petrol engines????
03-17-2005, 10:42 AM
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petrol engines???? hey guys i wasn't sure where t opost this so i just posted here since i always post here sorry mods if you gotta move it move it. Ok so i was watching speed the other night and this guy was talkign about petrol engines, no i heard this before but this got me wondering is petrol the same as gas?? or what is it??? Also on another note i read on here a few times about camless engines, whats up with that?????
03-17-2005, 11:23 AM
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And I'll take a stab at a "camless" engine.
Here's some background info:
Basically the camshaft in your specific engine is only perfect at one specific rpm (lets say 3800 rpm, just for arguments sake). Everywhere below 3800 rpm, the engine would run make more power (and emissions and use less fuel and....) with less duration and overlap. Everywhere above 3800 rpm, the engine would make more power with more duration and overlap. This is why Honda invented the VTEC stuff. As you get higher in the rpm band you switch to a longer duration camshaft, helping top end power out.
So what they're trying to develop is some time of engine inlet system that isn't mechanically timed. Something where you can change the duration at will depending upon what the PCM says to do. Would also be cool to be able to take specific cylinders and turn them off in specific spots (displacement on demand WITH the ability to open the exhaust port / intake port to minimize compression drag and such). I've seen some designs with rotary valves. I've seen some folks do it with electrically actuated poppet valves (valves just like we have now, only not electrically not cam / pushrod /rocker-arm driven. I haven't seen anything that is ready for full scale production, but I think we'll see it sooner or later.
15 years ago I thought direct injection (into the cylinder) would be a big hit, once they figure out how to do it. So far, I've only seen outboard motors use it in full scale production (of a gasoline engine, obviously diesels are almost all direct injection)
It'll be interesting to see somebody find a workable, reliable, and reasonably affordable method to eliminate the camshaft. The biggest single problem is finding a solution that is all of those things.
'Dreamin'
Here's some background info:
Basically the camshaft in your specific engine is only perfect at one specific rpm (lets say 3800 rpm, just for arguments sake). Everywhere below 3800 rpm, the engine would run make more power (and emissions and use less fuel and....) with less duration and overlap. Everywhere above 3800 rpm, the engine would make more power with more duration and overlap. This is why Honda invented the VTEC stuff. As you get higher in the rpm band you switch to a longer duration camshaft, helping top end power out.
So what they're trying to develop is some time of engine inlet system that isn't mechanically timed. Something where you can change the duration at will depending upon what the PCM says to do. Would also be cool to be able to take specific cylinders and turn them off in specific spots (displacement on demand WITH the ability to open the exhaust port / intake port to minimize compression drag and such). I've seen some designs with rotary valves. I've seen some folks do it with electrically actuated poppet valves (valves just like we have now, only not electrically not cam / pushrod /rocker-arm driven. I haven't seen anything that is ready for full scale production, but I think we'll see it sooner or later.
15 years ago I thought direct injection (into the cylinder) would be a big hit, once they figure out how to do it. So far, I've only seen outboard motors use it in full scale production (of a gasoline engine, obviously diesels are almost all direct injection)
It'll be interesting to see somebody find a workable, reliable, and reasonably affordable method to eliminate the camshaft. The biggest single problem is finding a solution that is all of those things.
'Dreamin'
03-17-2005, 11:34 AM
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Originally Posted by JustDreamin
And I'll take a stab at a "camless" engine.
Here's some background info:
Basically the camshaft in your specific engine is only perfect at one specific rpm (lets say 3800 rpm, just for arguments sake). Everywhere below 3800 rpm, the engine would run make more power (and emissions and use less fuel and....) with less duration and overlap. Everywhere above 3800 rpm, the engine would make more power with more duration and overlap. This is why Honda invented the VTEC stuff. As you get higher in the rpm band you switch to a longer duration camshaft, helping top end power out.
So what they're trying to develop is some time of engine inlet system that isn't mechanically timed. Something where you can change the duration at will depending upon what the PCM says to do. Would also be cool to be able to take specific cylinders and turn them off in specific spots (displacement on demand WITH the ability to open the exhaust port / intake port to minimize compression drag and such). I've seen some designs with rotary valves. I've seen some folks do it with electrically actuated poppet valves (valves just like we have now, only not electrically not cam / pushrod /rocker-arm driven. I haven't seen anything that is ready for full scale production, but I think we'll see it sooner or later.
15 years ago I thought direct injection (into the cylinder) would be a big hit, once they figure out how to do it. So far, I've only seen outboard motors use it in full scale production (of a gasoline engine, obviously diesels are almost all direct injection)
It'll be interesting to see somebody find a workable, reliable, and reasonably affordable method to eliminate the camshaft. The biggest single problem is finding a solution that is all of those things.
'Dreamin'
Here's some background info:
Basically the camshaft in your specific engine is only perfect at one specific rpm (lets say 3800 rpm, just for arguments sake). Everywhere below 3800 rpm, the engine would run make more power (and emissions and use less fuel and....) with less duration and overlap. Everywhere above 3800 rpm, the engine would make more power with more duration and overlap. This is why Honda invented the VTEC stuff. As you get higher in the rpm band you switch to a longer duration camshaft, helping top end power out.
So what they're trying to develop is some time of engine inlet system that isn't mechanically timed. Something where you can change the duration at will depending upon what the PCM says to do. Would also be cool to be able to take specific cylinders and turn them off in specific spots (displacement on demand WITH the ability to open the exhaust port / intake port to minimize compression drag and such). I've seen some designs with rotary valves. I've seen some folks do it with electrically actuated poppet valves (valves just like we have now, only not electrically not cam / pushrod /rocker-arm driven. I haven't seen anything that is ready for full scale production, but I think we'll see it sooner or later.
15 years ago I thought direct injection (into the cylinder) would be a big hit, once they figure out how to do it. So far, I've only seen outboard motors use it in full scale production (of a gasoline engine, obviously diesels are almost all direct injection)
It'll be interesting to see somebody find a workable, reliable, and reasonably affordable method to eliminate the camshaft. The biggest single problem is finding a solution that is all of those things.
'Dreamin'
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03-17-2005, 12:53 PM
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Originally Posted by PREDATOR-Z
There are also rotaries (MAZDA) which are camless