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Author Topic: Allroad Compressed Air Quick Spool Switch  (Read 38476 times)
prj
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« Reply #15 on: June 24, 2016, 11:45:35 AM »

The compressed air will do nothing to spool the turbo on the compressor side... I am not sure why you would even think that.
The whole point of the compressed air is the same as nitrous - provide boost before turbo is spooled up and help spool the turbo faster by creating more exhaust volume.

A turbo is spooled by the turbine wheel.
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nyet
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« Reply #16 on: June 24, 2016, 12:23:09 PM »

Exactly. As soon as you turn off the air (compressor side), the wheel will stall immediately; there is still no pressure, and suddenly ALSO no velocity.
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Carsinc
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« Reply #17 on: June 24, 2016, 07:39:20 PM »

Yes, yes I understand the turbine is the drive wheel and better designed for being driven
by a high pressure stream of air. I was talking theory not real life. In theory the correct
jet of air could spin a turbo to the boost threshold at least, stupid sure possible yes.

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prj
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« Reply #18 on: June 30, 2016, 12:56:15 AM »

Yes, yes I understand the turbine is the drive wheel and better designed for being driven
by a high pressure stream of air. I was talking theory not real life. In theory the correct
jet of air could spin a turbo to the boost threshold at least, stupid sure possible yes.

There is no theory, the air would go out of the airbox lol.
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Carsinc
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« Reply #19 on: July 02, 2016, 09:54:53 PM »

We are thinking different you and I, I'm talking a small high pressure jet of air ported in the housing directly on the wheel speeding the
wheel up. Yes the turbine would be better but the right pressure at the right angle would surely increase the speed of the compressor wheel.
To be honest there is no reason to futher this, because I agree that nitrous is better.
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prj
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« Reply #20 on: July 06, 2016, 12:21:12 AM »

We are thinking different you and I, I'm talking a small high pressure jet of air ported in the housing directly on the wheel speeding the
wheel up. Yes the turbine would be better but the right pressure at the right angle would surely increase the speed of the compressor wheel.
It wouldn't.
Quote
To be honest there is no reason to futher this, because I agree that nitrous is better.
Not "better" your idea has no merit whatsoever. Nitrous works.
If you want to use an air reservoir, you can use a Y pipe with an electronically controlled flap - provide boost from the air reservoir, and once the turbo spools up switch over gradually.
Though if you calculate the volume of air required it probably can't be done.

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Carsinc
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« Reply #21 on: July 06, 2016, 08:57:04 PM »

I have no clue how I ended up defending the op. Oh well I don't care anymore.
We will see if Volvo or the op uses it. On a side note I will stick to nitrous but if the air
thing works I will never let prj live it down. Grin
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TijnCU
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« Reply #22 on: July 07, 2016, 01:43:43 AM »

I think the air would aid the turbo in the way of reducing effort on the compressor side. If you  want to spool the turbo with the compresor, the turbine wheel would create a vacuum because it has no free resource of air(gas) thus in an extreme situation it would create a vacuum in the exhaust manifold between firing cilinders and possibly open up a black hole in space.
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Carsinc
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« Reply #23 on: July 07, 2016, 10:07:55 AM »

Ok but how do you tune for a blackhole.
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pablo53
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« Reply #24 on: August 12, 2016, 07:38:32 AM »

I still have several more months before I can start up this allroad build.  In all likelihood, I won't be adding anything to aid spool beyond good manifold and up-pipe design/diameter, but it has been interesting to think through this idea and its execution.


PRJ, I hear you regarding N2O; my thoughts are that if compressed air is viable then I'd be looking at ~$100 to build plus no bottles taking up space or getting refilled.


It seems like several people are describing a scenario that would only occur if the system was used indiscriminately.   

The idea is to trigger the compressed air at/above xxxx rpm under wide open throttle, thereby dropping maybe 500 rpm to reach full boost. Who would just press the button at random times while driving?  If that were to happen, the bypass valve and internal wastegate do still function as normal just as when using anti-lag.


Here are a couple more interesting related things:

Turbo Charger Pre-Spooler:  https://www.google.com/patents/US20140026538


I'd have a nozzle like this, except it would enter the turbine housing through the up-pipe





New-ish (2014) Volvo 450hp 2.0L making use of air pressure and electric motor driven compressors:  http://autoweek.com/article/car-news/volvos-new-electric-supercharger-explained


After reading the Auto Week article, makes me wonder about running a twin charger setup using an electric supercharger....

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nyet
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« Reply #25 on: August 12, 2016, 09:46:39 AM »

I still dont see what prevents the turbine from stalling as soon as the compressed air jet is shut off.
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Carsinc
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« Reply #26 on: August 12, 2016, 10:00:53 AM »

In theory it would not shut off till the exhaust gas had taken over.
I understand what your saying and I cant say i'm sure it would work...
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nyet
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« Reply #27 on: August 12, 2016, 10:17:58 AM »

In theory it would not shut off till the exhaust gas had taken over.
I understand what your saying and I cant say i'm sure it would work...


Without a shaft speed sensor or exhaust outlet pressure sensor I am unsure of how to know when to turn it off.
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ME7.1 tuning guide (READ FIRST)
ECUx Plot
ME7Sum checksum checker/corrrector for ME7.x

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
pablo53
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« Reply #28 on: August 24, 2016, 09:15:01 PM »

I still dont see what prevents the turbine from stalling as soon as the compressed air jet is shut off.

The normal flow of exhaust gas.   This is a parameter that will need to be determined.  I can see your point, if the air was shut off too soon.

 I expect parameters of operation to be something like:
1) 90% throttle or greater
2) Turn on @ around 2k to 2500 rpm
3) Shut off when requested boost is reached or just under (or whatever testing shows to perform best/smoothest)

I wish I had the skills to build this simple function into ME7.1.  output could just be a single 12v +.  This would then be the trigger wire for relay controlling an air valve.    Since I don't have those kinds of skills, I'll probably use a 12v timer relay... or something in between.
« Last Edit: August 24, 2016, 09:25:11 PM by pablo53 » Logged
pablo53
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« Reply #29 on: August 24, 2016, 10:05:49 PM »

Without a shaft speed sensor or exhaust outlet pressure sensor I am unsure of how to know when to turn it off.

Hopefully my last post touched on this enough to answer your question.   Shut off will likely be based directly or indirectly off of boost, actual.   Compressor map could provide an approximation of shaft speed.

BW offers speed sensors, and the EFR series turbos have a designated location to drill into the compressor housing for mounting.

I had intended to buy the add-on speed sensor with the turbo, but more for the initial purpose of testing nozzle sizes, locations, and of course, whether or not 120 psi of compressed air will affect spool enough to make it all worth doing.


 
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