NefMoto

Ever since I finished my last build here (http://"http://nefariousmotorsports.com/forum/index.php?topic=3034.0title="), I've wanted to build a single turbo setup on a C5 allroad.    Well, I found the perfect project car a month ago (2002, 6-speed, 152K miles, bone stock, and needing a lot of minor work), so I'll be collecting parts throughout the summer for a winter project.

While rebuilding the airspring compressor, a silly idea popped into my head.   Why couldn't you spool a turbo with a shot compressed air to the turbine blades?

When I searched, I didn't expect to find anything, but lo and behold: http://www.roadandtrack.com/new-cars/car-technology/news/a27515/volvos-diesel-turbo-lag-solution-is-compressed-air/ (http://www.roadandtrack.com/new-cars/car-technology/news/a27515/volvos-diesel-turbo-lag-solution-is-compressed-air/)

And what better platform to add this to than the allroad.  The car already has the most important capabilities to make this work.  Implementation with a nozzle drilled and tapped into the turbine housing or up-pipe, and switch to activate it on-demand somewhere near or on the gear shifter or steering wheel would be fairly straight forward.

Anyone have any opinions on this?   

I think having enough flow/volume to do anything to make it worth the hassle would be the hard part. Then you would have to have a large enough container and keep it full for the compressed air. I didn't read the article yet.

People spend way more time complaining about spool time than they do waiting for boost.
Big turbo power comes at a cost that cost is spool time. That said there are few things in
life like the way a big turbo builds on a low rpm 4th gear pull.

Making this work would rely on good placement of the air nozzle in the system and the velocity of the air stream rather than volume.   The allroad suspension operates at 120 psi.   Think about how much force is generated by your home compressor with the blow-gun nozzle attachment.....

Maybe it's not enough, but I've decided to at least test the concept once I have the turbo on-hand.   Testing should be pretty easy since the turbo I plan to use is the BW EFR 8374. The EFRs have an integrated speed sensor the sells as an optional accessory.


OK.  Who's complaining?  Are you saying that if you had a simple means of spooling your turbo at any engine speed, you would refuse?

"Big turbo power" doesn't necessarily cost spool time at all - you didn't check out the link, did you?    Also take a look into both the Kinetic Energy Recovery System (KERS) and the Motor Generator Unit - Heat (MGU-H) in Formula 1 racing.  Eliminating lag is exactly what they do.

I have no idea if incorporating this compressed air spool idea into the allroad will work or not, but hell, it's no skin of my back to look into it further.

Thank you for your feedback.   Keep it coming.   Any technical problems anyone can think of?

Ok, some how I think the turbo on that Volvo is going to be a bit smaller than the single you will buy,

The point I'm trying to make is that is a lot of extra air at very low rpms that could be very bad, and
would require a ton of fuel. It would also create very high cyl pressure which would be bad.
But hey what do I know, screw it I would say a 67mm on a 2.7 making 25psi at anything under 2500
rpms could get real interesting real fast.

Ahhh, wow, I can't believe I couldn't read between the lines on your first post.

Fueling takes care of itself - Intake path is not compromised.

What does the size of the turbo matter?  All control systems remain in place.  Boost would still follow LDRXN which can be tailored to keep everything well within safe pressure.

Injecting all that extra O2 between the MAF and the O2 sensor? Not sure I follow this reasoning..

The size of few things in life matter as much as the size of the turbo.

It has been done forever and ever.

It is called nitrous. Simply fit a 50 shot and you have exactly the same effect.

First off, turbo is the efr 8374 with .82 a/r internally wastegated turbine housing.   I figure I'd use some stainless tubing that would pass through between the two up-pipes as they merge, then straight through the t3 flange and an inch or two into the outside edge of the turbine housing.  Testing would determine best location and nozzle size.   Then add a stainless 1/8 npt or m10 on the outside of the up-pipe and tig it all up.  Can always plug the bung (te he), if it doesn't work out.     

Usage would only be for track and other special circumstances.   The setup would only be triggered at WOT.   I've been on hiatus the last couple of years, but wouldn't me7 fueling be running in open loop under these conditions anyway?

Narrowband 02 sensors will be upstream, in the up-pipes in any case. They will still be as close as I can get them to the t3 flange.   I'd already planned this O2 placement regardless of whether or not I continue on with the compressed air thing, so I am well aware of the possible issues of having them pre-turbo.  Apparently NTK makes narrowbands that do very well in the heat and pressure in case my stockers don't make it that long.


Good point


Concur!  What I meant was can you explain your logic for "Ok, some how I think the turbo on that Volvo is going to be a bit smaller than the single you will buy"?
I expect to get really good spool regardless, by building double walled, 1.5" ID up-pipes.   Everyone wants to do 2".
 

Wait, first nitrous is used to spool but it works way different than what we are talking about.
As far as manifold design I will message you direct to not change the course of this thread.
I agree that turbo will be awesome for a 2.7 but I see no reason for the compressed air thing, It
wont work unless it blows direct on the turbine or compressor wheel.

An allroad on track? Shrug.

As far as activation - it's a doable task. Binary control can be done with some unused stock valve output (N80, N112, etc).

This. The only way to supply enough (indirect) air is via supercharger or nitrous.

And blowing a tiny stream of air directly on either wheel is unlikely to change spool much unless the whole turbo system is designed to work that way from the ground up, imo.

That said, if you have time and money to waste, go for it.

Not sure how you'll get around fueling problems, though.

It actually works and is not a waste of time.
You do not need a lot of nitrous to spool the turbo, and a small well controlled shot won't actually hurt anything long term either.
Give it a go sometime. That's how all the small engines with big turbos are spooled...

I have, but the nitrous does not spray on the wheel of the turbo, it goes in the the intake.
which spools the turbo in a very different way than what is being talked about here.
If you spayed nitrous direct in a turbo housing I'm kinda curious as to why?

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.

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.

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.

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.

It wouldn't.
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.

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. ;D

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.

Ok but how do you tune for a blackhole.

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 (https://www.google.com/patents/US20140026538)


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

(https://s6.postimg.org/ksps2qwwh/Turbo_w_Air_Nozzle.png) (https://postimg.org/image/luzylafpp/) (https://postimage.org/)



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 (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....

(https://s6.postimg.org/cyp6hcp3l/valeo_electric_supercharger.jpg) (https://postimage.org/)

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

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.

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.

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.


 

I would expect it to make very little difference... Obviously yes when you do it to the turbocharger out of the car and you point your air line at the turbine/compressor, it spools up quick - however the turbocharger was stopped to begin with and if you keep on the air line, it doesn't get much better. Also think about what happens when you attach a boost hose to it and start actually compressing... The actual amount of energy being transferred into the rotating assembly is frankly sweet FA unless you're dumping a LARGE amount of air in!

As has been mentioned previously - think of ways to increase exhaust gas energy...

All IMHO of course.

I've still got a few months before I have the cash to start this build.   

Once I get to the point of testing, if I can't get 15-20k rpm with compressed air alone, I'll just bag it.  No harm done.

One other concern of mine is the potential damage and/or warping of turbine blades due to blowing air that is ambient temperature.   Looking at the design of the stock Volvo setup, air is injected as far away from the turbine section as possible.  I wonder if the reason for that is so the compressed air has a change to mix with exhaust gas prior to reaching the turbine blades.

I just wanted to post an update to this:

After running some tests with a journal bearing GTX3582R knock off, the compressed air with various nozzles ranging from 1/16" to 5/16" @ 120 psi just didn't generate enough rpm on the turbo.    I'm talking < 5k rpm.  

So I've ended up bagging the idea.   Perhaps with a ball bearing turbo of GT30 sized turbine would show some results.

I ended up going with a 12.8:1 compression ratio on this build for running 50% or larger ethanol content fuel and I expect to have much more noticable throttle response under all conditions.

Results will be posted in the vehicles section soon.

Appreciate the update,