On some cars bleed valves work very well, and are cheap.

I fitted a plastic fish tank bleed valve to my Volvo turbo estate. £1.89

Does the job perfectly.

Every application is different though, but as long as the w/g is sized well for the engine, then a simple bleed valve can be very good.

If people out there think they are shite and useless.....it must be because they dont understand how they should be used.

 

think the problem is that people blame the bleed valve for the engine melting
when the problem is that it wasnt made idiot proof
so any fuckwit can make their car go like fuck just with a couple little turns(not for long)

 

What would be the reasoning in using one in addition to the electronic control, I am guessing you obtain finer boost control?

Martin

 

No, you would just mess up the electronic unit's fine control.

You wouldnt buy a Motec to run your engine, then fit a megasquirt as well

 

Thats what I would have thought but thats the way I understand from Stus post.

Martin

 

the thing i dont understand is why a cossie would ever have one fitted?
the amal valve does a perfectly good job, and if you want to increase your boost, with a bleed valve or not, it is going to need to be mapped again, so why not map it with the amal valve?

 

Had one in my FRST, only problem I noticed was alot of boost fluctuation.

 

I had one on my escort cossie when it was converted to big turbo for 2 years it was never touched once set & never gave any bother boost was the same all the time went perfect , infact its one of the best cars ive had for boost with amal valves etc ive always had bother , air injectors sometimes the boost was funny not always the same bleed valve was ok.

 

Many people don't understand fully what is involved, they think it's just a case of increasing the boost, then wonder why there engines melted.

Martin

 

amal valves can fail,bleed valve is not electrical so the only thing that can happen is that it is turned somehow,so get a lockable one.
i fail to see how its any different from a massively expensive electric boost control module that you can also play about with and potentially melt your engine,funny that never gets mentioned though.

 

From what I've heard (feel free to correct me if I'm wrong here)

Bleed valves can be used and are safe....as long as the car is mapped to it's maximum safe level of boost. i.e you can raise and lower the boost as you see fit (for weather conditions, daily driving etc) but only to the maximum safe limit for your engine.

 

i love the bleed valves are wank topics, nothing wrong with them in essence.
even an electronic boost controller is a bleed valve (air to air are not the same), it's about allowing a small percentage of boost to not make it to the actuator, therefore reducing force acting against the actuator spring.
if your not an idiot, then you'll only open it up enough so it raises the boost safely enough without spiking/surging too much in a safe environment.
even an electronic boost controller can knacker an engine if someone sets it too high, so no worse than a bleed valve.
the only benefit to an EBC is that you can have various settings and still keep the valve close to the turbo so not increasing the pipe length and therefore keep spikes to a minimum and reducing chance of pipe splits that could occur on longer runs.

 

bleed valves are for those who cant afford air injectors only messing guys, I used one for a week or so when my amal valve decided to stop working

 

Might beg the question, why fit air injectors ?



What cant you see is different ? One is a simple adjustable orifice to bleed air, regardless of anything else.

The other can be a totally adjustable air bleed at any rpm, boost level, throttle, road speed....whatever way you want to map it.

Ultimately they are both simply air leaks. But it can be a little more complicated than that

 

thank you lol

as said set the actuator low
bleed the rest off

and turn it down again to lower boost


simple

 

You would never catch a tuner doing that. All you will end up with is very peaky boost curve and an engine that makes good torque and crap horsepower.

 

just saying how it can be done
was done to my car by ava a few years ago
but opinions vary on whether they are reputable or not lol

 

My bleed valve was fitted by a tuner as my Amal valve was not working properly. The car was then set up by the tuner and has run spot on for the last 4 years and 12k miles and I've never been tempted to up the boost. I can't see what the fuss is about.

 

steve,you have misunderstood me,i am VERY aware that the ability to do all those features is FAR beyond what a bleed valve does,but...when someone rants theyre dangerous because you can turn up the boost and blow an engine,then its the same,you can also do this with a boost controller,no difference between turning the valve to the right or pressing the + button too many times

 

pull the pipe off the actuator and see what happens any idiot can f#*k up an engine as stated.

 

Sorry, I never stated why I hate them...

1) too easy to adjust. These are rarely properly set and sealed so cannot be adjusted.

2) Most are cable tied to a boost hose or left dangling in the engine bay .... utter bodge IMO.

3) Unstable boost levels depending on ambient air temperature due to the thermal expansion of brass.
(plastic AMAL valves are less suseptable

4) I just really hate them !! lol

 

Interesting post.I always thought they were bad for the engine.

 

Brass and thermal expansion? lol come on now

 

no one has mentioned the fact that bleeding too much air off can damage the turbo as it has to spin faster to compensate for the loss of pressure on the compressor side, overspeeding can prematurely wear the turbo, not to mention the increase in back pressure required to make it spin faster, creating a loss in power at the same time

 

Its true.. to a point !

Are you saying metal doesnt expand ? ...LOL

The air gap is very small and expansion does affect the amount of air passed.
Also, the temperature of the air will affect boost level as the denser it is, the less it will pass.

I will say that the variations will be small the majority of the time.

I suppose anything other than true closed loop boost control is pants and unsafe IMO !

 

lol the needle would get longer (closing the gap) but then the body would get longer (opening it again) by a couple hundreths of a mm, not enough to effect the flow, surley then air temp (density) would be a factor to take into account lol

 

Yes it does, but also its usually in a linear fashion, along its length I believe.

The temperature issue will affect amal valves too of course, but Ford seem perfectly ok with it. LOL

For reference, what Simon the scaremonger is referring to as "Unstable boost levels " is instead of 20psi, you may indeed run 20.01psi instead due to thermal expansion and air density issues.

 

it will expand in every direction, we digress

 

Stu, I have witnessed far more variation than that on some setups .... up to around 5 psi.
Enough to unbalance AFR seriously, so hardly "scare mongering"

 

I stand corrected, thank you.

 

Whatever variations your have seen certainly weren't caused by the temperature of the brass or the air I assure you.

 

I find this thread mildly amusing as most of my mates have, or have had turbo cars with boost gauges, and when you ask them "what boost does it run?" they say "i dont know" or "not sure it goes up and down a lot" to which i normally answer oh i see.

 

i agree

 

Well, from my experience I certainly disagree !
I have removed several brass type bleed valves to fit an amal type valve in place with simple on/off control and the stability issues dissapeared.

I thought all quality tuners hated them or removed them on sight given the chance

 

You will probably find that those cars had too large a boost adjustment made to them by the bleed valve or were incorrectly fitted by someone. Amal valves score over the cheaper valves by their ability to be jetted which can aleviate some such problems. More expensive ones are also jetted.

 

Nothing wrong with a bleed valve. The thing that is wrong is the organic matter that won't leave it alone once one has been fitted and set up.

 

Mine is exactly the same as yours mate, was fitted when tuned before i got the car and i've never touched it.

Although i've always told myself im gonna get it back on an amal valve next time its set up

 

mates? do you have any lol

 

i do wonder what boost does your car run ryan?

 

lol da kin, ive driven it twice