engines without intake valves?

[1QUICK10TH]

Just a thought that has crossed my mind so bare with me if its ridiculous. Every one knows we have direct injection, and we all know its proven to be an excellent development. What if they were to develop a way to inject the perfect amount of air directly into the combustion chamber also? I know its a stretch but maybe it would be beneficial?

 

[GloomySVT]

Good idea, but that's already done with boost lol. The perfect amount of air to make traction a rare commodity :lol1:

 

[SID297]

Just a thought that has crossed my mind so bare with me if its ridiculous. Every one knows we have direct injection, and we all know its proven to be an excellent development. What if they were to develop a way to inject the perfect amount of air directly into the combustion chamber also? I know its a stretch but maybe it would be beneficial?

It's called a 2 stroke diesel engine. The perfect amount of air is always every molecule that can possibly be crammed in.

 

[bodge323]

Modern 2 stroke engines use reed valves.

 

[thomas91169]

How would you expel the expended fuel/air mixture?

 

[Mr. Mach-ete]

Call me stupid but don't all compression devices need intake and discharge valves? Intake valves allow air in but slam shut during the compression/ignition stroke?

 

[Ironhand]

Call me stupid but don't all compression devices need intake and discharge valves? Intake valves allow air in but slam shut during the compression/ignition stroke?

Nope. Some diesels use intake ports(without valves) with a blower to cram air in and they have 4 exhaust valves wrapped around an injector.

IIRC it was a 8V92TA, it powers the Armys HEMTT.

Compound Boost anyone?

 

[Silverstrike]

Another engine without any intake or exhaust valves is the Wankle Rotary

 

[Digital]

Nope. Some diesels use intake ports(without valves) with a blower to cram air in and they have 4 exhaust valves wrapped around an injector.

IIRC it was a 8V92TA, it powers the Armys HEMTT.

Compound Boost anyone?

Aww it's my cars daddy.

 

[SonicDTR]

I've made a post about this before too, no idea where.

My idea was a big "air injector" that would work jsut like a fuel injector, and then have exhaust ports similiar to a 2 stroke engine.

I think it was determine that the amount of energy required to power those air injectors would be quite detrimental and rediculous to engineer as well.

 

[10splaya22]

I've made a post about this before too, no idea where.

My idea was a big "air injector" that would work jsut like a fuel injector, and then have exhaust ports similiar to a 2 stroke engine.

I think it was determine that the amount of energy required to power those air injectors would be quite detrimental and rediculous to engineer as well.

A blower/turbo is the air injector you are looking for

 

[SonicDTR]

A blower/turbo is the air injector you are looking for

Except they still rely on a valvetrain.

My idea is a big direct injection of air from the top of the cylinder head, nearly identical to current direct fuel injection.

Lets assume a typical 2-stroke engine, except the intake ports dont exist, only an exhaust port near the bottom of the chamber. As soon as the piston comes up and seals past that port, the air is "injected" directly into the chamber with the exact amount you wanted, the piston compresses and the fuel is injected, then spark ignites it all, power is made and the piston moves back down allowing the exhaust to go out of the port. To make it work you would also need a blast of air while the exhaust port is exposed to clear the cylinder.

This would all require pretty crazy engineering and some extreme precision that just makes it all totally unfeasible.

I base this only referencing how the below 2stroke engine works(RC nitro engines), I assume larger 2 strokes are the same?

 

[thepizz]

In because i can be.

 

[James Snover]

I think the problem you're going to have is volume. You need 12-14 times more air than fuel. An injector made for that kind of volume would probably look something like ... an intake port. Sleeve valve engines, and Wankels, as far as I know, have been the only real competition to traditional poppet valves in a four stroke engine. Both sleeve valves and Wankels have their limitations. Wankels waste a lot of heat, more than 50%; and sleeve valves are very complicated and induce a lot of friction.

Except they still rely on a valvetrain.

My idea is a big direct injection of air from the top of the cylinder head, nearly identical to current direct fuel injection.

Lets assume a typical 2-stroke engine, except the intake ports dont exist, only an exhaust port near the bottom of the chamber. As soon as the piston comes up and seals past that port, the air is "injected" directly into the chamber with the exact amount you wanted, the piston compresses and the fuel is injected, then spark ignites it all, power is made and the piston moves back down allowing the exhaust to go out of the port. To make it work you would also need a blast of air while the exhaust port is exposed to clear the cylinder.

This would all require pretty crazy engineering and some extreme precision that just makes it all totally unfeasible.

I base this only referencing how the below 2stroke engine works(RC nitro engines), I assume larger 2 strokes are the same?

 

[SonicDTR]

I think the problem you're going to have is volume. You need 12-14 times more air than fuel. An injector made for that kind of volume would probably look something like ... an intake port. Sleeve valve engines, and Wankels, as far as I know, have been the only real competition to traditional poppet valves in a four stroke engine. Both sleeve valves and Wankels have their limitations. Wankels waste a lot of heat, more than 50%; and sleeve valves are very complicated and induce a lot of friction.

All good points...Perhaps you use half of an engines cylinders as the air "pumps" for the remaining cylinders?!

oke:

 

[Ry_Trapp0]

why don't we go back to square one and ask what we're actually trying to achieve here. because i'm definitely not seeing the benefit to this.

 

[slowr w/o blowr]

If you are looking at an "air injector", and don't want to be reliant on superchargers or turbochargers, you are still limited with atmospheric pressure. In order to inject the air into the cylinder, you have to draw the air into the "air injector" by causing a low air pressure event. So, now instead of the piston drawing the air in, now you are trying to draw it into the injector.

Same war, different battlefield.

 

[SonicDTR]

why don't we go back to square one and ask what we're actually trying to achieve here. because i'm definitely not seeing the benefit to this.

My concept when I thought about it before this thread, was to get a perfect A/F ratio everytime by injecting precise amounts of air and fuel, instead of measuring air and injecting the corresponding fuel to make it right.

We have direct injection down, and pretty precise valvetrain making it happen now, so I was wondering other ways to make it happen.

 

[shanezt]

why not get rid of valves all together? CSRV vs. Poppet Valve - Coates International Ltd.

i seem to remember reading they were able to get a stock ford 5.0 (or 4.0) to turn like 12-13k rpm. i could be wrong.

 

[James Snover]

You could, but traditional turbos and centrifugal blowers are more efficient at moving air than reciprocating air pumps.

All good points...Perhaps you use half of an engines cylinders as the air "pumps" for the remaining cylinders?!

oke: