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Sanctifier
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 Posted: Tue Mar 24, 2009 8:28 am Post subject: Secondary Air System... a.k.a. RalliArt ANTI LAG SYSTEM! |
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Hi luvnish. Here's info on the Secondary Air System... a.k.a. RalliArt Anti-Lag System.
Link--> How To "Evolutionize" your Lancer! - Page 9.
It's pretty long so I started a seperate thread here on the  Anti Lag System.
IMHO it was introduced to "homologate" ALS for rallying, using the "clean air" benefits as an excuse.
Anti-lag system - Part 1:
| luvnish wrote: | What are those two ports on the exhaust manifold for?
Can I delete that whole system? What is it's purpose? |
It's the "Secondary Air-injection System." It's that squiggly alloy tube running from a solenoid valve
connected to the tube near the intake plenum to two ports at the top of the exhaust manifold.
It's also the basis for the RalliArt Anti-lag System.
In rallying it's used to reduce turbo lag between gear-shifts.
I don't know how much residual benefit is derived from it without full-blown Anti-lag activated in the ECU.
It also "leans out the exhaust gas for emissions purposes" as you said.
So you can delete it if you want... but why worry?
| Quote: | How the turbo Anti-Lag System works: Bang-bang (also known as ALS which stands for Anti-Lag System)
is an engine management technique that allows to minimize the turbo lag time.
As you might be aware of, turbochargers display what is known as lag time which is the time needed for the
turbine to reach its full throttle from an intermediate rotational speed state. The duration of a turbocharger's lag
depends on many factors among which its inertia, airflow efficiency, back pressure, etc.
The issue is partly dealt with by fitting a turbo dump valve, which acts each time the driver lifts his foot from
the throttle. The dump valve will evacuate the pressurized air coming out of the turbocharger while the inlet manifold
is closed thus allowing the turbine not to stall and avoiding possible damage to its bearings.
In race cars it is very common to fit oversized turbochargers in order to be able to produce enough boost pressure
and assure a sufficient engine output. Big turbochargers display significant amounts of lag due to their
increased rotational inertia. In such cases the dump valve is insufficient to allow the turbocharger not to loose too
much speed when the driver lifts off. Additionally rally cars are fitted with a turbo restrictor, which is regulated by the FIA.
One of the restrictor' effects is to increase lag time. This is why in racing cars, and more specifically in rally cars,
where torque and engine availability are critical performance factors, most applications use anti-lag systems.
During lag time the engine is much less responsive and its output well below nominal.
To counter the effect of the turbocharger's lag time drivers used to anticipate the engine's reactions by
accelerating well before they would have done in a non-turbo car.
Others have used a technique, introduced by the German driver Walter R�hrl, known as "left foot braking"
where the driver uses his left foot to brake the car while his right foot accelerates to keep the turbocharger
in optimal load. Left foot braking is very hard on the brakes which are put into extreme stress but is very efficient
in keeping the turbo spinning.
ALS was a simple idea but one that was relatively difficult to implement.
Only when electronic engine management systems were advanced enough to allow taking into consideration
many more parameters, in real time, than in the past it became possible to use them efficiently in handling ALS.
To the best of my knowledge Toyota Team Europe were the first to use it in racing (Toyota's implementation is known
as Toyota Combustion Control System while Mitsubishi call the system Post Combustion Control System).
How ALS works: When the driver lifts his foot from the gas pedal the ignition timing is altered with
sometimes 40� or more of delay (retard) and the intake air and fuel supply mixture is made richer.
The inlet butterfly is kept slightly open or an air injector, bypassing the inlet butterfly, is used to maintain
air supply to the engine.
This results in air/fuel mixture that keeps getting in the combustion chambers when the driver no longer
accelerates. The ignition being severely delayed, the air/fuel mixture reaches the exhaust tubes mostly unburned.
When the spark plug fires, the exhaust valve is starting to open due to the ignition delay mentioned above.
Additionally, the exhaust temperature being extremely high, the unburned fuel explodes at the contact
of the exhaust tubes.
Luckily the turbo sits right there and the explosion keeps it turning (otherwise it would slow down since its
intake, the exhaust gases, is cut-off). The effect is vastly lower response times with some downsides:
�A quick rise of the turbocharger's temperature (which jumps from ~800�C to the 1100�C+ region)
whenever the system is activated
�A huge stress on the exhaust manifold and pipes (mounted on a street car a bang-bang system would
destroy the exhaust system within 50-100 km)
�The turbo produces significant boost even at engine idle speeds
�The explosions which occur in the exhaust tubes generate important flames which can, sometimes,
be seen at the end of the exhaust tube
�Reduced engine brake
The ALS effect is mostly dependent on the quantity of air allowed into the engine, the more air supplied
the more the ALS effect will be noticeable. Consequently ALS systems can be more or less aggressive.
A mild ALS will maintain a 0 to 0.3 bar pressure in the inlet manifold when activated whereas, when inactive,
the pressure in the inlet manifold with the throttle closed would be in the region of -1 bar (absolute vacuum).
Racing ALS versions can maintain a pressure of up to 1.5 bar in the inlet manifold with the throttle closed.
While the systems mounted in Toyota and Mitsubishi racing cars are relatively smooth and noiseless
those fitted in Ford and Subaru cars are much more noisy and aggressive.
The bang-bang system owns its name to the loud explosion noises one hears whenever the driver lifts off.
Most racing implementations have user selectable anti-lag settings depending on the terrain,
usually three settings can be selected by the driver going from mild to very aggressive.
Starting in 2002 new anti-lag techniques, such as Exhaust Gas Recirculation (EGR), are slowly
overtaking the method described above as they are kinder on the engine's mechanical parts. |
Link--> How the turbo Anti-Lag System works.
IMHO Anti-lag is really not a great idea for a street (or even occasional track) car as it severly
reduces the durability of the turbo and exhast manifold (and exhaust system too.)
| Forever Joey @ Blog Spot wrote: | To setup a full anti lag system you will need at least the following:
Some method of controlling the timing and fuelling of your car (programmable ECU)
A method of getting extra air into the exhaust system (either by holding the throttle open using a motor
or by dumping the air from the turbo into the exhaust manifold)
There is a basic anti lag setup on the standard Evo 5-6 (ECU) but it is not operational.
This uses the secondary air system to provide air into the exhaust manifold when you have been on
full throttle for more than 3 seconds and the engine is still above 4,000 rpm.
To get this to become a full anti lag setup what you need to do is to drill out the little jets that are present
in the current exhaust manifold inlet ports for the secondary air to make them larger and then
re-route the dump valve outlet into this system.
You can then run with a programmable ECU to change the fuelling (dumping extra fuel) and
the timing (retarding it so that it ignites the mixture when the exhaust valve is open) and that's all you need.
The only downside (as people have pointed out) is that you will need a new turbo and exhasut manifold
quite regularly as the maximum exhaust temperatures exceed 1000 deg C when running this setup.
If you use the anti lag method that holds open the throttle then you will also lose the servo assistance on
your brakes because you do not have the necessary vacuum in the inlet plenum chamber to run the servo.
To combat this, you can either run without the servo assistance and modify the brake system to provide
better feel or you can run an extra compressor to provide a seperate vacuum system for the brakes.
If you use the Secondary Air System method though, you will still have the assistance because the throttle
can remain closed during the use of anti lag and so you still have a vacuum after the throttle
but you are generating boost pressure before the throttle body. |
Link--> Anti-Lag Evo.
Everybody's $0.02�
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Last edited by Sanctifier on Tue Mar 24, 2009 8:48 am; edited 3 times in total |
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Sanctifier
Zorce Moderator
Joined: 07 Apr 2005
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Location: Good question!
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| Posted: Tue Mar 24, 2009 8:28 am Post subject: |
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Anti-lag system (ALS) - Part 2: (from Evolutionm.net)
Okay luvnish. Apparently you can tailor the amount of ALS obtained.
Here's Part 2 for those wanting to activate the ALS feature by re-flashing the ECU.
I still suggest that this be left alone, until you are VERY proficient with Evo Tuning and ECU Reflashing in particular.
My $0.02�
Link--> Evo Anti-lag ECU Disassembly.
His $0.02�
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luvnish
Rebel Speeder
Joined: 19 Jun 2008
Posts: 84
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| Posted: Tue Mar 24, 2009 1:33 pm Post subject: |
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Very interesting topic.
It seems that the USDM guys would love to set up the air injection system on their Evo's.
So this basic setup that comes standard on the 5's and 6's, is it ECU controlled? I cannot recall seeing any wiring going to the pump/valve
thing. I thought it was purely a mechanical part, not sure though.
I'm not clear on when it is activated though. Above 4000rpm, more than 3 seconds, full throttle? Is the air released into the manifold
when these conditions occur while still @ WOT? Or does the air release when the throttle is closed during shifts, sort of like a dump valve? |
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luvnish
Rebel Speeder
Joined: 19 Jun 2008
Posts: 84
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| Posted: Tue Mar 24, 2009 4:11 pm Post subject: |
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From doing some more reading into that thread you linked from evolution.net, some E5 & 6 owners from UK and Ireland were chiming
in as to what the usefulness of the SAS system really is.
The general idea I got from it was that the SAS system was implemented on the production model Evo so that it could be used for
Anti-lag on the rally car. Meaning that even if the hardware wasn't set up to function, it must still be there on the production model
of the car, based on rally rules or whatever.
Another guy said that the hole in the banjo bolt to the manifold is so small that it seemed useless.
Then another guy said that they drill out the banjo bolt to 1.5mm to accommodate more airflow to the manifold, making the
SAS sytem a bit more useful. |
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Sanctifier
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| Posted: Wed Mar 25, 2009 11:22 pm Post subject: |
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"Yes"... and "maybe" to the above. It's an area that I know NOTHING about at present.
It's icing on the cake... and DANGEROUS without complete research and info... too much stress on turbo.
I'll explore this (in a couple years) after ALL my other upgrades are complete... and only AFTER I'm totally
comfortable with tuning, compressor maps, ignition and fuel mapping and reflashing.
Even then, its best to take small "developmental steps" at a time... logging and testing as you go...
My $0.02�
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Last edited by Sanctifier on Tue Mar 31, 2009 12:50 am; edited 1 time in total |
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luvnish
Rebel Speeder
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| Posted: Mon Mar 30, 2009 4:28 pm Post subject: |
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Are you saying that there may be some adverse effect if the banjo bolt is ported bigger?
I was thinking about that valve that is used in the system, and if it could possibly leak under high boost, similar to how a recirc. valve
leaks over 20psi (for example).
The port is nowhere near as big, but a leaky SAS valve doesn't sound like fun.
I'm starting to think condemning the whole system might be the way to go.
Can it be that useful if it was never even implemented in the USDM evo's?
Maybe I could block off the vacuum hose that actuates the valve so it can't open, and then let the butt dyno tell if it makes a
difference between shifts.
So the final decision would be between porting an SAS equipped manifold (stock E5 or E6), or port the E8 manifold I have in
case I wanna condemn the SAS hardware. |
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Sanctifier
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| Posted: Tue Mar 31, 2009 12:54 am Post subject: |
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If you're never going to try Anti Lag... port the E8 manifold.
If you're going to try Anti Lag one day soon... port the E6 SAS manifold.
IMHO either can be reliable. The E8 manifold has the blank bosses cast in, not so?
So you can port the newer E8 manifold now (less metal fatigue)...
and drill holes for the SAS if needed later.
My $0.02�
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W2J
Pumpum Conqueror
Joined: 04 Sep 2005
Posts: 10
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| Posted: Wed May 13, 2009 10:55 pm Post subject: |
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| Sanctifier wrote: | If you're never going to try Anti Lag... port the E8 manifold.
If you're going to try Anti Lag one day soon... port the E6 SAS manifold.
IMHO either can be reliable. The E8 manifold has the blank bosses cast in, not so?
So you can port the newer E8 manifold now (less metal fatigue)...
and drill holes for the SAS if needed later.
My $0.02� |
its called secondary air pump (sap) and it does not work!!!! |
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Sanctifier
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| Posted: Wed May 13, 2009 11:21 pm Post subject: |
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Typo, W2J... just a typo.
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MadCrix
Los Paranderos de Zorce
Joined: 06 Apr 2005
Posts: 153
Location: Breaking in new gearbox
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| Posted: Thu May 14, 2009 1:01 pm Post subject: |
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well a leaky sas vavle will casue your idle to go crazy. my car has a leaky vavle and i idle at 3k rpm. i unplugged the vacum
house fromt eh manifold and blocked it off and idel went back to stock 
gonna change the vavle. i jsut liek it to retain the parts that it came with, regardless if it has no use
i mean how much weight i really will lose, 2 lbs? lol
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R. Mutt
Jedi Hopeful
Joined: 14 Apr 2005
Posts: 195
Location: New York
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| Posted: Fri May 15, 2009 8:00 pm Post subject: |
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From what I understand the SAS system has been tested to work on jdm cars though I've yet to dabble with it in Ecuflash as Mike's evo runs an aftermarket manifold. One of the critical component you need to get it working:
electrical solenoid that activates the SAS valve
Refer to this thread for the info on the hardware necessary to get SAS working.
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MadCrix
Los Paranderos de Zorce
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Location: Breaking in new gearbox
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| Posted: Sat May 16, 2009 7:29 am Post subject: |
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yup real bredders want to put it in. keepign it JDM is the way to go
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Sanctifier
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| Posted: Sun May 17, 2009 5:44 am Post subject: |
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| MadCrix wrote: | | yup real bredders want to put it in... |
^ ^ ^ Why?... Regular "Anti-lag" use = Frequent turbo replacement.
IMHO the minor turbo lag of even an Evo 6 TME (TD05HRA-16G6 -10.5T) isn't much of an issue,
especially for a daily driver.
My $0.02�
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MadCrix
Los Paranderos de Zorce
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| Posted: Sun May 17, 2009 7:28 am Post subject: |
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its more about makign it JDM wade.
to everyone, JDM is more importnat that the 1 second faster per lap
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Sanctifier
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| Posted: Sun May 17, 2009 4:22 pm Post subject: |
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Point taken, crix. Just as long as you don't activate the Anti-lag and use it all the time.
BTW if SAP parts are that important, they are available off any E4-E6.
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