U.K. to revert to imperial weight measures

[old man emu]

7 hours ago, onetrack said:

if you've got 400HP under the bonnet, that sounds so much better than 298.28kW!

Probably that's because one can visualise a horse, and they are considered to be strong, powerful animals. What's a watt? You can't get an idea of it by comparing it with something that you can see and feel.

 

To be honest, very few people know why this unit of power is called a horsepower. The term was adopted in the late 18th century by Scottish engineer James Watt to compare the output of steam engines with the power of draft horses. Watt defined and calculated the horsepower as 32,572 ft⋅lbf/min, which was rounded to an even 33,000 ft⋅lbf/min. He compared the power of his steam engines to the work that a horse could do because he was trying to sell steam engines to mine operators to replace the horses that provided the power for lifting in the mines.

 

Even more confusing is that when we talk of the maximum horsepower of an engine, we are talking about how fast it can produce torque. Horsepower is the mathematical product of torque and RPM. You know that. Your 90 HP Jabiru engine produces that amount of power at full revs - when you need it for take off to get the prop swinging quickly. Establish cruise and you reduce the RPM because you don't need to turn the prop so fast and whenever you turn the prop, you need torque.

[Fliteright]

It's a bit like MPG, the baby boomers could relate to that where as the Generation xyz (or whatever the current tag is) only wanna know how to start their car, numbers don't mean much to them as less & less wouldn't know how to turn a screwdriver much less use a tape measure😉

OME how do I get 90 HP at T/Off from my Jab 80 HP donk? Do tell😉

[old man emu]

3 hours ago, Fliteright said:

OME how do I get 90 HP at T/Off from my Jab 80 HP donk? Do tell😉

Bore it out oversize and stroke it😁

[facthunter]

 Those original pistons were at the maximum available oversize already. If you want to "stuff" an aero engine  increase it's displacement without knowing what you are doing. The  80 HP Motor was generally accepted of making 85HP. You can allow them to rev more (with reduced life) or Boost them (as well) reduced life. Military rated engines are often the same engine operated to different limits. You'll get more failures and a reduced TBO.

  Reduced thrust take offs on Bypass Jets increases engine life  The start cycle is often hard on them too. Nev

Edited September 20, 2021 by facthunter

[Yenn]

Does stroking an engine make it more powerful or is it like stroking the dog to settle it down?

[facthunter]

Geez Yenn I nearly replied in a more  "AAargGH way than your post. Remembering the high standards set here I removed it just in time. Bluddy close CALL MATE.. Nev

[spacesailor]

Stroking  !

It Will make it larger.

spacesailor

[red750]

You missed a whole lot. What about

 

Hectometre - 1/10 of 1 kilometre

Dekametre   - 1/10 of 1 hectometre or 1/100 of 1 kilometre

Metre            - 1/10 of 1 Dekametre or 1/1000 of 1 kilometre

Decimetre     - 1/10 of 1 Metre or 1/10,000 of 1 kilometre

Centimetre    - 1/10 of 1 decimetre or 1/100 of 1 metreor 1/100,000 of 1 kilometre

Millimetre       - 1/10 of 1 centimtre or 1/1000 of 1 metre or 1/1,000,000 of 1 kilometre.

[old man emu]

12 hours ago, Yenn said:

Does stroking an engine make it more powerful or is it like stroking the dog to settle it down?

 

What Is a Stroker?
As its name implies, a stroker is where we increase engine displacement by increasing piston stroke. When we increase stroke, we take the piston deeper in the cylinder bore, which increases displacement. The longer the stroke, the greater the fuel/air charge. Because mechanical advantage or leverage comes with stroke, torque does too. Think of stroke as you would using a breaker bar instead of a ratchet to remove a stubborn bolt. The longer the lever--or stroke--the greater the mechanical advantage.

 

You have to remember that what you want initially from an engine is torque, which is the mathematical product of the magnitude of the force and the distance from a pivot point at which it is applied.

 

In an engine, the location of the pivot point is taken to be the centreline of the crankshaft. The Force is applied to the pivot at a distance equal to the offset of the centre of the connecting rod journal from the centreline of the crankshaft (crank radius).

The Force is provided by the pressure of the expanding combustion products of the fuel/air mixture actin on the crown of the piston and thence to the connecting rod journal via the connecting rod.

 

If you alter any of these, then you increase the torque produced by the engine. For a standard factory engine, the way that is done is by introducing more fuel/air mixture. The next step can be boring out the cylinder to accept an oversize piston. That increases cylinder volume and hence more fuel/air mixture is drawn in. You could go the way of using pistons whose piston pin is closer to the crown than standard pistons. That would increase piston volume. Or you could use shorter connecting rods and piston with the piston pin lower (???).

 

SO NOW WE HAVE INCREASED THE TORQUE, WHAT ABOUT HORSEPOWER?

Horsepower is simply how much torque the engine can produce in a period of time - usually per minute. This is related to the number of revolutions of the crankshaft occur in that period of time. In doing the calculations, there is a constant value that takes care of the distances and times involved so that there are only three variables to deal with. The constant used depends on the measurement system used for torque.

 

 

 

 

 

[Fliteright]

OME I've got a headache now thanks to that😉 The Yanks used to have the belief that more cubes is best where the Japs has the belief more RPM is best👍

[old man emu]

2 hours ago, Fliteright said:

The Yanks used to have the belief that more cubes is best where the Japs has the belief more RPM is best

When you think of engine longevity, you have to be in the "more cubes are best" camp. Look at that thread on the world's largest engine. Massive cubic capacity, but slow revving. My Dad used to describe a big capacity engine in a vehicle as only firing every telegraph pole. 

 

Look at a Rotax 912. 59.6 kW (79.9 hp) at 5,800 rpm and a Continental A80 80 hp at 2700 rpm

 

Using the relationship HP = (T x RPM)/9550 you can calculate the amount of torque each engine develops per revolution.

(9550 x 80)/RPM = T

For the Rotax it comes out at 132 (units of torque) and for the A80 it is 282 (units of torque). Less propeller spinning ability but higher rates of wear and tear.

[onetrack]

It's interesting that the high-revving Rotax can get to 2000 hrs before overhaul, but most of the slower-revving Jabiru engines seem to have trouble making 1000 hrs before overhaul.

Something tells me the materials in the Rotax components are of a much superior grade of materials and hardness than the Jabiru components.

 

The old Caterpillar diesels from the 1940's and 1950's had cylinder liners so hard, it was difficult to hone them. Many of these engine did 20,000 hours or more before overhaul.

 

[spacesailor]

Red750

PICO

spacesailor

[Fliteright]

I prefer cubes but the Japs have got the sums correct when it comes to their screaming bike donks!

My old 4 Ltr Ford donk is approaching 1/2 Mill k's, never been touched & on dedicated gas. uses zero oil between changes, the Ford Barra engine is a huge success for Ford. I never take it over 3K RPM so it gets an easy mostly Hwy miles only life:-) The Lyc O320 can if well treated go well beyond it's 2000hr design life, that & the O235, Lyc's 2 best under-stressed donks:-) Jab donks are ok if maintained to within in inch of their life,(heat is the biggest enemy there) Rotax are enjoying & winner judging by the zillions out there!

In another life when I used to work on cars mainly pommy crap the Jag's enjoyed lots of lugging power & the 5.3L V12 was almost elect like with the power pulses overlapping each other closely.

[facthunter]

I wouldn't call the Jaguar "double six" (wet sleeve) any great engine and even the XK range high tensile steel crank was good at developing cracks. Many of those cars had Impala (Chev) engines fitted to the chagrin of the purists.. Much more trouble free and no SU  carburetters to leak and tune. Once a V8 with injection is hot the economy becomes quite good especially if the compression ratio is high and all the bearings are in alignment.  The Ford  4V Cleveland wasn't bad but pretty heavy but it breathed well..Every thing on it was  cast iron. 5.8 litres (Medium size) Nev

[Marty_d]

On 20/09/2021 at 9:59 PM, red750 said:

You missed a whole lot. What about

 

Hectometre - 1/10 of 1 kilometre

Dekametre   - 1/10 of 1 hectometre or 1/100 of 1 kilometre

Metre            - 1/10 of 1 Dekametre or 1/1000 of 1 kilometre

Decimetre     - 1/10 of 1 Metre or 1/10,000 of 1 kilometre

Centimetre    - 1/10 of 1 decimetre or 1/100 of 1 metreor 1/100,000 of 1 kilometre

Millimetre       - 1/10 of 1 centimtre or 1/1000 of 1 metre or 1/1,000,000 of 1 kilometre.

Have you ever used "hectometre", "dekametre" or "decimetre"?

 

Like I said.  Millimetres, metres and kilometres are absolutely all you need until you get to the big stuff (light years) or the very small (micrometres, nanometres).

[spacesailor]

Terametres :  TM

Is bigger.nanometre the smallest. 

spacesailor

[Marty_d]

1 hour ago, spacesailor said:

Terametres :  TM

Is bigger.nanometre the smallest. 

spacesailor

If you're going that big, I prefer Astronomical Units (AU) - roughly the distance between the Earth and the Sun.  About 150 million km.  

[old man emu]

But then there is the parsec – a unit of distance equal to about 19 trillion miles (more than 30 trillion km) 

[onetrack]

These are the only standard measurements you need to know! - the ones you use in everyday life! And this is the only rule you need to carry with you! 

 

 

[old man emu]

8 hours ago, onetrack said:

These are the only standard measurements you need to know! - the ones you use in everyday life! And this is the only rule you need to carry with you! 

 

 

No good for me. Doesn't convert beesdicks into poofteenths. 

[Fliteright]

There's too many 'rules' in life as it is😁 Ive still got my grandpops old 'blind man's' folding wooden ruler, kids would look at it now as a curiosity piece:-)

[red750]

I often wonderd if a pinch of salt was of uniform size for people of different finger sizes.

[old man emu]

One pinch of table salt weighs 0.36 gm ( 0.0126985 oz) That's 0.6% of the molar mass of sodium chloride.

[facthunter]

What's a molar mass?  Nev