swan

'ello all,

Concern/question on this one. If you set boost to x today and tomorrow or later the same day (without changing the dial) it shows y, can you safely (assuming it's now reading lower - y<x) up the boost again or should you leave it alone? If it's now showing higher boost (y>x) should you turn it down?

Regards,
Andre

john banks

The best EBCs will hunt out your target and stick to it effectively. It depends on how you are running the car - are you right on the ragged edge so that in hotter conditions where conceivably it might run lower boost it would be unsafe to turn it back up?

swan

'ello John,

I've got an MRT unit. Nope, running a fairly conservative setting but I've noticed a variance of up to .15.

john banks

.15 bar? 0.15 PSI would be more like it for the best EBCs, but I think the MRT boost controllers MIGHT not be full closed loop control. I find a Dawes manual boost controller stays within 0.03 bar, but I am only running boost about 0.2 bar above actuator tension which helps control.

swan

Yup. Most of the time it is fairly stable but as I say, othertimes it varies (normally downwards). If not full closed loop? What is actuator tension and how does your variance assist in control. Thanks for the info.

john banks

Corky Bell, Maximum Boost is a good book to read and discusses these sorts of things in great detail.

swan

Thanks, will look it up. A summary perhaps on the questions?

john banks

The actuator is usually about 0.5 bar. At this pressure it will crack open and waste gas instead of passing it through the turbine. If you run 1.2 bar then there is a 0.7 bar difference that is controlled from bleeding air off. If you run 1.2 bar with a 1.0 bar actuator you need to bleed less air off and it can often control things better. However, it sounds like either the MRT controller is not configured properly or it is not capable of the accuracy of boost control we are talking about. In hot weather you expect the boost pressure to drop unless the system has a strong closed loop control system which will pull it back into line.