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Old 19th June 2007, 10:30   #1
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Default A New type of engine -> NEVIS Engine, 2x Fuel Economy, 2 Stroke 2 Cyl 1000 cc 250hp

Will not add any of my comments besides, hmmmm...interesting..

Enjoy

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The NEVIS (New Exhaust Valve & Intake System) engine embodies a new two-stroke combustion cycle (the “Bortone” cycle after its inventor) and a new design than combines, among other features, annular (i.e., doughnut-shaped) pistons, modular cylinder construction and a sinusoidal camshaft similar to those adopted in engines with cylinders arranged co-axially around the shaft.
Nevis1
A NEVIS module. Click to enlarge.

The company claims that the engine offers efficient combustion at all levels of power demands, and that it can nearly double the fuel efficiency obtained by conventional internal combustion engine technologies.

All the extra juicy details can be found here
Source
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Old 20th June 2007, 02:10   #2
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Wow 85 views and no reply on a complete redesign of how an engine works..??


If you cant get to the page: here is more of the overview:

Quote:
The NEVIS Engine Company Ltd. has successfully closed its first round of seed funding to help it further test and develop its current two-cylinder prototype engine as well as to develop awareness of the technology. The Italian company has been developing the prototype with €2.5 million (US$3.3 million) in government grant money.

The NEVIS (New Exhaust Valve & Intake System) engine embodies a new two-stroke combustion cycle (the “Bortone” cycle after its inventor) and a new design than combines, among other features, annular (i.e., doughnut-shaped) pistons, modular cylinder construction and a sinusoidal camshaft similar to those adopted in engines with cylinders arranged co-axially around the shaft.
Nevis1
A NEVIS module. Click to enlarge.

The company claims that the engine offers efficient combustion at all levels of power demands, and that it can nearly double the fuel efficiency obtained by conventional internal combustion engine technologies.

Although the NEVIS engine is lighter and smaller than a conventional ICE engine of comparable cylinder displacement, it offers more power, due in part, the company says, to the engine offering six times the number of power strokes per revolution than a traditional four-stroke engine.

The two-cylinder prototype was put through a bench test with engine ignition for the first time in Lecce, Italy in early 2006 as part of the review process by MUIR (Ministry of Education, University and Research) for the government grants that funded the development of the prototype.
First NEVIS prototype
Cylinders 2
Displacement 1,000 cc
Bore 80mm int., 178mm ext.
Power kW (hp) Est. 187 (250) @ 2,000rpm
Average piston velocity 7.5 m/sec
Engine block Steel/aluminum
Weight 80 kg
Power/Weight ratio (kW/kg) 2.38
Compression ratio 7:1 to 38:1
Injectors per cylinder 3
Sparkplugs per cylinder 3

This first test confirmed the correct functioning of the Bortone Cycle and the basic mechanical operation of the NEVIS engine. Preliminary testing without ignition also confirmed nearly 50% less friction/pumping resistance for an engine with a comparable displacement.

The five key design concepts of the engine are:

*

Obtaining optimized scavenging without the need for an additional turbine or compressor.
*

Development of a new two-stroke cycle that allows partial loads to have an expansion stroke greater than the compression stroke (like the Miller cycle in a four-stroke engine, but in a two-stroke cycle). Enabling that is a controlled annular exhaust valve that allows for variable duration and phasing of its opening.
*

The use of a sinusoidal camshaft to transform the alternate motion of the pistons into rotary motion. The shaft in the NEVIS provides the ability to complete three combustion cycles within a single shaft revolution.
*

A variable compression ratio made possible at all rpm and power loads by the regulation of an annular screw element within the shaft.
*

The use of annular pistons to enhance thermal efficiency, allow for a light structure, and to integrate the engine’s other key concepts.

Within all that, the principal innovation of the NEVIS engine, according to the company, is the system used to vary load needs.

The extended opening of the exhaust valve allows the piston to expel the air that has replaced the exhaust gases through the cleaning phase. The longer the valve stays open, the smaller the amount of air available for the combustion that follows, and as the compression ratio may be varied as desired, it is possible to have very small quantities of air charge. In other words, the load is reduced but not the efficiency of the engine that totally utilizes the expansion of the combustion with an expansion stroke that is inversely longer in relation to the load entity.

If the opening time of the exhaust valve is short and the air is prevented from flowing out of the exhaust duct, the compression ratio can turn back to the initial proportion and significant loads can be achieved, especially if the inertia of the air in the intake duct causes some supercharging. For the sake of efficiency, it is better not to run the engine under pressures that are too high as this requires greater depressions in the combustion chamber that can only be obtained using the kinetic energy of the exhaust gases which, flowing out at high velocity, cause depressions. The more these are intense and durable the higher the velocity and the quantity of the exhaust gases. Thus, anticipating the opening of the exhaust valve when there is still a certain pressure in the combustion chamber improves the filling process, but causes a loss of efficiency as expansion doesn’t take complete advantage of the pressure given by the combusted gases.

The NEVIS engine overcomes a number of issues with traditional two-stroke engines:

*

The increased size of the intake and exhaust ports enable higher flow.
*

The scavenging of the NEVIS engine differs from that of the traditional two-stroke and it can be compared to four-stroke efficiency. It can be complete at all rpm and at all loads with an optimal expulsion of all combustion residues due to the new cycle, to the particular unidirectional outflow and to the longer scavenging phase.
*

The variable lifting law of the exhaust valve and its regulating timing system, in combination with the new “loading” method, avoids the losses of any quantity of fuel at the end of the scavenging phase; in fact, the exhaust valve during this precise phase will always be closed. The NEVIS engine also provides a time for vaporization that is 2.6 times longer than in the normal two-stroke engine: this allows the use of direct injection operating with relatively modest pressure and ensures good injection even at high rpm and high loads.
*

There is a longer-lasting pressure at the end of the stroke due to the modest height of the intake ports and that the opening of the exhaust begins at a point similar to that of a four-stroke engine (55-60 degrees of angle of crank) with respect to the bottom dead point.

The company is also exploring adapting the NEVIS for HCCI (Homogeneous Charge Compression Ignition). The NEVIS engine adapted for HCCI would not only increase efficiency further but would also do away with NOx without the PM (particulate matter) emissions of a diesel, according to the company.




Last edited by 1Day : 20th June 2007 at 02:12.
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Old 20th June 2007, 02:38   #3
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Moving it to the technical section to generate more visibility for the target audience.
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Old 20th June 2007, 05:36   #4
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Sounds like an excellent idea, but there have been technical innovations similar in magnitude to this before. Great ideas and even workable concepts like the aspin rotary valve, the wankel rotary engine itself, the orbital two-stroke engine, the beare six-stroke engine, all proved there is something better than the basic poppet-valved four-stroke.

But there is a problem. And that problem is the automotive industry's conservative attitude to adopting radically different technology. Name one engine-related innovation in the past 50 years that has become an industry standard, and isnt related to improving the poppet-valve four stroke engine. There are NONE!

Part of this is because most customers dont care HOW their engine works, and just expect the solid reliability they have been used to. A radically new engine isnt going to have that reliability no matter how good a concept it is. It needs considerable engineering muscle to achieve the four-stroke poppet valve engine's efficiency, reliability & relative ease of manufacturing.

Example: Mazda and NSU's wankel engineering. Mazda has spend 50 long years in developing the wankel, but the amount of money spent on it is miniscule compared to that spent on the conventional engine. Most of Mazda's research was materials based and that is going to be the case with any engine that has relative motion of parts different to what is "conventional".

The conclusion is, none of the major manufacturers are gonna come forward and use this engine in a big way. Dont get me wrong, I am all for it, but it aint gonna happen.
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Old 20th June 2007, 11:38   #5
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Still to read in detail, but...

Quote:
Originally Posted by ananthkamath View Post
the orbital two-stroke engine
whatever happened to the Orbital engine?
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Old 20th June 2007, 16:15   #6
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Quote:
Originally Posted by Steeroid View Post
Still to read in detail, but...



whatever happened to the Orbital engine?
key components could not be cooled many other parts could not be lubricated, overheating and all the start running shutdown issues of spark (read this on cycleforums long time back) some members were of the view that it was a technology supressed by Ford for political reasons (oil)
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Old 20th June 2007, 21:09   #7
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Quote:
Originally Posted by 2fast4u View Post
some members were of the view that it was a technology supressed by Ford for political reasons (oil)
Damn right it was Ford & the other two. Most technical problems werent of a serious nature and could have been sorted out with development. My best bet is that excellent but poorly-funded ideas like the orbital will end up in the hands of chinese manufacturers who will have the time and money to invest in a completely new idea and then dominate the world market with their other obvious advantages.
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Old 20th June 2007, 21:19   #8
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Quote:
Originally Posted by 1Day View Post
Cylinders 2
Displacement 1,000 cc

Bore 80mm int., 178mm ext.
Power kW (hp) Est. 187 (250) @ 2,000rpm
Average piston velocity 7.5 m/sec
Engine block Steel/aluminum
Weight 80 kg
Power/Weight ratio (kW/kg) 2.38
Compression ratio 7:1 to 38:1
Injectors per cylinder 3
Sparkplugs per cylinder 3
Is it for real?? 1000cc and 250 Bhp?? I gotta feel it to believe it
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Old 21st June 2007, 00:21   #9
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Forget the 250 horses. At 1000cc, it's still acceptable, considering the 800cc+ desmodromics clock 200 ponies. Look at the revs at which this engine makes that power...2000 RPM...???!!!! Holy mother of god...what's the torque on this mutha..?

Another point to note is the architecture...3 power strokes per cycle...

Someone once said..four strokes are a giant leap...backwards....this kinda emphasizes on that, eh...?
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Old 21st June 2007, 00:30   #10
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Didn't understand. :(
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Old 21st June 2007, 12:29   #11
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Quote:
Originally Posted by v1p3r View Post
Didn't understand. :(
Same here.

Can someone translate this into a more layman language?
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Old 21st June 2007, 18:21   #12
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Hm. This's something like the Wankel engine...just as different....the piston is pushed up & down through a shaft, by an ovoid half, through all cycles, instead of your regular crank/conrods...just take a closer look at the diagrams, guys...

One thing, though...the F1 engines have hydraulic "head gaskets" as well, that allow variable compressions...but this...is straight through the roof...38:1..? WAY radical...although the engine should be able to withstand those forces, owing to low piston velocity...(most of the high-revving petrols have piston velocities above 25 m/s...the NEVIS runs at 7, lesser than a low performance diesel...)

One question; what's the torque, yaar...?

EDIT; Just remembered...at verying compressions upto 38, a single engine can be used to run with petrol AND diesel, subject to fuelling...!!

Last edited by veyron1 : 21st June 2007 at 18:34.
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Old 21st June 2007, 20:55   #13
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The power to weight ratio should be really good. 80kgs @ 250hp is really good.
Ananth would bad fuel economy be a reason for the wankels to not catch up in popularity (political reasons aside)??
Are you suggesting that the existing 4-stroke is more efficient in comparison to the nevis?
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Old 21st June 2007, 21:02   #14
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My friend recently returned a RX08 he had on lease. Poor fuel economy (17mpg), oil consumption (1 quart every 3000 miles or so) were the 2 big issues and we all know about 45,000 engine rebuilds due to worn rotor seals. Bottom line, he was smart to lease it.
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Old 21st June 2007, 21:17   #15
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Quote:
Originally Posted by highwayblaze View Post
The power to weight ratio should be really good. 80kgs @ 250hp is really good.
Ananth would bad fuel economy be a reason for the wankels to not catch up in popularity (political reasons aside)??
Are you suggesting that the existing 4-stroke is more efficient in comparison to the nevis?
Its a combination of bad fuel economy and also sealing issues like Mpower pointed out. Its not uncommon to find RX7s with two or maybe more engine replacements in a 100,000 mile window.

I am not saying the 4 stroke is more efficient, I'm saying it has reached such a high stage of development that its very hard to match up to its combination of efficiency, reliability and longevity.
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