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Yeah, you got me on that one.....

I am gracious in defeat to the all mighty all knowing phunkdoktaspok..

Please continue you'r analitical disection of anyone who dares to defy you..

(Humor intended)

Dat 16 my point exactly, Thats the only thing you actually contributed to the topic, hte rest was pointless. If you arent interested just dont read it. Your an adult no one is forcing you too. And yes you are entitled to your opinion, but yet you seem to think mine and L18's should only be continued in private, Huh go figure. [qoute]The emotional outburst and uncalled for cursing just proves my point even more..

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Hey ####doctor, this is what i was refering to in the original post,yes there were other points raised aswell but I feel this was the main issue...

I do care what is written on this site as I have gained valuable knowledge into the workings of 1200's...

The last couple of pages became nothing more than a verbal stoush between you and L18_B110, neither of you were going to accept defeat and i couldn't see the point of going on with it....

Of course this is only my opinion which I thought everyone was entitled to in a free world...

The emotional outburst and uncalled for cursing just proves my point even more...

"Arguing on the internet is like running in the special olympics,wether you win or lose you'r still a retard."

Thanks for your time...

Something to remember is that this exhaust event takes approximately 16/1000ths of a second to form a gas packet. In a manifold if there are 20 packets contained then this would most likely take on a linear reducing time frame 16 X 20 / 2 = 160/1000ths of a second to dissapate. This would be about the same time it takes to build up a reservoir of "packets" in the manifold to provide energy to the turbine wheel.

The pulse theory is most important at very low engine speeds < 2500 rpm but above this the duration of each packet is so low they all start to become homogenous and must be considered as continuous flow.

The windwill will run with na lot of continuous puffs but make makes maximum torque with a continuous flow of air at a constant velocity.

A turbine doesnt have this luxury and has to deal with a wide range of gas flows from individual packets to solid flow.

I just reckon twin turbos will work if they have small enough turbines and similar size compressor wheels.

This is a good debate as it has got a lot of grey matter working and brought out some good descriptions of turbine operation.

There are no losers in this debate, especially 1200.com. More scientific debate will make it a better site. "PAX ULTIMAS"

Thats my two bobs worth.

Hmm, now the pressure in the exhaust manifold is only exerted against the turbine and not against anything trying to enter the manifold hey? That

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yes, you are right.
it's true that it spins up a little slower, but it's so negligible that it's not worth worrying about.

Like I said L18, I dont care if you choose to understand what I am saying, as I myself do.

It's obvious you only choose to read parts of my posts, As you ask;
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I have explained this all before, but one more time for you;
Let's look at what happens and causes a turbine to initially turn.
In your words a pulse hits the turbine and releases it's energy by causing the turbine to turn.
In the beginning of this topic you stated the properties of inertia on the turbine have to be overcome.
This means the energy of these pulses is reduced as a result of it being absorbed by the turbine.
Does this not mean the power of each pulse is reduced?
( L18 you are the one trying to argue that these pulses have a negative effect on the turbo's lifespan. If the power of each pulse isn't reduced by the properties of inertia on the turbine, how do you expect to argue that the pulses have a negative effect on the turbo's lifespan?)
Now like I said, break down a pulse and see what it actually consists of. This will then explain how these pulses loose some of their energy to the turbine.
Now if you can see how and why the pulses energy is reduced by the turbine, ( like I said, I am sure you won't) you will see why it comes down to gas flow volume and not the peak at the forefront of these "Gas Packets"
And once you can picture this, you will understand how the gas flow is initially restricted " Reduced". ( the gas volume exiting past the turbine isn't stopped or reduced, but when you look at the gas flow volume exiting the cylinders, it is restricted "slowed down" in front of the turbine. And since more gases are continuing to come out of other cylinders, this initially increses pressure, with this increased pressure increasing flow through the turbine.
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An exhaust manifold doesn't have a large capacity to store this charge, ( unlike a workshop compressor) so when the throttle is closed, the gas volume produced by the combustion event is instantly reduced. Therefore flow through the turbine is reduced.
If you think boost instantly stops the second the throttle is closed, Why does excess pressure vent back through the compressor or a BOV?
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No this isn't the case, and the above description of the exhaust manifold should partly explain why.
The capacity of the exhaust manifold isnt great enough to store a large charge, the pressure of this charge keeps a large volume of gases exiting the turbine quickly.
Now think, the more boost a compressor makes forces a larger volume of fuel/air into the cylinder. This will mean the combustion event is more explosive, and this will mean the peak at the forefront of the exhaust event will be stronger, and as you pointed out;
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so obviously the new exhaust gases are going to be stronger than the gases that have already had a chance to begin to cool.

L18 you seem to have trouble realising, that for any increase in exhaust manifold pressure, it is going to cause increased volume exiting past the turbine.
So as engine rpm increases - gas volume produced increases - the pressure of this increased volume = increased volume exiting past the turbine.
It's not until the gas volume required to flow past the turbine, is produced to quick for the turbines trim value, that power is lost.

Like I said I don't care if you choose to understand. But if you look deeper into what is actually happening in these events, you will see that your description is actually very limited in explination.

Cheers Steve.

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what does a restriction if not reduce flow?

And if you haven't reduced the flow of gas, how do you think you've built up pressure?

reducing the flow, slows it - loosing one of the two kinds of energy the exhaust gas has.

building up pressure also takes time - time in which the superheated exhaust gas is cooling rapidly - loosing the other kind of energy the exhaust gas had.

and contracting gasses take up less volume, extending the amount of time it would take to build pressure.

All of that is trivial of course, because this is not how a turbo works...You're putting a windmill in front of high energy, fast moving gasses. Not damming them up and using that stored energy.

If that was the case a turbo would continue to produce boost after the throttle was closed because it still has to let that store of gas in the exhaust manifold out past the turbine.

And pressure in the exhaust manifold also means you get less exhaust gas out of the engine in any given time (for example the time the exhaust valve is open). meaning you have more waste burnt gasses left in the cylinder in the next combustion event, reducing power produced (you can't burn it twice) and reducing the pressure of the exhaust gas in the cylinder for the next exhaust stroke, which then has to try and force it's way into the exhaust manifold. So you're left with even more waste gas in the cyl... it's a viscious cycle...and looses power...

Firstly I dont care what anyone thinks of this statement.
Dat16 if you dont know what the original post was about go back and ####in read it.
Tell me why the fuk I should take this off forum into PM's when it has everything to do with the ####in original post. And Dat16 if you dont care what is being written in this topic, plain and simply dont ####in read it.
Did your post give anything to add to the topic? No, so why ####in bother, same goes for a few others. If your adding a comment in humour fine then. But dat16 if your attitude is who cares dont ####in read it, no one is making you.

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First you say I wrote "stops flow" now its "increases" make up your mind!
But yes flow will be increased as a result of this restriction. Tell me, if pressure increases will this not force flow? will forced flow not mean increases flow?

L18 none of what you describe is wrong, and half way through this topic I made a point of saying yes these pulses are a contributor to the operation of a turbo.
I really think you should actually break down these pulses further and see what each pulse consists of, then you will see why originally I said we are talking about the same thing and then maybe( hopefully ) you will understand why I say it comes down to gas flow volume and how this effectively operates the turbo.
All of this still leads me to belive the use of the word "pulse" is the wrong wording to use when describing a turbos operation.
Your description of the pulse's energy and the actual use of the word pulse, puts thoughts into the mind of " Initial blast then sudden nothing" ( ie. stop, go) but if you break down a pulse you will see this isnt the case. Feral described the exhaust event best with two words (Gas Packet), yes this gas packet has its peak at its forefront but it doesnt just stop dead after the peak, it slowly dies off. This is because the gas packet has a volume.
Yes if you put these gas packets in a row, it is a pulse, but if you break these gas packets down you will see it is the flow of each gas packet's gas volume that effectively drives the turbine.

Early on it was agreed that the pulses from 4 cylinders is more ideal than that of 2 cylinders. And yes eventually this will have a detrimental effect on the turbo. ( how long? could be a long time!)
But your use of the word "Pulse" and the way you describe its energy, could be used in an arguement to say that the combustion events of and engine would lead to an earlier detrimental effect on the drivetrain on a 4 cylinder than that of an engine with more cylinders.
Do you see what I am saying about your use of the word pulse? ( I am sure you wont)

Ofcourse it will have its effect on a turbos lifespan, But the use of the word pulse could also be argued to say the pulses of a 6 cylinder are going to more detrimental on a turbos lifespan than that of a 4 cylinder.

"Pulse" doesnt effectively describe the exhaust event and the way its "Gas Packet" operate a turbine.

This is why I say I can understand the use of the word "Pulse" when describing Extactors. This is because you are describing how these Gas Packets ( pulses) are put into Order ( Rythm )

Ultimately L18 I dont care if you understand what I am saying, as I myself do. All this topic has shown is that there is no reason why 2 cylinders can't operate a turbo, and when sized correctly there is no reason why the turbo will not create boost down low.
And plain to see Go_The_Datto has made Twin Turbos work on an A12, even without using the best pulsing arangement of cylinders into each turbo ( ie. cyl's 1&2 for one turbo and cyl's 3&4 for the other turbo), With this setup's operation evident to 1200rallycar upon its placement into his own 1200.

Cheers Steve

just a question to pro-240c.
u say that having a/c ratios of two turbos equal to that of one is in effect the same, but wouldnt the friction of two turbo shafts on their bearings, although fractional, still cause the twin turbos to spool up one billionth of an rpm more slowly?
just a joke, heh heh heh!