Competition twins waste gate question

[Devan Manis]

How come in a twins setup do you run the secondary gate off of the boost from the primary?

 

[Devan Manis]

like these

 

[ThrottleJockey]

The secondary turbine speed is what your trying to control, or limit. The boost in the primary compressor is compounded, so it is a more accurate source of total boost being produced and vital to prevent overspeeding the smaller secondary turbocharger. The big primary can roll up to whatever total psi you have set on the primary wastegate, or blowoff valves if you prefer.



The goal is to limit overspeeding of the small charger for mapwidth enhancement and longevity. The primary can grenade the smaller charger easily.

 

[SRadke]

Put as simply as possible... . you want the gate to stay closed as long as possible so the secondary can spool up faster so you use the primary boost signal. As the big charger starts to come on it pushes the gate open and begins to bypass the secondary.

-Scott

 

[Devan Manis]

so why do some put the wastegate off of the secondary? Is it just personal prefference?

 

[ThrottleJockey]

so why do some put the wastegate off of the secondary? Is it just personal prefference?

Wow. To control peak turbo rpm.

 

[Devan Manis]

Wow? sorry for trying to learn I guess.



On edit: You may have misunderstood what I meant by putting the wastegate off of the secondary, I know it's to limit the turbine speed, i'm not a retard. What I probably should have said is; why do some put the boost referrence off of the secondary?

 

[Devan Manis]

#ad




Like these.

 

[12V Ford]

I asked this question to PDR one day and they said that if the twins were properly matched, you wouldn't need to wastegate the secondary off the primary. I'm not too sure about that, because the cat twin turbo motors are setup this way.



Most of the twin setups I've seen wastegate the secondary off the total boost like the BD twin pic above.



To me, it seems like you could do it either way. You just have to set the wastegate up different.



I asked this question before, on tdr I think, or comp. d, but I can't remember what was said. It seems someone gave me a really good answer. I'll try to find it.

 

[ThrottleJockey]

That is a better way to phrase your question, however, I don't think your second picture properly illustrates the question you are asking.



Where, exactly, do you think that wastegate line is coming from?

 

[Devan Manis]

That is a better way to phrase your question, however, I don't think your second picture properly illustrates the question you are asking.



Where, exactly, do you think that wastegate line is coming from?

Oil gallery on the other side, the one that feeds the vacuum pump.



Where do you think I think it's coming from? How can the second picture not illustrate the question? There is no intercooler so the boost pressure should be the same as if it came right out of the compressor housing on the secondary charger. Either way it's far from the cold pipe between the primary and the secondary turbo. I asked a simple question, you don't have to answer any of it, but when you come off as an arrogant prick I really don't care what you have to say.

 

[Devan Manis]

Looks to me like 12v ford knew what I meant as well.

 

[12V Ford]

Looks to me like 12v ford knew what I meant as well.

I understood fine. Sorry, I can't find where I had asked the question before.

 

[SRadke]

You can use whatever boost signal you want to control things. Just depends how you set it up. If you have and external wastegate you have the option of putting pressure to the bottom to (push the gate open) or the top (to push the gate closed). Some people control it with a combination of the two. Just depends on the desired effect.

-Scott

 

[ThrottleJockey]

Oil gallery on the other side, the one that feeds the vacuum pump.



Where do you think I think it's coming from? How can the second picture not illustrate the question? There is no intercooler so the boost pressure should be the same as if it came right out of the compressor housing on the secondary charger. Either way it's far from the cold pipe between the primary and the secondary turbo. I asked a simple question, you don't have to answer any of it, but when you come off as an arrogant prick I really don't care what you have to say.

No, I totally understand your feelings, however, I was simply trying to understand your question.



I could have SWORE you said 'Why do some put the boost reference off of the secondary?' I thought that boost line was going TO the wastegate actuator from the other side of the engine. As opposed to wastegating the big charger to control peak pressure? There are set ups that actually do both, as stated above to 'tune' a set of compounds to your particular truck, application and driving style. You can play with different wastegate settings to get your compound to spool quicker and dump peak boost sooner, later or not at all, etc...

Dumping drive pressure off the primary will have a different effect than the wastegate bleed from the secondary which will actually slam into the primary turbine and help with spooling the bigger turbo.

 

[SRadke]

I could have SWORE you said 'Why do some put the boost reference off of the secondary?' I thought that boost line was going TO the wastegate actuator from the other side of the engine. As opposed to wastegating the big charger to control peak pressure?

I think you're trying to confuse yourself

 

[Moose Truck]

Small HP Exhaust housing

Ok, I don't have Twins (Yet); however in talking with some guys that make them, you want to bypass the HP turbine, to free up exhaust gas flow around the Exhaust housing. The HP housing is smaller to make a "quick" spool, Where the LP Turbo makes up the air flow once the Turbo's are "Lit". If I don't have this right some one please set me straight. Moose

 

[Devan Manis]

You're dead on.

 

[Devan Manis]

No, I totally understand your feelings, however, I was simply trying to understand your question.



I could have SWORE you said 'Why do some put the boost reference off of the secondary?' I thought that boost line was going TO the wastegate actuator from the other side of the engine. As opposed to wastegating the big charger to control peak pressure? There are set ups that actually do both, as stated above to 'tune' a set of compounds to your particular truck, application and driving style. You can play with different wastegate settings to get your compound to spool quicker and dump peak boost sooner, later or not at all, etc...

Dumping drive pressure off the primary will have a different effect than the wastegate bleed from the secondary which will actually slam into the primary turbine and help with spooling the bigger turbo.

Yeah, what?

 

[SRadke]

Ok, I don't have Twins (Yet); however in talking with some guys that make them, you want to bypass the HP turbine, to free up exhaust gas flow around the Exhaust housing. The HP housing is smaller to make a "quick" spool, Where the LP Turbo makes up the air flow once the Turbo's are "Lit". If I don't have this right some one please set me straight. Moose

You're almost dead on. It is important to understand that the compressor on the primary (big) turbo is what determines flow volume. The small turbo affects spool, drive pressure, yadda yadda but overall flow is all from the big turbo.