Picking an A/R for primary/high pressure turbo...

[Hot COCOAL]

Hello mo fo's :hug:
:angel:

I have been slowly researching what it takes to put together and match multiple turbo configurations onto a diesel and, I have to say I feel quite amiss about all of it but keep trudging on. I suppose I'm being optimistic but someday I plan to understand some of this stuff

I've come to some mild awareness and understanding of what to look at in the turbo pressure maps and have a few configurations in mind but one of the things that keeps hanging me up is how to decipher what A/R to use for a given set up


Also, at what point/when do you know, when to incorporate a wast gate? Is there a certain percentage of pressure/bar difference between chargers that needs to be minded?

And then regarding wastegates, is it better to send excess pressure to the atmosphere with a traditional wastegate or BOV? Or would it be beneficial to incorporate a piston type diverter valve, and recirculate excess pressure back to the intake?

Has anyone done that, recirculate the excess boost pressure back into the intake?

Anyways, still just trying to learn, thanks for the skoolin

 

[hondarider552]

Tonight is not the night to inquire about truck parts, it's time to have a good time!

 

[BLKLMM]

:thumb:

 

[Hot COCOAL]

Tonight is not the night to inquire about truck parts, it's time to have a good time!

:thumb:

Lol, ur so right...after I made the thread I realized it might not be the best night for a technical discussion...

:roflmao:

Happy New Year:happy2:

 

[TLyons90]

In the words of myself and other DD peoples...

I am to drunk to answer your questions... :rofl:

 

[PureHybrid]

Your post is confusing. You talk of a wastegate and a BOV. A bov doesn't regulate boost, keeps them from surging when letting off the throttle. And you don't reroute gasses from the wastegate to the intake, that's called EGR. But I'm sure you knew that. Usually the only time a wastegate is vented to the atmosphere is on an aftermarket NON integrated wastegate on a single charger. Because race truck :angel:

 

[Harbin_22]

I loved atmosphere dumps on my Hondas. Sounded awesome.

 

[Hot COCOAL]

Your post is confusing. You talk of a wastegate and a BOV. A bov doesn't regulate boost, keeps them from surging when letting off the throttle. And you don't reroute gasses from the wastegate to the intake, that's called EGR. But I'm sure you knew that. Usually the only time a wastegate is vented to the atmosphere is on an aftermarket NON integrated wastegate on a single charger. Because race truck :angel:

Well, thank you for the response...
I never said a BOV regulates boost, did i

First, I never said anything of what you assumed in your post. I apologize for being confusing, misleading or vague, I'm at a loss for the proper knowledge to construe an adequate question which is why I started the thread

...my understanding is and has been:

A wastegate works off the turbine side, diverting gasses away from the the turbine for various purposes, but I've never been sure as to where the gasses get "gated off" to

A blow off valve is used on the compressor side of the system to avoid compressor surge, and I thought they typically released pressure to atmosphere

And a piston type diverter valve is something new to me that VW uses on my Golf R, is recirculates the excess boost, diverting back into the intake, reducing/eliminating compressor surge and also helping to keep boost up between shifts, or so the story goes

But this is just my understanding, so...

Let's (loosely) define these items:

Wastegate-
A '''wastegate''' is a [[valve] that diverts [[exhaust gas]]es away from the turbine wheel in a turbocharged engine system. Diversion of exhaust gases regulates the turbine speed, which in turn regulates the rotating speed of the compressor. The primary function of the wastegate is to regulate the maximum boost pressure in turbocharger systems, to protect the engine and the turbocharger. One advantage of installing a remote mount wastegate to a free-float (or non-WG) turbo includes allowance for a smaller A/R turbine housing, resulting in less lag time before the turbo begins to spool and create boost.<ref name="DW Performace">http://www.dwperformance.com/kommerce_productdata.aspx?class=155</ref>

Blow off valve-
A '''blowoff valve''' ('''BOV'''), '''bypass valve''' or '''dump valve''' is a pressure release system present in most turbocharged engines. Its purpose is to prevent compressor surge, and reduce wear on the turbocharger and engine. Blowoff valves relieve the damaging effects of compressor "surge loading" by allowing the compressed air to vent to the atmosphere, making a distinct hissing sound, or recirculate into the intake upstream of the compressor inlet.

I wanted to also add this, hoping someone will chime in about the content and how it would apply to our rigs
== Disadvantages ==
In the case where a (MAF) is used and is located upstream from the blowoff valve, the (ECU) will inject excess fuel because the atmospherically vented air is not subtracted from the intake charge measurements. The engine then briefly operates with a fuel-rich mixture after each valve actuation.
An alternative method for utilizing both a MAF and a blowoff valve is to have the MAF located down stream between the intercooler and the throttle plate. This is known as Blow-through rather than the traditional Draw-through set up.

Piston type diverter valve-
while I can't find a direct wiki link, my understanding is the the only difference between a diverter valve and a BOV is the how the valve is incorporated into the system. One is implemented to allow the diverted charge air back into the system rather than to the atmosphere, essentially they are the same, my guess is that they are only defined by how they are applied

I dunno, this is my understanding of it and I was just curious as to how to decide which route to take and at what point to take it...

 

[PureHybrid]

Hello mo fo's :hug:
:angel:

I have been slowly researching what it takes to put together and match multiple turbo configurations onto a diesel and, I have to say I feel quite amiss about all of it but keep trudging on. I suppose I'm being optimistic but someday I plan to understand some of this stuff

I've come to some mild awareness and understanding of what to look at in the turbo pressure maps and have a few configurations in mind but one of the things that keeps hanging me up is how to decipher what A/R to use for a given set up


Also, at what point/when do you know, when to incorporate a wast gate? Is there a certain percentage of pressure/bar difference between chargers that needs to be minded?

And then regarding wastegates, is it better to send excess pressure to the atmosphere with a traditional wastegate or BOV? Or would it be beneficial to incorporate a piston type diverter valve, and recirculate excess pressure back to the intake?

Has anyone done that, recirculate the excess boost pressure back into the intake?

Anyways, still just trying to learn, thanks for the skoolin

That's the confusing part. I didn't bother reading your last post yet, I'm on my phone

 

[Hot COCOAL]

That's the confusing part. I didn't bother reading your last post yet, I'm on my phone

Yes, I can see where that was confusing...

I guess what I meant by that was, wouldn't it be more useful/less wasteful to try and harness some of the diverted exhaust gasses or compressed air? Rather than send diverted gasses from the wastegate into the exhaust pipe or just blowing compressed air to the atmosphere...

I am just looking to find a way to create ultimate efficiency within the design of the system, in hopes to extract every bit of power and economy I can:angel:

 

[juddski88]

Jason, you do realize that when you utilize a wastegate on your high pressure turbo, it diverts into the hot pipe? Also, I had both an atmospheric forged blow off valve and a forged closed circuit piece on my last Saab, and I noticed no difference in response. It would look queer on a nicely put together Duramax without a doubt. However, if you are bent on using a blow off valve, I have a brand new Synchronic one here I never installed.

 

[PureHybrid]

The high pressure wastegate on a compound set would be rerouted to the low pressure turbine inlet, so the overall flow of gas isn't decreased. Don't try and reinvent the wheel here. If you take wastegated gasses and put it back into the same turbine inlet you are doing anything at all... I'm still confused at what you are trying/thinking of doing.

#Treed

 

[S Phinney]

It does sound like you are over thinking it some. The wastegate does go into the atmosphere through the exhaust in both applications if single vs compound. It does us the exhaust energy in a compound to push the atmospheres. There really isn't any other way that I can think of that could make better use if that exhaust energy. It main job is to regulate turbine speed to help protect the charger. This in turn helps keep the charger within its mapping provided everything is matched correctly. What other ways are you hoping to benefit? You can overly complicate the system and it not function very well together. Stupid simple probably works best sometimes.

Sent from my XT1080 using Tapatalk

 

[Hot COCOAL]

Thanks for the responses and guidance guys

I'm/me personally not really trying to re-invent anything here, just trying to get a better understanding for how these things work, they say a picture is worth a thousand words and, well, seeing something and being able to have hands on experience is priceless, right? I have yet to have had that priceless experience

I've never really "seen" a wastegate in person, just pictures. It's not always so simple to get the full scope of how the system works from a cell phone pic:joker:

Just recently I was modifying my Golf R and noticed it has a tube coming off the turbo inlet pipe routed over and into the intake runner, the airflow that goes through the tube is being controlled by a "diverter valve" that I assume is being utilized like a BOV to protect the compressor wheel against surge. Instead of wasting the diverted charge air VW redirected it back into the system.

I thought this was a pretty neat and cool idea that VW had implemented and was just wondering if anyone in the d-max community had done anything similar...? And, I was wondering what you guys thought of the concept, as well as I was hoping to gain a better understanding of wastegates and BOV's and their purpose and affect on a turbo charged diesel.

Thanks again...:hug:

 

[Hot COCOAL]

Jason, you do realize that when you utilize a wastegate on your high pressure turbo, it diverts into the hot pipe?

No I wasn't aware of that...

Just so I can understand here, a wastegate regulates the exhaust gasses on the turbine side of the turbo...right? And you are saying the wastegate on the high pressure turbo in a compound/twin setup diverts "gasses" into the "hot pipe" ....

Are you saying the gasses get diverted into the "charge air" hot side? The pipe coming off the turbo and going into the intercooler...

Please excuse my ignorance, I'm just trying to learn, thank you for the advise

 

[Hot COCOAL]

To get back on the thread topic, and also tie in how waste gates apply

What do you need to take into consideration when choosing an aspect ratio (A/R) for the high pressure turbo? And at what point would you incorporate a wastegate? I mean, I sorta understand that the wastegate will help with spool up by effectively changing the A/R, but how do you figure out what size wastegate to use with a particular charger/AR

For example sake only...
Let's say in a single turbo application, using a GT4202r, the ideal A/R might be a 1.01. But how do you know what size A/R to utilize for use in a twin set up, is the overall concern how much more air the low pressure turbo pushes and how much drive pressure the high pressure turbo will incur? Then, when would you know when to wastegate it, is a wastegate typically employed just for drive pressure regulation or spool up, or both? And how do you determine what sized wastegate to use?

 

[juddski88]

No I wasn't aware of that...

Just so I can understand here, a wastegate regulates the exhaust gasses on the turbine side of the turbo...right? And you are saying the wastegate on the high pressure turbo in a compound/twin setup diverts "gasses" into the "hot pipe" ....

Are you saying the gasses get diverted into the "charge air" hot side? The pipe coming off the turbo and going into the intercooler...

Please excuse my ignorance, I'm just trying to learn, thank you for the advise

Ok, let's be logical here....you've been around here for a while...posting for a couple years in turbo threads and starting your own asking the saaaaaammmmeeee questions over and over again. What good would diesel exhaust do being introduced to the intake? Think about that for a second. I know you "only asked a question" but seriously, it would be nice to have you just once ask a question after some forethought. Because if you are just typing out whatever you are thinking at the moment and reading responses without absorbing the information, you are doing more harm than good.

The hot pipe is the pipe that connects the turbine housing of the high pressure charger to the turbine housing of the low pressure charger and drives its turbine.

 

[S Phinney]

Exhaust gas is diverted around the primary and fed into the hot pipe between High pressure and low pressures. The tighter the a/r on the primary the more you can make use the waste gate to control turbine speed and alleviate back pressure/ drive pressure. If a charger in the single format has good drive pressure numbers it shouldn't get worse In a compound setup. Choosing the a/r for both becomes an art.

Sent from my XT1080 using Tapatalk

 

[Hot COCOAL]

Ok, let's be logical here....you've been around here for a while...posting for a couple years in turbo threads and starting your own asking the saaaaaammmmeeee questions over and over again. What good would diesel exhaust do being introduced to the intake? Think about that for a second. I know you "only asked a question" but seriously, it would be nice to have you just once ask a question after some forethought. Because if you are just typing out whatever you are thinking at the moment and reading responses without absorbing the information, you are doing more harm than good.

The hot pipe is the pipe that connects the turbine housing of the high pressure charger to the turbine housing of the low pressure charger and drives its turbine.

Yes, I have been around for almost 2 years. Yes, I have started, maybe 3 turbo related threads, and been part of several threads, sure, I've hardly been asking the same question, although I admit to being a bit dense at times, or even most times...

Given that the term "hot pipe" can have more than one meaning/application, and the fact I'm totally lost, clarifying which "hot pipe" you were referring to seemed relevant, I'm only trying to be crystal clear, instead of the norm "clear as mud" descriptions that often get given.
I didn't think that exhaust gasses would be good being introduced into the intake tract, I guess I should have put a bit more thought into my response realizing I was discussing twin turbo systems, but I've always been of the mind set "no question is a bad question" rather than assuming I understand something...and this is the first I've really delved into researching twin/triple turbo set ups since I've become a member, the single turbo stuff is complicated enough, lol

Thank you for clarifying....

Exhaust gas is diverted around the primary and fed into the hot pipe between High pressure and low pressures. The tighter the a/r on the primary the more you can make use the waste gate to control turbine speed and alleviate back pressure/ drive pressure. If a charger in the single format has good drive pressure numbers it shouldn't get worse In a compound setup. Choosing the a/r for both becomes an art.

Sent from my XT1080 using Tapatalk

:thumb:

So increasing the A/R of the primary turbo isn't really necessary when building a twin set up? I thought that the primary had to flow more on the exhaust side to compensate for the low pressure turbo forcing air into the primary in a multiple turbo configuration?

Drive pressures always seem to be a concern, what do I look for in a turbo that would give an indication as to what drive pressure it will produce? Is there a relationship between the compressor, turbine and A/R that determines drive pressure? Or is there more involved, like the relationship between the turbo and the system it's going into that determines what kind of drive pressure the turbo will run at?

There has to be a known formula/mathematical equation that is used as a guideline, somewhere, isn't there?

 

[juddski88]

it may be necessary. depending on your setup. tuning a waste gate isn't easy every time. The less wastegate foolery, the better.