The Petrol Engine - A New dawn ?

[Peterwl]

Will Mazda perfect and corner this new technology ( from an older idea ) for petrol engines.

https://www.youtube.com/watch?v=WBkfOUaEcWM

[Stefan]

I find that Jeremy Clarkson wannabe so damn annoying.

Cool tech though...reliability will be the challenge I guess.

[Bossxr8]

Other manufacturers have been working on this for the best part of a decade. Won't be long and they will put it into production too.

[comfortablynumb]

That poor old ecu is going to be working overtime, keeping up with all the parameters necessary for compression detonation. Given our massive variability in fuel quality as well as all the other inputs.

[Crazy Dazz]

Like a lot of things, its hard to get past the bull****, to actually understand what they are innovating.
I suspect that (contrary to that youtube flogger) it is probably the exact opposite to what he claims.
The problem with petrol engines has always been STOPPING compression ignition, and Mazda have made great inroads in their ability to increase the compression ratio whilst avoiding detonation. But that required direct injection, which has its own drawbacks.
My understanding is that they have now taken their technology one step further, so they can use port-injection (with much better mixing) but still with high compression, and somehow control the ignition point.

Its also a little misleading, because they still use a spark-plug, so its not ONLY compression ignition.

[yearby]

What a whole lot of big cow droppings.

Is that the best that Mazda engineers can come up with, must be trying to convince the Mazda been counters their jobs are worth keeping
All smoke and mirrors.

[ebv8]

there are so many things ready for production, we just have to wait for the car companies to need to use it before they introduce it

like electrically assisted turbos that spool the turbo at low speeds and gain energy from braking and reduce load on the engine
electriclly operated valves, no need for a valve train it will be all computer controlled
ultra high compression that can be adjusted by valves (like the HCCI)

the car companies just don't need these thing in production yet until either euro 7 comes out or the diesel fad ends

i don't think it will be long before a petrol engine can match or better the fuel consumption of a diesel

[Crazy Dazz]

Originally Posted by ebv8

there are so many things ready for production, we just have to wait for the car companies to need to use it before they introduce it

like electrically assisted turbos that spool the turbo at low speeds and gain energy from braking and reduce load on the engine
electriclly operated valves, no need for a valve train it will be all computer controlled
ultra high compression that can be adjusted by valves (like the HCCI)

the car companies just don't need these thing in production yet until either euro 7 comes out or the diesel fad ends

i don't think it will be long before a petrol engine can match or better the fuel consumption of a diesel

"Free Valve" technology holds a lot of promise if they can make it work, and do it in a way that requires less "power" than a cam shaft. Just imagine the tuning opportunities! Your entire "cam profile" reprogramable at will.

It could also give a completely new lease of life to diesel technology.
But the problem with diesels remains the emissions. Modern engine management works so well with the Cat, that emissions can be precisely tuned. Diesel just doesn't allow that. It alternates between extremes.

[XP6]

Try this video for an explanation without the Autoexpert nong, https://youtu.be/9KhzMGbQXmY

[yearby]

Originally Posted by XP6

Try this video for an explanation without the Autoexpert nong, https://youtu.be/9KhzMGbQXmY

Yes, I seen this explanation before, I don't see anything plausible about it.
Let's pick it to pieces.

If you increase the compression ratio with a homogeneous mixture, the increased pressure is going to force the Nitrogen atoms to combine with Oxygen to form the Nitrogen Oxides, thus an endothermic reaction.

If the engine is run leaner, this will increase the Nitrogen Oxide emissions, thus preventing the Hydrocarbons combining with the Oxygen to produce heat.

Okay, lets say the oxygen does not combine with the Nitrogen, let's say a fuel mixture is burn in an oxygen rich environment (fuel lean mixture). This is a kin to saying, hit the oxy trigger on my oxy cutting torch. If I was to calculate the temperature of the centre of the internal combustion burn at stoichiometric it would be about 3000deg C. As to an idea of what this temperature can do, aluminium melts at 660.3deg C, Goodbye pistons. The melting point of Iron is 1538deg C. Nitrogen oxides start to form about 2000deg C, ( I think).

Now the reason the spark ignition internal combustion engine doesn't melt is because there is a layer of un-combusted mixture between the flame front and the walls of the camber preventing heat transfer to the cylinder walls, piston etc.

If we now ignite this un-burnt mixture with combustion ignite, it will now transfer the full scope of the combusted temperature to the cylinder walls, piston etc.

The diesel engine is different.

Now to address the high combustion temperature, mass has to be injected into the combustion chamber, this will lower the temperature and raise the pressure, thus preventing nitrogen oxides, and enable the hydrocarbons to combine with the oxygen to produce heat. The most primitive way was water injection, but by far the common form is use of the exhaust gas via the EGR valve.

But increasing mass into the combustion chamber reduces the ability for the engine to combustion ignite, so the compression ratio has to be increased. But as the compression ratio is increased so does the Nitrogen oxides and separation of the homogeneous mixture. So more exhaust gas is injected into the engine which in turn reduces the possibility of combustion ignition. So the compression ratio will need to be increase again, which in turn produces more Nitrogen Oxide's. So on and so it goes with increasingly more design problems.

This is not the way to build an engine.

When some one comes to you with a break through idea, it should be simple, it should be elegant. You should be able to say WOW! that brilliant.
This concept is confusing, cloudy, and it definitely is not a simple or elegant proposal.

The only good idea is to reduce compression ratio while at the same time increasing the expansion rate of the combustion camber, there is big gains to be made in fuel efficiency here.

Peter

[willeng]

Hi Guys,

I found that video interesting.

Much is to be said about new technology, especially considering how inefficient the internal combustion engine really is. When you think about it things have not really come that far in over one hundred years & efficiency is the big concern.

I have built performance engines for over 30 years & the losses due the temperature differential of the intake & the exhaust, friction & pumping losses etc are what kills these engines.
You don't have to be Einstein to realise that it's where the PCP is, is what really determines the power output per X amount of fuel.
So maybe Mazda just might be looking in the right area to be honest depending on where there PCP is of course.

Going by what they said about injecting high pressure air may suggest they are in fact controlling the PCP for better power output?
Or maybe prolonging the PCP for a greater power output?

The suggestion of a Spark Plug as well may indicate that they may have unburnt fuel remaining after combustion so they inject air & fire it again with the spark plug, this would prolong the PCP making for greater output & a more efficient burn of there fuel.

Cheers

[yearby]

willeng

Remind me what does "PCP" stand for?

Peter

[willeng]

Hi yearby,

Peak Cylinder Pressure

Cheers

[yearby]

Originally Posted by willeng

the losses due the temperature differential of the intake & the exhaust,

If you reduce the volumetric efficiency of the engine and increase the expansion volume the temperature differential tends towards the same for each port.

That is if you decrease volume efficiency by say 20% and increase the expansion volume by say 20%, the exhaust temperature will drop dramatically. So does the exhaust noise, it will become very quiet.
If you was to pursue this idea it is possible to get the exhaust so quiet as that the muffler can be deleted.

By doing this it is feasible to get a 30% increase in fuel economy.

It is not suited to an racing application where all out power is a must, but is very suited to a road going vehicle where fuel economy is of concern.

Okay, by dropping the 20% in volumetric efficiency, the power and torque curves are going to take a big hit in performance, so to compensate start the engine build by choosing a 20% bigger engine.

An analogy is needed here-

Say we hypothetically build 2 engines with identical torque and power curves.
One a small 4 cylinder with high volumetric efficiency, ie turbo charged.
The other a largish V8 with low volumetric efficiency and high expansion volume.

The larger V8 (even thou it is heavier) will have far superior fuel economy for the same torque and power.

In a round about way, this sort of what Mazda is doing when they delay the inlet valve opening to reduce volumetric efficiency.

Peter

[yearby]

Originally Posted by willeng

Hi yearby,

Peak Cylinder Pressure

Cheers

Thanks

Peter

[yearby]

I forgot to say, that when you reduce the Volumetric efficiency, you will need to also increase the mechanical compression ratio to compensate for the lower peak cylinder pressures.

Peter

[ivorya]

So, Mazda 'May' have increased compression to 15:1 to 16:1..... whats so new??

Motorcycle engines have been around that for a while now. Ducati's new bike engine is 16:1.
Question is, why haven't car manufacturers done it earlier?? and Will it make that much of a REAL world difference?

[solarite_guy]

Actually, is not simply a matter of going 16:1.

There are a couple things we know. The engine switches between spark ignition and compression ignition (even though it is petrol fueled).

Also we know a high pressure air injection is used.

Other things we can only speculate on. What determines the switch between spark and compression ignition? How is this managed?

When exactly is the air injection employed? Speculation might lead one to believe during the combustion process. Is it used during both spark and compression ignition? At what point during the combustion process? What is the effect on burn efficiency and the cylinder pressure curve? Does this affect fuel requirements?

Just a couple thoughts.

[yearby]

Originally Posted by ivorya

So, Mazda 'May' have increased compression to 15:1 to 16:1..... whats so new??

Motorcycle engines have been around that for a while now. Ducati's new bike engine is 16:1.
Question is, why haven't car manufacturers done it earlier?? and Will it make that much of a REAL world difference?

What Mazda is trying to do is increase efficiency, that is increased power with less fuel usage.

First is, they are trying to burn all the fuel in the chamber on the power stroke instead of letting some of the fuel burn on the exhaust stroke.
When the remanet's of the unburnt fuel air mixture remain in the chamber after the power stroke, it burns pressurising the piston in such a way as to try and force the piston in reverse direction to the crankshaft rotation. Thereby the engine losses power.

An hypothetical example-

Take the exhaust manifold off an engine such that it is possible to see the exhaust valves in the exhaust ports. Run the engine and it is possible to see a flame shoot out the exhaust port. This is un-burn fuel burning on the exhaust stroke pressurising the piston and the exhaust port.

If the Ducati engine had mastered this it would be a quiet engine with no need for a muffler.

When Mazda states that they are running 18:1 compression ratio for economy, they are not really compressing the mixture at 18:1. That is just the mechanical compression ratio. The reality is that their engine is running under low Volumetric efficiency and then compressing it at 18 to 1. In other words the actual compressed ratio maybe only say 10:1, but the mechanical compression ratio is 18:1. They do this by restricting inlet charge.
By letting the burnt gas expand more with a greater expansion volume releases more energy into crankshaft motion.

The Ducati needs the 16:1 compression ratio for a different reason. Being a bike engine, it will make high horsepower by use of high rev's.
When building a engine for high rev's, the flame travel across the combustion chamber is too slow at 9:1, to increase the speed of the flame travel, what you do is increase the compression ratio.

What difference will all this make?
If Mazda can make their engines run with the 18:1 expansion ratio, I would say that their engine would be about 60% efficient instead of the normal 33.3% of your typical petrol engine.
This would mean that your weekly fuel bill will be halved, that the green house emissions from petrol engines would be halved. Diesel engines would be replaced by this new design of petrol engine. And the electric vehicle will now have some very serious competition.

Now I like what Mazda is trying to do, but to me it is all wrong. Some of the thing that have been said, or released are nothing but cock and bull.

Peter

[willeng]

Hi Guys,

Not sure about the low VE comment, think about it, what does it take for 95 or 98 Octane fuel to work in a CI engine.
High Temperature & High Pressure, more than diesel, our fuels to date are based on avoiding self ignition so to create this on purpose we have to have high compression rates to increase temp & high pressure in the chamber.

Also think about a Stratified charge & what this really is, you hear a lot of comments with people thinking this is due to fuel being injected.
A Stratified Charge is the way the fuel charge is richer in the chamber & leaner in layers say as it goes down this is what we try to create by introducing swirl into the chamber.

They must be controlling the PCP as suggested or else you will only end up with broken pistons or bent rods if not controlled?

Cheers

[solarite_guy]

Interesting point.

When we were running Yates heads, we started off with with a Don Losito/UPM CNC port. Then we had our own mod to specifically increase swirl. This didn't always increase flow but it would always increase power.

[b0son]

Originally Posted by yearby

When some one comes to you with a break through idea, it should be simple, it should be elegant. You should be able to say WOW! that brilliant.

Why? F1 engine tech is hardly elegant, but judging by the thermal efficiency they're achieving, its hard to argue it isn't effective.

[yearby]

Originally Posted by b0son

Why? F1 engine tech is hardly elegant, but judging by the thermal efficiency they're achieving, its hard to argue it isn't effective.

The original idea was simple, the F1 engine is just further development of a very early elegant idea.

In 1794 Robert Street patented an internal combustion engine, it was this original idea that the internal combustion engine became what it is today.
He did not just go out and say " today I will build an F1 engine)

[malazn mafia]

China has just signed a treaty to eliminate internal combustion engines by a certain year. This could spell the death warrant for the good old internal combustion engine...

[yearby]

Originally Posted by malazn mafia

China has just signed a treaty to eliminate internal combustion engines by a certain year. This could spell the death warrant for the good old internal combustion engine...

Yeah! I seen that, guess it had to happen.