Homemade electronic boost controller from boost gauge with peak/warn

[muleunit]

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So I was thinking about making my own electronic boost controller using the prosport elite boost gauge with the peak/warn function. What I want to do is use the peak light as a signal line to open a selenoid to the wastegate. Any input on this? comments? Concerns? before I destroy a perfectly good boost gauge?

 

[ed1380]

I would recommend a relay between the light and the solenoid. but that looks like it should work

 

[muleunit]

Ok, so then I would need another power source for the selenoid. Would 12v from the battery work?

 

[dsmdeliveryboy]

Im no electrical engineer, why would I need a relay? Where would it go?

Ok, so then I would need another power source for the selenoid. Would 12v from the batter work?

So you can switch it ON/OFF

 

[ed1380]

the relay is incase the solenoid draws too much power.

a relay is just a switch. only difference is that it is flipped electronically vs manually with your finger. and it stays flipped only as long as power is going to it. so if the peak light only flashes then the wastegate will only be open part of the time. the peak light must stay on as long as you are over your set boost.

 

[muleunit]

well thats what im asking, will the boost be wildly fluctuating with the light coming on, the wastegate opening and boost dropping, thus turning of the peak light, closing the selenoid, raising the boost again, ect, ect, ect making the boost flutter up and down?

 

[polarmoment]

well thats what im asking, will the boost be wildly fluctuating

Yes. You'll see about a ~5psi oscillation when you first hit full boost that will settle to around 2-3psi oscillation.

And an LED drive circuit probably won't even sink enough current to drive a relay. You'd probably have to use a transistor.

 

[MichGS96]

Yeah, I would use a transistor like a driver for the relay's coil

 

[Ravewolf]

I wouldn't take chances amigo. Just save up a little and get a nice ebc and be done with it.

If you still want to try it, make sure it's perfect. I.e.,set it up how you want to the solenoid, and make sure it works accordingly. It pays to be paranoid sometimes.

 

[polarmoment]

I don't think it's a terrible idea, it just doesn't switch fast enough to control boost reliably. The pressure switch style EBC works ok at about 15psi, but above that it gets unstable.

If you want to try a different approach, see if you can find a cheap APC from a saab. It's basically a knock-based boost controller that uses PWM to control a boost solenoid. It gives full boost unless it sees knock, then it pulls it back. There's quite a bit of info on them on the net, including full electrical schematics. Changing the values of the pots on the board and a few resistors lets you change the scales it operates on, etc. There are 3 pots on the board- one is boost level, one is boost rise rate and the third is a knock sensor constant that shouldn't be fiddled with. If you're looking for something you can experiment with, it might be right up your alley..

 

[forcefed86]

Doesn't work... or doesn't work well anyway.

I used an adjustable boost pressure switch and did the same thing. The switching effect isn't fast enough. I had my boost switch set to 20psi. Boost would hit 20psi then drop to 15 then jump to 25 then fall to 15 etc....

You need a WG solenoid and something with decent pulse width modulation. Not usually cheap....