Quote from: NAKID on March 26, 2009, 09:14:30 AM
I got the impression that he was relieving cylinder resistance, not crankcase resistance which is why I'm confused...

Other than lowering compression, volumetric efficiency or mechanically altering the engine, the only way I can see to lower piston resistance is to lower crankcase pressure, could be wrong.

Quote from: Speeddog on March 26, 2009, 10:16:28 AM


I *think* it's a controlled air leak into the intakes, after the throttle bodies.

BUT, there's so much smoke and so many mirrors, it's impossible to know for sure. 

That's a possibility.  It wouldn't work so well in these days of lean mixture and closed loop.

Here's what I've found during a brief investigation:

It's nothing more than a vacuum bleed that operates when the throttle is closed. Basically it lets air past the throttle on engine braking, which in turn reduces engine braking. It's also sucking this air from the crank, which in turn reduces crank pressures and can boost HP by a very, very small amount (once the throttle is open, no more vacuum, crank quickly gets pressurized again)

If you're after reduced engine braking... well why not simply set your idle higher? I suppose this could be a PITA for street riding, so there's some value here.

Now here's where I think the snake oil comes in:
During Hp measuring on a dyno the engine is left to slow in gear so they can measure power loss on the drivetrain to measure "true" brake HP.
This valve is going to seriously reduce engine braking by creating a vacuum in the crank. When read on a dyno, it's going to make it look like they've reduced engine braking. The dyno would read this as a reduction in power loss through the drive train. Giving a false reading of more crank bhp.

Basically, this is really only going to be "adding power" when the throttle is closed.

What's wrong with this picture?

And where is the significant emissions gains?

Quote from: ato memphis on March 26, 2009, 02:35:36 PM
And where is the significant emissions gains?

I hear snake oil is very clean burning 

I probably lowers the ammount of oil geting above the piston. It could also lower wear on your rings by not having them slam up upon vacuum.  It might work as advertised.

Tim

The problem is that increased vacuum in the crank would increase blow-by from combustion... But yeah, I guess this could prevent oil from making it's way past the rings and into the combustion chamber.

But again, this is only going to help motors with shot rings during engine braking. And I can see this "blow by" valve potentially sucking up (and burning) engine oil.

Still, as an engine braking reduction tool, it has promise.

Quote from: Drunken Monkey on March 26, 2009, 01:44:53 PM
snip

Basically, this is really only going to be "adding power" when the throttle is closed.

What's wrong with this picture?

By keeping the throttle closed at all times your fuel economy will soar - consequently lowering emissions as you use less fuel. 

Looks like a controlled air leak in the intake. And, from my IC Engines class...

Engine breaking would be reduced because the bike isn't trying to suck air past the almost/completely closed throttle body. 

A carb'd bike, might see some fuel economy increases at part throttle due to reduction in pumping losses (energy spent to suck the air into the engine)... but I would think that the greater effect would be to reduce overall airflow through the carb preventing proper fuel mix, reduction in power, and burn issues at all throttle positions.

A FI bike, the ecu would be constantly adjusting to keep the air/fuel in stoich.  So you would have the full amount of air going into the engine, and the ecu pumping enough fuel through the injectors to keep the bike at stoich... and I'd say you'd have a problem where either 1) the fuel pools in the intake runner / valve area or 2) the bike continues to produce near full power assuming the fuel vaporizes and makes it into the cylinder.  Imagine letting of the throttle and the engine not slowing down 

Either way, it's a bad idea.

I'll bring the idea up to my IC-Engine professor and give a much better and more detailed explanation of why it's totally ridiculous.