2 solenoid valves to control boost.
Turbo Mini Forums

i plan on using 2 solenoid valves to acheive 3 different boost levels, 1) actuator boost, 2) first valve open, 3) 2nd valve open.

the first solenoid valve i have is the metro turbo unit, i have read on here it doesnt flow much, about 4psi, which is perfect, and the 2nd solenoid valve is a high flowing unit, a N75 valve from a vw/audi. they will be controlled with 2 seperate switches, heres how i plan to do it :



with both solenoids closed i will run on actuator boost (4psi), with the poor flowing metro turbo valve open, bleedinng off an extra 4psi which should give me 8psi, which imo is great for pottering about, the 2nd high flowing valve open i will reach the pre-set bleed valve boost, (18psi)

will this work ok? any help/ideas/critism welcome :)

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

i tried something similar but with less pipe work.

basically set your actuator to 8psi then just use a solenoid to restrict flow...


Snail > 3 way solenoid one output to actuator and the other to a bleed valve then t piece into the actuator.

when its off it runs actuator setting, when its on it will flip over to the other 2 and run the bleed valve.

i seen your thread a while ago johnny, i could easily just run on 4psi then flick to 18psi, but i have a spare solenoid lying around, so i thougt i would try to encorperate it for an 'inbetween' boost level.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

Wouldnt you have to have some way of changing the timing and fuel aswell if you have two different boost settings?

Yrs but I would jut set it up at 18psi and let it run rich at the lower settings, I do have another valve in the part throttle lean off which may help.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

Does anyone think this will not work?

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

it's a very crude option.

It would be cheaper and easier just to use a two position electronic setup. Or just fit a bleed valve inside the car.

Or opt for a proper electronic boost controller which will allow you total control from inside the cabin and no cocking about with multiple valves or solenoids.

And a bleed valve along with 2 further solenoids doesnt make sense.

Either the bleed valve controls the bleed, or the solenoids control the bleed

Something like this already does what you are after, and would save a lot of dicking about

http://www.ebay.co.uk/itm/turbo-smart-twin...f6#ht_500wt_949

Or whilst more expensive, will offer better control. But this is still a cheap unit.

http://www.ebay.co.uk/itm/Gizzmo-Boost-Con...3#ht_1232wt_932

Edited by stevieturbo on 7th Oct, 2011.

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

I don't know why you want 3 boost levels, 2 is more than enough.

I use the standard 5psi most of the time, then switch in the bleed vale for the high boost level.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

It's cheaper to do the above as it has cost me a tenner for a solenoid the other I already have, the easiest option to achieve 8psi for the road then 18psi at the flick of a switch would be to use the cossie actuator and just the one solenoid like a fair few people do, but since I had the 2 solenoids here I thought I would try to make them both work.

In my eyes it will work, as long as the 2nd valve flows enough I can leave the 1st valve closed to go from 4psi to 18psi, for the likes of drag racing etc just like many on here do, but I have the choice of a few extra psi over actuator boost when needed.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

Just go for the high flowing solenoid and bleed valve in car mate.

Then you can leave the BV at 8-10psi and wind it out when you feel the need for more!

If something is worth doing, it's worth doing half of.

I don't really 3 boost levels, I agree 2 is enough, I can't help thinking 4psi isn't quite enough,, I have got the bleed valve in the car, but its a pain adjusting the boost time and time again, ill be having s new turbo soon so shouldn't be a problem.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

get a better actuator so you can run 7-8psi on the actuator then use the bleed for more.

If something is worth doing, it's worth doing half of.

You can switch between ignition maps aswel if you are using megajolt.

not bothered about that really, ill hopefully be getting my hands on a new turbo soon anyway so dont need to worry , actuator boost is 7psi=perfect for road imo.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

Does the MJ have a spare PWM output that could be used for a proper boost control setup ?

or is it purely ignition only ?

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

you can earth circuits based on RPM or boost.

Edited by apbellamy on 7th Oct, 2011.

Why not run 18psi all the time and control boost with the accelerator? Or like has been said just run two settings.

Controlling boost with your right foot is all very well in theory, but the devil sits on your shoulder all the time !

having too many solenoids creates boost spikes when you floor it (well it did with mine) so thats why i got the 3 way one.

its simple. set the pre load on the actuator to your lower limit and then have a bleed valve set to the higher limit, and incorperate a 3 way solenoid into the equation

Full boost or nothing :)

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

I totally agree steve, it may well be the next thing that people start fitting. I know it really helps with the hilclimber.

I used to agree with Ron about controlling boost with the throttle. But what I found is that on a daily driver it used a LOT less fuel having the boost set low, especially when cruising or pootling around in traffic.

But I still don't understand the 3 levels, 2 should be enough, even though 3 will work.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

With regards to switching megajolt maps this is just using an option that most people have already paid for, basically you can run more advance on the low level and possibly switch the part throttle lean circuit on aswel. I will be using it to help with traction in low gears next year, only until I get a proper controller though.

You don't need a switchable map in your megajolt. That's the whole point of the M.A.P. sensore. It adjusts your ignition based on manifold pressure.

The graph is RPM on one axis and MAP on the other. Limiting boost just lowers the map value and uses the settings you have there. You just need to make sure your map is scaled to cover the entire range of boost and RPM that you will use. Job done.