Vacuum free 4-cycle?

[DKJones96]

Does anybody here know if someone is working on an engine that has no manifold vacuum?

I have a few things i've gome up with that involve an IC engine with no manifold or chamber vacuum at part throttle. The engine basicly purges the charge from the cylinder again into the intake manifold(against a reed valve to create a bit of pressure to force exhaust out on overlap) until it reaches your 'throttle' point. My way of doing it is infinately variable and completely mechanical and to help with this I've developed a completely mechanical way to have variable compression ranging say from 8-12:1 and also thought of a low pressure direct injection system for it. I plan on building this for a Toyota 5M-GE I6 engine starting in a couple weeks.

I was just wondering what you guys thought about efficiency increases and if anyone is working on this kind of stuff. Sadly...I'm only 22 so most people don't take me seriously. Just wondering what you guy thought.

 

[patprimmer]

Ummm

Why are pumping losses all that different at closed throttle or WOT.

At closed throttle, you have more suction against the piston on the induction stroke, but you have less pressure against it on the compression stroke. +1-1=0

At WOT you have less suction against the piston on the induction stroke, but more pressure against it on the compression stroke. -1+1=0

I agree with turbocohen, there is energy lost to the intercooler, but less manifold pressure is necessary to move the same mass of air into the engine.

If people think that the deceleration felt when lifting off the throttle is proof of increased pumping losses, they certainly need to think through all the other things that are happening, like inertia, friction etc

This engine braking goes away at light throttle not because of a change in pumping losses, but because the engine starts making power by burning enough fuel to overcome pumping and inertia and friction losses in the engine, drive train and chassis.

Regards

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[GregLocock]

Sorry, my point was that at part throttle you /want/ a pumping loss, unless you think that the loss past the butterfly is somehow different in quality to the loss around the intake valve.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[mishar]

Something I proved to myself many times: every second step in any evolution or analyses has to be big picture and major lows of physics. Otherwise, in a very few steps everybody is about to reinvent perpetuumobile.

Regarding pumping loses, I think that there is no point to evaluate it on part throttle because that’s only way Otto engine is regulated. If, by any miracle, we succeed to lower them, we would need to introduce more of them immediately in order to lower the power output.

Way to lower them under WOT is to reduce resistance and utilize resonance.

Supercharging just increase those losses because there is more flow trough same configuration.

 

[wwest]

An "infinitly" variable displacement engine (swashplate? rotating piston group??) would be the ideal method for doing away with engine throttling via limiting intake airflow.

 

[turbocohen]

WWest, vario setups galore have one thing in common. Cost/Risk to manufacture. The crankshaft will be with us for a while.
A mechatronic piston driving a linear generator seems like a good idea but a fuel cell is even better until you have to deploy it under all of the conditions that the ole crankshaft does everyday.