Euro 5 on the doorstep Watercooled

Smogbob said:
From BMW Will

The concept is supported by the new digital engine control and an electronic fuel injector with an opening width of 52 mm and what are known as “two-jet injection valves”. The engine lubrication system was also optimised, and has an oil supply which is adapted to the riding condition and style and piston crown cooling with injection oil.
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Thanks
 
blueranger said:
Up to a point...then further excess air cools the combustion process at the expense of power...hence more Cc'd needed.
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That’s right. The point at which it becomes cooler is at 14.7:1, right where the engine spends most of its time. At 14.7:1 (+/- a bit) your engines exhaust gas is the hottest—in theory, all the fuel is consumed and all the oxygen is consumed, and you get a hot burn. When you richen the mixture, the unburned fuel cools the burn. If you add some air, that cools the burn too. So peak EGT occurs when your engine burns all the fuel and all the oxygen with none of either left over.

Our bmw motorcycle engines have been running at the same hot set point since the late 90s. The difference has been that as each new model is introduced, they expand the area where 14.7:1 is used to reduce emissions. Under high power though all our engines use a richer mixture.
 
If you keep adding air you also slow the burn so you want to hold the mix longer to extract as much energy as possible. Beyond that you are then just using the fuel to heat air...which helps to reduce NOx.

Emissions are measured as a % of the gas that passes the sensor not total volume of gas out of the exhaust.

Therefore more air down the exhaust dilutes the concentration of the emissions.

As such the volume of gas is greater and you have less time to get rid of it...hence larger exhausts which flow more freely.

https://images.app.goo.gl/m7bnkjFCA6F7ocDS6

Should add anyone who works in combustion outside of automotive will be very familiar with excess air because of the emissions benefits.
 
Finally....the change to liquid cooling was naff all to do with leaner running. It's purely a matter of oil/air can not remove the heat that 125bhp generates reliably in a variety of conditions.
 
Very informative stuff.

I think I’m right in saying euro 5 has stricter nox emissions. What effect does that have on fueling or will leaner running in a wider band naturally meet the new nox targets ?
 
Sorry to cut you down but your not correct at all.
Your statement implies that the change from the dohc hexheads power output to the LC included the AFR becoming leaner and thus generating more heat than oil cooling could provide. This is an incorrect assumption. See 2nd para post #45

Think about it....There is a reason the xr400r is air cooled yet a crf450r is water cooled....more power generates more heat even at a constant AFR.
 
blueranger said:
Sorry to cut you down but your not correct at all.
Your statement implies that the change from the dohc hexheads power output to the LC included the AFR becoming leaner and thus generating more heat than oil cooling could provide. This is an incorrect assumption. See 2nd para post #45

Think about it....There is a reason the xr400r is air cooled yet a crf450r is water cooled....more power generates more heat even at a constant AFR.
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Ohh well there you go :cool:
 
Delboy777 said:
Ohh well there you go :cool:
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In older more primitive fuelling systems and certainly those targeting peak power only ran/run at an AFR around 13.7 (I think) thus if it ran lean then you ran the risk of detonation and much higher combustion temps with the well known issues.

My 2000 ZX7R has larger main jets in the centre 2 pots than the outer despite being water cooled...precisely to reduce combustion temperature through mixture adjustment....

But that's old hat....It's an open loop with no feedback

The current closed loop with feedback systems are designed to operate at peak AFR already...so they can't really get that same issue however the AFR they do run at still leaves them at risk of detonation hence the knock sensors.
 
blueranger said:
In older more primitive fuelling systems and certainly those targeting peak power only ran/run at an AFR around 13.7 (I think) thus if it ran lean then you ran the risk of detonation and much higher combustion temps with the well known issues.

My 2000 ZX7R has larger main jets in the centre 2 pots than the outer despite being water cooled...precisely to reduce combustion temperature through mixture adjustment....

But that's old hat....It's an open loop with no feedback

The current closed loop with feedback systems are designed to operate at peak AFR already...so they can't really get that same issue however the AFR they do run at still leaves them at risk of detonation hence the knock sensors.
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Everyday is a learning day. Obviously you know what your on about im stricktly an amateur and not that good of one. Basic understanding thats about it. I wont post again unless im sure of what im posting. :):D
 
Whilst I'm a mechanical design engineer, automotive is far removed from my specialism. In my view these are the basics people should understand before they go dicking about bolting stuff onto their engines or get someone to frig their ecu's. Most of the stuff I know is from reading book's on engine tuning.
 
blueranger said:
Whilst I'm a mechanical design engineer, automotive is far removed from my specialism. In my view these are the basics people should understand before they go dicking about bolting stuff onto their engines or get someone to frig their ecu's.
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Amen to that, unless I knew and had seen something tested beyond a whisker of death, would not let it near my bike, most are safe here then as nothing was done to their ecu. :beerjug:
 
Getting back to E5...

This of course is pure speculation...

In theory the change to using a wideband o2 sensor means you get analogue feedback over a wide range as opposed to an too lean / okay / too rich type signal from a narrow band.

This allows you to instantaneously tweek injection pulse width to keep the AFR at optimum under all conditions.

Conversely, they could also use it to take the engine beyond 14.7:1 by adding excess air way beyond what's necessary to achieve complete hydrocarbon combustion...to give the effect I eluded to earlier if NOx is a problem.

In the graph I posted you can see that there is then a trade off between lowering concentration of emissions against fuel economy and power....which of course is counter productive.

The slower burn I eluded to could mean combustion takes place outside the cylinder which is of no use...This would obviously cause all sorts of issues.

One big balancing act.

It's like Gemi-gate all over again ..is there a magic value setting AFR that could be tweaked.
 
blueranger said:
Getting back to E5...

This of course is pure speculation...

In theory the change to using a wideband o2 sensor means you get analogue feedback over a wide range as opposed to an too lean / okay / too rich type signal from a narrow band.

This allows you to instantaneously tweek injection pulse width to keep the AFR at optimum under all conditions.

Conversely, they could also use it to take the engine beyond 14.7:1 by adding excess air way beyond what's necessary to achieve complete hydrocarbon combustion...to give the effect I eluded to earlier if NOx is a problem.

In the graph I posted you can see that there is then a trade off between lowering concentration of emissions against fuel economy and power....which of course is counter productive.

The slower burn I eluded to could mean combustion takes place outside the cylinder which is of no use...This would obviously cause all sorts of issues.

One big balancing act.

It's like Gemi-gate all over again ..is there a magic value setting AFR that could be tweaked.
Click to expand...

Reading and learning some very interesting info, I can understand some basic things, but got myself lost with Gemi-gate.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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