h a l f b a k e r ynon-lame halfbakery tagline
add, search, annotate, link, view, overview, recent, by name, random
news, help, about, links, report a problem
browse anonymously,
or get an account
and write.
register,
|
|
|
Replace the air in the crankcase with Hydrogen or Methane. At 7% or 55% the mass of air respectively, this means quite a drop in pumping losses.
A blow-by sensor (registering CO2 or humidity) regulates the influx to keep the internal atmosphere uncompromised'ish. The crankcase exhausts to the engine's
intake manifold.
(As an annoying side effect this means that that 'HHO' crap theoretically works if you run the H's through the crankcase on their way to the intake manifold)
Googling for 'crankcase vacuum horsepower'
http://www.google.c...al&client=firefox-a
most of the articles talk about reducing the crankcase atmosphere to half an atmosphere. That would be the equivalent to using CH4; Hydrogen would be almost equivalent to a vacuum. [FlyingToaster, Aug 16 2011, last modified Aug 02 2013]
[link]
|
| |
Are you talking about the turbulence losses from air and oil mist moving around in the crankcase ? |
|
| |
...pistons moving air back and forth, non-aerodynamic rods shuttling around, etc. The CO2 sensor is there to detect blow-by and the system responds by moving some of the air, through a filter, to the intake manifold. |
|
| |
And a less viscous gas is really going to make that much difference ? |
|
| |
F'rinstance, on a four cylinder, four pot engine, two go up as two go down. There's no change in volume in the crankcase, except (as you point out) from blow-by, which is dealt with by the crankcase breather into the inlet manifold. |
|
| |
On a side-by-side two-pot, same story. |
|
| |
Straight six with a 120 degree crank throw ? It all balances out ... |
|
| |
V8 ? Oh, this is looking familiar ... wonder why ... |
|
| |
Before addressing turbulence losses (which do some good actually, by spreading the oil mist around), why not think about ring-to-wall friction, journal bearing frictive losses, low mass silicon nitride pistons, or bringing down the losses in the powertrain - particularly those wasteful Borg-Warner automatic transmissions so beloved on the North American continent, where it has been generally adopted as the natives apparently don't have the wit to be able to work a manual shift gearbox in conjunction with a clutch, rather than an energy-sucking torque converter ? |
|
| |
Hmmm. Should there have been a <rant> tag somewhere further back in the anno ? |
|
| |
Meanwhile, this would be turbulent but with a lighter atmosphere. Interesting though possibly non-sequitur point about oil mist: droplet size might have to be smaller to maintain an aerosol percentage in a stationary gas, but this one will be moving around just as much as it normally does. |
|
| |
This is the same thing as the "let's make it a Hydrogen Tunnel instead of a Vacuum Tunnel". |
|
| |
//losses in the powertrain// non-circular gear pair complementing the engine's power pulses,between engine and transmission, but that's another post. |
|
| |
Just what percentage of the total energy produced by the combustion of fuel in the powerplant is lost to gas turbulence in the crankcase ? |
|
| |
none, since turbulence is an effect not a cause. |
|
| |
[8th], come share our citystates and drive our traffic. You'll love our projectile weapons and beer, but unless you're obsessed with maintaining rigid control of your vehicles each and every subfunction, you'll learn to love driving a slushbox in our commuter madness. |
|
| |
// turbulence is an effect not a cause // |
|
| |
"what percentage of the total energy produced by the combustion of fuel in the powerplant is lost to joule heating arising from gas turbulence in the crankcase ?" |
|
| |
// you'll learn to love driving a slushbox in our commuter madness // |
|
| |
Thankyou, but we've seen the last bit of A New Hope where Luke flies his X-wing down the trench with Darth Vader shooting at him, and it looked quite a lot like it could all get rather loud and expensive, so no. |
|
| |
//slushbox// Horribly wasteful yes, but they do allow more of the driver's attention to be on the road. |
|
| |
//sharp// "turbulence" isn't the issue if you use a valid definition of the word. Joule heating, not so much either. [edit: okay fine: "Joule heating"; I'm still drawing the line this side of "turbulence" though: using it to simply mean "unwanted air flow" is contextual to a planned hydrodynamic system, not a system where *all* airflow is unwanted.] |
|
| |
While researching for a diferent post, I read numbers bandied about of 20 to 30 horsepower increase in racing engines by creating even a *partial* vacuum in the crankcase. |
|
| |
Crankcase vacuum systems are commonplace in motorsport. The fact that an F1 car carries an engine driven pump to reduce crankcase pressure is testament to the gains available. |
|
| |
Quite apart from the losses generated by thrashing con-rods, the displacemnt of each piston shifting air from one end of the engine to the other is a substantial loss. |
|
| |
I can think of two problems with using a light gas: |
|
| |
1) replenishment - blowby accounts for a reasonable rate of gas displacement through the crankcase. Your vent would allow a mix of light gas, CO2 and air to escape. To keep the crankase filled with light gas you would need to constantly top it up. |
|
| |
2) both methane and hydrogen are flammable gases. Your vehicle will need to carry a store of the required gas and a means to ensure that it is only delivered to the crankcsase when the engine is running (and ingesting from the breather) and possibly a means to purge the crankcase when the engine stops, to prevent pooling of the light gas in the air filter etc. |
|
| |
H2 is easily replenished with an electrolyser. CH4 I was ruminating for an engine that's already run on the stuff so a supply is at hand. |
|
| |
// I read numbers bandied about of 20 to 30 horsepower increase in racing engines by creating even a *partial* vacuum in the crankcase.// |
|
| |
For a while now, modern engines have been pulling a partial vacuum in the crankcase using the inlet. This is partially to reduce the pressure in the crank case to increase efficiency. But mainly, it's about emissions. Engines generate positive crank case pressure and this used to be vented to the atmosphere. This is no longer deemed acceptable since there will be oil and possibly fuel vapor released to the atmosphere. So, by routing this into the intake, the engine will burn any excess. Or at least it's supposed to. |
|
| |
What actually happens is that the oil carbonizes in the inlet manifold. That used to be constantly washed off by fuel, but now engines are direct injection, there's no fuel in the manifold. The whole thing is exacerbated by turbos. It's a bit of a scandal how many modern gasolene direct injection engines barely reach 100k miles before needing a major clean up, which is just manual scraping. Often, it writes the car off. |
|
| |
Where is Flying Toaster? Did we loose another one? |
|
| |