Boost controller question

[racinrob]

I purchased a Stinger boost controller.  We were trying to see where it would open with a hand pump tonight, but we ran into an issue.  There is a very small hole on the back side of the controller, opposite, but lower than the port that goes to the wastegate.

First, is it supposed to have that hole?  We can't get the valve to build any pressure unless we cover that hole with a finger.

Is it possible to set the desired pressure the controller will open the way I described?  This is on a road race car that is not street legal, so I can't just run it up and down the road to try to dial it in.

Thank you in advance.

[Stinger]

Yes, it's supposed to have the hole. It won't function properly without it since the boost pressure would have no way to escape once you let off the throttle and boost quits forcing the ball off the seat. It would be a sealed system and would continue to hold the wastegate open which would kill boost response the next time you got on the throttle since you need the wastegate closed to initiate the process of building boost again.

You can set the pressure that the boost controller opens the way you describe (if you plug the hole temporarily) but your wastegate is half of the equation so 1) you'll never be able to make less boost than the wastegate spring pressure and 2) you can't be positive that the pressure the controller is set to is what you'll get at the engine. This is because there will be a pressure loss through the intercooler that effects total boost depending on where your boost signal for the controller is coming from (pre IC or post IC). It also can't account for any deficiencies in your wastegate circuit. By this I mean, you may not have enough exhaust flow through the wastegate to prevent boost creep, which can't be controlled by any boost controller regardless of the design. Boost controllers only work as designed on setups that don't have any other boost control oddities.

So long story short, the hole is supposed to be there and setting the controller the way you describe can get you in the ballpark, not exactly to where you set it in your test.

[racinrob]

Thank you.

I wasn't thinking about relieving the pressure to let the wastegate close.  I'm assuming the hole is so small that it still sends enough pressure to the acuator.

If our wastegate actuator starts to open between 9-10 pounds (it is an OEM TC actuator) and the controller is set for 11-12 pounds, should that have us in the 10-12 pound ballpark?  The signal for the controller is pre-IC.  It is an 87 TC engine, bone stock (with stock intercooler) other than the controller and a cheap cone air filter.

This car is endurance racing (14-1/2 races over 2 days or 12 hours straight), so my intention is to be on the conservative side.

Again, thank you for your product and your knowledge.

[Stinger]

Yes, the hole is small so it doesn't effect anything when under boost, only once you let off the throttle. It also needs to be small since it's a vacuum/boost leak and if it's larger, it would effect the engine like a vacuum/boost leak would.

With the controller signal coming from the turbo outlet (pre-IC), you'll see a 1-2psi pressure drop through the IC which means if you set it to 12psi, the end result will probably be in the ballpark of 10psi. If your signal is post-IC, it would be closer to 12psi.

[racinrob]

Okay, got it.

If you are ever up in the northeast at a 24 Hours of Lemons race, let me know.  I'll give you a few laps.

[Stinger]

OK, sounds good!