My compound turbo set-up

[turbo addict]

So what you are saying is that a nonturbo engine does not pull a vacuum from the turbo until it makes boost??

The big turbo has no idea that the little turbo is there it just ingests more air like a bigger motor.

What you are trying to say is that a turbo 2.0 liter(at 15psi) that makes 400hp and a na 4.0liter that makes 400hp (make the same power) will not flow the same air from a drawthrough mas (aka the meter behind the airfilter)??

I don't think that you understand how it works. So if the little turbo does the work then how much air flow will be pulled into the system BEFORE the big turbo to make 600hp? if we are making everything simple and saying that 1lb/min = 10hp. maybe half because there are are two turbos. ;-) sorry to be a tool but think about it.

 

[turbo addict]

I know that it works too. I had a long talk with the guys at the supra meet (that make the compound kit) and I asked them why they were using a gt42 for the big turbo (pretty small turbo to those guys) and they said that they werent going for big numbers just a really wide powerband, they said that it will only make as much power as the big turbo can flow but it drives like a V10 motor.

99gst racer I think you know what I am saying. I think that some of the others are getting a little confused.

 

[1gentalonfan]

Bastard!! you beat me to it!! haha i've been drawing up plans for a compound turbo setup for my 1g since last summer but havent had enough money to really do much. I'm going to mount my turbos different though, and im using a way more efficient intercooler that will give me extremely short ic piping(has to do with water. The only thing i havent decided is whether i want to run a gm maf or a speed density. I want to vent my bov and i wont really have enough straight section in my ic pipe to mount the maf, i barely have room for the bov, but mafs are so much more accurate and easy to tune. Argggh. Nice work though, let me know how tuning goes for you.

 

[turboglenn]

That BoostLogic kit is dead sexy, but I'm not able to fit that size package in the engine bay of my 2G. I specifically choose some of my components due to price and overall size and compactness. If it proves to work well, a more appropriate manifold and turbo set-up may be in order.

I'll have some more pictures and updates at the end of this week.

Here's a shot of both compressors on the car:

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WOW!!! I've been interested and following this since you started mentioning well before this thread was started, and the only thing i I ever questioned was if it was going to fit under the hood of a 2g car, and the picture does all the talking. even if you have to "relieve" the hood of a sqaure foot of it's mass the product willbe worth looking through when you see those compound blowers! As for your fuel i was thinking about that and I think that ultimately you son't have to go too huge because the only real time you have the need for such large injectors is making HUGE top end power. Don't get me wrong 600 is a lot, but down low where this system is really going to hit hard and need fuel the engine revolutions are low enough to the point of having very, very large pulsewidths compared to near redline. Just a guestimate because it's late and i cant' think but i would say thataround 8000 RPM you have about 7 - 7.5 ms if total injection time, But at say 4000 RPM the jump would be so substantial that yoou should have some where in the range of 12 - 14 ms available. SO all in all unless you're making very high numbers at a high RPM you can do a lot more with a lot less injector. Just imagine if it was a v8 running the same injection cycle per number of revolutions or ignition event, then you'd have some where around 14ms at 7500 - 8k and an ungodly ~24ms puslewidth at 4 - 4500RPM!!!!!! I think you're going to need an allison tranny and i think the torque numbers will put the leak HP numbers to shame and make he average joe that looks at the dyno chart think it's a supercharged v8 running through a restrictor plate

Good luck with getting all the little tid bits of final assembly out of the way! I know this is goingto be just an insane monster of a car that alot of people will steer clear of building copies of because of the amount of broken driveline parts you'll probably start to post about when you hit 500lb/ft at 3800 RPM.

But then I have this vision that you'll start a new fast and furry trend fr all the ricer kiddies to see wheh this thread makes it's way to www.riceyhondas_withwings_n_alltezzas.com/forums and we'll start to see 17 year old kids piling up 6 t25's using press bent auto parts store aluminized pipe, muffler clamps and no support, running no hoods, Tuning with an SAFC and crushed OEM FPR with 550's and a blown HG saying he runs 9's daily on street tires

I got faith in you, can't wait to see it come to life... going back to bed now.. I wake up constantly in the night, sit on PC, move to bed or couch, sleep 3 hours, and repeat some how i pull it of for a month or so then sleep for 2-3 days and the again repeat.... I need drugs to stop my brin from working when i need to sleep.. i'm always waking up to think, especially if i'm on a bad-ass project, so if you are anything like me i bet you haven't slept in a year and probably wont' untill the blow off valve sounds and the AFR's hold true...


The you'll just have the nightmares from tilton saying we can't give you any more clutches to to the machine shop telling you that there's no stronger material to build your CV's and driveshafts from that will fit in the car...then it wil just have to become a monster truck.... ok, i'm reallly stopping now...love it Oaul, keep it up and post us the vids when you get em

 

[SpeedAddict62]

Paul, a quick word; I don't want to keep stirring up the poo in this thread and get on with the build but there are a few things you said which don't make any sense to me.

lbs/min is a measure of mass flow rate, not volume flow rate. Actually, it is a measurement of force per unit time. If we wanted to be technical, we would measure in kilograms or slugs per min...but anyway. It is not a measure of volume flow rate like you said, and I wanted to make that clear. If you wanted volume, you would probably use CFM (cubic feet per min). Therefore, both turbos must flow the same in lbs/min airflow. I think the trick will be, designing the system so that both turbos are operating as efficiently as possible, that should yield the best results. Knockgoon24 has the right idea with his modified picture.

 

[RipperXX]

Wow some people are just dense... I think the guy is honestly just too confused at this point to get it. Although it's pretty damn simple if you want it put it into REAL simple terms.



Atmospheric air pressure at sea level is 14.7psi correct? You take that with say the Evo turbo and compress it further to 22psi of boost which is pretty normal resulting in a absolute pressure of 36.7psi

Now think of it like this, instead of starting out at 14.7, Think of it like he is starting out around 30psi atmospheric pressure and compressing it to 22psi of boost. Resulting in 52psi absolute pressure. HOLY SHIT I know that was hard to comprehend.....

 

[dsm-onster]

Compressors ARE pressure multipliers and they ARE volume movers. Debating how the compressors work together to yield more boost/flow earlier in the intake manifold is rather moot. We all know it works, regardless of how we feel it works. The main issue 94awdcoupe is having is accepting that the flow bypassing the 16g turbine through the 44mm (1.75") external gate is enough to power the 60-1 turbine. More discussion on either subject will just clutter the thread. As it is, someone is going to be eating a huge piece of humble pie anyway. Let's not make this any more rediculous than it is. . . Back to build details, pics, and progress reports!

Glenn you need a nap . . . I get the exact same way. Melatonin: over the counter. It helps regulate rhythmatic functions of your body that trigger fatigue and hunger.

 

[talontd92tsi]

#### it. I give up explaining. It's not like I don't know how this shit is going to work.

You explained it very clearly. I was thinking the same thing as him, and after doing some simple googleing, what you are stating makes perfect sense. You have to be able to think outside the box for this to make sense ... I remember reading about this a few years ago and wondering how it would work on a DSM, I guess i will finally find out. Will you be attending the DSM Shootout in Norwalk this year? I looked at your car there last year and would really love to see this setup in person.

Compressors ARE pressure multipliers and they ARE volume movers. Debating how the compressors work together to yield more boost/flow earlier in the intake manifold is rather moot. We all know it works, regardless of how we feel it works. The main issue 94awdcoupe is having is accepting that the flow bypassing the 16g turbine through the 44mm (1.75") external gate is enough to power the 60-1 turbine. More discussion on either subject will just clutter the thread. As it is, someone is going to be eating a huge piece of humble pie anyway. Let's not make this any more rediculous than it is. . . Back to build details, pics, and progress reports!

Glenn you need a nap . . . I get the exact same way. Melatonin: over the counter. It helps regulate rhythmatic functions of your body that trigger fatigue and hunger.

The flow of the gasses going through the 16g's 44mm gate has absolutely nothing to do with it considering the entire path of the exhaust, gated and post turbine, goes to the 60-1 turbine.

Why is he arguing?

Regardless this is a sick undertaking and I cannot wait to see it work. Congrats on being innovative Paul, and if it works that good, maybe my little 14b has a permanent home.

Subscribed

 

[99gst_racer]

@ Glenn's post.

Will you be attending the DSM Shootout in Norwalk this year?

I'll be there for sure. And as long as the car is still in one piece, it will be there too.

 

[dsm-onster]

The flow of the gasses going through the 16g's 44mm gate has absolutely nothing to do with it considering the entire path of the exhaust, gated and post turbine, goes to the 60-1 turbine.

I know

 

[94awdcoupe]

I never stated a compound turbo system doesnt work.
I simply stated I believe this particular setup will not flow well enough to reach the 600whp goal. I think it will work fine to the 450-500whp range. after that the small turbo will spin too fast from too much back pressure.
Then some technical discussions took place and very poor terms were used.

"saying the small turbo is a volume multiplier"
"saying big turbo doesnt need to flow total mass needed to reach HP goals"

both statements are without intelligence

a turbo is not a volume multiplier. that would be impossible. a turbo multiplies pressure. volume is reduced in size. the opposite of multiplication. mass does not change. whatever mass goes in a turbo must come out.

 

[99gst_racer]

94awdcoupe - I need a good laugh. Explain to me in detail how you think a compound turbo set-up works to achive high pressure and how that helps create more horsepower.

 

[b00stedtalon2]

Paul - I am glad you have this project log posted elsewhere, because I do not have the patience for all the reply's and text in this thread!

 

[dsm-onster]

a turbo is not a volume multiplier. that would be impossible. a turbo multiplies pressure. volume is reduced in size. the opposite of multiplication.

A turbo most certainly is a volume multiplier. Have you logged the VOLUME flow (hertz count) difference of an n/t 4g63 and a stock 14b powered 4g63?

I agree that mass in mass out. The limit in flow is the FEEDING turbo not the larger turbo. He's oriented the large turbo to be the feeding turbo, so he's fine reaching his goal. 60lb/min can very well equal 600whp, since airflow per hp is different for different setups. There's other things going on under the hood. As well, as already mentioned by Paul, the airflow per hp curve is not linear. As you go up in hp, less and less airflow is required to net the next higher hp goal.

I simply stated I believe this particular setup will not flow well enough to reach the 600whp goal. I think it will work fine to the 450-500whp range. after that the small turbo will spin too fast from too much back pressure.

Do you still maintain that the 16g is stopping up the flow? Why, why, why? You havn't given any basis for your speculation that the 44mm gate controlling the 16g turbine won't bypass enough gases. Or that the 44mm pipe from the gate plus the exhaust from the 16g turbine won't be enough to power the 60-1. I think most of us are frustrated that you are really just saying no it won't work with no explination. Simply, 'The 16g will choke it up'. It's not like we havn't given several different versions of our explination. And, one last time. . .

You do agree, right, that 14.7 psia feeding the 16g nets 11psi boost in the manifold when the compressor is spun to maintain just a 1.7PR? And 35psia or 14.psia plus 20psi boost from a larger turbo nets 46psi boost in the manifold when the 16g compresor is spun to maintain just 1.75PR? You do agree, right, that a compressor map is rendered in PR and volume flow, and only later corrected to mass flow based on inlet pressure? You do agree, right, that the compressor rpm determines the net work required from the turbine? You do agree, right, that the compressor rpm equals the turbine rpm? You do agree right, that a wastegate effectively controls shaft rpm, supplied work, NOT boost. PR is related to shaft rpm through volume demand. You're not asking the 16g to spin fast enough to net 46psi on its own. You're simply asking it to multiply the pressure 1.75 times. That takes no more energy from the exhaust than if you were asking for 11psi feeding it 14.7psia (sea level stock intake pipe) because you're requiring a certain PR not boost. Thus, the 44mm wastegate controlling the 16g OPENS even though the mass flow through the 16g compressor is 55-60lb/min. A compressor is volume flow machine a volume multiplier. Now, you have a 1.75" (44mm) tube of gases plus the turbine flow of the 16g to feed the big 60-1 turbine. The gases are shunted so that all the 16g needs to do is maintain that 1.75PR. PR is related to shaft rpm though volume demand not massflow. And shaft rpm is proportional to the energy required to maintain that shaft rpm. The shaft rpm and consequently energy is low to maintain 1.75PR (46psi in the manifold, where the inlet pressure is 22psi over ambient being fed by the 60-1). The 16g gate opens, shunts all energy beyond the demand. The 60-1 turbine is fed all the gases, shunted and used by the 16g. The remaining energy in the exhaust (plenty because the 16g needs very little energy to maintain 1.75PR) spins the 60-1 shaft and backpressure is equalized between the 16g turbine and the 60-1 turbine.

Paul is probably going to rout the 16g wastegate signal from the intake manifold. So that 1.75pr will be seen with respect to the ambient conditions (14.7psia). So the 16g 44mm WG will open up VERY early and VERY wide. Why would the 16g turbine over spin? It has plenty of bypass around it and it is not asked to do more tha 1.75pr. As the 60-1 keeps climbing in shaft speed, the 16g gate will open wider and wider. Energy to feed the 16g does not deminish because the motor is flowing more mass as the 16g gate is more and more. the 16g isn't choking the flow because the wastegate is opening wider and wider as the mass flow in the exhaust increases.

The small turbo will not spin too fast. The huge 44mm wastegate will allow the exhaust mass to bypass the 16g turbine. After all it takes lower backpressure to run the larger turbine of the 60-1. And the 60-1 has a wastegate too. The 60-1 gate signal should be plumbed into the intake manifold. So that once the final desired boost is reached, it will open as well. The backpressure in the turbine housings are the same at that point. And that 60-1 gate is the gate that controls the total amount of energy the turbines have to work with. The 16g will take it's portion with it's turbine efficiency (a smaller portion because it flows less). And the 60-1 will take it's portion with it's higher efficiency (a larger portion because larger turbine wheel generally are more efficient and definately flow more). Because remember, turbine work {or energy applied} = specific heat X massflow X (temp in - temp out).

I sent you an 8000 character PM outlining the same thing. And you said I was focusing on the compressor .

 

[94awdcoupe]

A turbo most certainly is a volume multiplier. Have you logged the VOLUME flow (hertz count) difference of an n/t 4g63 and a stock 14b powered 4g63?

I agree that mass in mass out. The limit in flow is the FEEDING turbo not the larger turbo. He's oriented the large turbo to be the feeding turbo, so he's fine reaching his goal. 60lb/min can very well equal 600whp, since airflow per hp is different for different setups. There's other things going on under the hood. As well, as already mentioned by Paul, the airflow per hp curve is not linear. As you go up in hp, less and less airflow is required to net the next higher hp goal.

The small turbo will not spin too fast the huge 44mm wastegate will allow the exhaust mass to bypass the 16g turbine. After all it takes lower backpressure to run the larger turbine of the 60-1. And the 60-1 has a wastegate too.

When can we stop being idiots? here is the definition of volume:
The volume of any solid, liquid, plasma, vacuum or theoretical object is how much three-dimensional space it occupies

Turbos do not multiply volume. They induce a volume of air and cram into a smaller space. that is the complete opposite of volume multiplication.

hertz count does not measure volume. it measures mass of air passing. thats why they are called mass air meters. maybe we should change the name to volume air meters. then we can all look stupid together.

I agree with all your second paragraph except the last sentence.

The third paragraph is bench racing whether or not it will work. Lets wait and see and then discuss.

94awdcoupe - I need a good laugh. Explain to me in detail how you think a compound turbo set-up works to achive high pressure and how that helps create more horsepower.

No problem.

The way I see it:

engines are air pumps. they suck air in and pump air out.

turbos increase the pumps ability to move larger volumes of atmospheric air.

They do this by compressing air into smaller spaces (IC pipes and intake manifold) so the air moving in and out of turbo charged engine is more dense compared to atmospheric air.

A compound turbo setup has two compressors running in series. First turbo (big) compresses air and moves that compressed air to the second turbo (small) to be compressed to yet even smaller space. So the air now moving in and out is potentially even more dense than a single turbo setup.

A compound turbo setup has increased turbo efficiency over a single turbo setup as there are two compressors splitting the load of moving compressed air. No different from your shop air compressor than powers your air tools. Two cylinder compressors are more efficient at compressing air than one cylinder compressors are. less electricity needed to compress same amount of air. or same amount of electricity results in more compressed air. In turbo terms less exhaust energy is need to reach same HP level with one compressor. Or same amount of exhaust energy will yield higher power output potential.

More air you cram into and engine the more power you can make. Getting fuel to engine is dirt bag easy in comparison.

 

[dsm-onster]

turbos increase the pumps ability to move larger volumes of atmospheric air.

This increase in volume airflow certainly can't be defined in a mathematical coefficient

When can we stop being idiots? here is the definition of volume:
The volume of any solid, liquid, plasma, vacuum or theoretical object is how much three-dimensional space it occupies

Turbos do not multiply volume. They induce a volume of air and cram into a smaller space. that is the complete opposite of volume multiplication.

hertz count does not measure volume. it measures mass of air passing. thats why they are called mass air meters. maybe we should change the name to volume air meters. then we can all look stupid together.

I agree with all your second paragraph except the last sentence.

The third paragraph is bench racing whether or not it will work. Lets wait and see and then discuss.

An utterly foolish, senseless post. You've really put your foot in your mouth. And I'm glad others will see so as not to trust your input in this thread. Only you look stupid.

First to argue over semantics concerning where the multiplication takes place. How does the massflow go up with a bigger turbo or by having a turbo? Did you change the weather? Or did you beam your car onto a mountain top, Spock? The volume flow goes up at the meter with a turbo vs. not having one. Period. More volume flow at the meter is just as effective at increasing massflow as lower temp at the meter, or higher baro at the meter.

Which leads to the next foot. What's the point of the baro reading and temp reading fed to the ecu if the hertz count isn't a volume flow count? Think, please.

 

[94awdcoupe]

Do you still maintain that the 16g is stopping up the flow? Why, why, why? You havn't given any basis for your speculation that the 44mm gate controlling the 16g turbine won't bypass enough gases. Or that the 44mm pipe from the gate plus the exhaust from the 16g turbine won't be enough to power the 60-1. I think most of us are frustrated that you are really just saying no it won't work with no explination. Simply, 'The 16g will choke it up'. It's not like we havn't given several different versions of our explination. And, one last time. . .

"My first sentence stands. There are only two paths for the exhaust heat to reach the second turbo. Through the 7cm/5h wheel and through the 44mm wastegate. The wastegate hole itself is going to flow very poorly as gases do not make 90 degree turns well. You are in attempting to make 600hp through those two small openings. The result will be the small turbo getting too much ex heat and the large turbo not getting enough."

"My 25g setup had same tube mounted between two runners as you do. You saw the picture posted. The path of least resistance was not through the wastegate. thats why there was creep. It was easier for the gasses to go to the turbine and over spool it."

Those were my statements and I will now expand on the subject.

wastegates dont quite operate like people think they do. If you have a turbo making 400whp at 25psi the back pressure will typically be 50psi. The power needed to drive the compressor to move that 25psi may only need 30 psi back pressure. So most would think if you had a 44mm gate and you were seeing 50psi back pressure then all you need to do is add larger 60mm wastegate and get that back pressure down to 30psi. (HP would go up to ~415whp) Problem is the 60mm gate would result in the same 50psi back pressure. reason is wastegates receive signal to dump from the boost intake manifold pressure. If boost pressure starts to drop from 25psi the wastegate will start to close at the same time. So if you can understand that you might be able to understand that the 44mm gate will flow the same as 60mm gate.

there is a local here who understood this concept very well and designed a wastegate with multiple passages and multiple diaphragms. His goal was to have a waste gate that could control boost and control exhaust gas pressure at the same time. the first section of his wastegate operates as normal. the second part operated a little differently. It was the same as regular gate except the signal to open and close valve was received from ex manifold back pressure. last I heard he was putting them 1750whp cars and making 1900whp with no other changes.

Hopefully from this you can see that the 44mm gate in this setup is trying maintain the boost signal at the intake manifold and may not be open enough to control the back pressure.

 

[dsm-onster]

No I can make 500whp or 700whp at various backpressures above or below 50psi. It's called turbine matching. An evo3 16g turbine itself flows enough mass for 500whp. A 44mm gate even with a 90* turn added to that is plenty. I've already explained how the 16g 44mm gate will be wide open for anything after the desired boost is reached, you know later in the rpms, when the motor is developing 550whp.

When the 60-1 (2nd gate) opens, that doesn't mean the first one closes. It's set to open at 10-11psi, whatever resulting volume flow is neccesary to get the 60-1 spooling faster. When the 2nd gate opens, backpressure in both turbine housings go down. Yep, the 16g slows in rpms, but who cares the 60-1 is maintaining the boost. Afterall, it's already spooled enough to open the 2nd gate. As well, the 16g doesn't increase in spool speed or take any more energy from the exhaust once its wastegate opens (1st gate). It looses energy transfer very quickly, since the state of the gases upstream of the 16g turbine equalize to the state of the gases down stream of the 16g turbine. Where there is no temp change there's no work done. Eventually the 16g compressor/turbine/shaft is free wheeling. It's done it's job. The 60-1 is on boost.

 

[94awdcoupe]

This increase in volume airflow certainly can't be defined in a mathematical coefficient


An utterly foolish, senseless post. You've really put your foot in your mouth. And I'm glad others will see so as not to trust your input in this thread. Only you look stupid.

First to argue over semantics concerning where the multiplication takes place. How does the massflow go up with a bigger turbo or by having a turbo? Did you change the weather? Or did you beam your car onto a mountain top, Spock? The volume flow goes up at the meter with a turbo vs. not having one. Period. More volume flow at the meter is just as effective at increasing massflow as lower temp at the meter, or higher baro at the meter.

Which leads to the next foot. What's the point of the baro reading and temp reading fed to the ecu if the hertz count isn't a volume flow count? Think, please.

If you have 2 cubic feet of air and multiply it by 2 you now have 4 cubic feet of air.

the term 500cfm for turbo chargers is only a measure of what enters the turbo. if you have a 500cfm drawing in 500cfm the air coming out will be less than 500cfm. its not multiplying it to 1000cfm, 500cfm goes in but after the compressor is done the air is compressed to smaller space. its no longer at 500cfm its gonna be way less.

this is exactly why everyone is getting so upset when I am just trying to correct the terms used to describe what it happening. I am sorry I threw the first insult but this discussion will not further itself by trying to insult one another.

That's why I said when talking about turbos it is far wiser to use the term lbs.min.
It makes calculation far easier to understand. the 50lbs/min that goes into a turbo will result in the same 50lb/min coming out.

 

[dsm-onster]

YES! if you have 2L of volume flow read by the karmen meter, then add a turbo and see 4, then you've multiplied the volume airflow. The compressor inlet temp didn't change nor did the baro at the intake pipe. PV=nRT. WHAT THE HELL CHANGED!?!?!?!

NO ONE HERE IS TALKING ABOUT POST TURBO VOLUME FLOW BUT YOU!!!!! The rest of the group is discussing compressor maps and their inlet flow predictions as what's normal.

You yourself said that a turbo increases volume flow at the intake pipe. That can be calculated actually with a known coefficient. A coeffient is a multiplication factor of a variable. Semantics: if it increases a certain percentage over not having a turbo present or having a smaller turbo, then the volume flow at the intake pipe, ALL WE CARE ABOUT, is multiplied by a percentage over original. Stop talking in terms that no compressor map employs. Everyone else here is sharp enough to know that, when talking about volume flow, discussing it with respect to the intake pipe is a given and redundent to confirm.

It is not better to talk about compressor flow in terms of mass movement because some of us race in the rockies and would be sorely disappointed in our 49lb/min 50-trim logging only 44lb/min. It makes discussions about compound charging as difficult as you are making it, as well.

Why the hell do you want to run everything over to a mass flow number anyway. The gt35r .82 a/r turbine map only goes to 32lb/min but the compressor flows 65lb/min. How can the turbine flow enough to max out a gt35r (82mm) compressor? Converting every thing to a massflow doesn't explain that any more than using volume flow.

You're piss stinks and is killing the flowers.

 

[94awdcoupe]

What in the World make you think that for 55 lbs/min to come out of a turbo that 55 lbs/min has to enter it first? The 16G receives a volume of air and further compresses it to a higher volume. That's the way ANY compressor works

I was just trying to correct this statement.
would you like me to send this statement to a few turbo rebuild shops and ask what they think of it?

 

[dsm-onster]

It was already corrected. Why are you bringing up incorrect statements about how the MAF works, or whether or not the volume flow into the system is multiplied, or discussing volume flows not referred to on a compressor map, or that the wastegate wont open all the way choking the exhaust (even though it will be set for 10psi and he's going to be seeing 30+ in the intake manifold)? You're saturating the mulch here.

 

[viperlp01]

So what you are saying is that a nonturbo engine does not pull a vacuum from the turbo until it makes boost??

The big turbo has no idea that the little turbo is there it just ingests more air like a bigger motor.

What you are trying to say is that a turbo 2.0 liter(at 15psi) that makes 400hp and a na 4.0liter that makes 400hp (make the same power) will not flow the same air from a drawthrough mas (aka the meter behind the airfilter)??

I don't think that you understand how it works. So if the little turbo does the work then how much air flow will be pulled into the system BEFORE the big turbo to make 600hp? if we are making everything simple and saying that 1lb/min = 10hp. maybe half because there are are two turbos. ;-) sorry to be a tool but think about it.

No... They air flow will be nowhere near the same ...

 

[94awdcoupe]

Matt, you need to go over to wikipedia and see how many times the word volume is used to describe turbo function. this is the only one I can find

Manifold pressure should not be confused with the volume of air that a turbo can flow.

 

[dsm-onster]

No one is talking about boost. We all here are interested in the volume flow into the system boost is arbitrary and the result of increasing the volume flow. Forcibly increasing the PR down stream naturally increases the volume flow into the system. We've already corrected discrepancies in semantics. I need to go no where. This is basics. I need to stay. The turbo multiplies the volume flow into the system. But you should tell Theodore von Kármán that he missed a variable or 2 in his equations.