Tree Monkey MS462 - PART 2

[tree monkey]

My Dad said that in the olden days, some car makers put vacuum gauges in their dashboards and called them "fuel economy gauges" ... more vacuum, higher economy.

yep my dad added one to his 69 dodge truck. remember it clearly

 

[Wood Chopper]

filter pic sent in pm

I'm afraid to look..

Waaaaay too much filter and not enough of... well..Everything else Scotty lol

That thing was flocked. No saw dust gettin by that. phew

 

[tree monkey]

My Dad said that in the olden days, some car makers put vacuum gauges in their dashboards and called them "fuel economy gauges" ... more vacuum, higher fuel economy.

I know diesel engines don't have any vacuum, but gas engines ... even at full throttle, it seems to me they still have to have some vacuum, otherwise air wouldn't be drawn into the cylinder. And I bet if you put a vacuum gauge on the intake manifold, you'd still see at least some vacuum (i.e., pressure would be lower than local ambient pressure).

no vacuum in the intake at full throttle, no vacuum hoses on race cars, unless they add a vacuum pump

 

[Stump Shot]

So...why then in a two stroke engine, the Primary compression measured at the crankcase and the Secondary compression measured at the spark plug?

 

[XP_Slinger]

no vacuum in the intake at full throttle, no vacuum hoses on race cars, unless they add a vacuum pump

Because the throttle plate is restricting ambient pressure entry at idle. Full throttle or no restriction on entry will still pull 1 to 2 inches of mercury...very very close to no vacuum.

 

[Stump Shot]

 

[RedGas]

If there were no pressure differential between ambient and inside the cylinder, air would never have gone into the cylinder except through Brownian motion.

Also, I suspect that there may be difficulties (due to the Bernoulli Principle) in measuring air that is moving at high velocity (as in an intake manifold). Normally a fluid or gas that is moving fast will be at a lower pressure than fluid or gas that isn't moving as fast (which is why airfoils and venturis work)...

 

[tree monkey]

proof that there is pressure and vacuum in the crank case.
pressure occurs between the time the intake closes and the transfers open on the down stroke. very short window of time.
vacuum occurs between the time the transfer close and the intake opens.

 

[Redfin]

Air is like golf balls

What would this world be if they were sausage balls?

 

[tree monkey]

did you make the video?

 

[Stump Shot]

did you make the video?

Maybe ... why? Lol

 

[cus_deluxe]

Yes, I am nitpicking semantics and I have mentioned some reasons why making those distinctions are important, but you are now attempting to mix them. How/why did principles of thermodynamics get introduced when they have nothing to do with the elements (basic physics IMHO) supporting this discussion? Once the fire is about to be lit in the cylinder and the gaseous energy exchange processes commence we'll be talking thermodynamics... but those terms are irrelevant at this stage.

Enthalpy, in a nutshell, is the tendency toward disorder in the universe. Its why when you spray febreeze after taking a *s-word, a few minutes later you smell the febreeze elsewhere. Any time there is a potential difference (whether its pressure/temperature/concentration of a certain element/compound etc...) things move from an area of high potential to low potential (or in this case an area of positive pressure to an area of negative pressure). In the case of a two stroke engine, this potential is created by the movement of the piston, in the definition above the “work required to make room for it (the system- 2 stroke engine crankcase) by displacing its environment and establishing its volume and pressure.” I dont understand at all how it could be explained in a way where the piston was not directly responsible for the function of a 2 stroke engine.

 

[tree monkey]

Maybe ... why? Lol

I would like to see what the gauge does with the saw running

 

[CR888]

Motors are electric
Engines are gas

Hope I’m not coming across as a dick but your wrong

Does this mean General Motors (GM) has secretly been making hybrids for about a century? Did steam engines have hidden gas tanks? Are motorbikes just the wrong term for a two wheeled gas engine powered bike? I'm confused now so I'll sit back. The strato subject has gotten so far off topic we ended up on the beach with the 'hoover lady'!!

 

[cus_deluxe]

My Dad said that in the olden days, some car makers put vacuum gauges in their dashboards and called them "fuel economy gauges" ... more vacuum, higher fuel economy.

I know diesel engines don't have any vacuum, but gas engines ... even at full throttle, it seems to me they still have to have some vacuum, otherwise air wouldn't be drawn into the cylinder. And I bet if you put a vacuum gauge on the intake manifold, you'd still see at least some vacuum (i.e., pressure would be lower than local ambient pressure).

Yes theres always some vacuum in a gas engine at full throttle, but very close to zero. Diesels do not have a throttle body to create vacuum, they regulate power/rpm w fuel delivered rather than the air fuel mix in a gas engine. Ever seen a diesel engine run away? Pretty scary

 

[XP_Slinger]

I would like to see what the gauge does with the saw running

THAT would be interesting

 

[Stump Shot]

I would like to see what the gauge does with the saw running

That saw does not run, yet. But I can with another saw tomorrow. Will be interesting to see.

 

[tree monkey]

we have to consider lag in air movement as well

 

[tree monkey]

That saw does not run, yet. But I can with another saw tomorrow. Will be interesting to see.

idle and full throttle please, I bet the needle barely moves at full throttle. but I could be wrong

 

[EvilRoySlade]

I bet it can’t react fast enough but that’s only speaking of the gauge.