Jim Galbally

ok lets see if we can get some info on this for the techie room or Q&A Room or essay room etc

the only post i could find on the BB about drilling out restrictors etc was this one

http://passionford.webheberg.com/for...ic.php?t=19287

and i thought that mark was slightly wrong on what he was saying (ie run the car with no actuator pipe connected) seemed a little weird to me...

ok so on an amal valve you have 3 pipes right...

C which is your input
W which is your output
R which is your bleed

the way i understand it when the valve is in position 0 then C goes straight to W therefore it works as if there is no amal there and bleeds nothing so you will hit the boost that your actuator is set to

when the valve is in position 1 it will open the valve so that some of the air is bled via port R so as an example half of the air might be released via port R and so only half will leave by port W so your actuator will only see half the boost (in this example i'm assuming you have the restrictor on port R drilled out to bleed half the boost)

am i right sofar?

ok so then you need to go fiddling with your restrictors as you want to bleed more/less air out of the amal valve and also affect the way the boost comes in...

as i understand it if you increase the hole in port R you get more boost (in high mode) if you decrease the hole you get less boost

ok, so what about restrictions elsewhere. the valve i have has no restriction in port W but has a restrictor with a TINY hole in port C

from what i rememebr on threads from ages ago (ie not much!) this restrictor affects the reaction time. therefore a smaller restriction will mean the wastegate stays stuf for longer which will make the boost come in with more of a bang. it would also make the boost peak to a high figure and then drop right down to your decent held figure... right? (hence the peak n held boost a lot of people refer to)

so if you were to remove this restrictor completely it would make little or no difference to your overall held boost reading, but it would mean that you do not peak n then drop back... right?

so this is what you would want to do on a car that you intend to run boost very close to the Chip's Overboost function (ie if the overboost kicks in at 10psi you want it to peak 9 and hold 9 rather than peak 12 and hold 9 or peak 9 and hold 6)

are you following me sofar?

the amal valve i have here at the moment has NO restrictor in port W, a restrictor with a TINY hole in port C and a restrictor with a medium sized hole in port R.

since my car is one of those mentioned above with the overboost functionality, that would mean i want to remove the restrictor in port C does it not? and then adjust the size of port R untill i hit my desired boost setting... right?



ok, if i'm right (unlikely) this would be a good essay, but just needs all the questions removed from it so it looks like i know what i'm talking about... lol

Phil

iTrader: (1)

jim, i think im speaking for us all when i say, how the hell did you manage to turn something as simple as an amal valve into a post that long?!!!!

foreigneRS

good post jim, now we'll see who answers sensibly and knows what they're talking about, who takes the piss but still knows what they're talking about, and who just takes the piss

Karl

Jim for your car the best setting for the amal valve is with the electrical plug disconnected. LOL

Jim Galbally

lol karl.

can you just tell me if i'm right or not mate.

its what youve taught me (indirectly) in the past that this is based on, but ive got a bad memory and the posts where you told us on RSBB have been lost so cant re-read em

Karl

Jim, I dont usually advise on specific jettings because each car is different depending on actuator type and preload.

However as a very basic guide, you must always run a restrictor in the compressor union of the amal of around 2.5mm (or smaller if you require increased boost).

You can then alter the size of bleed restrictor to obtain the desired boost, a small restrictor in the bleed giving the smallest boost rise, where as leaving the bleed union totally unrestricted will give the maximum boost rise. (This is the same effect as unscrewing a bleed valve further, i.e. we make the bleed larger)

Jim Galbally

unfortunately karl i have no idea WHY that is. and ive just been scratching my head trying to think about it. could you be so kinda to enlighten us please. as long as youre not giving out any secrets that is.

also i understand why u dont want advise on what to do on my car so how about in general terms?
the restrictor in port C on this smal i have is TINY, about 1mm ish? ive never examined a 100% std valve so dunno if this one ive got off mike is standard or not.

also the restrictor in port R is about 3mm and looks like its been drilled

(ps im talkin diameters)

Stu @ M Developments

iTrader: (12)

Reason 1 Jim,
The sudden boost spike blows the fooker apart without a restrictor.

Jim Galbally

oh ok.

looking at this valve the tiny restrictor in port C is a threaded bit of metal and i can unscrew it (how cool is that!) is this standard or has mike modded it? (i await the "ask him!" reply)

will the 1mm restrictor in port C be BAD in my case.

i intent to run half hole on the actuator (should give me about 3-4psi going on previous experience) and then use the smal to acheive a max of 9 but it cant peak any higher than 9 as if it hits 10psi it'll overboost n kill the ignition

kjc300

iTrader: (1)

Can you get half a hole!!!!????? Lol.

Stu @ M Developments

iTrader: (12)

They are plastic as std, thats a shonky old carburettor jet jim

Get some std restrisctors and start from there.

Until you tell us what "you" want it to do, we cant tell you how to do it now, can we?

Stu @ M Developments

iTrader: (12)

Then stu reads the post properly.......

Std compressor restrictor, unblocked W port, 3mm C port.

That should be you sorted Jim lad.

Guinnless

Interesting point Stu.


Mine has no restrictor at all in the C port and the R port is almost fully opened up. Airbox is obviously drilled too.

Jim Galbally

so u recon those sizes of restrictor i allready have in there are sufficient?

what u mean tell me what i want stu?

i want to run 9psi on high boost

i dont want it to ever hit 10psi

whatever i get in low mode i dont really care to be honest

thats all my requirements really TBH

i'll edit this post tonight to turn it into a mini-essay for the FAQ section methinks

Stu @ M Developments

iTrader: (12)

Read the above.. ie, this:



The fact the bleed port is almost open means the internal pressure isnt as high as it would be with the port bunged, so its not too bad.

The other issue with the C Jet is slowing the mass of airs passage to the actuator, to bring her on boost harder and faster by effectively keeping the signal pipe depressurised a little longer...

The topic can go on... complex little things really if ya know what to do with em

Jim Galbally

ok cool...

anyone wanna explain the restrictor in more detail then as i certainly cant

Stu @ M Developments

iTrader: (12)

How much bloody detail ya want Jim?

Jim Galbally

i dont want any as i understand all i need to.

but some might...

c'mon... we need to fill up these other sections with usefull FAQs

Guinnless

Cheers Stu

Marc sierra

iTrader: (1)

Bringing this post back from the dead as it was the best I could find on the operation of the amalvalve.


Am I correct in thinking that the bleed through the R determines how high the boost can be. But the boost doesn't necessarily go that that value, as the chip will determine at what pressure the amalvalve will close the R port?


So for instance if the restrictor in R is quite small, the boost might not be able to go above 1.2 bar, even though the chip is good for 2.0 bar. On the other hand if the restrictor has a bigger hole (or is even missing), the boost might go to 2.5 bar, but the chip will limit it to 2.0 bar (if that is the maximum for that chip)?


Or should you match the restrictor in the R port so that the maximum boost possible by the amalvalve matches the maximum boost allowed by the chip to prevent it doesn't boost too high?

Gavinbat

Hi,
The way I read it from the training manual is the valve bleeds boost off to delay the actuator operating.
So if you set the actuator to open at 10psi, if piped directly, then the amal bleeds off boost to prevent it opening until you reach 20.
The only reason I can think of for altering the amal is if you fit a really strong actuator to run higher boost and the amal won't flow enough to open it?
Cheers,
Gavin

martysmartie

iTrader: (1)

That would be one reason, but the jet size can change the characteristics as well.

Martin

Gavinbat

Hi,
Is it not possible to change the characteristics of the amal by using the amal table in the ECU? Reading above it all seems a complicated way to do things when there's a table to adjust it in the ECU?
Cheers,
Gavin

martysmartie

iTrader: (1)

I think it's more to do with physics, when tuning, the standard jets are not big enough to flow the desired amount of boost. The ECU still controls it.

Martin