Wastegate Position / manifold design
06-06-2006 | 11:23 PM
#1
Thread Starter
Junior Member
Joined: Sep 2003
Posts: 13
Call me lazy if you like. 
Would like to hear your opinions on this topic. >
http://ausrotary.dntinternet.com/forums/vi...ic.php?t=101806
Would like to hear your opinions on this topic. >
http://ausrotary.dntinternet.com/forums/vi...ic.php?t=101806
06-07-2006 | 12:41 PM
#4
Senior Member
Joined: Oct 2003
Posts: 1,420
From: Boston Ma.
Im in the process of making a new turbo manifold & im up to mounting the gate. I am thinking about putting the gate off 1 runner only to maintain a true divided setup.
Has anyone done this & had any trouble with the setup?
Its finished & fitted up now, I'll find out next week on the dyno if it does or doesnt work.
Has anyone done this & had any trouble with the setup?
Its finished & fitted up now, I'll find out next week on the dyno if it does or doesnt work.
06-07-2006 | 06:55 PM
#5
Member
Joined: Apr 2006
Posts: 83
Thats stupid as hell!
If you have a divided turbine housing then the air has to go into the turbo and come backwards down the other runner to bypass the turbine. Even if there is no boost creep which i think there would be, its still stupid.
I dont know that it would make high boost on one rotar, but if it did it would probably be on the rear rotar and thats bad.
I dont know though, i dont really think it would, the exhaust pressure btwn the rear rotar and turbo would be higher but that just means alittle less new air would enter the rear combustion chamber (a very very small amount less). It would just cause boost creep is all that i can see, and that may not be bad either, but that set up just doesnt make any sense. Intake manifold pressure is equal on both sides, so boost pressure is the same on both rotars. Its still stupid though, if he wants to do it that way he needs to have 2 small wastegates.
If you have a divided turbine housing then the air has to go into the turbo and come backwards down the other runner to bypass the turbine. Even if there is no boost creep which i think there would be, its still stupid.
I dont know that it would make high boost on one rotar, but if it did it would probably be on the rear rotar and thats bad.
I dont know though, i dont really think it would, the exhaust pressure btwn the rear rotar and turbo would be higher but that just means alittle less new air would enter the rear combustion chamber (a very very small amount less). It would just cause boost creep is all that i can see, and that may not be bad either, but that set up just doesnt make any sense. Intake manifold pressure is equal on both sides, so boost pressure is the same on both rotars. Its still stupid though, if he wants to do it that way he needs to have 2 small wastegates.
06-08-2006 | 04:06 AM
#6
Thread Starter
Junior Member
Joined: Sep 2003
Posts: 13
Nospig, I expect it to either work & hold boost @ the desired 20psi or will Creep. Will be 1 or the other I imagine. Another possibility I think might happen is boost might come on softer/slower.
Ronin, I havent put it on the dyno yet. Booked for this time next week. Will be sure to post results.
WankelTII, I dont think you understand how a turbo & wastegate work together.
More boost to rear rotor simply because that rotors exhaust runner doesnt bypass the turbine? Dude, Theres no intake restriction to the rear rotor so it will recieve the same intake pressure as the front.
Ahha, boost creep.
Ronin, I havent put it on the dyno yet. Booked for this time next week. Will be sure to post results.
WankelTII, I dont think you understand how a turbo & wastegate work together.
More boost to rear rotor simply because that rotors exhaust runner doesnt bypass the turbine? Dude, Theres no intake restriction to the rear rotor so it will recieve the same intake pressure as the front.
It would just cause boost creep is all that i can see, and that may not be bad either, but that set up just doesnt make any sense. Intake manifold pressure is equal on both sides, so boost pressure is the same on both rotars. Its still stupid though, if he wants to do it that way he needs to have 2 small wastegates.
Ahha, boost creep.
06-08-2006 | 09:02 AM
#7
Member
Joined: Apr 2006
Posts: 83
Its a completely divided set up, (i assume that means the turbine housing is divided too) air from the rear rotar cannot get to the wastegate without actually going into the turbine housing and coming back down the front rotar's exhaust runner. I dont think the air can or will do that, so the creep wont just be a small amount.
Do you understand how wastegates work?!?! If the air cant get around the turbine then it will continue to spin the turbine wheel.
Someone else said there would be high boost on one rotar, i realized in a matter of 3 sentences that wasnt possible, i just didnt go back and take out my thought process. But your right intake pressure is intake pressure, ok duh.
Even if it works, I still think its a ridiculous way to do it. Its got to cause some wierd stress on the bearings or something to have way more exhaust pressure on one rotar. Why not just do it the normal way, or with 2 smaller wastegates? Neither are difficult, this just looks like you got lazy or something.
Do you understand how wastegates work?!?! If the air cant get around the turbine then it will continue to spin the turbine wheel.
Someone else said there would be high boost on one rotar, i realized in a matter of 3 sentences that wasnt possible, i just didnt go back and take out my thought process. But your right intake pressure is intake pressure, ok duh.
Even if it works, I still think its a ridiculous way to do it. Its got to cause some wierd stress on the bearings or something to have way more exhaust pressure on one rotar. Why not just do it the normal way, or with 2 smaller wastegates? Neither are difficult, this just looks like you got lazy or something.
06-08-2006 | 12:30 PM
#8
Senior Member
Joined: Jul 2005
Posts: 244
A properly sized wastegate anywhere before the turbine will technically work.
Obviously, dont use a little 28mm wastegate on this setup. I would use the largest you can find. You have to remember that a wastegates function is to equalize the pressure before and after the turbine. The more pressure you can release, the more control you have (larger is always better in theis case).
Its not a good design, but it should do what you need it to, but you may have some creeping issues depending on the rest of your system.
Obviously, dont use a little 28mm wastegate on this setup. I would use the largest you can find. You have to remember that a wastegates function is to equalize the pressure before and after the turbine. The more pressure you can release, the more control you have (larger is always better in theis case).
Its not a good design, but it should do what you need it to, but you may have some creeping issues depending on the rest of your system.
06-08-2006 | 06:20 PM
#9
Member
Joined: Apr 2006
Posts: 83
Yes, but how does the pressure get equalized if the only way for it to escape the rear exhaust runner is to go through the turbo? There is undoubtedly going to be high pressure between the rear rotar and the turbine housing, I guess since the turbine is rather large and the front exhaust runner could possibly get close to atmospheric pressure when the wastegate is fully open, the creep might stop somewhere fairly reasonable, but i am willing to bet that the boost will be more than the wastegate spring was rated for.
06-08-2006 | 06:40 PM
#10
Senior Member
Joined: Oct 2003
Posts: 1,420
From: Boston Ma.
I think everyone is shooting down the idea before it even gets tested.
I have some theories about that setup and what it will do. Some positive, some negative that I think I will hold on to until it gets dyno'ed.
I have some theories about that setup and what it will do. Some positive, some negative that I think I will hold on to until it gets dyno'ed.