location: Tampa
Posts: 780
Total Cats: 0
Default To Dump or not to Dump, that is the question.

A little background.
I am thinking of getting a smaller T3 to put on the car. Right now I have a T3/4 that, I want to say is a 50 trim with a 60 Compressor and a .48 turbine. I need to measure the wheels to be sure, but they are huge compared to the T3 I that I am looking at now. Anyway the turbo itself is big, and since this was my 1st set up I learned my lesson regarding spool. The new T3 is the same 5 bolt pattern, and I was thinking of going with a Vband flange instead of the flange welded to the dp. Here is the question. If I redo the dp for vband, should I make the external wastegate open dump, or should I route the gases back into the dp? Any benefits to the open dump? Thoughts?
96rdstr is offline   Reply With Quote
Old 02-18-2009, 11:32 AM   #2
Hear me Meow
iTrader: (3)
 
skidude's Avatar
 
Join Date: Apr 2008
Location: Outside Portland Maine
Posts: 1,994
Total Cats: 13
Default

I've heard very mixed things on the open dump pipe. things like "It sounds wicked ******* sweet, dude" and "It sounds like total ***, like a really fat guy farting into a megaphone"

I would imagine it helps performance but I don't know how much.
skidude is offline   Reply With Quote
Old 02-18-2009, 03:01 PM   #3
Elite Member
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,797
Total Cats: 248
Default

Route the EWG back to to the exhaust system. Several reasons to do so.

1) Open dump tube is loud as ****. If it's a street car, noway.
2) Open dump is a bit more dangerous. Best is to route it to underneath the car, which takes more work.
3) Open dump can cause some exhaust gases to be picked up by the intake, causing less oxygen in the mixture. While there are dyno proven results that show an open dump helping HP, there's also some where hooking the dump back to the exhaust or routing it further from the intake made more HP.
4) Still loud as ****

Now, if you hook it back to the exhaust, it's quieter, and a bit safer, possibly more powerful, possibly less powerful, depending on how comparable dump tube was installed. Granted it will disrupt the flow in the exhaust some. How much, depends. But IMO it's not the end of the world. Best thing to do here is to have it separated as long as possible, and have it dump in at a angle close to parallel with the exhaust.

If it was a race car, I'd have a long dump tube that dumped under the car. If it was anything else, it would have a long tube that tied back into the exhaust smoothly. Mine ties back in after like 5", and it's practically 90* perpendicular to the exhaust. Not ideal at all. Works fine though, car hauls ***, so...
patsmx5 is offline   Reply With Quote
Old 02-18-2009, 03:30 PM   #4
Elite Member
iTrader: (12)
 
Join Date: May 2007
Location: Austin, TX
Posts: 1,923
Total Cats: 0
Default

During regular driving running an open dump tube is no louder than any other setup.

As for the 1-4 that Pat listed, I disagree on all of them. But if you're like him and want your car to be as quiet as a Camry, then an open dump isn't for you either.
JayL is offline   Reply With Quote
Old 02-18-2009, 07:08 PM   #5
Senior Member
iTrader: (1)
 
Join Date: Mar 2006
Location: Tucson "it's 110" Arizona
Posts: 1,017
Total Cats: 0
Default

Quote:
Originally Posted by 96rdstr View Post
should I make the external wastegate open dump, or should I route the gases back into the dp? Any benefits to the open dump? Thoughts?
Look for videos, then decide. On my non-miata DD, I'm currently rerouting the external dump back into the downpipe. The turbo just sounds too good to me, and I really dislike the attention it demands.

Benefits to external dump are more power (how much depends) and better boost control, which is very possibly not a concern. Another benefit is simpler routing/design.

A couple things to note: Normal driving is the same, of course. As you approach full boost, the gate begins to open and the noise increases. It's loud. Will it be too loud? That depends on you and you only. And possibly your girlfriend. It will be louder than your exhaust and turbo. One time I opened it up to merge, the gate opened, and a nearby jogger nearly fained. Not a joke. If I was younger, or more of a dick, it would be funnier. For me, it's too much.

You can help quiet the dump tube by extending it. (Test this by pulling off the tube completely and listen at full boost.)

How loud the dump tube will be also depends on how much boost you are running on what turbo. Less boost = loud-*** external dump. More boost = quieter external dump. This is because more exhaust is routed through the turbo hotside to maintain more boost, thus less is expelled out the wastegate. Less exhaust, less noise.

Going to re-route it back into the downpipe? Try to do so a couple feet downstream in the exhaust. I've heard 18" tossed around. Will you lose power? Depends on the info above mainly, but you're really not loosing that much anyway you look at it, even with the exhaust reintroduced at a "bad angle." Are you running a cat? Reintroducing the exhaust into a turboback with a cat forces all the exhaust to travel through it, instead of a partial amount. This is also true with the turboback. Running 3" exhaust? Dumping will provide you slightly less benefit than if you are running a restrictive stock exhaust.

I've found that the external dump is really only great for one thing (not counting ricers), and that's Harleys. Harleys are loud to be loud, I don't like that. When they open it up full throttle in my window, I like to return the favor.
UofACATS is offline   Reply With Quote
Old 02-18-2009, 08:53 PM   #6
Elite Member
iTrader: (12)
 
Join Date: Jan 2007
Location: Hermosa Beach, CA
Posts: 2,575
Total Cats: 11
Default

I agree with Jay, pat has some weird thing about his car being quiet as ****..

Dump it

1) Its only loud when you are at full throttle.

2) If you dump it under the car it wont "mix" with the intake like pat said...

3) It will help power, and help boost control

4) It takes way less work

5) It sounds awesome!
cardriverx is offline   Reply With Quote
Old 02-18-2009, 09:26 PM   #7
Newb
 
Join Date: Mar 2008
Posts: 19
Total Cats: 0
Default

I went open dump last year..I will never go back, the sound is off the hook..also picked up 25whp at 22psi
50trimrecord is offline   Reply With Quote
Old 02-18-2009, 09:51 PM   #8
!!! NOT CONFIRMED !!!
 
Join Date: Feb 2009
Posts: 53
Total Cats: 0
Default

I have had one open, by the way its just awesome. I loved it.

But it does put much more heat and exhaust in the engine bay, if it is opened up and not rerouted.
WESamiss is offline   Reply With Quote
Old 02-18-2009, 10:48 PM   #9
Elite Member
iTrader: (12)
 
Join Date: Jan 2007
Location: Hermosa Beach, CA
Posts: 2,575
Total Cats: 11
Default

Quote:
Originally Posted by WESamiss View Post
I have had one open, by the way its just awesome. I loved it.

But it does put much more heat and exhaust in the engine bay, if it is opened up and not rerouted.
lol not routing the gas under the car would be semi retarted.
cardriverx is offline   Reply With Quote
Old 02-18-2009, 10:50 PM   #10
Elite Member
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,797
Total Cats: 248
Default

Quote:
Originally Posted by cardriverx View Post
lol not routing the gas under the car would be semi retarted.
And I've seen it done so many times.... Mainly the FWD honda crew. Love to bolt an EWG to a manifold and let it blow down on the radiator/block/right next to the air filter. Hence why I said what I said earlier.

And not my fault you guys haven't developed an appreciation for a quiet car yet.



patsmx5 is offline   Reply With Quote
Old 02-18-2009, 11:03 PM   #11
Former Vendor
 
Join Date: Dec 2007
Location: Texas Hill Country
Posts: 271
Total Cats: 16
Default

Get the best of both configurations; put a small muffler on the wg dump. Glass packs come in all sizes and shapes.
Corky Bell is offline   Reply With Quote
Old 02-18-2009, 11:04 PM   #12
Elite Member
iTrader: (12)
 
Join Date: Jan 2007
Location: Hermosa Beach, CA
Posts: 2,575
Total Cats: 11
Default

Quote:
Originally Posted by patsmx5 View Post

And not my fault you guys haven't developed an appreciation for a quiet car yet.



Psh there is a reason to have a separate DD. When I romp on my miata I want it to growl . Plus I never got how you dont like the intake sound lol!
cardriverx is offline   Reply With Quote
Old 02-18-2009, 11:35 PM   #13
Junior Member
iTrader: (1)
 
Join Date: Oct 2008
Location: Edmonton, Alberta
Posts: 86
Total Cats: 0
Default

I thought about it...but it sounded like *** imo.
aphongt is offline   Reply With Quote
Old 02-18-2009, 11:46 PM   #14
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,684
Total Cats: 1,562
Default

Where did all of these noobs come from and why don't they have any location info under their names or car info in their signatures?

I like the open wg sound on other people's cars, but mine needs to be quiet.

Edit: FWIW, I guess you could tell pretty quick if your wg was leaking or creeping open early if it was open.
sixshooter is online now   Reply With Quote
Old 02-19-2009, 12:04 AM   #15
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Lexington, SC
Posts: 2,084
Total Cats: 0
Default

Quote:
Originally Posted by Corky Bell View Post
Get the best of both configurations; put a small muffler on the wg dump. Glass packs come in all sizes and shapes.
it would be like having a moped under the hood

I know what your saying pat about some people dumping all that shiz under the hood. I've got a friend who dumps it between the rad. and motor
mazda/nissan is offline   Reply With Quote
Old 02-19-2009, 12:29 AM   #16
Junior Member
 
Join Date: Sep 2007
Location: Brisbane, Australia
Posts: 112
Total Cats: 0
Default

Screamer pipes sound awesome when you come on boost, but at the same time it is probably way too loud for a road car, and yes I know its only when you come on full boost. I guess it all depends on what the local law enforcement are like, if I were to go out with a open screamer and give it some I would more than likely have a cop pulling me over within seconds. Around here all he would have to do is take one look and ask me if I brought a bottle of KY with me cos he is going to bend me over the boot and **** my arsehole and that doesn't appeal to me much at all.
zoomzoom is offline   Reply With Quote
Old 02-19-2009, 12:56 AM   #17
Senior Member
iTrader: (1)
 
Join Date: Mar 2006
Location: Tucson "it's 110" Arizona
Posts: 1,017
Total Cats: 0
Default

Quote:
Originally Posted by sixshooter View Post
Edit: FWIW, I guess you could tell pretty quick if your wg was leaking or creeping open early if it was open.
It will also tell you if you've developed any significant boost leaks.


Quote:
Originally Posted by 50trimrecord View Post
I went open dump last year... picked up 25whp at 22psi
Sounds about right. Are you running 3" exhaust/cat?
UofACATS is offline   Reply With Quote
Old 02-19-2009, 10:40 AM   #18
Newb
 
Join Date: Apr 2008
Location: Northern VA
Posts: 31
Total Cats: 0
Default

I have about 18" of pipe running from my external wastegate that dumps out under the car, no merge with the 3" exhaust.
It's startling when it cracks open the first time, now I'm ALMOST use to it.
I wouldn't say that it sounds "good" but it kinda gets lost in the induction and exhaust noise, which sound awesome (3" all the way from turbo flange to tail pipe). I purchased enough pipe to run the WG line all the way to the rear but by the time I was finished with the exhaust I didn't feel like welding anymore, for a little while anyway.

However, I seem to have settled on 18psi for my boost target, so I only hear from the wastegate when I'm indulging in the blatant disregard for all traffic laws (the heat will be more interested in my rate of travel than my noise level). Under "normal" driving conditions the WG is never heard from and very seldom during aggressive driving (that doesn't result in extra-limit excursions in a hurry).
I will say that IF I was to set my boost target such that the WG duty was increased anywhere near my normal driving range, I would muffle it in some way, either merge it with the exhaust or run it all the way out the back.
wroark is offline   Reply With Quote
Old 02-19-2009, 11:57 AM   #19
Senior Member
Thread Starter
iTrader: (4)
 
Join Date: Oct 2006
Location: Tampa
Posts: 780
Total Cats: 0
Default

Good input guys. I looked at YT videos with DSM's with open dumps and so on. I need to hear it in person.

One more thing. I like quiet when cruising and driving around town under light loads. I don't need to be in boost all the time, but when I am in full boost, having the wrath come out isn't a bad thing. That is why I like my HKS SSQ BOV. Under full throttle and lift that thing screams "don't eff with me bitches". I love it.

Thanks for all the input. I am snagging that new turbo this weekend. I guess the outcome will depend on how motivated I get.
96rdstr is offline   Reply With Quote
Old 02-19-2009, 11:59 AM   #20
Hear me Meow
iTrader: (3)
 
skidude's Avatar
 
Join Date: Apr 2008
Location: Outside Portland Maine
Posts: 1,994
Total Cats: 13
Default

Quote:
Originally Posted by 96rdstr View Post
One more thing. I like quiet when cruising and driving around town under light loads. I don't need to be in boost all the time, but when I am in full boost, having the wrath come out isn't a bad thing. That is why I like my HKS SSQ BOV. Under full throttle and lift that thing screams "don't eff with me bitches". I love it.
I like this too, but I'm having the dilemma of mine being a little too loud around town, but just right in full-fun-mode.
skidude is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
MS PNP requires reading and following directions??? satisfied MEGAsquirt 141 10-06-2015 11:44 AM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 11:28 PM
I hate this... SGTZ28 Insert BS here 69 09-11-2015 05:32 PM
What to do about scored cam journals? Joe Perez Engine Performance 12 09-01-2015 11:16 PM
A couple DIY questions Dow.tom DIY Turbo Discussion 61 04-19-2007 01:08 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 08:18 AM.