Ben Z.

Hi,

In two weeks I'm planning on installing a new fuel rail. At the same time I'm planning on replacing my vacuum lines. I'm going to take off the intake manifold to make things easier, and I'd like to remove my cycling valve. I read awilson40's post where he used his reliaboost as a boost controller inline from the banjo bolt to the WG. I'd also like to do this, but I have a LBE. He and others have mentioned that a LBE shouldn't be used for this purpose.

I read one of Danno's posts about the bleeding behavior of this type of device and it's interaction with the wastegate. I'd just like to know what is so much different between the LBE and the various manual boost controllers. I read about a "bleed hole" in the reliaboost, but never figured how this helps. I'll be using a boost gauge so I can keep track of what's happening. I'm probably going to give this a try unless somebody warns me that I might cause some catastrophic (i.e. money intensive) problem.

Sorry for the length and thanks a lot for your help!

Ben Z.

Ok. I did some more research. It sounds like the big problem with some MBCs is boost spiking/fluctuations. Some MBCs have been shown to have much smoother boost curves (provided a good wastegate), but the boost comes on much slower than with the LBE. I've heard the LBE described as a check valve and the other MBCs described as bleed valves. Russ Murphy and David Salama mentioned that they put a LBE and MBC inline. To me this sounds like a good solution to get quick boost pick-up, then a more steady curve up to redline. Unfortunately Pat Kennedy blew his headgasket doing the same thing. It sounds like some (Tony Garcia, et. all) have had very good results with an MBC, but I really like the fast response of the LBE. Maybe electronic is only way to go? What do you guys think?

Thanks again!

FityOne

Ben Z

The bleed hole is to protect against boost spikes. Pressure builds up in the line when the wastegate shuts. The bleed vents the tiny excess of overpressure, preventing the spike. These spikes, thought short lived will over time take a toll on your motor. If you use the LBE by itself, direct to the wastegate, you will spike. Ask me how I know ;-) . The Reliaboost has all the features of the LBE, but also includes the boost spike protection. I currently use it direct to the wastegate for over a year now. Never had a problem or a boost spike to speak of. I would suggest going the reliaboost route. As for using to controllers in series, do not do this. You should only have one controller regulating your boost. Else you are asking for trouble.
The reliaboost is also a snap to adjust and fine tune.

FityOne

Russ Murphy

I guess I've been asking for trouble for a long time.
Two years and seven DE's to be precise and never a spike. I'm not sure how a LBE and a MBC after it are any different than a "gated" manual controller like turboXS or Turbosmart or you name the brand. If two devices make you leery, get one of these.

Ben Z.

Thanks guys. Just curious, do you think it would be possible to modify the LBE so it would be able to bleed-off some of the overpressure? Is there a schematic that shows how the reliaboost is able to do this?

toddk911

Just drill a small hole.

I went from LBE to reliaboost. No spikes at all and boost comes on just as quick. To make it come on quicker, you can change out the internal springs on the LBE or Reliaboost with a stiffer spring.

Jake951

Just be aware that the bleed hole on the Reliaboost is very, very small. I'm not even sure you could find a drill bit that's small enough.

Duke

How is the bleed hole designed so that it only bleeds out the excessed air and not bleeds all the time?
It sounds like it's basically a combined check vavle controller with a tiny tiny bleed valve. But hey, what works works..

Jake951

The bleed hole is located on the body of the Reliaboost between the internal check valve (actually it's a ball and spring type of valve) and the wastegate. There is bleed only when there is pressure in the line to the wastegate. This occurs when the valve opens to pass pressure to the wastegate, so a small amount of air (insignificant, I think) is diverted away from the wastegate through the hole. When the valve closes, any residual pressure in the line is bled through the hole, reducing pressure and closing the wastegate faster than would occur without the hole. When building boost and the valve is closed (and there is no residual pressure in the WG line), there is no bleed through the hole.

ewainwright

Quick question rregarding the Reliboost. Mine only allows for 15-16 psi boost. Is there a way to increase it to 17? If so, and it is the spring, where can I get it. Sorry for hijacking the tread. Thanks in advance ed

Ben Z.

John-
Would you or anybody know the size the hole is? We have some ridiculously small bits at work that I could borrow. They won't even fit in a regular chuck.
Thanks

Sami951

My absolutely accurate eye-based guess says it's around 1 or 2 mm... so 1/25" or 2/25", or whatever sizes you have available in that range

Chas

okay I'm confused....I thought pressure to the wg opens it up, thus dropping airflow to the turbo hotside thus lowering boost. So wouldn't a hole, or any other means of decreasing pressure to the wg - contribute to raising the boost?

Ben Z.

Thanks Sami. I will try this modification when I go home in 2 weeks. I'll let you guys know how it works out. It shouldn't really matter where the hole is as long as it's "upstream" from the valve, right?

Duke

I assume the hole is at the end that connects to the "turbo to IC"-pipe?