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[Speed Phreak]

I recently dropped a JRSC onto my daily driver. Classically I've been a turbo guy, but I came across a deal I couldn't pass up on the S/C. I ended up trying to make it as "factory" of a setup as possible, so I decided to include a way for the ECU to control the JRSC. How I did this was by re-purposing the IAB tank and vacuum setup to allow the the ECU to control the JRSC bypass valve/S-tube.

Mechanically the GSR secondary runners work the same way as the JRSC bypass valve, so it's a fairly straight forward trick. Using Crome I am able to switch the bypass valve vacuum circuit between active/inactive depending on engine conditions. Mainly I use this for preventing boost below a set MPH/RPM(or other criteria) to prevent wheel spin on launch. Alternatively this also stops boost before the engine is at proper operating temperature or during a CEL event. Alternatively the circuit can be controlled via a simple switch to allow the bypass to stay active at all times, handy for "valet mode" or poor weather where no boost would be safer.

For Turbo applications, it could be a cheap setup to work 2 different boost controllers if you removed the check valve and routed the lines a bit different and basically changed the whole diagram....maybe it doesn't really matter for turbo cars, or figure it out yourself.


So it's fairly simple setup, feel free to comment or go fuck yourself.

Chassis: DB8
- Stock exhaust (yes I know i'm losing power but I like quiet, might get a WS2 later on)
- 12Ga relayed fuel pump re-wire
- Crome chipped/tuned + TunerView II in dash

Engine: Stock GSR engine
- Scion TC injectors(330cc)
- Ebay FPR set @ 60psi
- DIY Icebox = KN Filter + 4" lower intake pipe and velocity stack in the stock airbox.
- RMF Narrow Clone header + cat delete
- B20 crank Pulley
- Boost controlled by IAB + ECU

Made 238 WHP/180 TQ, still gets 30~32Mpg... not shabby for a 200k mile beat down GSR.

IAB Attachment and lines


Vacuum Diagram


Crome Config.


*disregard intake temp setting, it's a glitch.

[ratcityrex]

Sweet deal, got a buddie that just put a jrsc on his awd wagon. Ill have to bookmark this setup.

[92CXyD]

Debating on this way of controlling the a/c style clutch on my SC14, since I have a P72 in my car.

Or just sticking with the P30 A/C control with TPS % setting and max rpms. of 7k revs. 

[ratcityrex]

Russ your shit is so mad max nigger rigged......lol I just remeber that thing eating more belts than fuel

[Speed Phreak]

Just add Mel Gibson

[92CXyD]

Russ your shit is so mad max nigger rigged......lol I just remeber that thing eating more belts than fuel

Not anymore the s/c is ridge mounted now. 

[HiProfile]

Cool shit! I will use this for my brother's car. I might be forced to use a stepper pulley (I have 2 questionable jrsc pulleys), which will be too much even with a 4.2 pulley. It will be an auto-x car so he wants 5-6psi max.

Any idea what frequency and/or duty cycle you used?


BTW this should work with Prelude/Accord IAB parts too. I think their canisters are even larger for more reserve vacuum.

[Speed Phreak]

Cool shit! I will use this for my brother's car. I might be forced to use a stepper pulley (I have 2 questionable jrsc pulleys), which will be too much even with a 4.2 pulley. It will be an auto-x car so he wants 5-6psi max.

Any idea what frequency and/or duty cycle you used?


BTW this should work with Prelude/Accord IAB parts too. I think their canisters are even larger for more reserve vacuum.

Depending on intake and exhaust restrictions (or lack of)  you ll probably see less boost than what you size your pulley for. I have a 4.0 and B20 pulley setup on mine with a decent header and intake. Allegedly I should see 9 9psi but I've never seen over 8.9... I've read a few places that cams any bigger than GSR tend to loose power too.  Just FYI,.

Also, no duty cycle needed, just on or off. The S-tube/bypass still does the normal Operation...  But since you mentioned it, I did think about doing a PWM solenoid in place of that setup and doing modulated boost per gear... But i got lazy and cheap. It might work but I wary of the bypass valves response to a PWM vacuum signal.

[HiProfile]

So you're seeing ~9psi normal, and 0psi when the controller is working? I figured you had this set for PWM control, which would keep the bypass slightly cracked to only bleed off a little boost.

I know I've seen people try boost controllers so they can use boost by gear & such. I presume you could also have the PWM parameters set such that you could reduce tip-in issues commonly seen with the JRSC due to boost coming on so fast. If nothing else, you could just route a 1-way solenoid (no vent) from the manifold to the tb-sc tube, which would reduce boost simply by bleeding it off. You wouldn't be able to reduce it much near redline, but would have much finer control. AFAIK, you can still use that stock IAB solenoid as a PWM solenoid. You'd just have to do some tests to find it's optimal frequency.

[Speed Phreak]

So you're seeing ~9psi normal, and 0psi when the controller is working? I figured you had this set for PWM control, which would keep the bypass slightly cracked to only bleed off a little boost.

I know I've seen people try boost controllers so they can use boost by gear & such. I presume you could also have the PWM parameters set such that you could reduce tip-in issues commonly seen with the JRSC due to boost coming on so fast. If nothing else, you could just route a 1-way solenoid (no vent) from the manifold to the tb-sc tube, which would reduce boost simply by bleeding it off. You wouldn't be able to reduce it much near redline, but would have much finer control. AFAIK, you can still use that stock IAB solenoid as a PWM solenoid. You'd just have to do some tests to find it's optimal frequency.

Very good points, to be quite honest I'd try PWM if I used the S/C more... As is I flick in on when I need passing power or to shut down some asshole in traffic. Other than that it stays in bypass mode, lol.

[ratcityrex]

As is I flick in on when I need passing power or to shut down some asshole in traffic. Other than that it stays in bypass mode, lol.

Sounds like my turbo car. But my switch is my gas pedal.