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Rb25 Dual Stage Boost

e_Dog

By e_Dog,
in Engines & Forced Induction

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e_Dog

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Referring to the following topic in the Tuorial/DIY section;

HOWTO: RB25DET High Boost mode with standard solenoid

I posted a question in there that no one has been able to answer. At the start of the thread it says if you have an aftermarket boost controller you dont have to make the mod (cutting the ground wire to the solenoid and grounding it all the time so that the turbo is in high boost mode all the time).

My question is, if you have only installed a manual boost controller...a Tpiece/bleed valve or something, then wont the car STILL be running in dual stage mode because the ECU is still controlling the solenoid??

Does this mean that if you have an aftermarket MANUAL boost controller, that you still need to do this mod to remove the dual stage operation?

Please, please post if the above explanation isn't descriptive enough and i'll explain further.

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https://www.sau.com.au/forums/topic/211208-rb25-dual-stage-boost/
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e_Dog Collaborator

e_Dog

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if you have a manual bleed valve, you wouldnt have a standard boost controller solenoid,

you should run one or the other, not both

hmmm...my mechanic has installed a bleed valve, but the car still runs dual stages. Why does installing a manual BC mean you would have to remove the boost controller solenoid?

Anyway, thanks for your response...i dont think were gonna be able to solve the argument tho

(B1) MR_fanny Grand Master

(B1) MR_fanny

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when installing a manual one it should bypass the soleniod all together so the hoses going into the soleniod should be going into the bleeder instead. you dont have to remove the stock solenoid its just not connected to anything thats all. when i had my bleeder i just stuck dummy vac hoses onto the stocker that went nowhere to hide the bleeder.

e_Dog Collaborator

e_Dog

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when installing a manual one it should bypass the soleniod all together so the hoses going into the soleniod should be going into the bleeder instead. you dont have to remove the stock solenoid its just not connected to anything thats all. when i had my bleeder i just stuck dummy vac hoses onto the stocker that went nowhere to hide the bleeder.

AWESOME, cheers fanny, you've answered the question perfectly. Alright, now go figure out what the hell the mechanic has done?????

thanks all

**RB2530** Proficient

**RB2530**

Posted
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You can do it either way..

It is really quite simple...The more air you bleed away from the WG actuator the less it will open and therefore the more boost you will have...If you run a bleed valve + leave the solenoid you will still have two stages of boost...the second stage occurs at 4500rpm when the soleniod opens..

The more you open the bleed valve, the difference in the two stages will actually reduce...

If you want to get away from the 2 stage boost I would disconnect the solenoid instead of wiring it to ground permanently...

e_Dog Collaborator

e_Dog

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You can do it either way..

It is really quite simple...The more air you bleed away from the WG actuator the less it will open and therefore the more boost you will have...If you run a bleed valve + leave the solenoid you will still have two stages of boost...the second stage occurs at 4500rpm when the soleniod opens..

The more you open the bleed valve, the difference in the two stages will actually reduce...

If you want to get away from the 2 stage boost I would disconnect the solenoid instead of wiring it to ground permanently...

so your saying you can have both connected and run dual stage at a higher boost (with reduced difference between the stages). This is important because it means that my mechanic is possibly not a massive tard like i thought 10 minutes ago!!

**RB2530** Proficient

**RB2530**

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so your saying you can have both connected and run dual stage at a higher boost (with reduced difference between the stages). This is important because it means that my mechanic is possibly not a massive tard like i thought 10 minutes ago!!

Yep I sure am saying that..If you run a bleed valve and the solenoid you can increase the boost with the bleed valve and the when the solenoid opens you will bleed even more air of so you will get a second stage..

The GTST solenoid is binary meaning that it is either on or off (not like in an EBC where the solenoid is pulse widht modulated). When it is off (below) 4500rpm it doesn't allow any air through. When it is on it opens and lets a small amount of air to flow through it so it is acting like a bleed valve...The ait flows though an orifice in the solenoid that is roughly only 0.5mm dia.....not sure of the exact number but it is small..

The reason that the two stages are not so far apart is when you use a bleed valve you drop the pressure in the feedback line and therefore the not as much air will flow through the solenoid when it opens

Oh and a hint with the bleed valve is make sure you place it somewhere where it wont get too hot...Many bleed valves when they get hot will bleed different amounts of air depending on whether they are hot or cold...So put it some where in the engine bay where it gets air flow and away from the exhaust etc..Otherwise you be constantly adjusting it....

Hope this makes sense..

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