Mazda 6 Forums banner

1 - 20 of 20 Posts

·
Registered
Joined
·
2,256 Posts
Discussion Starter #1
As the title says, I have been studying some books and magazines regarding turbo cars and trying to learn how it works and that.

But come across the mention of "dump pipe" which to what I gather so far, is connected to the wastegate to release some of the pressure of the exhaust side of the turbo.

Now I never heard of anyone here mentioned of this term and failed to find with the search of any reference on this forum.

So I am assuming this motor of our SPEED6 doesn't have one.

Just wonder why? and what is the pros and cons for having one?

Thanks for anyone who can clear this puzzle from me.
 

·
Registered
Joined
·
156 Posts
In my experience a dump pipe connects to the external wastegate and dumps the excess exhaust. Some dump this back into the down pipe, other run a dedicated pipe out the bottom of the car.
Any other feedback?


Thanks,
Jason
 

·
Registered
Joined
·
2,371 Posts
You are correct. Ours is built in to the bellmouth design of the downpipe.

-Andy
 

·
Registered
Joined
·
2,256 Posts
Discussion Starter #5
Thanks for the explanations guys.

So, is there any benefit for system which runs a dump pipe?

And to the external ones, does it just dump ( as its name suggest I imagne ) the exhaust gas through another pipe, other than the exhaust pipe itself? And I assume this gas won't pass through any cat at all, correct?
 

·
Registered
Joined
·
2,371 Posts
Nope. Once the stock boost control selenoid reaches a certain pressure sourced from the turbo intake housing (limited by the ecu), it opens your wastegate (via vacum control) to allow exhaust gas to escape the turbo exhaust housing through the wastegate into the downpipe (dump pipe is the means by which it gets there). This is what keeps the turbo from exceding the limits the ecu places on it, and why a boost controller is to be placed between the turbo and the turbo intake housing. However, if you control the boost and set it too high, your wastegate may not be able to keep up. By this I mean that the wastegate might not be able to release enough air though it (due to size, shape, design, ect...), and there will be no peak. Your boost readings will rise to the point at which you set it, but then continue to rise much slower. This uncontrollable situation is known as boost-creep (very bad).
 

·
Premium Member
Joined
·
9,080 Posts
the plus side of an external wastegate is it typically creates turbulance in the exhaust flow, allowing for less back pressure. that is a general rule of thumb if it's done the best way possible on the 2 systems.

you'll see on some high hp cars (that don't care about smog) where it actually "dumps" without going back into the exhaust stream, thus creating no turbulance at all. (i actually think wagners setup for the 3.0 did that?)

the added weight, space and engineering for an external WG is typically what keeps it out of OEM cars. people do weld their internal WG closed and go to an external sometimes, but usually easier to do when upgrading turbo's, just get one setup for use of an external to begin with.
 

·
Registered
Joined
·
2,256 Posts
Discussion Starter #8
Thanks for this detail infos, now I am getting a much clear picture.

So to me, the dump pipe is mostly only applicable to system that runs an external wastegate, as it needs to run a seperate pipework to channel the exhaust gas either back to the stream of the main down pipe or externally. Is this assumption correct?

And apparrently, with the exception of the extra weight and cost, there is benefit for system that runs an external wastegate due to the turbulance which the wastegate reates, is not within the path of the main exhaust path anymore, hence less backpressure and much freer exhaust flow.
 

·
Registered
Joined
·
112 Posts
Thanks for this detail infos, now I am getting a much clear picture.

So to me, the dump pipe is mostly only applicable to system that runs an external wastegate, as it needs to run a seperate pipework to channel the exhaust gas either back to the stream of the main down pipe or externally. Is this assumption correct?

And apparrently, with the exception of the extra weight and cost, there is benefit for system that runs an external wastegate due to the turbulance which the wastegate reates, is not within the path of the main exhaust path anymore, hence less backpressure and much freer exhaust flow.
[/b]
You can also have an internal wastegate and a downpipe with a dump pipe divorced from the exhaust.

STI Downpipe:
http://www.jscspeed.com/wrx/uppipedownpipe...ownpipe_cat.htm
 

·
Registered
Joined
·
2,256 Posts
Discussion Starter #10
Thanks for the info on this STI downpipe.

Would it be beneficial to have something like this for our downpipe? Or due to the bellmouth flange we have, it isn't possible or neccesesary??
 

·
Registered
Joined
·
2,371 Posts
Thanks for the info on this STI downpipe.

Would it be beneficial to have something like this for our downpipe? Or due to the bellmouth flange we have, it isn't possible or neccesesary??
[/b]
It is. Look at the cp-e website, and you can see it.
 

·
Registered
Joined
·
68 Posts
Thanks for the info on this STI downpipe.

Would it be beneficial to have something like this for our downpipe? Or due to the bellmouth flange we have, it isn't possible or neccesesary??
[/b]
Its mainly about preferance. Some will argue to the death that the divoriced is the way to go while others state that having the larger piping is sufficient to decrease the turbulance.
 

·
Registered
Joined
·
207 Posts
Does this give that "chipmunk laughing" sound as well? :) or does it need to be fully divorced and dumped to atmosphere for that?
 

·
Registered
Joined
·
167 Posts
As the title says, I have been studying some books and magazines regarding turbo cars and trying to learn how it works and that.

But come across the mention of "dump pipe" which to what I gather so far, is connected to the wastegate to release some of the pressure of the exhaust side of the turbo.

Now I never heard of anyone here mentioned of this term and failed to find with the search of any reference on this forum.

So I am assuming this motor of our SPEED6 doesn't have one.

Just wonder why? and what is the pros and cons for having one?

Thanks for anyone who can clear this puzzle from me.[/b]

M6Gr8,

This confusion all started by author of the book you were reading using the wrong terminology. A" dump pipe" is an exhaust exit (gate) from the main exhaust system, usually installed after the down pipe but before the catalytic converter and muffler. It can be opened and closed to allow the relief of back pressure and hot exhaust gases from the exhaust system, similar to a set of headers. The dump pipe can be opened manually, electronically or can be boost pressure activated. This system will actually allow your engine to produce more horsepower than a closed system can. Many people think it's because of the decrease in back pressure, but it's not, it's actually the increased velocity of the exhaust gases exiting the system, which if designed properly creates a scavanging effect that increases the velocity of the escaping gases by sucking it out faster than it would normally be allowed to exit, without this effect. In turn, this makes it a far more efficient system.

Now, basically every gasoline powered engine has a down pipe. Typically on a naturally aspirated engine it is just the pipe that is connected to the exhaust manifold, that exits the engine compartment and connects to the exhaust system under the car, mufflers, piping, resonators and so on. Now on a forced induction engine, turbocharged or supercharged, the down pipe attaches to the hot exhaust gas end of the turbocharger or supercharger, then usually runs through a catalytic converter or two, a muffler/resonator and out of the exhaust pipes into the atmosphere.


So basically, every automotive gasoline engine has a down pipe to facilitate the removal of the hot exhaust gases generated by the engine, from the engine to the exhaust system, which typically cleans it, then deposits it into the atmosphere through our exhaust systems.In other words it's just the connection pipe from the exhaust side of the engine to the exhaust system of the vehicle.

Regards,

Rocket 6 :drive:
 

·
Registered
Joined
·
2,371 Posts
M6Gr8,

This confusion all started by author of the book you were reading using the wrong terminology. A" dump pipe" is an exhaust exit (gate) from the main exhaust system, usually installed after the down pipe but before the catalytic converter and muffler. It can be opened and closed to allow the relief of back pressure and hot exhaust gases from the exhaust system, similar to a set of headers. The dump pipe can be opened manually, electronically or can be boost pressure activated. This system will actually allow your engine to produce more horsepower than a closed system can. Many people think it's because of the decrease in back pressure, but it's not, it's actually the increased velocity of the exhaust gases exiting the system, which if designed properly creates a scavanging effect that increases the velocity of the escaping gases by sucking it out faster than it would normally be allowed to exit, without this effect. In turn, this makes it a far more efficient system.

Now, basically every gasoline powered engine has a down pipe. Typically on a naturally aspirated engine it is just the pipe that is connected to the exhaust manifold, that exits the engine compartment and connects to the exhaust system under the car, mufflers, piping, resonators and so on. Now on a forced induction engine, turbocharged or supercharged, the down pipe attaches to the hot exhaust gas end of the turbocharger or supercharger, then usually runs through a catalytic converter or two, a muffler/resonator and out of the exhaust pipes into the atmosphere.
So basically, every automotive gasoline engine has a down pipe to facilitate the removal of the hot exhaust gases generated by the engine, from the engine to the exhaust system, which typically cleans it, then deposits it into the atmosphere through our exhaust systems.In other words it's just the connection pipe from the exhaust side of the engine to the exhaust system of the vehicle.

Regards,

Rocket 6 :drive:[/b]
WOW!

First; what you are refering to as a "dump-pipe" is called a cut-out. A dump-pipe is as stated; a pipe connecting a divorced wastegate either back into the exhaust (post turbo) or out by itself. It is to bleed exhaust pressure around the turbo.

Second; only turbo cars have down-pipes (or dump-pipes for that matter). N/A cars have headers (or a header) that pretty much always makes it to the bottom of the engine bay, followed by a mid-pipe with whatever asortment of cats and mufflers utilized by the company that designed it.

Third, superchargers don't have anything to do with exhaust gases at all, so I'm not sure where that comment came from.

Not trying to be a dick, so sorry if it came off that way, just trying to reduce the confusion here.

-Andy
 

·
Registered
Joined
·
167 Posts
M6Gr8,


So basically, every automotive gasoline engine has a down pipe to facilitate the removal of the hot exhaust gases generated by the engine, from the engine to the exhaust system, which typically cleans it, then deposits it into the atmosphere through our exhaust systems.In other words it's just the connection pipe from the exhaust side of the engine to the exhaust system of the vehicle.

Regards,

Rocket 6 :drive:[/b]

M6Gr8,

I guess I forgot to add that the down pipes that are normally discussed on this messageboard, are aftermarket high performance designs. These are normally made of 300 series stainless steel and would normally be about 3" o.d. These down pipes would come either with highflow performance catalytic converters or no catalytic converter at all, to accelerate the exhaust gas exit. These less restrictive down pipes can add quite a few horsepower to your turbocharged vehicle by just being a free flow design. I've heard from 20 to 40 HP on some cars. They will also have sensors on them and one of the big issues is designing them so that you don't trigger CEL's.


Regards,

Rocket 6 :drive:
 

·
Registered
Joined
·
167 Posts
:drive:
WOW!

First; what you are refering to as a "dump-pipe" is called a cut-out. A dump-pipe is as stated; a pipe connecting a divorced wastegate either back into the exhaust (post turbo) or out by itself. It is to bleed exhaust pressure around the turbo.

Second; only turbo cars have down-pipes (or dump-pipes for that matter). N/A cars have headers (or a header) that pretty much always makes it to the bottom of the engine bay, followed by a mid-pipe with whatever asortment of cats and mufflers utilized by the company that designed it.

Third, superchargers don't have anything to do with exhaust gases at all, so I'm not sure where that comment came from.

Not trying to be a dick, so sorry if it came off that way, just trying to reduce the confusion here.

-Andy[/b]

Ate Baller,

O.K. O.K. O.K........that's my Joe Pesci impersonation.....HA,HA,HA.

Terminology again, your so-called cut-outs were called dump pipes way before a turbocharged car had seen the light of day. Again terminology,
I'll accept yours on this, to reduce confusion. I agree, they were also called dump pipes, as well.

No, every gas powered automobile I've ever seen, unless it came from the factory with factory headers, has a down pipe from the cast iron manifold to the exhaust system. That's all a down pipe is, is a pipe that connects your exhaust manifold to your exhaust system. Granted, on a turbocharged car it connects
from the exhaust end of the turbo to the exhaust system, but it's basically a routing out of the engine compartment to the exhaust system, either way.

Third,....I knew that,.... I guess I just lost my head and added superchargers by mistake, because everybody knows they're belt driven and rob horsepower from the engine, but you don't have to wait for exhaust gas pressure to build, (lag time) like you do to spool up a turbocharger.

No, I didn't think you were being a dick, I screwed up in a couple of places, I think because I was distracted by a visitor in my office when I was typing that post.
Anyway, thanks for the corrections.......I didn't want to confuse M6Gr8 anymore than he was.

Regards,

Rocket 6
 

·
Registered
Joined
·
2,371 Posts
No, I didn't think you were being a dick, I screwed up in a couple of places, I think because I was distracted by a visitor in my office when I was typing that post.
Anyway, thanks for the corrections.......I didn't want to confuse M6Gr8 anymore than he was.

Regards,

Rocket 6[/b]
So how hot was she??? j/k

Gotcha, I've always heard and spoken of it as a cut-out, but hey, pancakes and flapjacks, right. Also, I thought we were talking specifically of aftermarket DPs, my bad.
 

·
Registered
Joined
·
167 Posts
So how hot was she??? j/k

Gotcha, I've always heard and spoken of it as a cut-out, but hey, pancakes and flapjacks, right. Also, I thought we were talking specifically of aftermarket DPs, my bad.[/b]

Ate Baller,

Does the fact that I was typing a post about "dump pipes" while she was in my office, give you a hint............EW,EW,EW.

Regards,

Rocker 6 :laugh: :laugh: :laugh:
 

·
Registered
Joined
·
2,242 Posts
on a naturally aspirated car, I thought the pipes connected to the exhaust manifold were "mid pipes"

the pipe connected to a turbo exhaust housing is a down pipe

and the pipe connected to an external waste gate is a "dump pipe"

My GTO had JBA catted "mid pipes"

My Buick Grand National had a dump pipe (not routed back into the down pipe) connected to my external Tubonetics wastegate


I don't know of anyone running external wastegates on the speed6's yet........never say never???????????
 
1 - 20 of 20 Posts
Top