Modifying Stock Boost Solenoid

[courier33]

I am in the process of modifying my r33 gtst, but would like to keep it as stock looking under the engine bay as possible.

I am running a GT30, and have read that aftermarket boost controllers are not legal in VIC, but i would like more boost than the stock 9psi. Therefore I have started looking into how the factory one works. From what I can tell, and I may be wrong here, is works like this:

Boost pressure from intake pipe goes through a rubber hose with a sort of calibrated restrictor in it, and then to the wategate actuator.

The solenoid bleeds air from this hose via the t-piece, and routes the air back into the intake, thus controlling the boost by how much air is bled off.

As far as I know the ECU doesnt know how much boost there actually is (in psi).

So heres my theory:

If you get rid of the hose from the intake pipe to the t-piece, and replace it with a hose that has a pice of brass in it with a hole drilled through (to a specific size), and by controlling the size of that hole, the boost could be increased while still looking like its stock.

I hope that made sense!

Does anyone know if the factory solenoid has only the 2 specific bleed rates (7 + 9psi) or can it vary?

Im not sure what size hole would have to be drilled in the restrictor because i threw out my factory hoses in favour of one of those $22 dollar boost controllers.

[SevenAngryPenguins]

isn't it illegal to whack a after market turbo on to??? why worry about the boost controller....

But yeah stock boost solenoid just opens and bleeds air from the actuator at a set RPM by the ecu (5000 RPM or something)

I think what you said is feasible.

what you could possibly do is use a t-piece in place of the solenoid and play around with the size of the hole (fill 1 hole on tee piece with solder and use drill to adjust hole size) on the bleed part of the tee then just plug it back into the stock location when done if that makes any sense. (sounds dodgey hey)

Just throwing ideas your way.

[Jmaac]

Yes you can bleed off the air like that. Theres a tube with a restrictor in it already somewhere - i believe it has a yellow dot on it to identify. Change the size of the restrictor or even just prick small holes in it with a hot needle until you achieve your required boost.

you can also cut the solenoid arm in half, thread it, add a threaded sleeve to rejoin it, hence giving you full adjustment

you can use the stiffer spring from an r32 and run the slightly higher boost

remove the spring, drill a hole in the top and weld a nut to it, insert a bolt and fit a spring seat to the otherside. This will allow you to adjust spring pre-tension, thus giving you full adjustment

All these retain the factory setup

[R338OY]

Hide a tee-piece.

Cheap, no effort, and if hidden well (i.e. behind piping) is hard to defect if stock solenoid 'appears' to still be in use.

Muahahahaha

[DECIM8]

Why dont u just buy a GTR solanoid? or HKS adjustable.. Looks stock and does the job without them noticing the boost solanoid..

Enjoy

[MANWHORE]

A GTR solenoid does squat over what the gtst solenoid does.

Why dont u just buy a GTR solanoid? or HKS adjustable.. Looks stock and does the job without them noticing the boost solanoid..

Enjoy

[R33GOD]

i know what he's talking about.

jetting it down to trick the stock solenoid = more boost. not very good on skylines bro as they spike quite badly

get yourself a good ebc and be done with it... afterall you got a gt30 lol

good luck

[stolen_s15]

Mate if you have hidden the GT30 then you can hide the boost controller, at least from the cops.

But if you get sent to the EPA @ Mcleod your stuffed, those blokes know their stuff. They will surely find a GT30!

Personally I would use a modified or adjustable wastegate actuator for "stealth" boost control.

Good luck!

[R338OY]

Personally I would use a modified or adjustable wastegate actuator for "stealth" boost control.

+1 This guy's on the money

I think HKS make them

[DECIM8]

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Edited December 7, 2007 by DECIM8

[H@ME]

+1 This guy's on the money

I think HKS make them

x 2 i think that this is the safest optioin for stealth boost controll with an aftermarket turbo..

[courier33]

Cheers guys, some really good options in that lot

Your right with the GT30, bit hard to hide, but ive still got it std position and done the job on the stock cover to make it fit and look roughly like standard. You can tell when you look at it from the front and theses a 4" pipe coming off it that it shouldnt be there.

I did have a play around with the wastegate actuators, and eneded up with one off some really small garret I had laying around. With the hose going straight from the manifold to the turbo actuator, it holds 7psi to about 4500, then goes to 10 - 11 psi up to the redline.

This is all the boost it can handle at the moment, as the stock injectors hit 80% at 6250. So I think i will try out one of the restrictor/hole in the hose ideas as posted above when i fit bigger injectors and are looking for a few psi more boost.