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External wastegate dumping form manifold to atmosphere?
by
RadoTD
on 12 Mar, 2011 23:12
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I think I'm going to run an external wastegate that completely bypasses both turbos, hoping that will help control egt's at full boost.
I'm wondering if anyone has tried dumping their wastegate to atmosphere? It would be easy to set up that way, just need to braze it to my manifold and I'm done. I'm afraid it's just going to sound like my engine is attempting to dismantle itself... any opinions on this?
The plan is to tune the pump so I'm not blowing any black smoke at full boost (30psi or so), so soot shouldn't be an issue, as the wastegate won't open until full boost
It'll also point straight at the ground, so I'm not blowing more hot air into my engine bay
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#1
by
DJPyro
on 13 Mar, 2011 07:18
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I don't know how you could get it to stay attached to the stock cast manifold... Brazing will let go for sure, but external wastegating shouldn't be an issue other than that, lots of gasser guys run screamer pipes. It'll just be silly loud every time your wastegate starts to open.
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#2
by
theman53
on 13 Mar, 2011 07:24
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would it work to dump it into the ex pipe after the turbos? pointing rearward of course. Just thinking.
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#3
by
macka
on 13 Mar, 2011 07:50
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Pyro,
nice to see another NWO dubber. How would brazing let go? If he does it right, ie heat the manifold, do the brazing, then slow cool it in an oven, he should have 70G psi tensile strength. Its non structural and the turbos won't build internal pressures to pop it. The braze shouldn't work harden as its a softer then a standard weld, and the cast shouldn't crystalise if he preheats and slow cools it.
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#4
by
RabbitJockey
on 13 Mar, 2011 08:32
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theres no gain to an external dump except for that its easier to do
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#5
by
RadoTD
on 13 Mar, 2011 09:51
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I know an old school car guy who has brazed everything imaginable and that wouldn't be a tough job for him. My biggest fear was that it would sound like a bag of hammers being dropped off the CN tower
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#6
by
R.O.R-2.0
on 13 Mar, 2011 10:51
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I know an old school car guy who has brazed everything imaginable and that wouldn't be a tough job for him. My biggest fear was that it would sound like a bag of hammers being dropped off the CN tower
its not gonna be like a bag of hammers, but it is going to sound like your exhaust manifold/turbos fell right off the head.. thats how loud its gonna be..
in other words, SUPER DUPER RIDICULOUSLY LOUD when the wg opens up..
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#7
by
DJPyro
on 13 Mar, 2011 14:35
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I suppose that brazing might hold, but I feel like all the vibration and heat from his diesel engine, plus the weight of the wastegate hanging off it would cause it to fatigue and break. I may be wrong though, I don't have a lot of experience with brazing. At the very least, I'd be leaving it to someone with a LOT of brazing experience on exhaust systems.
Like everyone's been saying, it'll be loud as all get out, but yes, you could route it back into the downpipe post-turbo, that's what most people with external gates tend to do. It'll keep it to a sane volume, and you'll still see the benefits of an external gate.
macka: If you're on the vortex as well, check my build thread over there. She's slowly but surely turning into something.
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#8
by
R.O.R-2.0
on 13 Mar, 2011 18:00
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I suppose that brazing might hold, but I feel like all the vibration and heat from his diesel engine, plus the weight of the wastegate hanging off it would cause it to fatigue and break. I may be wrong though, I don't have a lot of experience with brazing. At the very least, I'd be leaving it to someone with a LOT of brazing experience on exhaust systems.
Like everyone's been saying, it'll be loud as all get out, but yes, you could route it back into the downpipe post-turbo, that's what most people with external gates tend to do. It'll keep it to a sane volume, and you'll still see the benefits of an external gate.
macka: If you're on the vortex as well, check my build thread over there. She's slowly but surely turning into something.
even if you dump it back in the downpipe, its still going to be loud unless you run a muffler..
and with compound turbos, i wouldnt be running a muff..
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#9
by
Bugsy_malone 666
on 14 Mar, 2011 02:51
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See I know with alot of the aircooled turbo motors in beetles/campers people run external wastegates that just dumps to atmosphere, out the back right next to the main exhaust.
I was wondering, what type of manifold are you running? Eg how ate the turbos bolted on? Basically I know from experience that sometimes welding cast can be a right PITA, my dads been doing brazing for years (since I was born!) and depending on the quality of the manifold casting sometimes you struggle to braze it, where as if you have mild steel/stainless pipe between manifold and turbo you could maybe put something in there?
Alternatively I was thinking maybe getting a different exhaust manifold (depending on budget) from a mk4 golf and use the EGR valve takeoff point for your wastegate to bolt onto instead, no welding to manifold, no worries! So then run the pipe from the wastegate down and back into the exhaust just past the 2nd turbo as, in theory if I am right because the exhaust gas is going out of the exhaust it will create a bit of vacuum behind it helping to continue to draw exhaust gases through the turbo. Thats my theory and I know it can work with some stuff.
Just an idea on the table there, similar to what others have said.
As also mentioned if your not running any mufflers it might be a bit loud, but at the same time as its not going to be for long periods of time it probably wont be noticeable. If you were really creative you could make a mini muffler for your wastegate
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#10
by
R.O.R-2.0
on 14 Mar, 2011 09:37
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but but but!!!
what could be cooler than getting on the throttle, having the boost come up, then have the engine get 4x louder?!
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#11
by
Thezorn
on 14 Mar, 2011 22:49
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Yea like everyone has said alot of gasser guys just dump it into the atmosphere. But when you think about it, with a diesel if you have the dump anywhere in your engine bay you whole bay will be covered in soot in no time. And if you going to have it dump under your car, it would be just as easy to cut a small hole in your DP or anywhere in the exhaust and route then weld the dump to it.
Thats what Im going to do for the external controlling my K14.
The exhuast manifolds are made of of cast iron right? You can mig weld mild steel to cast iron. It will be a bit more brittle, but as long as you run a bit of flex hose in the dump there wouldnt be any problems. Im going to weld a piece of tubing onto the manifold and route it into a bit more open area where there is room for the wastegate. And from all the warnings/lessons Ive ever gotten at work and school Im not sure If braze would hold all that well, especially with all the diesel vibrations
Im not sure If you saw it, but I cut the internal wastegate system off my K14. Check out the pics in the thread. Not sure If it was the best Idea but I cant see it being any different, once I weld it up, then having the wastegate not open.
On a side note, how is your car doing? how much boost are you seeing from the turbos?
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#12
by
bugnut
on 15 Mar, 2011 17:39
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Why would you want to bypass both turbos? That seems counter productive. You put the second turbo on to force more cool air into the turbo and compound it with the small one. You would want all the exhaust to go through both turbos. If you need to control the egt play with the wastegate settings on both turbos. The larger turbo should not be a choke for the engine so egt's should not be a concern. I think for keeping egt's in check you need a large enough wastegate on the small turbo.
Thezorn, if you check my thread I did the same thing with my k14 turbo. Got a few pictures of it. Cut the wastegate off and installed a external. I brazed the tube on. It was a pain, that cast was real dirty. Poor cast job I guess. Time will tell if it breaks off.
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#13
by
Thezorn
on 15 Mar, 2011 20:59
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Thezorn, if you check my thread I did the same thing with my k14 turbo. Got a few pictures of it. Cut the wastegate off and installed a external. I brazed the tube on. It was a pain, that cast was real dirty. Poor cast job I guess. Time will tell if it breaks off.
Wow thats awsome, I remember seeing your thread a long time ago. How did it end up turning out? Now that I see that I think Im going to do the same thing for the external on mine, looks alot easier then bucking a hole in the manifold.
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#14
by
RadoTD
on 15 Mar, 2011 21:21
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Is the TDI manifold a straight bolt on? I can call around and hopefully get one for a decent price. I like that idea.
If it was just straight to atmosphere, I'd run the pipe from the wastegate down to the bottom of the engine bay and point it at the ground under the car, I think I'll just run it into my downpipe though. Keeps it legal anyway...
I have a feeling that EGT's are going to be limiting my power, so for now I'm just trying to think of as many little tricks to lower it as I can. I could set up the K24's wastegate to the pressure I want and that would work fine, but then 100% of my exhaust gas is still running through the K14. An external wastegate off the manifold will make it so that not all of the gas will run through the K14 at full boost. Whether that'll be significant or not, I'm not sure. It won't hurt though.
The car is running good.. my timing is retarded right now, likely around stock timing, but I'll fix that soon. K24 wastegate is set at 20psi, K14 is set at 10psi manifold/absolute. Still need to weld a fitting onto the K14's wastegate so it can run at a pressure differential between my intermediate boost pipe and the intake mani. Still bypassing the intercooler, but I'll get that hooked up soon. About 1500km on the engine now. I've been really busy lately, but soon I'll have some free time and can get around to finishing everything up. Launch video will come once I've got the intercooler and timing dialed
