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Home > Help Needed / General Tech Chat > Bleed valve

Yoda74

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97 Posts
Member #: 11728
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Uden, Holland

Hi guys,

I知 running a MG Metro Turbo engine in my Clubman Estate with the Ecu and boost Solenoid still fitted.
As I知 looking for a bit more performance I知 thinking about taking out both and fitting a bleed valve to upgrade the boost mainly in lower revs and maybe a tiny bit in high revs.
Question one is what bleed valve to go for? Are they all ball and spring?
I see a few different ones, which one gives a good solid boost and can be locked so it won稚 wander or vary.
Turbosmart, Grimmspeed, GFB, QSP, H-gear, or different?
Are there good or bad ones around?
Does in car add any value? Or dual stage?
What is a max boost for a pretty standard healthy Metro Turbo engine?

Cheers


stevieturbo

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Northern Ireland

if you want boost to do something different at different times, then no mechanical bleed valve will do that.

You will need some form of electronic control.

And if it's cheap you want, a simple fish tank bleed valve will allow you to dial on some degree of leak in the system for negligible cost.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will


Yoda74

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97 Posts
Member #: 11728
Advanced Member

Uden, Holland

Cheap is not what I'm after, I want a bleedvalve that once it's set, I lock it and have no worries about it, always works well and wont malfunction, just simple and reliable.


stevieturbo

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Northern Ireland




On 20th May, 2022 Yoda74 said:
Cheap is not what I'm after, I want a bleedvalve that once it's set, I lock it and have no worries about it, always works well and wont malfunction, just simple and reliable.


A bleed valve will not allow you different boost, at different times.

And a lot of the expensive ones....really are no better than a cheap plastic one. Some may have some form of boost blocking feature to try and assist spool, although I would probably suggest against that on a Mini

But if you want "quality", stick with the usual brand names like Turbosmart etc.

Certainly not "All" as he claims, but not a terrible video, just lacking in all.

https://www.youtube.com/watch?v=hYIL_XvlYTE

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will


Yoda74

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97 Posts
Member #: 11728
Advanced Member

Uden, Holland

Adjustable boost is not what I want, just set it once at lets say 8psi, and leave it like that.
The only kind of adjustment that I would consider is the dual stage from turbosmart. 2 locked positions, say one at 5 psi for cruising and one at 9 psi for trashing it around.


stevieturbo

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Northern Ireland




On 18th May, 2022 Yoda74 said:
Hi guys,

As I知 looking for a bit more performance I知 thinking about taking out both and fitting a bleed valve to upgrade the boost mainly in lower revs and maybe a tiny bit in high revs.


This suggested you wanted boost to vary at different rpm's. Which cannot be achieved with a simple mechanical valve.

Some EBC's are quite cheap, and with adjustability in-car.....they do make a lot of sense for the user when used sensibly.
Especially if it is one you can dial boost in vs say rpm, road speed etc.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will


Yoda74

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97 Posts
Member #: 11728
Advanced Member

Uden, Holland

Ah, not translated that well, what I meant was that by fitting a bleed valve and set it to let痴 say 9psi, the boost will be higher than with my ecu fitted. The ecu keeps the boost at 4psi in lower revs, 7 in higher, so the power will be better mainly in low revs and a bit in high. My Dutch To English translation sometimes is not perfect *wink*


Mr Joshua

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Luton Bedfordshire

first things first if your running with the T3 as originally fitted to the Metro turbo that puppy can boost over 2 bar thats 28psi. you don't want that.

In order to do what you want you need to add a bleed valve to your already fitted boost control. The bleed valve needs to be fitted in the boost sense line into the ecu.

This way when you open the bleed valve you are reducing the boost pressure the ecu sees and forcing it to control the boost to a higher pressure. Thus the turbo needs to produce more pressure to overcome the leak you have introduced. now you can control what your max boost will be. How much boost a standard engine can take i can not say.

Own the day


e5tus

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Dorset

On 18th May, 2022 Yoda74 said:

Does in car add any value? Cheers

I've always avoided having any adjustment within reach, the devil makes work for idle thumbs and all that. If you can reach it, you'll fiddle. Expense awaits!


Yoda74

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Uden, Holland

I think you may be right e5tus. Under the bonnet Will be safer.

@Joshua: why keep the ECU and solenoid? Why not loose them Both ?


stevieturbo

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Northern Ireland




On 24th May, 2022 Yoda74 said:
I think you may be right e5tus. Under the bonnet Will be safer.

@Joshua: why keep the ECU and solenoid? Why not loose them Both ?


if you retain the OEM control as well, you could still try and achieve a rising boost. But say instead of the 4psi/7psi, it might be 7psi/11psi as you would be tricking the ecu into thinking there is less boost overall, but it would still behave in a similar manner

Running less boost in the mid range, your gearbox will be happier and live a little longer, so maybe not a bad thing.

Although you then have a couple of boost control items in there which is a little messy. I'd far sooner prefer a single boost controller.
With a suitable EBC, you could ramp boost with rpm, throttle, and/or road speed or gears ( as long as you can give this information to the unit )

But that's maybe a little less simple than just a cheap bleed valve.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will


Mr Joshua

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Member #: 1954
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Luton Bedfordshire




On 24th May, 2022 Yoda74 said:
I think you may be right e5tus. Under the bonnet Will be safer.

@Joshua: why keep the ECU and solenoid? Why not loose them Both ?


If you only had the bleed valve then max boost will only be achieved at max revs. the ecu is reading intake pressure and maintains the programmed in max pressure by controlling the waste gate via the solenoid valve.

by introducing a controlled leak into the sense line off the ecu you can lower the sense line pressure, from the 7psi down to say 2psi. This would cause the ecu to stop operating the solenoid valve closing the waste gate and causing the boost pressure to climb until there is enough flow of boosted air to overcome the leak. To achieve this the turbo might have to spool up to produce say 12 psi before the ecu registers 7psi and starts operating the solenoid valve to open the waste gate. So now the ecu is seeing 7psi but the intake is at 12 psi.

Own the day


stevieturbo

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On 25th May, 2022 Mr Joshua said:



On 24th May, 2022 Yoda74 said:
I think you may be right e5tus. Under the bonnet Will be safer.

@Joshua: why keep the ECU and solenoid? Why not loose them Both ?


If you only had the bleed valve then max boost will only be achieved at max revs. the ecu is reading intake pressure and maintains the programmed in max pressure by controlling the waste gate via the solenoid valve.

by introducing a controlled leak into the sense line off the ecu you can lower the sense line pressure, from the 7psi down to say 2psi. This would cause the ecu to stop operating the solenoid valve closing the waste gate and causing the boost pressure to climb until there is enough flow of boosted air to overcome the leak. To achieve this the turbo might have to spool up to produce say 12 psi before the ecu registers 7psi and starts operating the solenoid valve to open the waste gate. So now the ecu is seeing 7psi but the intake is at 12 psi.


The OEM system is a very crude simple open/closed solenoid with an rpm trigger ( 4500rpm ) which opens the solenoid to allow a higher boost level.

It does not have any means of closed loop control to actually control or target any boost setting

Really though the best thing is just get rid of the OEM stuff and just run either a bleed valve or proper EBC.

If it's still a low boost setup, the extra boost low down will make it feel a lot faster.

Having used many forms of boost control over the last few decades....I would absolutely use a decent electronic boost controller.
They just give you more flexibility and options even if a simple mechanical valve can work too.

Plus whilst there are caveats with in car adjustability....it also makes setting up a lot easier than driving, getting out, bonnet open, messing, back in, drive about...repeat etc.

Same with carbs vs EFI.....both can work, the former usually very annoying when tuning, the latter a little less so.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will


Mr Joshua

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Member #: 1954
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Luton Bedfordshire

The OEM ecu as fitted to the metro turbo has a boost reference line from the plenum chamber into the ecu. As stated above in standard trim above 4500 rpm the ecu ramps up the boost by means of rapidly opening and closing a solenoid valve bleeding pressure of the back of the waste gate actuator. The ecu carries out this function in order to raise the boost pressure from 4psi up uoto 7psi in some cases I have heard of 10psi. In order to hold this higher pressure it reads the pressure in the plenum chamber and when the the higher pressure is reached it regulates the solenoid valve to maintain this pressure. So above 4500 by the the introduction of a bled valve you can increase your maximum boost from 7psi to what ever you wish knowing that even at a mind bending 9000rpm your only developing the boost you want. The ecu cannot control to a boost pressure unless it knows what the boost pressure is.

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Mr Joshua

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Member #: 1954
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Luton Bedfordshire

Double post deleted

Edited by Mr Joshua on 28th May, 2022.

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Mr Joshua

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Member #: 1954
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This is the line I am referring to. Note I'm guessing most people only pulled this to the fuel pressure regulator. In the metro turbo this line has a tee to feed pressure into the ecu.


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Steve220

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Shropshire

Bin the ecu completely, fit a EBC (i recommend the AEM one) and enjoy!


stevieturbo

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Northern Ireland




On 29th May, 2022 Steve220 said:
Bin the ecu completely, fit a EBC (i recommend the AEM one) and enjoy!


EBC's make a lot of sense.

The factory thing....not so much lol

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will


Yoda74

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97 Posts
Member #: 11728
Advanced Member

Uden, Holland

Do you mean this one?

https://www.aemelectronics.com/products/boo...ontroller-gauge

Isn稚 the harness much to extensive?
How do you plumb it in?


stevieturbo

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Northern Ireland

The AEM is a very very basic EBC with few options for control.

At the budget end, even this offers more including boost by rpm which can be useful.

https://ldperformance.co.uk/product/electro...ost-controller/

And you plumb the solenoid in exactly the same way you plumb a bleed valve in. ( wel..as per instructions for the controller )
Wiring can be as minimal as you want to make it, depending on features needed.


Or for multiple control options ( maybe too many )
https://sirhclabs.com/

Edited by stevieturbo on 19th Jun, 2022.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

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