interesting articles on the subject of pneumatic wastegate control

[TimpanogosSlim]

I came across these old articles that go into detail on how to construct reasonably sophisticated boost control out of common industrial pneumatic parts.

We're all pretty familiar with 'dawes devices', manual boost controllers, etc, but these articles provided me with a nicely demystified version of the general theory, and a good roadmap for implementation:

http://www.autospeed.com/cms/A_111348/article.html
http://www.autospeed.com/cms/A_111350/article.html

Mostly applicable to older, non-ECU-controlled turbo systems of course.

Also came across the installation instructions for 3 Bar Racing's "manual boost controller selector", here:

http://www.3barracing.com/mbcsinstructions.html

which is really just a solenoid valve and some brass fittings. The one they are using is normally closed, which means that you have to energize the solenoid to select the 'low' boost option. I don't really think that's a fabulous idea. I think it's best if failure to operate the solenoid results in less boost. So, good thing normally open solenoids are available.

I briefly looked into some of the more advanced pneumatic control valves (4-way 5-port devices, etc) and unfortunately i don't think they really work for this application. Their design typically uses the air pressure to create the seal, and they typically need about 22psi on the source port to work properly.

But that's ok. If you need more settings than "normal" and "MORE BOOST", you're better off with an electronic boost controller.

[monomer]

Even better, c02 control:
http://www.leashelectronics.com/Boost-Leash-Boost-Controller-BEST-SELLER-BL2011.htm


It's what a lot of the high horsepower drag cars run locally. I'm not sure about the controller I linked, but most are accurate to 1/10 psi.


My friend has had nothing but issues with an electronic setup on his car.

[TimpanogosSlim]

Almost six hundred bucks and it's still a pneumatic solution at it's core. weird.

My daily right now is a Mk5 GTI. Sufficiently advanced electronic systems are flatly awesome. I don't think the article at that link qualifies, tho. just saying that the onboard diagnostics and controls in a modern VW are nothing to sneeze at.

I will probably stick with passive pneumatic controls unless/until i go with a VNT setup.

[TimpanogosSlim]

I noticed one thing - in case anyone else read these two.

In the first article, it states about the regulator:

The pressure regulator that is used is very similar to the regulators used on compressed air systems - it reduces the inlet pressure to a constant outlet pressure. But instead of feeding (say) an air tool, the pressure is being fed to the dead-end of the wastegate diaphragm, meaning that a 'self relieving' pressure reg is required. This allows the air that would otherwise be trapped between the reg and the wastegate to escape when the boost pressure being fed to the reg drops.

But then in the 2nd article he adds a reverse-biased check valve between the wastegate and the boost source.

Which would appear to do the same job as having a self-relieving pressure regulator, except better.

Which means that the regulator used can now be precisely those used on compressed air systems, unless I'm very confused?

[smutts]

I've been meaning to find and post the link for the autospeed site. Lots of good stuff to be found on it.

Look up the experiments on standard air filters, some suprises there.

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