Porsche working on variable compression engine design

[spectras only]

As if today's engines aren't complicated already, Porsche makes it even more so

http://www.enginelabs.com/news/porsche-working-on-variable-compression-connecting-rod/

[video=youtube;ABNZY3Enykg]https://www.youtube.com/watch?v=ABNZY3Enykg[/video]

 

[RiverDave]

Pretty cool idea!!

I would think it would be easier to just have the piston be high compression, and then drop compression by valve timing?

RD

 

[spectras only]

Pretty cool idea!!

I would think it would be easier to just have the piston be high compression, and then drop compression by valve timing?

RD

Valve timing only alters where the powerband is, ie; VVT systems . Did you mean by opening valves releasing cylinder pressures? Not the same as static compression given in a cylinder.

 

[Bigbore500r]

Finally.....a thread exploring Dynamic vs Static compression in the lounge
:thumbsup

 

[spectras only]

Older two stroke r/c aircraft engines had a moving puck where you could adjust compression ratio by moving the puck down [ making it a diesel engine ] in the cylinder or raise it with the T handle screw after the engine fired up, like this concept here> Lotus once showed off a 2-stroke HCCI concept that used a movable puck in the cylinder head to increase or decrease the combustion-chamber volume.

 

[pronstar]

Pretty cool idea!!

I would think it would be easier to just have the piston be high compression, and then drop compression by valve timing?

RD

It's being done now, to a degree.

We have engines that can operate as Otto Cylce under some conditions, and Atkinson Cycle under other conditions, all by varying valve timing. Atkinson closes the intake valve very late on the compression stroke, reducing pumping loss while also introducing a very small fuel:air mix into the combustion chamber.

Also, with cooled EGR technology, you're effectively reducing combustion chamber volume by using inert exhaust gas to "take up space" inside the cylinder, while also reducing pumping loss.

 

[mjc]

Do you think with all these exotic parts these engines will ever last 200k miles like your basic SBC?

 

[wsuwrhr]

Do you think with all these exotic parts these engines will ever last 200k miles like your basic SBC?

Last? Missing the point I think, bad ass HP/cu is the goal. Figure out how to make it live afterwords.

Are you one of the guys complaining about having to go through a Fuel engine after every pass?

Brian

 

[RiverDave]

Valve timing only alters where the powerband is, ie; VVT systems . Did you mean by opening valves releasing cylinder pressures? Not the same as static compression given in a cylinder.

By delaying the opening of an intake valve you can reduce the amount of air ingested into a cylinder on the inhale stroke, or leaving it open longer on a compression stroke it pushes the air back out.. There's some play there in the exhaust side as well, but a lot less then intake.

I'm not sure how else you would word that other then valve "timing." I think you are reading what I said as "cam" timing, which is varying a set of parameters that is fixed on the intake / exhaust one direction or another.. That's not what I'm talking about.

RD

 

[mjc]

Last? Missing the point I think, bad ass HP/cu is the goal. Figure out how to make it live afterwords.

Are you one of the guys complaining about having to go through a Fuel engine after every pass?

Brian

Nope but in my car I want it to last as long as possible, I don't change cars very often.

 

[sirbob]

The hell with all the valve talk - that piston is really cool [emoji106]

As the rpm increases it changes the compression- great thinking at work

 

[AzGeo]

if the engine package is able to control detonation, pinging, pre-ignition, what ever you want to call it, when it's in high compression ? Maybe I want to run 87 gas in my $100K sports car ? Direct injection seems to be working quite well in some 'moderately high compression engines' today . Would not a 'computer controlled 3rd valve' be infinitely more adjustable ? I'm missing the point of "dragging the same parts around with less power" ? (strength and cost) IE: 3/8" rods in a 250 HP BB VS 7/16" rods in the performance models .

 

[OCMerrill]

Finally.....a thread exploring Dynamic vs Static compression in the lounge
:thumbsup

This will go over like the Plane on a treadmill. That deal really drew a line through RDP. LMAO.

 

[OCMerrill]

By delaying the opening of an intake valve you can reduce the amount of air ingested into a cylinder on the inhale stroke, or leaving it open longer on a compression stroke it pushes the air back out.. There's some play there in the exhaust side as well, but a lot less then intake.

I'm not sure how else you would word that other then valve "timing." I think you are reading what I said as "cam" timing, which is varying a set of parameters that is fixed on the intake / exhaust one direction or another.. That's not what I'm talking about.

RD

It's called a Miller Cycle Engine and Mazda has used that tech, for a while.

If you leave the intake valve open past BDC then you need a super charger to hold more pressure in the intake than your bleeding back.

Mazda Mellenia used this tech. It's worked well on constant RPM engines like a generator but not so well for Mazda.

 

[dribble]

By delaying the opening of an intake valve you can reduce the amount of air ingested into a cylinder on the inhale stroke, or leaving it open longer on a compression stroke it pushes the air back out.. There's some play there in the exhaust side as well, but a lot less then intake.

I'm not sure how else you would word that other then valve "timing." I think you are reading what I said as "cam" timing, which is varying a set of parameters that is fixed on the intake / exhaust one direction or another.. That's not what I'm talking about.

RD

What your referring to does not change a conceptual compression ratio like that connecting rod does. In an engine with a 10:1 compression ratio even if the valves were open for all 360 degrees the compression ratio would still be 10:1 there would just be no compression pressure. This changes the ratio while running which alters the squish or quench area. Altering valve timing can't do that. Pretty cool.

 

[wsuwrhr]

Nope but in my car I want it to last as long as possible, I don't change cars very often.

If an engine hoist is not your friend, then auto exotica might not be for you.

 

[shockwaveharry]

Looks kinda heavy to me... I could see Porsche using something like that on a future 2.0 turbo SUV. Bump compression for better throttle response off the line, then drop it for when the boost comes on. I don't think it'll make it to a 911TT though.

 

[pronstar]

It's called a Miller Cycle Engine and Mazda has used that tech, for a while.

If you leave the intake valve open past BDC then you need a super charger to hold more pressure in the intake than your bleeding back.

Mazda Mellenia used this tech. It's worked well on constant RPM engines like a generator but not so well for Mazda.

Miller Cycle is basically Atkinson Cycle with forced induction.

Lexus' new wide-range VVT can switch between conventional Otto cycle, and Atkinson cycle, on the same engine and on the fly, controlling it all via valve timing.
It's on a naturally-aspirated engine in the RFC, and also on the new 2.0T engine in the NX Turbo (effectively Miller Cycle though we call it Atkinson).

 

[AzGeo]

It's called a Miller Cycle Engine and Mazda has used that tech, for a while.

If you leave the intake valve open past BDC then you need a super charger to hold more pressure in the intake than your bleeding back.

Mazda Mellenia used this tech. It's worked well on constant RPM engines like a generator but not so well for Mazda.

What has worked for Mazda ? I read on the net, "top ten worst cars", "one of the cars you never buy used", etc . Mazda is always on the "loser lists" and pretty much everything they did with Ford years ago, isn't running today . "Let's make cars so exotic, expensive, and unreliable, that everyone will just end up taking the bus" . HA HA

 

[OCMerrill]

Miller Cycle is basically Atkinson Cycle with forced induction.

Lexus' new wide-range VVT can switch between conventional Otto cycle, and Atkinson cycle, on the same engine and on the fly, controlling it all via valve timing.
It's on a naturally-aspirated engine in the RFC, and also on the new 2.0T engine in the NX Turbo (effectively Miller Cycle though we call it Atkinson).

So now you know when I stopped reading Car and Driver. Right about 2006.

 

[Wicky]

I just want an engine that will split atoms...is that asking too much??

 

[pronstar]

What has worked for Mazda ? I read on the net, "top ten worst cars", "one of the cars you never buy used", etc . Mazda is always on the "loser lists" and pretty much everything they did with Ford years ago, isn't running today . "Let's make cars so exotic, expensive, and unreliable, that everyone will just end up taking the bus" . HA HA

I think they make great cars.
Car mags certainly like them as well.

Their problem is, no products that appeal to the masses.
Unless you're BMW, you can only ride the "sporty car" train for so long...

No matter what Mazda does, they can't gain market share.
That's because there's volume in vanilla - Camry, Accord, Fusion, Corolla, Civic, etc.
So consumer choice alone - low sales volume - shows that Mazda doesn't have anything with mass-market appeal.

 

[OLDRAAT]

Videos and photos do not show size comparision or lists bore to stroke, wonder what rod length is, rpm band?
One would think it would have to be on the smaller is due to what appears to be quite of bit of rotating mass.
Be nice to know the inside track on the principles and control of the damping sysem too.:thumbup:

OR

 

[elco]

[video=youtube;Bch5B23_pu0]https://www.youtube.com/watch?v=Bch5B23_pu0[/video]

 

[Bigbore500r]

What your referring to does not change a conceptual compression ratio like that connecting rod does. In an engine with a 10:1 compression ratio even if the valves were open for all 360 degrees the compression ratio would still be 10:1 there would just be no compression pressure. This changes the ratio while running which alters the squish or quench area. Altering valve timing can't do that. Pretty cool.

My 2 cents - which may or may not be worth 2 actual US issued pennies [emoji1]

Altering valve timing does change the "running compression" or better known as dynamic compression. This is why larger cams that result in later intake valve closing points require a higher static compression ratio. More of the compression created on the upward piston stroke is lost through the open intake valve as it is on its way closing against the valve seat. One way to combat this running compression loss Without raising the SCR is to advance the intake lobe of the cam, which closes the intake valve sooner and effectively narrows the lobe seperation angle. This builds more cylinder pressure and running compression. But....doing this makes the power band peakier, harder hitting and it will fall off sooner on the top end. To extend the powerband if needed as a result - an even larger intake duration is needed, which results in a later closing yet again....etc etc. You reach a point where drivability suffers due to overlap and the only cure is increasing the static compression ratio to get away from narrowing the LSA / advancing the cam any further. Its a vicious cycle........[emoji1]

VVT offers a partial solition, in that you can advance the cam (valve closing points) on the bottom end of the rpm range, then retard them on the top end to give back the rpm range that would have been lost if the cam was stuck in that advanced state.

Where a smooth idle is needed - A small intake duration cam can be "crutched" to carry power up into the upper rpm ranges, by fitting it with a very wide LSA and extending the exhaust duration for a wider split. This would be at the expense of low end torque and throttle response, unless the static compression ratio was increased to make up for the low DCR the combo would create. Perfect example is the C6 LS7 motor. 11.5:1 with a very small cam (for a 427) on a 118.5 LSA, almost a 20 degree split between intake and exhaust. Passes smog, 600rpm idle, 7000rpm redline.

 

[OLDRAAT]

Thanks for the info Big. :thumbup:

OR

 

[AzGeo]

you are talking about 'flow rates' and 'power bands', but the static compression does not change, only the 'volume used/not used and at what speed' . Why would a changing compression ratio be a benefit, even with VVT or ? Also, I would expect the compression to be higher at lower RPMs to create 'more torque to move the load', and lower compression at 'cruising speeds' were you have steady RPM/load use . This must be in anticipation of a very small, high RPM motor, otherwise, why bother .

 

[rivermobster]

This will go over like the Plane on a treadmill. That deal really drew a line through RDP. LMAO.

STFU you...

This thread has REAL potential!!!

 

[pronstar]

This must be in anticipation of a very small, high RPM motor, otherwise, why bother .

You're almost there...it's also to increase efficiency in a large, powerful motor.

 

[AzGeo]

You're almost there...it's also to increase efficiency in a large, powerful motor.

Please enlighten me on how this is going to "increase efficiency" in any 'gas/alcohol' engine .

 

[rivermobster]

BMW has had VVT since 2001 or so?

BMW also started sporting VVT combined with VVL (variable valve lift, no throttle body required anymore, other than the need for a redundant system and to build vacuum for accessories) since around 2012?

I remember going to training when I worked for BMW, many years ago now, and back then they were talking about a day where there will be no more cylinder heads. It will be a one piece block. Fully electric solenoids that will control the airflow into the engine cylinders. No more cams, no more valves, no more springs or lifters. They had a working model of it back then. I'm surprised its on the market yet.


Yesterday I spent the day at the SEMA garage. Its a Almost fully functional facility that will help after market companies engineer, design, build, showcase and market products for the future. The place was FUCKING amazing.

The are installing two MILLION dollars of dyno equipment. All for designers to get their products CARB complaint. Fully climate controlled chassis dyno cells.

One of the things I was blow away by was a ray gun looking thing, that you could point at any object. It would scan the object, and then their 3D printers will recreate the scanned object for you, so you can reverse engineer it.

The technology out there in the world today is absolutely amazing. There are things in the works today that we wont see for years, but will be mind boggling when they finally do make it to market.

https://www.semagarage.com/

:thumbsup:thumbsup

 

[pronstar]

Please enlighten me on how this is going to "increase efficiency" in any 'gas/alcohol' engine .

Varying valve timing certainly improves efficiency & power output.
Combined with reduced emissions and smoother operation, it's why nearly all engines for road use use it.

Low rpm/moderate load
Retard intake valve closing timing to reduce pumping losses and improve efficiency.
Or we can delay the opening until the piston is near the top of the compression stroke (Atkinson cycle), further reducing pumping loss and significantly increasing the expanion ratio.

Low rpm/high load
Advance intake valve closing timing to improve both efficiency and torque output.

High rpm/high load
Retard the intake valve closing timing to improve both efficiency and torque output.

...that's just for the intake valves.
Exhaust valve timing also pays dividends.

 

[AzGeo]

What about the original question I keep asking and everyone keeps going back to valve timing ? How does this 'variable compression piston/rod' improve efficiency and or useable performance ?

 

[rivermobster]

What about the original question I keep asking and everyone keeps going back to valve timing ? How does this 'variable compression piston/rod' improve efficiency and or useable performance ?

Variable compression would be a most useful tool on a boosted engine. Fuel consumption could be reduced while offering good power by running a high compression ratio during low loads. Engine response would also be improved in this scenario as turbo lag would be holding back power potential. When boost is needed and cylinder pressures increase, the compression ratio could be lowered to reduce the chance of detonation. Variable compression could also be useful in flex-fuel engines, running a high compression with E85 and lower compression with gasoline.

No doubt exhaustive testing and validation will be required before such a system will be offered, but it?s an interesting idea that follows the current trend of increasing adjustability in an internal combustion engine.

Copy and paste from the link in the original post.: http://www.enginelabs.com/news/porsche-working-on-variable-compression-connecting-rod/

 

[zboater]

Gas engines are the steam engines of 100yrs ago. Electric motors is where it's at. Get with the program old timers.

 

[OCMerrill]

I remember going to training when I worked for BMW, many years ago now, and back then they were talking about a day where there will be no more cylinder heads. It will be a one piece block. Fully electric solenoids that will control the airflow into the engine cylinders. No more cams, no more valves, no more springs or lifters. They had a working model of it back then. I'm surprised its on the market yet.

:thumbsup:thumbsup

They haven't come out with it yet because they would loose a fortune with their fucking blown head gaskets and warped heads.:thumbsdown

 

[AzGeo]

Variable compression would be a most useful tool on a boosted engine. Fuel consumption could be reduced while offering good power by running a high compression ratio during low loads. Engine response would also be improved in this scenario as turbo lag would be holding back power potential. When boost is needed and cylinder pressures increase, the compression ratio could be lowered to reduce the chance of detonation. Variable compression could also be useful in flex-fuel engines, running a high compression with E85 and lower compression with gasoline.

No doubt exhaustive testing and validation will be required before such a system will be offered, but it?s an interesting idea that follows the current trend of increasing adjustability in an internal combustion engine.

Copy and paste from the link in the original post.: http://www.enginelabs.com/news/porsche-working-on-variable-compression-connecting-rod/

BUT it states 'a most useful tool' in boosted engines, but does not state that IT IS 'more efficient in any way' . Many companies may be working on any number of unusual 'mechanisms' , and I would state again that if this 'static compression change' were actually needed, it would be better suited as a 'third valve' (adding chamber volume for a turbo/blower) or another method within the cylinder head, and NOT in the rotating mass . Ford is controlling 'turbo lag' and 'poor fuels' with great success, while delivering saleable fuel economy and power . When 'boosted gas/alcohol engines' reduce static compression ratios to gain 'volume of air/fuel flow', that greater volume always comes at a loss of MPG, at near or equal power output levels . Looking at the given diagrams of this piston and rod, I'm reminded of the 'Rhodes Lifters' . There may be another/secondary 'pressurized oil system' to control it's functions, but doing this in the rotating mass seems expensive and unrequired .

 

[DaveH]

think of it this way...while you are altering CR......think of it more as changing the volume of the combustion chamber.....

the reason this is a big deal is because there is friction and "pumping losses" in an engine when there is vacuum in the cylinder due to a closed throttle. OEM's currently use EGR as a way to minimize these losses so the cylinder doesn't have to "suck" against a closed throttle. the simply replace some of the volume of the cylinder with post combustion exhaust to essentially decrease cylinder size...which has the effect of increasing efficiency.

an easier way to grasp it is almost like a variable displacement engine...small engines are more fuel efficientl, but cant make big power. this is an attempt to have the best of both worlds.

 

[AzGeo]

Was it back in the 90's or the early 2000's that BMW actually stopped using 'flat tappet cams' and went with 'hydraulic lifters' like the civilized world ? If that is not the point, then what are "BMW's self adjusting valves ?" Hello, many US brands had 'self adjusting valves' back in the 1950's, and some in the 1970's went to 'exhaust valve rotators', for the heat of crappy gas and valve materials . I am amazed at the advancements in automotive design (by so many world wide) since the 70's, but as they get more complicated and expensive, to what point ? Does anyone here remember, three on the tree, radio delete, crank up windows, and rubber floor mats ? I really like discussing different points on here, with people who know what's going on, and have a view to offer . I may not always agree, but I'm always ready to learn .

 

[Sleek-Jet]

I owned a 1995 525i that had VANOS on the exhaust side, it had hydraulic followers as well.

 

[rivermobster]

Was it back in the 90's or the early 2000's that BMW actually stopped using 'flat tappet cams' and went with 'hydraulic lifters' like the civilized world ? If that is not the point, then what are "BMW's self adjusting valves ?" Hello, many US brands had 'self adjusting valves' back in the 1950's, and some in the 1970's went to 'exhaust valve rotators', for the heat of crappy gas and valve materials . I am amazed at the advancements in automotive design (by so many world wide) since the 70's, but as they get more complicated and expensive, to what point ? Does anyone here remember, three on the tree, radio delete, crank up windows, and rubber floor mats ? I really like discussing different points on here, with people who know what's going on, and have a view to offer . I may not always agree, but I'm always ready to learn .

The "point" in most cases is emissions standards. This shit is shoved down the manufacturers throats, and the do what they have to to deal with it.

The other half of this equation is CAFE standards. Ever manufacturer has to meet an overall MPG goal, or pay a ridiculous "gas guzzler" tax.

The manufacturers are not playing this game because they want to, they play because they HAVE to!!! At least in this country anyway.

The flip side of the coin is huge performance gains due to the massive R&D being performed.

In the end, it all benefit us as consumers, as long as you are willing to pay the price (of a new high end performance car).

If not, that's how guys like me make a living by restoring all the old pre smog cars.

It all works for me either way. [emoji6]

 

[AzGeo]

think of it this way...while you are altering CR......think of it more as changing the volume of the combustion chamber.....

the reason this is a big deal is because there is friction and "pumping losses" in an engine when there is vacuum in the cylinder due to a closed throttle. OEM's currently use EGR as a way to minimize these losses so the cylinder doesn't have to "suck" against a closed throttle. the simply replace some of the volume of the cylinder with post combustion exhaust to essentially decrease cylinder size...which has the effect of increasing efficiency.

an easier way to grasp it is almost like a variable displacement engine...small engines are more fuel efficientl, but cant make big power. this is an attempt to have the best of both worlds.

OK, the throttle is closed, it should have high vacuum . EGR is mostly used at 'part to WOT', and it's effectiveness in cylinder temp controls is under load . If the use of EGR during closed throttle operation is used for anything, it's to stop the motor from 'sucking oil past the rings and the valve guides', but your point brings back one of your first statements . What kind of "pumping losses" are there in a motor while it is at closed throttle (at idle or) and decelerating ? These factors are what makes the engine 'slow back down to idle' . When the TPS sees closed throttle and the MAP sees high vacuum, the ECM reduces the injector pulses to a minimal amount (along with the pressure regulator dropping fuel pressure) and the motor slows down . What 'pumping losses' are happening here, there is no or minimal load ? Also, please explain "the simply replace some of the volume of the cylinder with post combustion exhaust to essentially decrease cylinder size....which has the effect of increasing efficiency . " WTF ? EGR is cooling and smog, totally the opposite of efficiency . Please list true racing engines that use EGR . I also disagree with your statement about "small engines are more fuel efficient", size and efficiency have NO direct correlation . "Pumping losses" would be when the static compression ratio is so high that at 'open throttle load or WOT conditions', the "force required to create the compression ratio desired, reduces the overall effective output of power being generated overall" .

 

[AzGeo]

The "point" in most cases is emissions standards. This shit is shoved down the manufacturers throats, and the do what they have to to deal with it.

The other half of this equation is CAFE standards. Ever manufacturer has to meet an overall MPG goal, or pay a ridiculous "gas guzzler" tax.

The manufacturers are not playing this game because they want to, they play because they HAVE to!!! At least in this country anyway.

The flip side of the coin is huge performance gains due to the massive R&D being performed.

In the end, it all benefit us as consumers, as long as you are willing to pay the price (of a new high end performance car).

If not, that's how guys like me make a living by restoring all the old pre smog cars.

It all works for me either way. [emoji6]

"self adjusting valves" ! What year did BMW go from 'flat tappet, to hydraulic' that's all . I took the TV ad as being "we at BMW are now joining the hydraulic lifter group, 40 years after the fact, and you should all be amazed by it" . Right or wrong ? I don't care either way, I'd just like to know the year .

 

[rivermobster]

"self adjusting valves" ! What year did BMW go from 'flat tappet, to hydraulic' that's all . I took the TV ad as being "we at BMW are now joining the hydraulic lifter group, 40 years after the fact, and you should all be amazed by it" . Right or wrong ? I don't care either way, I'd just like to know the year .

Ziggy might know. Honestly I don't remember.

It also depends on the car...

The M3 had adjustable valves long after the rest of the fleet was not.

Too long ago for me to remember. [emoji12]

GM is still building dinosaur push rod engines, and calling em high tech!

Lipstick on a pig. It's all in the marketing.

[emoji106]

 

[AzGeo]

I just thought it was 'really funny' HA HA, that BMW would brag about finally getting into hydraulic lifters, like their core buyers didn't know . Sure everyone makes "jewels and pigs", it's all about the Benjamin's . It is interesting that GM has built 'a number of cammers' and still sticks with "old shit", but always comes back with "better old shit" . Viable MPGs for the power, reliability, minimal maintenance, good handling, all the perks, and resale . People rent and lease Ford, etc, while everyone else buys GM and drives them for many years . Restoration is a good business to be in when you just can't tolerate the 'waste of talent ' in mass production .

 

[pronstar]

No racing engines use EGR, because they aren't worried about emissions or efficiency.

Current BMW's, and some Infiniti's, don't even use traditional throttles. They regulate airflow using intake valve timing and lift alone.

We're at the point where massive investment to realize minimal gains are what's left, as all of the "low hanging fruit" of easy gains are already being used.

A carmaker will spend cubic dollars to eek out a 2% efficiency gain, all to meet .gov CAFE standards.

 

[DaveH]

OK, the throttle is closed, it should have high vacuum . EGR is mostly used at 'part to WOT', and it's effectiveness in cylinder temp controls is under load .

while some EGR systems use coolers....pumping high temperature exhaust into the cylinder would have the opposite effect.

If the use of EGR during closed throttle operation is used for anything, it's to stop the motor from 'sucking oil past the rings and the valve guides', but your point brings back one of your first statements . What kind of "pumping losses" are there in a motor while it is at closed throttle (at idle or) and decelerating ?

it takes fuel to keep a motor running, unless at high engine RPM with a closed throttle (coasting down a hill in a low gear for example) where the rotating inertia of the rotating assembly will slowly diminish rather than rapidly. so any loss or friction that can be reduced means the engine can operate by making less power and reduce fuel consumption and emissions.


These factors are what makes the engine 'slow back down to idle' . When the TPS sees closed throttle and the MAP sees high vacuum, the ECM reduces the injector pulses to a minimal amount (along with the pressure regulator dropping fuel pressure) and the motor slows down . What 'pumping losses' are happening here, there is no or minimal load ?

well the single largest factor is the fact that the engine is choked of air via the throttle body. again, there is friction in an engine that has to be overcome, even at idle, and the more vacuum the engine pulls, that is basically work the engine has to over come as well. it's kinda like those stupid water toys people used to squirt you with...you stick the end in the lake..and vacuum draws water in.....if the opening gets smaller, its takes more effort to draw the water in. the same thing happens when your engine is choked for air. by putting EGR into the cylinder and reducing the volume of the cylinder, the engine doesn't have to make as much power to over come that.

Also, please explain "the simply replace some of the volume of the cylinder with post combustion exhaust to essentially decrease cylinder size....which has the effect of increasing efficiency . " WTF ? EGR is cooling and smog, totally the opposite of efficiency .

using less fuel means more efficiency and less pollution. you achieve this with a smaller engine compared to a larger one.


Please list true racing engines that use EGR .

racing enignes are not emissions or CAFE standards compliant. they care about power. i can't think of any racing application for EGR.


I also disagree with your statement about "small engines are more fuel efficient", size and efficiency have NO direct correlation . "Pumping losses" would be when the static compression ratio is so high that at 'open throttle load or WOT conditions', the "force required to create the compression ratio desired, reduces the overall effective output of power being generated overall" .

look up BSFC (brake specific fuel consumption). if there wasnt and advantage to a smaller egines efficiency...then one size should fit all right? why would the OEM's design other engines for smaller cars when they could just shove a v8 in there and electronically limit power output to keep the thing safe and driveable?

 

[Racing97]

Although I have never been a fan of Porsche Motorsports based on the folks I new in the organization I do hold their technology in high esteem. The Le Mans records are supposed to fall this year due to the 919 Porsche's power a little of this is explained in this link.
Wow how would you like to sit right next to a voltage source that can create 400 HP that my friends takes a bit of courage on it own.
http://gas2.org/2014/03/09/porsche-919-hybrid-racer-explained-15-photos/
reagards

 

[AzGeo]

OK, the throttle is closed, it should have high vacuum . EGR is mostly used at 'part to WOT', and it's effectiveness in cylinder temp controls is under load .

while some EGR systems use coolers....pumping high temperature exhaust into the cylinder would have the opposite effect.
No it does not, it displaces A/F which reduces the flame travel and reduces heat .
If the use of EGR during closed throttle operation is used for anything, it's to stop the motor from 'sucking oil past the rings and the valve guides', but your point brings back one of your first statements . What kind of "pumping losses" are there in a motor while it is at closed throttle (at idle or) and decelerating ?
IF EGR is used, most use it under light loads .
it takes fuel to keep a motor running, unless at high engine RPM with a closed throttle (coasting down a hill in a low gear for example) where the rotating inertia of the rotating assembly will slowly diminish rather than rapidly. so any loss or friction that can be reduced means the engine can operate by making less power and reduce fuel consumption and emissions.
What are you trying to say, above ? Deceleration is not controlled by EGR, the IAC controls engine slow down .

These factors are what makes the engine 'slow back down to idle' . When the TPS sees closed throttle and the MAP sees high vacuum, the ECM reduces the injector pulses to a minimal amount (along with the pressure regulator dropping fuel pressure) and the motor slows down . What 'pumping losses' are happening here, there is no or minimal load ?

well the single largest factor is the fact that the engine is choked of air via the throttle body. again, there is friction in an engine that has to be overcome, even at idle, and the more vacuum the engine pulls, that is basically work the engine has to over come as well. NOT WHEN THE THROTTLE IS CLOSED TRYING TO STOP/SLOW THE CAR . it's kinda like those stupid water toys people used to squirt you with...you stick the end in the lake..and vacuum draws water in.....if the opening gets smaller, its takes more effort to draw the water in. the same thing happens when your engine is choked for air. by putting EGR into the cylinder and reducing the volume of the cylinder, the engine doesn't have to make as much power to over come that. There is no "reducing of cylinder volume going on here at all, it's just "throttle body/IAC intake and or RGR recirculation" . The motor REMAINS 6.0 L or whatever it is . 6.0L IN and 6.0L out, like a compressor .

Also, please explain "the simply replace some of the volume of the cylinder with post combustion exhaust to essentially decrease cylinder size....which has the effect of increasing efficiency . " WTF ? EGR is cooling and smog, totally the opposite of efficiency .

using less fuel means more efficiency and less pollution. you achieve this with a smaller engine compared to a larger one.
Using less fuel and making substantially less power (poor engine design) is not efficiency, and I reject the thought of 'smaller is more efficient' it's just not true . True efficiency can be better measured in "wasted heat", "fuel use per output power", but not by size . YOU could have three 3.0 L gas engines, one with a 'one side flow' style cylinder head, the second with a 'cross flow' style cylinder head, and the third with a 'VVT, twin overhead cam' style cylinder head . I promise you than NONE of them will measure equally (all 3.0L !) for power output, performance, fuel economy, nor EFFICIENCY .

Please list true racing engines that use EGR .

racing enignes are not emissions or CAFE standards compliant. they care about power. i can't think of any racing application for EGR.
CORRECT, and EGR is never equated with efficiency . EGR, is to help smog engines not burn themselves up .

I also disagree with your statement about "small engines are more fuel efficient", size and efficiency have NO direct correlation . "Pumping losses" would be when the static compression ratio is so high that at 'open throttle load or WOT conditions', the "force required to create the compression ratio desired, reduces the overall effective output of power being generated overall" .

look up BSFC (brake specific fuel consumption). if there wasnt and advantage to a smaller egines efficiency...then one size should fit all right? why would the OEM's design other engines for smaller cars when they could just shove a v8 in there and electronically limit power output to keep the thing safe and driveable?

BSFC can be manipulated in the tune up, try BMEP for performance (how efficiently the engine is using the fuel to make it's power throughout it's powerband) . Why offer the 'simple minded statement about "one size should fit all" ? Efficiency is in the DESIGN of the engine/package, not it's size .

 

[AzGeo]

most of my responses got trapped within the quote bubble .