Single Overhead Camshaft V8s

[angry hampster]

The intake phase of the cycle starts when the tip of the rotor passes the intake port. At the moment when the intake port is exposed to the chamber, the volume of that chamber is close to its minimum. As the rotor moves past the intake port, the volume of the chamber expands, drawing air/fuel mixture into the chamber. When the peak of the rotor passes the intake port, that chamber is sealed off and compression begins.
Compression
As the rotor continues its motion around the housing, the volume of the chamber gets smaller and the air/fuel mixture gets compressed. By the time the face of the rotor has made it around to the spark plugs, the volume of the chamber is again close to its minimum. This is when combustion starts.
Combustion
Most rotary engines have two spark plugs. The combustion chamber is long, so the flame would spread too slowly if there were only one plug. When the spark plugs ignite the air/fuel mixture, pressure quickly builds, forcing the rotor to move.
The pressure of combustion forces the rotor to move in the direction that makes the chamber grow in volume. The combustion gases continue to expand, moving the rotor and creating power, until the peak of the rotor passes the exhaust port.





FWIW.

 

[TehMac]

Ah I see, this clarifies a ton, thanks guys. Also, I checked out Jules' link, and damn that's very cool and very helpful.

I guess my big question now is:

I know the accelerator pedal actually operates a linkage that when the pedal is depressed, creates a vacuum in the intake manifold, and so air comes in, and this introduction of air makes the engine go faster because it has more air...

then I'm sort of lost, because
a) How is it possible to flood the engine by jabbing the accel pedal if all you're doing is creating a vacuum
and
b) I'm trying to figure out how more gas comes into the chamber...I guess it's the fuel pump just doling out an automatic amount...or what?

 

[BlackTigers]

Ah I see, this clarifies a ton, thanks guys. Also, I checked out Jules' link, and damn that's very cool and very helpful.

I guess my big question now is:

I know the accelerator pedal actually operates a linkage that when the pedal is depressed, creates a vacuum in the intake manifold, and so air comes in, and this introduction of air makes the engine go faster because it has more air...

then I'm sort of lost, because
a) How is it possible to flood the engine by jabbing the accel pedal if all you're doing is creating a vacuum
and
b) I'm trying to figure out how more gas comes into the chamber...I guess it's the fuel pump just doling out an automatic amount...or what?

Pump the pedal while you're starting it, but don't let it actually turn over. Your injectors will spit out fuel.

 

[TehMac]

Pump the pedal while you're starting it, but don't let it actually turn over. Your injectors will spit out fuel.

why?

 

[BlackTigers]

why?

youll send power to the ignition system, to the fuel pump, and the injectors will flow.

but if you dont let the engine actually start, the fuel will build up becasue everything is moving when the starter moves jsut a little bit

 

[exdeath]

BTW-I'm actually registered as republican.

I'm sorry

 

[exdeath]

You cannot flood a fuel injection system with the pedal, all the pedal does is open the throttle blade (lowering vacuum btw) and the computer must respond to the increased air flow and change in throttle position by changing injector pulse width. If the engine isn't running, movement of the throttle does absolutely nothing.

Some systems will note the throttle position when the engine is starting, ie: flooring the throttle while starting the engine will cause the computer to go into a limp or diagnostic mode as a purposely programmed "back door". But just the act of pressing the throttle with the engine off does nothing.

The only way a fuel injection system gets flooded is if the pressure regulator, injectors, or temperature sensor are faulty. You cannot build up excess fuel while starting, as the fuel is either ignited or pumped out the exhaust valve with each cycle of the cylinder. This isn't anything like a carb where you can pump the accelerator and keep shooting fuel into the intake manifold with or without cranking and regardless of actual air flow or RPM. Note that with fuel injection even if you pump the throttle while cranking, there is also a corresponding increase in air flow with each opening of the throttle and the computer will match it with the correct amount of fuel always.

EFI computers also have numerous modes of operation, including a "starting" mode which aids in starting by compensating for cold fuel and ignoring things like sudden throttle transition (accelerator pump logic), O2 sensors, etc while starting/cold/etc.

 

[BlackTigers]

You cannot flood a fuel injection system with the pedal, all the pedal does is open the throttle blade (lowering vacuum btw) and the computer must respond to the increased air flow and change in throttle position by changing injector pulse width. If the engine isn't running, movement of the throttle does absolutely nothing.

Some systems will note the throttle position when the engine is starting, ie: flooring the throttle while starting the engine will cause the computer to go into a limp or diagnostic mode. But just the act of pressing the throttle with the engine off does nothing.

The only way a fuel injection system gets flooded is if the pressure regulator, injectors, or temperature sensor are faulty. You cannot build up excess fuel while starting, as the fuel is either ignited or pumped out the exhaust valve with each cycle of the cylinder. This isn't anything like a carb where you can pump the accelerator and keep shooting fuel into the intake manifold with or without cranking.

I know it's easier to flood a carb'ed motor, but I have definitely flooded my car before.

I replaced the plugs after I drained the cylinders and it started, but I was definitely able to get fuel to puddle up in the chambers.

 

[LTC8K6]

Ah I see, this clarifies a ton, thanks guys. Also, I checked out Jules' link, and damn that's very cool and very helpful.

I guess my big question now is:

I know the accelerator pedal actually operates a linkage that when the pedal is depressed, creates a vacuum in the intake manifold, and so air comes in, and this introduction of air makes the engine go faster because it has more air...

then I'm sort of lost, because
a) How is it possible to flood the engine by jabbing the accel pedal if all you're doing is creating a vacuum
and
b) I'm trying to figure out how more gas comes into the chamber...I guess it's the fuel pump just doling out an automatic amount...or what?

You need to advance the timing too, if you want the engine to run faster...

 

[LTC8K6]

Most EFI systems will not flow any fuel if you crank the car with the throttle wide open.

This duplicates what you used to do with a carburetor if the engine was flooded.

 

[Eli]

The starter motor initially turns the motor over and starts the process. This draws air and fuel into the cylinder which ignite. Pushing the piston down, turning the crank shaft, turning the cam, which allows air and fuel into the cylinder, which ignites... You get the idea.

Some direct injected engines use a crank sensor and inject a little fuel into whichever cylinder is in the right position and ignite it, instead of using a starter motor.

You're lost because you can't figure out where the energy in the equation comes from, you're forgetting the fuel/air

lolwut

 

[LTC8K6]

lolwut

http://www.etas.com/data/RealTimes_2006/rt_2006_01_34_en.pdf

Direct Start has been possible for a long time, actually...

 

[EightySix Four]

lolwut

http://news.google.com/newspapers?n...TkzAAAAIBAJ&sjid=HBQLAAAAIBAJ&pg=3012,1357638

 

[Demo24]

Ah I see, this clarifies a ton, thanks guys. Also, I checked out Jules' link, and damn that's very cool and very helpful.

I guess my big question now is:

I know the accelerator pedal actually operates a linkage that when the pedal is depressed, creates a vacuum in the intake manifold, and so air comes in, and this introduction of air makes the engine go faster because it has more air...

then I'm sort of lost, because
a) How is it possible to flood the engine by jabbing the accel pedal if all you're doing is creating a vacuum
and
b) I'm trying to figure out how more gas comes into the chamber...I guess it's the fuel pump just doling out an automatic amount...or what?

Technically the acc pedal is not creating a vacuum, it simply acts as a restrictor. The pistons themselves create the vacuum in the intake manifold when they enter the downward motion, thus the valves open and it pulls in air and gas. At least that's how a carb engine works. On a EFI engine, it's just sucking in air gas is injected electronically at a specified moment. Think of it as a flap in the intake like this: |-|, now at idle it will be open just enough to keep the engine running at whatever speed it's set to. Open the throttle all the way and it becomes this: |||, so the flap turns 90 degrees and the maximum amount of air is traveling through the intake and into the cylinders.


Now in modern EFI cars the fuel pump pressurizes the fuel rails. When a piston is reentering the upward motion a set amount of fuel is sprayed into the cylinder(this is highly pressurized) and thus the combustion process occurs.

Edit: Oops, meant to post.. not edit.

Moderator Eli

 

[Eli]

Technically, the engine doesn't pull anything into it. The atmosphere pushes in to fill the void.

Also, injecting fuel directly in the cylinder is a relatively new technology when it comes to gasoline engines. In most EFI engines, the fuel is injected into the airstream before the valve.

 

[LTC8K6]

Also, injecting fuel directly in the cylinder is a relatively new technology when it comes to gasoline engines.

Several WW2 aircraft engines used gasoline direct injection.

It's really not all that new, having been used extensively over the years in various forms on gasoline engines. Even in it's modern form, it's closing in on twenty years.

 

[DivideBYZero]

http://news.google.com/newspapers?n...TkzAAAAIBAJ&sjid=HBQLAAAAIBAJ&pg=3012,1357638

:hmm: Got any links to commercial application of this?

 

[PlasmaBomb]

Several WW2 aircraft engines used gasoline direct injection.

It's really not all that new, having been used extensively over the years in various forms on gasoline engines. Even in it's modern form, it's closing in on twenty years.

The luftwaffe used fuel injection in planes during WW2, I'm not aware of any direct fuel injection though... Do you have more info?

 

[EightySix Four]

:hmm: Got any links to commercial application of this?

Supposed to be a feature on the next-gen Bosch PCMs for DI motors. I was incorrect that it is completely starter-less though. It is supposed to use a crank angle sensor, direct injection, and a very small starter to get the motor to where it is self sustaining in less than .3 seconds.

Next gen Bosch means BMW will probably run it first, but you never know.

 

[PricklyPete]

http://news.google.com/newspapers?n...TkzAAAAIBAJ&sjid=HBQLAAAAIBAJ&pg=3012,1357638

Does anyone know of a car yet that is actually using this though? I'm intrigued.

Edit...I see DBZ already asked this question...

 

[EightySix Four]

Does anyone know of a car yet that is actually using this though? I'm intrigued.

Read the post one above you

 

[PricklyPete]

Read the post one above you

LOL...yeah...I'm coming to very slowly this morning. :awe:

 

[Eli]

Several WW2 aircraft engines used gasoline direct injection.

It's really not all that new, having been used extensively over the years in various forms on gasoline engines. Even in it's modern form, it's closing in on twenty years.

Direct injection into the cylinder?

Anyway, yeah. I meant for production engines I guess.

 

[LordMorpheus]

The timing chain (or belt but I hate timing belts) runs up from the crankshaft to each cam.

Link if image doesn't work

That's a good engine but it's a little weird. That's the only SOHC engine I know that uses three valves per cylinder instead of 2.

 

[LTC8K6]

Direct injection into the cylinder?

Anyway, yeah. I meant for production engines I guess.

Yes, but keep in mind that compression was a tad lower than what we have today.

DB605 inverted V-12 with Bosch Direct Injection.

http://en.wikipedia.org/wiki/Daimler-Benz_DB_605

Junkers Jumo 210G with Direct fuel injection.

http://en.wikipedia.org/wiki/Junkers_Jumo_210

Wright R-3350 radial had carbs replaced with direct injection near the end of WW2. Solved a lot of problems.

http://en.wikipedia.org/wiki/Wright_R-3350