Supercharged nitro engine
#1
Thread Starter
Joined: Mar 2014
Posts: 8,054
From: Virginia, Near DC, USA
Yes, I know bolt-on superchargers for nitro engines don't work, at least not well enough to justify the extra complexity. I'm just pondering something.
Nitro engines are designed so the exhaust port opens before the transfer ports do, to release exhaust pressure so exhaust doesn't blow down through the transfer ports and block inflow of fresh air and fuel. The side-effect of this is the exhaust port also closes after the transfer ports do, reducing the engine's compression, even with a tuned pipe on the exhaust to "bounce" the escaping fuel and air back into the cylinder before the ascending piston seals off the exhaust port.
But what if you engineered a nitro engine specifically to work as well as possible with a supercharger? If the crankcase were sufficiently pressurized by a supercharger, you wouldn't have to worry as much about exhaust blowing down through the transfer ports, so you could have an exhaust port that opens at the same time as the transfer ports, or even opens *later* than the transfer ports. (the exhaust port could be made wider to compensate for not being as tall, so it would still have the same flow-rate.) That would mean the transfer ports could stay open after the exhaust port closes, and the intake valve on the crankshaft could be adjusted to stay open for longer while the transfer ports are open, which would allow the supercharger to actually pressurize the combustion chamber properly.
Thoughts?
Nitro engines are designed so the exhaust port opens before the transfer ports do, to release exhaust pressure so exhaust doesn't blow down through the transfer ports and block inflow of fresh air and fuel. The side-effect of this is the exhaust port also closes after the transfer ports do, reducing the engine's compression, even with a tuned pipe on the exhaust to "bounce" the escaping fuel and air back into the cylinder before the ascending piston seals off the exhaust port.
But what if you engineered a nitro engine specifically to work as well as possible with a supercharger? If the crankcase were sufficiently pressurized by a supercharger, you wouldn't have to worry as much about exhaust blowing down through the transfer ports, so you could have an exhaust port that opens at the same time as the transfer ports, or even opens *later* than the transfer ports. (the exhaust port could be made wider to compensate for not being as tall, so it would still have the same flow-rate.) That would mean the transfer ports could stay open after the exhaust port closes, and the intake valve on the crankshaft could be adjusted to stay open for longer while the transfer ports are open, which would allow the supercharger to actually pressurize the combustion chamber properly.
Thoughts?
#3
Thread Starter
Joined: Mar 2014
Posts: 8,054
From: Virginia, Near DC, USA
Interesting. That's a four-stroke, though. I was thinking of a two-stroke valveless engine.
Also, it seems that my posts in Nitro On-Road Engine Zone don't show up in the search results when I search the forum for posts I've made.
Also, it seems that my posts in Nitro On-Road Engine Zone don't show up in the search results when I search the forum for posts I've made.
#4
If possible you should inject compressed mixture on the moment when the exhaust closes. A small oneway port directly connected to the turbo with an own (2nd) carburator just above the exhaust should make that possible.
Thinking about it, a few years ago there was a devellopment of (real) car engines using 2-stroke and 4-stroke technology...... so yes, my idea of small ports can also be translated to valves although high revs can cause floating valves and enough valve spring pressure will give a lot of resistance so it must be a rotating valve or an injector.
Thinking about it, a few years ago there was a devellopment of (real) car engines using 2-stroke and 4-stroke technology...... so yes, my idea of small ports can also be translated to valves although high revs can cause floating valves and enough valve spring pressure will give a lot of resistance so it must be a rotating valve or an injector.
#8
yes same goal but completely different ways of delivering that air u cant even compare turbos are so much more complex and what is needed to drive them ,,,,
#9
#10
Tech Fanatic
Joined: Dec 2010
Posts: 805
Just Google "OS Supercharged" and you will see pictures of it dismantled, here it is on the OS web-page, though not dismantled.
https://www.osengines.com/history.html
#11
No, that is not a turbo, that is a roots blower. To the best of my knowledge no one has ever tried to use a turbo on a engine of this size.
Just Google "OS Supercharged" and you will see pictures of it dismantled, here it is on the OS web-page, though not dismantled.
https://www.osengines.com/history.html
Just Google "OS Supercharged" and you will see pictures of it dismantled, here it is on the OS web-page, though not dismantled.
https://www.osengines.com/history.html
#13
#14
Tech Fanatic
iTrader: (1)
Joined: Aug 2017
Posts: 834
There was a guy on RCU that was going to attempt to adapt a keychain turbocharger to a Nitro engine. I suspect it won’t work though.
#15
Your post that I quoted has you saying it works great and I can tell you it does NOT work. I’ll also tell you there are two different kinds of superchargers. Roots type and centrifugal. The latter look similar to turbochargers.
There was a guy on RCU that was going to attempt to adapt a keychain turbocharger to a Nitro engine. I suspect it won’t work though.
There was a guy on RCU that was going to attempt to adapt a keychain turbocharger to a Nitro engine. I suspect it won’t work though.



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