CosRush

Can anybody please enlighten me as to why this is done, When it is needed and basically how it is acheived......?

Cheers

Mark_w

somebody will correct me if im wrong but they havent in the other post as i see it.....the amal valve is set up for a standard cossie,it is a safety precaution ....in normal mode,it operates your actuator and it bleeds to airbox so will not open your actuator easily....if your ecu detects a problem,it operates amal valve and diverts pressure to actuator ,therefore opening it and reducing boost............when a cossie is modified you could adjust the actuator preload to any degree ,but if you shorten rod to much i dont think it would be accurate as it would be out of actuators operating parameters....as explained in other post you set up actuator to make sure it will not open by turbo pressure alone and then set by restricting or opening amal outlet hole......the hole is normally to big so will open actuator too early..decrease size of hole and it will hold the boost longer.....calling..stu to explain it better

Mark_w

try this cosrush and you will see what i mean..if you have standard actuator...disconnect actuator pipe completely.....set actuator with no preload ie...rod goes over wastegate with about 1mm pull...run car and record boost pressure....now shorten actuator to 1/4 of a hole preload...run car and record boost again...boost will have increased because of the preload.........there is no pipe connected to open actuator and bleed boost ...it is pressure in exhaust side of turbo forcing wastegate open and releasing it.....so before you start playing with amal valve you need to make sure actuator can hold the maximum boost you require....give it a go,and when your actuator is set to your max boost,reconnect amal pipe and run...the boost will now drop amal valve will open actuator too early...this is when you experiment with different size holes(smaller to get your required setting)

CosRush

Mark RS,

Thanks very much for the reply.
I see what you mean

So once the actuator alone is set to say 12psi (standard 4x4) and the Amal Valve reconnected the boost will drop, then its a case of reducing the Amal Valve jet (is this the one to the airbox???) until the boost pressure is back upto 12psi...???
Is that right?

Cheers

CosRush

Also,

When you start reducing the size of the jet is there any danger of making it too small and increasing the boost to high??

Mark_w

you can reduce it by smaller hole in amal outlet to actuator or increasing hole in outlet to airbox,i tried the latter and could not get it right.....so i lathed up a piece of nylon the size of amal outlet i/d and cut a piece about 5mm long...drilled 1mm hole in it ,removed original restrictor and superglued it in.....i had already set up actuator to hold 26psi by running with pipe disconnected and gradually shortening actuator rod....when i connected amal valve i tested and it was the same so gradually opened hole (1/2mm)at a time until when run boost would tail off and hold 23 psi

Mark_w

you cant increase boost too high as your actuator is set up to hold the max boost u need only and with pipe connected can only get lower not higher....im not very good at explaining this might help...this is how i did it to run 26 psi peak dropping to 23 psi held but is same adjustment technique for any setting


1-remove actuator pipe and set actuator at 1mm preload,then run at full boost and record result
2-wind in actuator rod 1/2 a turn at a time and run under load until the boost held is 26 psi...you now know that your actuator will hold 26 psi and not be forced open by exhaust pressure
3-replace actuator to amal pipe and when i run again boost held had dropped to 17 psi
4-i then put 1mm restrictor in amal outlet to actuator and run again,boost was still 26 psi held which meant not enough pressure was going through restrictor to open actuator.
5-drilled restrictor to 1.5mm and run.... boost went to 26 psi then dropped to 24psi held
6-drilled restrictor to 2mm and run....boost went to 26psi then dropped to 23psi held....job done

i would like stu to come on here and comment on above technique...i see it as failsafe as actuator will only just hold the max boost you require before exhaust pressure opens wastegate,therefore if actuator pipe split or come off you know you cannot overboost

mark

CosRush

Thanks Mark RS for the help.

Its much appreciated

As soon as i get a chance i'll go out and try it

CosRush

MarkRS,

Been out for a drive and this is what happened.

Removed Actuator pipe.
Set preload to half a hole.
Drove car and as soon as it started producing boost it dies.
When i say dies, the accel is really quick then its as if someone has stamped on the brakes, as the surge just stops.
When this happens ts barely producing any boost.
Stopped, adjusted act. 2 complete turns.
Drove again, no different.
Refitted Amal Valve and it started producing boost again, albeit to low....

So not sure what is going on really.

Any thoughts?

Mark_w

as my post above.....at first set preload so arm only needs about 1mm pull to get over wastegate....half a hole is far to much

Mark_w

sounds like your over boosting ...like i said at first ,do it careefully and gradually....follow this guide here but change to your required boost....

1-remove actuator pipe and set actuator at 1mm preload,then run at full boost and record result
2-wind in actuator rod 1/2 a turn at a time and run under load until the boost held is 26 psi...you now know that your actuator will hold 26 psi and not be forced open by exhaust pressure
3-replace actuator to amal pipe and when i run again boost held had dropped to 17 psi
4-i then put 1mm restrictor in amal outlet to actuator and run again,boost was still 26 psi held which meant not enough pressure was going through restrictor to open actuator.
5-drilled restrictor to 1.5mm and run.... boost went to 26 psi then dropped to 24psi held
6-drilled restrictor to 2mm and run....boost went to 26psi then dropped to 23psi held....job done

CosRush

Does this point to a suspect Actuator?

Surely at Half a hole it should be producing a fair degree of boost, but it wasn't......

Why does it boost with the amal connected, but not without?

Any other idea's?

Mark_w

when you set it to half a hole it sounds like you were overboosting!the actuator controls the wastegate so if you disconnect pipe it cannot open to release boost so it has got to produce boost unless actuator is completely weak.......with pipe off and setting it at half a hole there is too much preload so you have overboosted

CosRush

Im sure you know much more about this than i do but it still doesn't explain why i get boost (on the gauge) with the amal connected and yet virtually none with it disconnected.

The difference in acceleration is exactly the same except with the amal connected it keeps going up where as without it it just stops......

It jusn't make any sense to me so i must be missing something