Would this reduce pumping losses?
 

I have been thinking of a way to reduce pumping losses. I have a few ideas, but the most practical may be to accelerate with lots of throttle, maybe half to three quarter open, but not open enough to go into open loop, but still shift at the same low RPM. I would try it, but I have an auto:( It could even be implemented into P&G. What would the problem with that be? There surely must be a problem with that. What is it?

So how many MPG could be gained by doing that? Would it cause excessive engine wear?

What years is your civic, or whatever you're driving?

It is a 2005 Civic and I put a VTEC motor in it.

New stuff, like that, you'll only be able to change the shift patterns with reprogramming, assuming that's possible.

Older stuff with a separate transmission control module, you could fool it in to not thinking the throttle is open much.

Even older stuff with a kickdown cable, you could mess around with even easier. Well, if you could reprogram without much effort, that would be even easier. ;)

That's a better way to accelerate, yes. Once you're up to speed though, your pumping losses are pretty much a function of gearing, unless you pulse and glide. On the highway, many on here will accelerate under high load, then throw it into neutral (or shut the engine off) and let the car coast for a while, rinse and repeat.

In my Insight pulse and glide helps very little, since it has a small engine with very tall gearing - it's already running at high load most of the time. In my previous car, which had very short gearing and a large engine, I found that if I was very determined with my pulse and glide, I could improve my highway economy from ~30-35 at steady speeds, to 50+ by pulsing and gliding.

Does pulse and glide also yield good results with diesels / turbo diesels?

That's how I accelerate with my Mustang. Most of the time. ;)

My numbers aren't too bad for a 4-liter V-6 in a 3500# car.

Less than gasoline. You still save a bit on parasitic losses from accessories and some friction, but at least with older diesels, there's no throttle plate. Probably not worth the effort in most cases, unless you're going for records.

Accelerate with your torque converter fully locked up at the least and you'll see a gain.

Yes, that will help you gain mpg. Gasoline engines produce their best brake-specific fuel consumption numbers when with WOT and an operating speed at/near the RPM at which the engine makes peak torque.

Another trick you can do is to coast down hills, accelerate hard while going up them. That way, your vehicle gains potential energy efficiently because it is WOT. It is more useful to go WOT while up hill, because you gain potential energy without encountering a large amount of wind drag. You can start at the bottom of the hill at 40mph, floor it until you are going 60mph, and then coast for a mile or so down the other side of the hill without a high peak velocity that would cause much wind drag losses.

The most efficient an engine will be is based on its bsfc chart also. For my 1.6L Honda it was 75-80% throttle from 1700-2200. You should look up what your vehicle likes. For it being automatic I'm sure whatever rpm your torque converter fully locks up then add some throttle to match up rpm/g/s fuel consumption to output to get the most efficient rate of speeding up.

Another way to reduce pumping losses is by carefully increasing the EGR rate (for engines with external EGR) at part load so that a larger throttle opening can be used for a given torque output. Cooling the EGR with a water-cooled heat exchanger works better because reduces heating of the intake charge (most modern diesels have EGR coolers). This is part of what Toyota did (along with Atkinson Cycle) in order to achieve 40% brake thermal efficiency on the new 2018 2.5L non-HEV version of the Camry, but the basic idea has been well known for years. It also changes combustion phasing, so having access to reflash the ECU to change spark timing is essential. At very light loads, residual can also be increased by changing valve overlap on engines with VVT and can also reduce pumping losses, but it also increases charge temperature. Some versions of VTEC should allow you to do this.

Nowadays I'd rather try to work on the valve overlap in an engine fitted with VVT instead of dealing with an external EGR.

VVT works well at light load conditions. At higher loads, you need the ability to cool the EGR and there is no way to do that except with an external EGR loop. The Prius has done this for the last 2 generations and it is becoming more common. It is particularly helpful for part-load knock mitigation with boosted engines or engines running Miller Cycle.

I have a challenge to you guys for my *serious-idea about reducing pumping losses.

Ok, it's not complicated.

Has anyone added a valve or multiple breather valves to their spark plugs ?

How this would work is that compressed air could escape out of the breather valve of the spark plug when open and not when closed.

It would be cheap to add : three drilled holes ? solenoids ? tiny-valve-stems ?

As well as being non-invasive to the engine.

Comments ?

Sounds good in theory.

But adding aome of those piezo valves could give you programmable valves.


Two things i am not sure of with your idea:

First will the holes provide enough flow?
Second, would fuel and air not enter with the compression stroke and potentially burn up your solenoid?

Not sure yet. But air compresses easily and I'm thinking how pin-hole size (0.5 - 2mm ?) pressure relief valves could relieve pressure.

I know my cylinders get to 160psi with a compression tester.

If I concentrated I could probably calculate [ie find on google] how much air can flow through 3x 2mm diameter holes at say 1200 rpm.

I was only thinking of using this as part of cylinder deactivation when no fuel was being combusted. So when fuel was applied to the cylinders, the valves would close.

But arent your solenoids outside thr combustion chamber?

I'd rather try something all-mechanical (though it could be servo-actuated and fully-integrated to the cylinder deactivation), operating in the opposite principle of a Jake-Brake.

That's what I was thinking.

It would be a mechanical valve, but having some type of hydraulic/electrical actuator to control the valves. Which would look like standard inlet or exhaust valves only on a much smaller scale.

Maybe such valves are already being made for r/c planes or small engines.

The actuator/control-mechanism would obviously be on top of the plug.

Alternatively you could retard your inlet cam under light loads, reducing the pumping losses by having two 25mm holes in the top of the head until the piston is half way up the bore. On many engines no extra hardware would be needed and you wouldn't have the engine management hassles brought about my having metered air being vented.