R/Cpullerdude

On a passive crankcase supercharged 4 stroke, how much hotter would the intake air be? Thanks.

Flyboy Dave

My Feedback: (21)

....what is a "passive crankcase", and why would you care about the "air" ?

FBD.

R/Cpullerdude

Don't ask me what it is, all I've found is the name and application on another site, found with google. May the site have had incorrect info? BTW, it was explaining the system YS engines use, and called it "passive crankcase supercharging". I'm thinking it's supposed to be "positive" instead of "passive", as that'd make more sense, but, all I know is what the site said.

The reason I'm asking is to figure out if supercharging will work on a model diesel. If it heats the air too much, it'll mess with the timing, and make it impossible to run. What kind of boost could one expect?

Flyboy Dave

My Feedback: (21)

....diesels utilize "compression ignition"....meaning that as the compression
of the engine reaches very high compression, the molecules of the fuel heat
up to the point where they explode....without an external ignition source.

Many diesel engines have been "supercharged" over the years....there is no
actual increase in the air temperature from the supercaharger. [sm=teeth_smile.gif]

FBD.

mmattockx

Yes there is, Dave. You cannot compress air without heating it somewhat. The rise can be mild to extreme, depending on your compressor efficiencies. Also adding to the air temp is the fact that you are pumping it through a hot crankcase (in the YS engines).

I don't see why you couldn't supercharge a model diesel engine, but I have no firsthand diesel experience to base that on, just general engine knowledge. The intake air temperature would be consistent once the engine was warmed up, so you could probably account for it in your timing setting, though.


Mark

Flyboy Dave

My Feedback: (21)

....yep, when air is compressed it does heat up slightly. However, this minute
increase does not effect the crankcase temperature of our engines.

The crankcase temperature of a YS engine is the same as any other four stroke
engine. Air is not "compressed" in the YS crankcase....rather the increase in crankcase
pressure, due to the piston moving downward is utilized to increase the intake
charge at the carb, and into the pressure chamber. To say this increase in pressure
also equates to an increase in temperature is certainly a stretch.

Are you trolling, or bait fishing ? [sm=teeth_smile.gif]

FBD.

the pope

Are you trolling, or bait fishing ? Whatever he was doing he certainly got a bite. Cheers the pope

Cyclic Hardover

My Feedback: (3)

You guys crack me up. Like arguing with my son whos and engineer. I can tell him to look up and see that the moon is falling on us. he'll say "no its not, we're falling on the moon!"

R/Cpullerdude

I'm not trolling, or baiting, just gathering info.

I'd love to have a diesel with forced induction, just like my truck, but my truck has fuel injection, timing is fixed. The model diesel relies soley on heat of compression to not only ignite, but also time the ignition. Compressed air gets hot. Boost is compressed air. More boost=more compressed air=more heat. Now is were the problem would come, if the IAT is at X degress F at idle, with almost no boost, but rises to Y degrees F at WOT, then the timing would be more advanced at WOT. Now, here is my next question. With the design of the YS charger, would it not provide the same amount of boost at every speed? The same volume of air is still being pumped in. If this is the case, then it would be possible, as the charge air would be compressed the same amount every RPM, and thus, have the same heat.

Motorboy

Heated air entered in the engine has a disadvantages, heated air means less oxygen who make less power in the engine. The turbocharged engines has intercooler to keep air cooled before entering in the engine.

In some modern cars with common rail dieselengine has electronic controlled air temperature who are about 20 degree celsius, it has both heated air and cooled air from intercooler to regulate constant air temperature at 20 degree.