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Location:
North Sydney
Registered:
May 2002
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 Twin wastegates??? Advantage or not?
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Mon, 30 September 2002 11:04
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Hey guys, have any of you got any experience or done any dyno testing with regards to twin wastegates.
Any power advantages and less restrictions? I'm thinking it may help reduce massive amounts of backpressure when on boost which should help prevent any chance of a head gasket failure. Ideas?
What I'm talking about doing is using 2 wastegates for greater cross sectional area and better flow.
The first being the factory intenal wastegate which is on the CT26, although it's small, combined with the external one would it be beneficial taking into consideration the turbulance created in the dump pipe immediately after the turbo when it opens?
The second being a HKS 32mm external wastegate which i'll soon be bolting on my car with a decent HKS manifold. This will branch into the exhaust 1 foot downstream and will join into the existing 3 inch exhaust.
I'll be using an electronic boost controller and it would be simple to plumb them both up to work simultaneously.
Anyone got any experience?
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Mon, 30 September 2002 12:04
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| SUPRAGTE wrote on Mon, 30 September 2002 21:04 |
I'll be using an electronic boost controller and it would be simple to plumb them both up to work simultaneously.
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I have no idea about wastegates, but would it really be simple? I mean plumbing them both in a parallel type arrangement, they will be opening at different times? Wont they? What way are you thinking about plumbing them both together? I'm interested!
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Location:
North Sydney
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Mon, 30 September 2002 12:44
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They'd be opening at the same time. I'll be taking the signal from the manifold in one line then through the boost contol solenoid and into a y-piece and off to the two actuators. It's pretty easy to me, that part shouldn't be a problem.
So anyone got any ideas on the initial post?
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I supported Toymods
Location:
Perth WA
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Mon, 30 September 2002 13:10
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You are right, the integral wastegate for the CT26 seems like it would contribute to more turbulence after the turbo that may reduce flow through the turbo. It may be simple to try it out on dyno by just disconnecting the pressure line to the wastegate on the CT26 and usin just the external wastegate. If the 32mm gate is inadequate, or if you feel that there is a performance/control advantage to extra wategate area, you can plumb in the integral wastegate.
You have to make sure that at least the two wastegates have similar pressure thresholds to opening. I think it would be interesting to see, but I doubt much benefit. (IMHO)
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Location:
North Sydney
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Tue, 01 October 2002 09:47
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Yep, spose i'll have to wait till i get on the dyno. Was interested to see any evidence before hand, cause it might save me a heap of time either way 
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Location:
North Sydney
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Thu, 03 October 2002 01:51
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Cmon guys, who's running external wastegates? Anyone?
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Location:
Arthurs Creek, Victoria
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Thu, 03 October 2002 03:32
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I would advice against using twin wastegates. To start with, consider the fact that how many millions of people out there COULD have had their internal and external wastegates working in parallel, but HAVEN'T? ask yourself that one.
And in addition: The internal wastegate of the ct26 will leak boost. As a result, it's boost control pattern tapers off around the correct figure required. Combine that with the fact that the HKS wastegate will NOT leak boost in the same fashion, so you will not have a decent boost control. Not a good idea.
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Location:
North Sydney
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Thu, 03 October 2002 10:22
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Kewl, i decent response
But the electronic wastegate should keep both wastegates shut unit close to boost hey? So this should eliminate most of the wastegate differences?
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Location:
Melbourne
Registered:
July 2002
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Re: Twin wastegates??? Advantage or not?
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Thu, 03 October 2002 13:55
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Hey SUPRAGTE did you get a HK$ manifold or your looking for one!! i've got one for my 7m with a to4 but i'm stuck on the external wastegate,...i just dont want to pay $660 that they're asking for one,..i'm looking for a second hand one you, would'nt know of one for sale!! hows your 7mgte going.....cheers.
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Re: Twin wastegates??? Advantage or not?
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Thu, 03 October 2002 14:13
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However, wastegates do not meter boost !!!
they bypass exhaust gas, and release turbine back pressure.
Which results in boost control.
I think that if your internal ct26 wastegate was handling boost control ok before then an aditional external gate will control it BETTER, and further release back pressure.
Your EVC will not see them as two wastegates but as one entity which has a certain (combined) response, hence effect on boost, to the manifold pressure that is fed to them. The EVC will modify the signal (manifold pressure) that they recieve to gain the boost control it desires.
Not many people run both internal and external wastegates because most who do run external gate turbos have bought the turbo for that purpose, without internal gate.
Matt
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Location:
North Sydney
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Fri, 04 October 2002 13:32
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I think what stradlater is trying to say and I understand what it is. He means wastegate creep, not actually leaking boost but them creeping open and at different rates that would cause inconsistencies.
No sorry grande, i dont have one for sale. I bought a manifold and wastegate together. Was that 660 for the 32mm hks one new?
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Location:
Melbourne
Registered:
July 2002
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Re: Twin wastegates??? Advantage or not?
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Fri, 04 October 2002 13:53
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SUPRAGTE its $660 for a 45mm turbosmart external wastegate,..the manifold i got is a HK$ with a t04 flange,got it from the states,....what did yours cost you were they new! did you put them on yet!!
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Re: Twin wastegates??? Advantage or not?
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Fri, 04 October 2002 14:44
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Paul did your car suffer from creep b4 though ?
I assume you are running the same turbo and stuff as on your old car ?
if it didnt creep b4 it wont creep now.
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Location:
North Sydney
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Fri, 04 October 2002 23:09
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Grande91, ill pm you with the cost and details. I havent put it on yet as i've found a major crack through the water pump,housing, timing housing, everything is stuffed which i couldn't see until we cut the front of the car off with an angle grinder.
Toyo,(same turbo as before yes) all the ct26's and actually all integral wastegate turbo's suffer from creep, some worse than others but with the boostcontroller it does cut this donw dramatically so no i didn't really have any creep thats noticeable.
Just worried they will have different opening thresholds. IE if i'm running 10psi the ct26 internal wastegate will begin to open at about 7psi and would be pretty slow. But with the HKS one it would begin to open at the same time(because its getting the same manifol pressure line) but i think it would crank to a pully open position very fast, too fast because it would have to closed again to a degree so it will let the manifold go up to 10psi.
I think it would be even worse when i'm running 14psi!
I think it would even be visible on the dyno graph because you can see these problems when using a pnuematic bleed valve, thats why i figured sooner or later i had to go electronic boost controller as i have.
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Location:
Victoria
Registered:
September 2002
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Re: Twin wastegates??? Advantage or not?
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Mon, 07 October 2002 02:30
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I thought twin wg/bov were only suitable for applications over 20psi.
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Location:
North Sydney
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Mon, 07 October 2002 09:58
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Wastegates are totally different to BOV's. BOV'S go psssshhhhhhkt and wastegates don't. Wastegates divert exhaust gases past the turbo.
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Location:
Canberra
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Mon, 07 October 2002 11:36
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If you are worried about exhaust gas turbulance and back pressure after your wastegate, why not consider having an exhaust shop fabricate a separate discharge pipe for the wastegate?.
Has been done, commonly called screamers if they vent to atmosphere, but you could always re-introduce the gases back into the main exhaust a few feet further down.(RTA requirement)
Damn sight cheaper than an extenal wastegate, and its associated plumbing.
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Location:
Sydney
Registered:
July 2002
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Re: Twin wastegates??? Advantage or not?
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Mon, 07 October 2002 13:21
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That HKS external wastegate used to have a screamer but it was too loud on boost.
Paul, why can't you try it both ways? Try it with both, then try it with just the external? That external was good enough for the T04 it should be good enough fot the CT26. And with that controller there was NO fluttering over boost at all. Would go to the pre set value and stay there. Wouldn't flutter under it either come to think of it.
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Location:
North Sydney
Registered:
May 2002
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Re: Twin wastegates??? Advantage or not?
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Tue, 08 October 2002 12:06
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Yeah ill try both, i just wanted to see if anyone here had ever run both, if it was a good idea or not. Just searching for some more power really.
Already got the external wastegate chuck, probably will do a screamer with it too but i just want even more power!
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Location:
Sydney
Registered:
July 2002
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Re: Twin wastegates??? Advantage or not?
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Tue, 08 October 2002 23:37
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Would be interesting to find out the difference between running the internal, the external and both.
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