Hi,

I take off the amalvalve this w-e, because it's ticking
Correct me if I'm wrong but if I take off the amal valve, I will have full boost
I have a stage 2 t3 with -31 garret actuator ... I run only 6psi at 5000rpm under the gauge displays no boost, and the dump valve doesn't open ... But I have massive torque, the car burn so easily in 1,2,3,4 and the clutch burned (ap racing stage 2)
What's wrong ?
I didn't short the wastegate arm or anything, must I do it ?


thanks !

 

I have same problem, when I connect boost gauge to inlet mainfold plenum I have only 6 psi but when I connect boost gauge before throttle butterfly (on crossover pipe) I have 10 psi.

I think you have big boost but you dont "see it" on gauge.

 

No, if u take off the amal valve you will NOT have full boost. It bleeds off pressure from the actuator.

 

thanks mate
Someone tell me If you disconnect amal valve you have full boost or low boost
I owned several turbo'd cars, the wastegate hose was connected on the compressor housing... thus for me I could make same thing on the erst

 

yh if i take the amal valve off the tubro just pushes the acttuator rod out fully lol u need to put a bleed vavle so u can adjust the boost your self

 

I think that when you get off amal valve, you will have same pressure as before, but you will have max boost (depends on actuator rod lenght) in all gears. sure, you must connect actuator ro turbo when remove amal valve.

 

yep it's what I did
but I have only 6psi, tomorrow I'll try to shorten the actuator arm

 

it dont matter if u shorten the arm lol if the turbo is connected direct to the actuator its sending full air preasure to the autuator makeing it open the less it opens the less the wasgate open the more boost it runs with a amal valve u have the third pipe going to the air box is were all the access air gose wen the valve opens making the car run more boost same with a bleed valve but only thing with that is u can set ur own boost

 

yes but if I remove amal I will have same max boost ? only difference is that I will have max boost in all gears, isnt?

1 turn on wastegate arm is 1 psi i think

 

2 turns is 1 psi im sure some one wil correct me if im wrong

 

No, the amal valve is nothing to do with gears.

 

isnt amal valve electronical boost switch. Under low boost conditions the valve directs pressurised air it receives back into the airbox. when the ecu senses that boost level needs to be reduced, valve opens and diverts the pressure to actuator which then opens the wastegate and reduces boost. when pressure has dropped the valve switches back to low boost setting.

 

Correct me if I'm wrong. My understanding of the amal valve is that it variably bleeds off pressure to the set boost level. So, with standard amal valve and ecu setup, no matter on the length of the actuator rod, the amal valve will control the boost by variably bleeding off the pressure to the wastegate.

Therefore if you use no amal or bleed valve, you will only achieve minimum boost/maximum lag, as the wastegate will open far too little/early.

eg. A bleed valve bleeds off a set amount of pressure to "Fool" the wastegate and make it open at a much higher pressure than normal, although it's still receiving 8psi (-31) or whatever.

I may be getting the complete wrong end of the amal valve stick but I'm just looking at it logically.

Lee

 

man above is right!

 

Yay! First time for everything I suppose

 

 

""Therefore if you use no amal or bleed valve, you will only achieve minimum boost/maximum lag, as the wastegate will open far too little/early. ""

I think if you remove power on alam valve you will have minimum boost, but if you connect wg directly to turbo, you will have boost that much , how much you set actuator rod.

 

That's not how I see it. In that situation (no amal valve) a standard wastegate will open at 6psi as that is what the preload on the spring is set to. Therefore opening and only holding the 6psi. If you had a -31 you'd get 8psi, -34 10psi or whatever it is.

An amal valve or a bleed valve work to vent off anything above a set level to ensure that a standard actuator only ever sees 6psi but in fact the turbo has spooled up 14psi (for example) of boost, just the other 8psi was vented off before it got to the actuator. If you had no amal valve and had a theoretical 14 psi of pressure, you'd rip the rod right out of the actuator. The bleed valve will introduce an air leak if you will, so that a greater amount of work is required for little pressure, or in the case of a turbo spool up a lot more boost, by fooling the actualor into thinking there is less than there actually is

 

sorry all, but my actuator is a -34 garret, 6psi with a -34 is not normal, does it ?

 

thing is getting little complicated for my bad english

I will now just read.

and leave my amal valve connected

 

All the above is complete rubbish i'm afraid!

The amal is NOT closed loop, it is a simple on and off valve which will bleed off a fixed percentage of pressure.

Jack-of-all-Trades

How much preload do u have?

 

Rick, what do you mean by "preload" ? Sorry but english is not my first langage, I don't know all the technical terms in english

 

Who said it was closed loop?

and please dont rubbish people's theories

 

You are wrong. You are saying that a bleed valve or amal valve vent off anything above a set pressure. They don't, but they do work in the same way. If it bleed off above a set pressure, it would need to know the boost it was seeing, then bleed a specific amount off to reach the target or set level - hence closed loop - and it doesn't!

Lets go back to how an actuator boost control system works.

At low rpm, there isn't enough exhaust gas to spin the turbo, but suddenly. there is an exponential increase in gas, which generates, boost, which generates boost..... a highly unstable positive feedback system.

We use a wastegate, and a wastegate actuator to limit this boost. The wastegate is a simple valve, which directs exhaust gas around the turbo straight out of the exhaust pipe, altering the speed of the turbo.

THe actuator consisists of a pressurised canister, diaphram, spring, and rod. When u feed pressure into the actuator, the rod moves, which is attatched to the wastegate. Different actuators have different lift off pressure's. The std one is 4psi, the -31 is 7 psi, and the -34 about 14psi.

These figures are the LOWEST AMOUNT OF BOOST YOU CAN EVER RUN WITH THAT ACTUATOR. The lift off pressure is when the the actuator rod starts to move. So if u feed in 6psi to a -31, it will just sit there, but at 7psi it will move, and start to open the wastegate.

How do you adjust boost pressue with an actuator? By adjusting the rod. If you shorten the actuator rod, you are compressing the spring (this is what you are doing when u stretch the rod to slide onto the wastegate arm). Imagine you have shortened it by 4mm or so, and it's a -34 actuator. Upto 12psi, its not moving at all. Then when we hit 14psi, it starts to move internally - ie the spring . This never changes, no matter what the rod length is. But, although it's moving internally - the ROD isn't moving yet - the boost pressure is instead opposing the extra tension that you put on it when you shortened it. The result is more boost - AND it comes in faster and harder - because there is less wastegate creep.

Waste gate creep? At the std lenght, the -34 starts to move at say 13psi, and the wastegate starts to open at this point. Because it is opening, there is less gas to spool the turbo, and from this point to wherever the boost settles at, the boost rises slower. If you imagine the actuator with the smaller shorter rod - at 13psi, the wastegate is still firmly shut, so boost is still rising quiclky. This is why a std actuator gives sloppy boost response - it starts bleeding off at 4psi!

****The stiffer the actuator, the faster and harder the boost comes in, with less boost spikes, and less drop off at top end****

I keep saying "std rod lenghth" etc. What is this? Well, it's probably THE most important thing when setting one up. We know that we can lengthen the actuator to reduce boost. So why can a -34 run 12psi minumum? How come i have a -34 and i get 6psi?!! It's because there is not enough preload. Every actuator has a maximum rod length, which is associated with it's preload.

If the rod is too long, what happens is as soon as the car sees any boost whatsoever, it opens the wastegate. With the wastegate open, u will never see any proper boost. What usually happend is u might see 5 or 6 psi at the very top end of the revrange, and the car is very sluggish. What is the max rod lenght? It's known as "half a hole preload". What this means is that when u are putting the rod onto the wastegate, you need to stretch it at LEAST half the diameter of the hole in the arm which slides over the wastegate.

Amal valves and Bleed valve info to follow...

 

Ah well Rick, saves me looking for that other essay now you've re-written it

 

As Rick and maybe others have said.

The Amel valve is a electronic bleed valve, which is controlled by the duty map in the ECU.

So if disconnected, the car will run the least posible boost.

 

thanks all

a web page explain what the amal valve is doing and the switch mod:
http://www.cosworth.hu/?p=22

 

would'nt the car boost with or with out a bleed vavle because of it having a -34 actuator it's just i throught that the lift off pressure is 14psi

 

ha just reread this thread he has'nt a -34 he has a -31 actuator

 

lol

 

he sais he has a -31, then says it'a -34.

slimwynn

not if he doesnt have enough preload.

 

Rick
as you said it was a preload prob, I set up it and now there is no prob -> 14psi !