legacycentral bbs

I'm still looking at cheap yet effective MBC solutions.
http://www.dawesdevices.com/boost.html

Yes, im using the Dawes Hybrid.

It works perfectly on our cars. Mine is set to about 16-17psi of boost.

I've been using Dawes Devices "Graigner Valve" for quite a few years now on my previous Turbo Dodges.

They are great, simple, and cheap. Boost goes right up to your setting and stays put with very little spike.

Only problem, spikes easily when in high gear (15psi) so you gotta keep an eye on your gauges.

Cheap but very effective. Plan on getting one I had for the Legacy. It would be a great upgrade over the stock computer controlled solenoid IMHO. Gets to boost fast and it just stays there. You'll love the 25$ invested

Take care

OK... I just installed the $25 version and it's much better than my old bleed valve. But it still has spikes. I looked on their website and they have the same damn description and features listed for both the $25 version and the "Hybrid" $43 version. What is the fundamental difference between these two valves?

If I were to invest the $43 in the "Hybrid" valve, would it solve the boost spikes (and/or possibly the boost spread) I observe with the $25 "Basic" valve?

I think the difference is that they replace the stainless steel ball bearing with some kind of ceramic ball or something, and use valve grinding compound to polish the seat.

ah, I see. So it might seal better or something. I still don't understand why they call it a "hybrid" controller though. Sounded to me initially like they had a ball-and-spring controller with a controlled leak or something for super precise control over boost somehow. Interesting...

Yeah, I think the idea is that it seals better and also can open and close faster.

It's a hybrid between the off-the-shelf Grainger valve and a homemade ball-and-spring valve.

TurboXS' "high performance" MBC is a hybrid between a ball-and-spring valve and a bleed valve. You could also make one yourself at home; I did once using some parts from the hardware store. I never tried it on my car but the DSM guy who has it now says he loves it.

forgot about the reduction in mass, opening and closing faster is definately an advantage over the basic unit. I may have to invest in the better Dawes unit sometime...

Any idea how the hybrid ball-and-spring/bleed valve works? I'm having a bit of trouble picturing the internals of that one. It seems as though the TurboXS Standard Boost controller (that I had on my car before the Dawes) with a ball-and-spring on the horizontal fitting would result in something that looked like their High Performance controller with an adjustment for the bleed and an adjustment for the spring tension.

What would the advantages be to this approach, though, over a pure ball-and-spring controller? It seems like a step backwards to me.

Yeah, what you're describing is about how the TurboXS HPBC is constructed.

I think the basic idea is to have the bleed downstream of the ball-and-spring. Basically, instead of having the standard little fixed bleed hole that all ball-and-spring MBCs require, you make that bleed adjustable.

I don't know what the advantage of having that adjustable really is... Maybe it lets you reduce spiking by making the turbo rapidly spool up until it overpowers spring tension and then have it spool a little less rapidly until it reaches equilibrium? Once you build some boost, more boost always comes fast anyway.

I see, an adjustable wastegate pressure relief bleed. I suppose that could be useful somehow. I just ordered the better Dawes MBC, I want to see how that does first. Then if I feel it would be beneficial, I can take apart my TurboXS bleed controller and combine it with my basic Dawes internals and fittings and make one. I have faith in a properly-made ball-and-spring controller, though. Hope it gets rid of my spikes, I definately have spikes now (peak and settle). They were just much worse with the bleed valve - slower, and looked more like weak control.