Brickley Engine: friction tests on proof-of-concept engine 1

[boonebucker]

It's been a number of years since I've posted on the forum. During that time a proof-of-concept engine has been designed, built, and tested. Third party tests are in progress. Since many of you folks out there have a great deal more experience than I in testing engines, I wanted to see if a characteristic that I am observing is experienced with other engines as well. I'm doing a motoring friction test where the engine is brought up to operating temperature under firing conditions, the spark plugs removed and then the engine motored. What I am noticing is that there is an initial period of a few seconds when the friction is quite a bit less. Is this a phenomenon present typically? What are your thoughts?

 

[gruntguru]

Greg. The chart you posted shows ring friction in the absence of gas loads - so significantly reduced. Gas load effect is added in a curve higher up.

je suis charlie

 

[boonebucker]

Greg, the chart shown is(b)for diesel. Is(a)available for SI? Oil viscosities perhaps?

 

[gruntguru]

Different source but this is SI.

je suis charlie

 

[boonebucker]

Here is another link that might be helpful. Closer to my engine in displacement, but 2 cylinders Link

 

[RodRico]

Attached is a brief from Ricardo titled "Calculation of Friction in High Performance Engines" presented at their 2010 European User Conference. It provides a lot of information regarding friction in the various components and subsystems of a high speed racing engine under both motored and loaded conditions. The below table showing friction of key components at 9,000 RPM was taken from slides 41, 43, and 45. Column M is FMEP (bar) when motored, L is FMEP (bar) motored, M% is percent of whole engine fiction when motored, and L% is percent of whole engine friction when loaded.

[pre]
M L M% L%
Whole Engine : 2.10 | 3.80 100% | 100%
Top Piston Rings : 0.04 | 0.04 1.9% | 1.9%
Oil Control Rings : 0.12 | 0.07 5.7% | 1.8%
Piston Skirts : 0.50 | 2.25 23.8% |59.2%
Small End Bearings: 0.01 | 0.01 0.4% | 0.3%
Big End Bearings : 0.14 | 0.15 6.7% | 3.9%
Main Bearings : 0.20 | 0.23 9.5% | 6.1%
[/pre]
From the above, piston skirts are the largest single contributor to engine friction at 9,000 RPM. The plot of skirt friction on slide 41 shows a marked increase of motored skirt friction as RPM increases (+100%) and a marked decrease (-33%) of loaded skirt friction. I assume the decrease of skirt friction with engine speed relates to transition from mixed lubrication to hydrodynamic lubrication on the Stribeck curve of slide 6. I'm guessing the increase of motored skirt friction with RPM has to do with piston kinetics.

Per the chart below from an MIT class on Engine Friction and Lubrication, mechanical friction accounts for 3% (full load) to 9% (part load) of engine losses. By my calculations, a 50% reduction in skirt and bearing losses would result in efficiency gains of 1% (full load) to 3% (part load). That would be a pretty significant accomplishment in my opinion. Whether or not that gain can be accomplished and what increase in cost and complexity manufacturers are willing to accept to attain it is beyond me.

 

[BrianPetersen]

Organizing the crank actuation mechanism to (almost) eliminate side loading on the pistons could be expected to reduce, but not completely eliminate, the piston skirt friction, and it's a pretty big factor - the above chart is good. Other methods of addressing this in engines of conventional layout include using long rods, using pistons with minimised and optimised skirt-contact area, and so-called "desaxe" layout in which the centerline of the crankshaft is offset from the centerline of the cylinders by a few millimeters away from the power-stroke thrust side. So, there is something worth pursuing. At what cost ... is a darn good question.

Actuating the pistons through a linkage of some sort isn't a completely new idea. The Nissan variable-compression engine, in production today, does that. They did it for a different reason, but one of the side effects of their linkage design is that it reduces the angularity of the connecting rod through the power stroke (which is when it matters most).

https://www.youtube.com/watch?v=j0An3RbXcPg

 

[boonebucker]

I can't tell you how many times I have re-calibrated and improved my test equipment because I have not believed the results I am getting. I must say at this point that the gains are far more than 1 % at full throttle and 3% at part load.

 

[BrianPetersen]

Lack of anything else to do prompted a wee bit of digging, and it seems that you've taken this concept MUCH further than most inventors do!

https://www.youtube.com/watch?v=ihd4JcjF0Rs

I'd love to see how you did the cylinder heads and valve mechanism.

 

[boonebucker]

The Harbor Freight engines that I cannibalized have pushrods that run along the side of the engine. I kept all eight pushrods on the same side of the engine by turning two of the cylinders upside down. All four pushrods that meet from the two cylinders opposite each other are actuated by one cam lobe via roller followers. One lobe, two cams placed one above the other, chain driven from the crank. Two lobes drive all eight pushrods.

 

[RodRico]

I must say at this point that the gains are far more than 1 % at full throttle and 3% at part load.

Congratulations! That's very impressive! There's should definately be a market for those kinds of gains.

you've taken this concept MUCH further than most inventors do

Indeed. His first patent application was filed 12/16/05, and he's stuck with it all the way to prototype. He's an inspiration for everyone who has an idea and pursues it with perserverence. That's the spirit of the individual inventor.

 

[boonebucker]

In my hand, on a 'good' day, I have three or four pieces to some 10,000 piece jigsaw puzzle that in all honesty I have yet to identify. Practically speaking, on a moment by moment basis, the impact of those few pieces, which I can't help but mistake for much more than three or four pieces, have the possibility of crushing what life can become. So it is my privilege and responsibility in being, having come upon this, to choose a life leaning toward a spirit of discovery.

 

[boonebucker]

I apologize for going abstract and philosophical in my last comment. My thanks to each of you for your kind input!

 

[gruntguru]

We don't tolerate philosophy here!

je suis charlie