Push to pass boost control

[rb92673]

Looking for options for a push to pass switch to up the boost level on demand for our endurance racecar. We run about 14 hours of racing in a weekend, so I want to keep boost level conservative to keep heat down and fuel economy up, but want an option to flip a switch to up the boost levels to pass or if we need some extra power for a bit of time.

Current setup:
- 745 Wagon
- B230 FT
- Microsquirt
- Garrett T04E with .8 bar kinugawa actuator, ATP 3" wastegate
- 3" exhaust, Borla straight through muffler
- stock intercooler
- Forge blow off valve

I have a Mac 3 port solenoid valve I can install. I also have a .5 bar wastegate actuator as well.

Thanks

 

[JohnMc]

Can microsquirt do electronic boost control?

When I had the redblock 16V turbo in my Volvo just for grins I had a an unused switch on the dash (since I wasn't doing E85 fuel switching) and decided to run the electronic boost control signal through it on the way to the boost control valve. Switch off, it was base wastegate pressure (12 psi??? something like that). Turn it on, and it would be doing whatever the boost control tables said. 16-ish psi on gas, 22 psi on E85.

 

[rb92673]

Can microsquirt do electronic boost control?

When I had the redblock 16V turbo in my Volvo just for grins I had a an unused switch on the dash (since I wasn't doing E85 fuel switching) and decided to run the electronic boost control signal through it on the way to the boost control valve. Switch off, it was base wastegate pressure (12 psi??? something like that). Turn it on, and it would be doing whatever the boost control tables said. 16-ish psi on gas, 22 psi on E85.

Others are doing it on Microsquirt I believe, I have not yet. I didn't know you could switch it on and off.

 

[JohnMc]

All the ECU is doing is grounding the boost control wire, you have switched 12V+ on the other side. Break that ground circuit and the boost control valve just stays open and no boost control happens.

I never got closed loop/feedback boost control working well at all, I had it doing open loop duty cycle boost control. Hand tune the tables a bit, it's pretty stable.

 

[rb92673]

All the ECU is doing is grounding the boost control wire, you have switched 12V+ on the other side. Break that ground circuit and the boost control valve just stays open and no boost control happens.

I never got closed loop/feedback boost control working well at all, I had it doing open loop duty cycle boost control. Hand tune the tables a bit, it's pretty stable.

That makes sense. Now I need to figure out a spare output. I have already used ALED (shift light 1), WLED (Temp light), FIDLE (shift light 2), and TACHOUT (Tach). I guess I can run the tach signal from the coil.

 

[James M]

That makes sense. Now I need to figure out a spare output. I have already used ALED (shift light 1), WLED (Temp light), FIDLE (shift light 2), and TACHOUT (Tach). I guess I can run the tach signal from the coil.

I might be missing something but this doesn't seem like anything the ECU has to be involved with. A physical switch can just power the solenoid and be done with it.

 

[rb92673]

I might be missing something but this doesn't seem like anything the ECU has to be involved with. A physical switch can just power the solenoid and be done with it.

The way I understand it, the ECU controls the opening and closing of the solenoid to hit your target boost pressure.

 

[linuxman51]

sam did it in his chumpcar with a timer circuit and microsquirt. so the system is totally independent of microsquirt, although if you have a low/high boost function (Which would be microsquirt controlling a solenoid) the timer circuit would go on the power side of the solenoid and ms won't know if it's not working unless you're trying to do closed loop boost control.

 

[rb92673]

sam did it in his chumpcar with a timer circuit and microsquirt

Sam and Randy's cars were my inspiration! I was curious how they did it.

 

[Harlard]

You could use a kickdown switch from a BMW to activate the timer circuit. One way to keep hands on the wheel.

 

[bobxyz]

I'd think you could do it with your 3-port valve, switch, and a MBC. In the normal position, the valve would select a straight-through wastegate line. In ExtraBoost position, the valve would switch the wastegate line to the MBC path. If you want to get fancy (aka Sam), replace the switch with a pushbutton and a timer.

 

[rb92673]

You could use a kickdown switch from a BMW to activate the timer circuit. One way to keep hands on the wheel.

Good idea. I don't envision it being used much, but sometimes you get behind a car that is really slow and blocking in the corners but fast on the straights. It would be nice to have a little more power in that situation.

 

[rb92673]

I'd think you could do it with your 3-port valve, switch, and a MBC. In the normal position, the valve would select a straight-through wastegate line. In ExtraBoost position, the valve would switch the wastegate line to the MBC path. If you want to get fancy (aka Sam), replace the switch with a pushbutton and a timer.

I like that idea. I like simple.

 

[culberro]

Does anyone have insight on the durability of the MAC valves or the Pierburg valves when racing?
For the KISS approach, I like the MBC + solenoid valve.

 

[linuxman51]

I don't think the timer is expensive, if sam sees this he can comment on that part, but the timer is adjustable so you don't have to remember to flip the switch. pierburg or mac are probably fine in the kiss situation. pierburgs may be easier to come by depending on local junkyard inventory

 

[Harlard]

Does anyone have insight on the durability of the MAC valves or the Pierburg valves when racing?
For the KISS approach, I like the MBC + solenoid valve.

That's not timer-limited, but agreed on the KISS approach there. a big red thumb button on the steering wheel using the horn ground as a bull-down would make it nice and easy.

 

[petercz]

I'd think you could do it with your 3-port valve, switch, and a MBC. In the normal position, the valve would select a straight-through wastegate line. In ExtraBoost position, the valve would switch the wastegate line to the MBC path.

Exactly what I have

 

[rb92673]

Now the question is what boost levels should I go with. I am thinking .8 and 1.0 bar to start.

 

[Superhans240]

Mac valves work good here’s a tip for you.... industrial pneumatic supply stores have any flavour of them you want for 30-50$ in that size.... less than 1/2 the cost of ones automotive rip off companies re sell... just use any random business that would use anything pneumatic’s cash account. They even gave me filters and fittings for free cause they had so many around

 

[Dvroofer]

I use a aem tru-boost x controller. It has a scramble boost setting you can put to a button and time. It works well.