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]

Oil pressure (and therefore oil pump parasitic drag) building up?

je suis charlie

 

[TugboatEng]

Why would you remove the spark plugs for such a test? You're introducing a pumping loss that wouldn't be present during normal operating conditions.

 

[boonebucker]

There is a small oil pump that distributes oil to the top of the engine, however all lubrication is splash. At 1500 rpm the distribution pressure is 20kPa(3 psi). Something I failed to mention is that what I am observing occurs only after the first time it is spun after the plugs are removed. Spinning the engine subsequent times, the friction remains at the greater of the two measurements. Regarding the second response, testing with the plugs has as well been performed.

 

[MikeHalloran]

Now it's time to turn on (or install) a normal pressurized oil distribution system so you can measure how well the splash system isn't working.



Mike Halloran
Corinth, NY, USA

 

[boonebucker]

Granted a normal pressurized oil distribution system is almost a necessity for crank journal bearings on a typical engine but the engine I'm talking about doesn't employ journal bearings on the crankshaft mains or big end. Any other thoughts?

 

[MikeHalloran]

Okay, there's a roller bearing crank and maybe a roller big end, but upstream of the conrod are a crapload of oscillating bearings that are not likely to develop hydrodynamic pressures even with pressure feed. Who checked for that?




Mike Halloran
Corinth, NY, USA

 

[BrianPetersen]

My little Honda single-cylinder motorcycle engine has gone 60,000 km (of mostly wide-open throttle!) thus far with only a circulating oil pump. Rolling-element bottom end including the con-rod big end (it has a pressed-together crankshaft with the con-rod and its needle roller bearing built into the assembly). Wrist pin and piston rings are splash lubricated just like on any other engine. There's an oil squirter nozzle in the end of the hollow camshaft and a jet on each cam lobe that squirts oil against the rocker-arm sliding face by centrifugal action from the spinning camshaft. Camshaft has ball bearings. Timing chain is splash lubricated because oil return from the cylinder head to the bottom end is via the timing chain tunnel.

As for why you have a few seconds of lower friction, the only thing I can think of is that the oil is somehow adding drag when it gets into the works, or maybe if you were quick with removing the spark plugs, the oil temperature may have gone up locally during a heat-soak period resulting in a short period of the oil having higher temperature (lower absolute viscosity) as it first starts pumping.

 

[btrueblood]

I'm thinking a lot of oil channels drained back to the sump, leaving air pockets in the channels. These purge fairly quickly when oil begins pumping again, but offer little fluid resistance as they do so.

 

[boonebucker]

Brian, I too was thinking along the the lines of lower absolute viscosity at the rings from the recent combustion temperatures, but you got me thinking about something else. Getting back to my original question, I had been wondering if what I was observing was present with other engines. Something I had not realized prior to this exchange is that maybe because my total FMEP is so much lower than a typical engine, the blip I am observing could be showing up as significant because it is a higher percentage of the total FMEP.

 

[RodRico]

I have nothing to add in regards your measurement changing (oil and temperature seem likely), but this statement caught my eye:

because my total FMEP is so much lower than a typical engine

If I understand your approach correctly, I believe your prototype uses the top end (pistons, rings, cylinders, valves, etc.) from an existing engine. What differences in FMEP are you seeing between your Watts Link engine and the unmodified crank driven engine?

 

[boonebucker]

Comparing FMEP numbers is tricky business; what is included or not included and under what conditions. The tendency to compare my best with someone else's worst. Right? Let's just say that my original predictions of being able to cut friction in half with my engine design were too conservative.

 

[RodRico]

Let's just say that my original predictions of being able to cut friction in half with my engine design were too conservative.

Looking at the core mechanism, I don't see how you get such a large FMEP reduction, but I'm probably missing something. When I get a chance, I'll read your old blog posts and "ask me anything" session on Reddit. Do you plan to publish your prototype test results and, if so, when and where?

P.S. I agree 100% with your Jan 17 2010 post about the need to continue refining the internal combustion engine in spite of the trend towards battery electric automobiles. Peter Senecal (Convergent Science... CFD/Multiphysics simulation software) gave a TED talk on the subject and maintains a dialog on LinkedIn.

 

[BrianPetersen]

Wow. Interesting. I count 25 spots where something pivots, not counting the crank main and big-end rod bearings, several of which may share a common axis, 20 spots if you count the spots where three things pivot on a common axis as one each. And presumably it will share the general design of a valvetrain mechanism with a normal engine, except if you use a normal cylinder head arrangement the camshaft has to spin at an axis perpendicular to the crankshaft - can't just use a normal timing chain or timing belt, it needs to turn the rotation 90 degrees - and two such mechanisms since it is an upturned flat-four thus needing two cylinder heads. Or maybe there's something unique planned for valve actuation as well, which isn't shown there.

My little rolling-element-bearing Honda single spins over with pressure from a pinkie finger until you put the piston and cylinder on (piston ring friction), and even then, it doesn't require appreciable force to spin over until you install the cylinder head and timing chain for the camshaft and valve mechanism (spark plug removed), at which point you have to overcome the valve spring pressures against the cam lobes.

When Japanese motorcycle manufacturers moved from mostly single-cylinder and two-stroke engines (all of which used, and still use, rolling-element bottom ends) into making multi-cylinder 4-stroke motorcycle engines in the 1970s, they continued using rolling-element bottom ends and built-up crankshafts for some time, because that's what they knew how to build. They all switched to hydrodynamic bearings and pressure lubrication decades ago, though.

 

[boonebucker]

I split the case halves on the Web for a look at the real thing. Maybe you haven't seen it.

 

[GregLocock]

I'm surprised pistons (not rings) are such a big contributor in this chart.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[BrianPetersen]

I split the case halves on the Web for a look at the real thing. Maybe you haven't seen it.

No, I haven't. Link?

 

[boonebucker]

I'm assuming posting a link to my website is fine with forum posting procedures? I'll be glad to remove it if my assumption is incorrect.
Link

 

[GregLocock]

No worries, linking to relevant stuff is fine.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[gruntguru]

So the design seeks to reduce friction by replacing rotating bearing surfaces with oscillating ones. Also (I assume) by eliminating side loads and rocking of pistons.

Looking at Greg's chart, eliminating the pistons and crankshaft completely still wouldn't achieve the 50% friction reduction claimed for the Brickley Engine.

je suis charlie