advanced engine technics

Many car engine manufactorers have many different approach to increase engine efficiency and maintain or even raise performance.
The main goals is to achieve the most perfect burning invironment, the least engine friction and the best possible termal efficiency.

The future is at piezo direct injection, solenoid intake and exhaust valves (rather than camshat), laser ignition (rather then spark plug) and of course electronic engine control.

Well piezo direct injection is allready the reality, laser ignition and solenoid valves will be reality from 5-8 years.

But at these point I will like to discuss about present technics.
VAG has FSI, which is solenoid/piezo direct injection engine with EGR and special intake plate so engine can operate under wery lean mixture at partial load.
BMW has valvetronic, whic is throttless engine, instead of it it has variabile camshaft timing and lift electronic control. The engine aslo comes with solenoid direct or manifold injection type.
Toyota, Honda uses VVTi, whic is also direct injection engine with variabile valve timing and lift electronic control.

There are also many more manufactorers with different tehnics.

But what is the essence of variabile valve timing and lift electronic control?
In simplification it is desire for valves to open later and shallower at low RPMs and sooner and deeper at high RPMs.

There are also some technics used to prevent swirling of the intake air in the intake system. If I am correct at low RPMs air travels at the longer tube that at high RPMs.

Turbos...
Many manufacorers proceed to small supercharged engines, because small engines use less fuel. These kind of engines have biturbo system - smaller for low RPMs and higher for high RPMs, so there are no turbo lag.

EGR..
this technic was used in the past only for diesels, but now all gasoline direct injection engines have it.
It is a bypass from exhaust manifold to intake manifold with electronic controled EGR valve and EGR cooler.
Engines before that used variabile valve timig and lift control to achiev EGR - exhaust valve didn't left all the exhaust gases out of the cylinder.

So do gasoline engines have all of these technics or just some of them?
(VAG's FSI for instance don't have variabile valve timing and lift control)
Why diesel engines don't have variabile valve timing and lift control?

diesels dont have valve timing controls because they do not have throttles, and are running at full throttle all the time.
they vary the power output by increasing or decreasing directly the ammount of fuel that enters the engine.

diesels also have direct injection, so that is another reason they are more efficient/ better.

i dont really get your questions though,
not all engines can have all the things you talk about.
besides, it is very expensive to produce those devices, so if every engine had them, there would hardly be any cars that you could buy for less than 40K

To my knowledge toyota and honda don't have direct injection.
Nissan does, they call it "Neo".

Exhaust gas recirculation is used to lower peak cylinder temperatures and reduce NOx formation.
I understand that the old method was to take it from the exhaust, and feed it to the intake. But the preferred method is to control the valve timing to the extent of retaining exhaust inside the cylinder when needed.

This requires very clever valve control, like the solenoids you mentioned (but I'm sure this isn't the only way).

Diesels don't need variable valve timing as much because their rev ranges are smaller and they don't have the rough idle problems that petrol engines suffer from with a more aggressive cam.

Intake manifold lengths are tuned to pulse charge cylinders (force more air in through natural resonance). Intake manifolds with variable lengths can make this happen through the rev range, rather than at specific points.

To my knowledge toyota and honda don't have direct injection.
Nissan does, they call it "Neo".



Honda do have a direct injection engine, used with VTEC in the new Logo/Jazz.
Although its Mitsubishi who have the edge with the technology, having had in use in cars for well over 10 years now.

Honda do have a direct injection engine, used with VTEC in the new Logo/Jazz.
Although its Mitsubishi who have the edge with the technology, having had in use in cars for well over 10 years now.

How new are we talking? My grandmothers jazz isn't even Vtec. It's a 2004 I think.

How new are we talking? My grandmothers jazz isn't even Vtec. It's a 2004 I think.


Since at least then, but of course its not in all of them.
I know there was a JDM version that used a super high efficiency engine, where Direct Injection was only one its many features. How many other markets the engine was released in I don't know, and I have no idea how many were sold in Japan along side less advanced models.
I would be willing to bet your grandmothers Jazz is VTEC, Honda haven't sold a non-VTEC car since the late 90s. They just don't always advertise it, and by 2004 its so advanced and subtle you don't notice its there.

Since at least then, but of course its not in all of them.
I know there was a JDM version that used a super high efficiency engine, where Direct Injection was only one its many features. How many other markets the engine was released in I don't know, and I have no idea how many were sold in Japan along side less advanced models.
I would be willing to bet your grandmothers Jazz is VTEC, Honda haven't sold a non-VTEC car since the late 90s. They just don't always advertise it, and by 2004 its so advanced and subtle you don't notice its there.

Found it, the DSI engines, NZ new it's a 1.3litre.
I'd also bet that the grandmothers jazz has variable valve timing. But for differing goals than the usual ricer VTEC, hence the lack of branding.

Even my 98 Nissan with a QG18DE has variable valve timing.

Honda also have different types of v-tec, differentiated by an i or e suffix if i recall. Might've changed since then though.

diesels dont have valve timing controls because they do not have throttles, and are running at full throttle all the time.
they vary the power output by increasing or decreasing directly the ammount of fuel that enters the engine.

you must be a very smart person to figure that out :screwy:


diesels also have direct injection, so that is another reason they are more efficient/ better.

diesel engines are more efficient because diesel fuel have more energy density, because pistons have longer stroke (better thermal efficiency), and because they run almost intire time at excess air and air is a good thermal isolator, so less heat is lost through cylinder walls. that's rougly it.


To my knowledge toyota and honda don't have direct injection.

of course they do!


Exhaust gas recirculation is used to lower peak cylinder temperatures and reduce NOx formation.

correct, but in gasoline engines it also enables the engine to operate at extra lean mixture when at idle or partial load.

I understand that the old method was to take it from the exhaust, and feed it to the intake. But the preferred method is to control the valve timing to the extent of retaining exhaust inside the cylinder when needed.

As I know diesel have bypass and control valve/plate as aslo the EGR cooler.
as for gasoline engines, only the small amount of EGR can be applied with valve timing and lift as internal temperature has to stayed low if we want to prevent fuel self-ignition.


This requires very clever valve control, like the solenoids you mentioned (but I'm sure this isn't the only way).

solenoid intake/exhaust valves are not yet in the use, they will be in the future


Diesels don't need variable valve timing as much because their rev ranges are smaller and they don't have the rough idle problems that petrol engines suffer from with a more aggressive cam.

as far as I understand the meaning of valve timing it can be explain with fluid dynamics. At low RPS we want the intake valve to open at the begining of the intake stroke, but at high RPS we want the intake valve to open sooner, because the air has its inertial resistance. so I don't really get the point why diesel engines won't have variabile valve timing control as it is the fact that more air than we forced into the cylinder more fuel we can apply. and at full load also the diesel engine runs at lambda<1 and that is the reason we see black smoke from the exhaust pipe.


Intake manifold lengths are tuned to pulse charge cylinders (force more air in through natural resonance). Intake manifolds with variable lengths can make
this happen through the rev range, rather than at specific points.

yes, and why don't engines have vaiable manifolds lengths as it is the cheapest technik to boost engines power.

and there are also more technics to boost internal engine efficiency...
mazda uses miller cylce engine (honda uses for its hybrid versions of cars), saab uses variable compression (SVC) in its 1.6 turbo gasoline engine.

diesel engines are more efficient because diesel fuel have more energy density, because pistons have longer stroke (better thermal efficiency), and because they run almost intire time at excess air and air is a good thermal isolator, so less heat is lost through cylinder walls. that's rougly it.

This is very wrong.
The energy density does not influence an engines efficiency, only it's fuel economy.
The two main reasons a diesel has better efficiency is the higher compression ratio (roughly double a petrol engine) which gives higher thermal efficiency and lack of a throttle plate which reduces pumping losses.


correct, but in gasoline engines it also enables the engine to operate at extra lean mixture when at idle or partial load.

EGR doesn't change the oxygen/fuel ratio, it simply dilutes the oxygen with inert, burnt gases. It does not make the engine run lean, although many engines with EGR also feature lean burn.


as far as I understand the meaning of valve timing it can be explain with fluid dynamics. At low RPS we want the intake valve to open at the begining of the intake stroke, but at high RPS we want the intake valve to open sooner, because the air has its inertial resistance. so I don't really get the point why diesel engines won't have variabile valve timing control as it is the fact that more air than we forced into the cylinder more fuel we can apply. and at full load also the diesel engine runs at lambda<1 and that is the reason we see black smoke from the exhaust pipe.

Variable valve timing is primarily a benefit on naturuall aspirated engines.
Some diesels do feature variable valve timing. But when you've got a turbo feeding up to 45psi into the inlet manifold, the benefits of variable vale timing are limited.
Diesel engines never run rich (greater than lamba 1), even at a smoke limit they are running lean.

Many production petrol engines do have variable length inlet manifolds, it's a mature technology.
But again it's only really useful on a naturally aspirated engine. The changes in density and temperature of the charge in a turbocharged engine alter the resonant frequencies too much and too often.

another reason you won't see vvt on many diesel engines is because the benefits of having more air in the cylender is much less because most of the diesels you see on the market aren't meant for performance so they won't want to burn extra fuel. the extra air in the cylender might give a very small increase in fuel economy at best.

another reason you won't see vvt on many diesel engines is because the benefits of having more air in the cylender is much less because most of the diesels you see on the market aren't meant for performance so they won't want to burn extra fuel. the extra air in the cylender might give a very small increase in fuel economy at best.

Only in America dude. The whole rest of the world is full of high performance diesels.

USA AND canada

anyways in those performance diesels how lean are they running?

we're finally starting to see some "sporty" diesels here, well we're finally starting to see ONE sporty diesel. the volkswagen 2.0TDI is apparently pretty fun to drive, i don't think there are many other diesel cars here with any kind of performance to them.

USA AND canada

anyways in those performance diesels how lean are they running?

we're finally starting to see some "sporty" diesels here, well we're finally starting to see ONE sporty diesel. the volkswagen 2.0TDI is apparently pretty fun to drive, i don't think there are many other diesel cars here with any kind of performance to them.

The modern diesels run from as lean as required to idle, up to just below the smoke limit. Modern diesels don't smoke.

Some of them are running serious boost, BMW's 3.0l diesel was running 42psi boost about 3 years ago. They've pushed power and torque up considerably since then.
Compound turbos are stock on several engines from Ford/PSA, mercedes and others.

i believe BMW are venturing into compound turbocharging too with a new (or at least updated) 3-litre diesel.

This is very wrong.


correct, please forgive me my big mistake.
I can see you have a lot of knowledge regarding internal combustion engine so I would like to discuss some more of my understanding the topic.

Well because fuel has became quite expensive (at least in Europe, it is a 2-3 times more expencive than in the States) and because people talk more and more about harmfulness of the CO2 (my personal opinion is that it's harmless to people and to the invironment as global warming is just natural process because of the changes in the Sun's heat radiation), Europe and Asia cars manufacturers try to make more fuel and environment friedly engines.

So almost all new diesel cars sold in the EU are turbocharged with variable geometry turbocharger and intercooler. Also many more new gasoline cars sold in EU have smaller engines, but to keep cars performance these kind of engines run at high boost pressure. But because gasoline exhaust gases are to hot to use VGT (like in the diesels), they have system with twin turbos or a supercharger and a turbocharger, so there is no turbo lag.

So if I summarize todays internal combustion engines technics:

DIESEL CYCLE:
Common rail piezo direct injection with pressure up to 2000 bar
Variable geometry turbocharger with intercooler
Exhaust gas recirculation bypass with EGR valve and EGR cooler
Oxidation catalyst converter with oxygen control plus NOx catalyst with NOx and temperature control and particulate fillter with pressure difference sensor control

OTTO CYLCE (Naturally aspirated)
Common rail piezo direct injection with pressure up to 200 bar
Spark ignition angle control
Variable valve timing and lift electronic control
Variable resonance induction system (with one or two plates)
Exhaust gas recirculation (with exhaust valve timing control – hydraulic or electric)
Three way catalyst converter with oxygen senor control and NOx catalys converter with NOx and temperature sensor control

OTTO CYLCE (turbocharged)
Common rail piezo direct injection with pressure up to 200 bar
Spark ignition angle control
Twin turbo or turbo+compressor
Exhaust gas recirculation (with exhaust valve timing control)
Three way catalyst converter with oxygen senor control and NOx catalyst converter with NOx amd temperature sensor control

The modern diesels run from as lean as required to idle, up to just below the smoke limit. Modern diesels don't smoke.

Some of them are running serious boost, BMW's 3.0l diesel was running 42psi boost about 3 years ago. They've pushed power and torque up considerably since then.
Compound turbos are stock on several engines from Ford/PSA, mercedes and others.
ok, i was thinking of diesel engines like those in our trucks that run so far from the smoke limit that increasing fuel delivery can add as much as 150hp to an otherwise stock engine. in that case the extra air wouldn't really do anything for power.

i believe BMW are venturing into compound turbocharging too with a new (or at least updated) 3-litre diesel.

It's been in production since about 2003.:grinyes:

Well because fuel has became quite expensive (at least in Europe, it is a 2-3 times more expencive than in the States) and because people talk more and more about harmfulness of the CO2 (my personal opinion is that it's harmless to people and to the invironment as global warming is just natural process because of the changes in the Sun's heat radiation), Europe and Asia cars manufacturers try to make more fuel and environment friedly engines.


The reason for the focus on CO2 emissions, is due to it being a direct result of fuel consumption.
Burning a litre of diesel creates about 16% more CO2 than burning a litre of petrol, but since diesel is much more than 16% more efficient, their CO2 emissions are lower.

The car and engine combination with the lowest CO2 emission will have the lowest fuel consumption.
Car makers in the past have bought in initiatives to reduce NOx emissions at the expense of increased CO2. I believe such a compromise was bought about by the high profile NOx problem of cities like Los Angeles.
But I also believe that NOx is less of a problem to the global environment than CO2 and the unnecessary burning of extra fossil fuels.

Your other statements I pretty much agree with. But there are a lot more that we don't know about.

ok, i was thinking of diesel engines like those in our trucks that run so far from the smoke limit that increasing fuel delivery can add as much as 150hp to an otherwise stock engine. in that case the extra air wouldn't really do anything for power.

That's the engines being derated so they'll last to the million km mark without major work. But there's also emissions controls in there, running a diesel with more excess air (and excess boost) gives lower in cylinder temps and less NOx.

And as you've mentioned, gives great scope for winding the power levels up.