Quick and easy.

[nextse7en]

During a compression test, what is the acceptable range of values in PSI?


Thanks,
Patrick

[oab_au]

Originally Posted by nextse7en

During a compression test, what is the acceptable range of values in PSI?


Thanks,
Patrick

With the throttle wide open:
171 to 206psi Standard.
142psi limit.
28psi difference between cyl.

Harvey.

[YourConfused]

Originally Posted by oab_au

With the throttle wide open:
171 to 206psi Standard.
142psi limit.
28psi difference between cyl.

Harvey.

W.O.T. and all 6 plugs removed...

[svxistentialist]

Originally Posted by YourConfused

W.O.T. and all 6 plugs removed...

Is this a wind-up?

How exactly could you turn over an engine to generate pressure in one cylinder with all 6 plugs removed?

I had always thought that each cylinder was measured independently, with ignition in the other 5 contributing the motive power.

If I am wrong in this, can somebody please explain what turns the cylinders to apply the pressure?

Joe

[Crazy_pilot]

Originally Posted by svxistentialist

Is this a wind-up?

How exactly could you turn over an engine to generate pressure in one cylinder with all 6 plugs removed?

I had always thought that each cylinder was measured independently, with ignition in the other 5 contributing the motive power.

If I am wrong in this, can somebody please explain what turns the cylinders to apply the pressure?

Joe

The starter motor?

[oab_au]

Originally Posted by svxistentialist

Is this a wind-up?

How exactly could you turn over an engine to generate pressure in one cylinder with all 6 plugs removed?

I had always thought that each cylinder was measured independently, with ignition in the other 5 contributing the motive power.

If I am wrong in this, can somebody please explain what turns the cylinders to apply the pressure?

Joe

No I would not do it that way Joe

We just use the starter.

Harvey.

[svxistentialist]

Originally Posted by Crazy_pilot

The starter motor?

Accepted, but that's a simplistic answer to the question. Assuming the starter motor could turn over the engine, why would you need all six plugs removed, unless you had six discrete pressure readers screwed into each cylinder?

I'm making the assumption that the test involves only one pressure reader. Why not "run" the engine on 5 cylinders?

[svxistentialist]

Originally Posted by oab_au

No I would not do it that way Joe

We just use the starter.

Harvey.

OK.

Why?

Joe

[YourConfused]

Originally Posted by svxistentialist

Is this a wind-up?

How exactly could you turn over an engine to generate pressure in one cylinder with all 6 plugs removed?

I had always thought that each cylinder was measured independently, with ignition in the other 5 contributing the motive power.

If I am wrong in this, can somebody please explain what turns the cylinders to apply the pressure?

Joe

are you serious?

[Crazy_pilot]

Originally Posted by svxistentialist

Accepted, but that's a simplistic answer to the question. Assuming the starter motor could turn over the engine, why would you need all six plugs removed, unless you had six discrete pressure readers screwed into each cylinder?

I'm making the assumption that the test involves only one pressure reader. Why not "run" the engine on 5 cylinders?

I think (I've never done a pressure test, so this is only speculation on my part) that the goal is to get the piston to stop at top dead center to get an accurate reading. With no spark plugs and no compression on the other cylinders the starter has an easier time turning the motor to get where you want.

[oab_au]

Originally Posted by svxistentialist

Accepted, but that's a simplistic answer to the question. Assuming the starter motor could turn over the engine, why would you need all six plugs removed, unless you had six discrete pressure readers screwed into each cylinder?

I'm making the assumption that the test involves only one pressure reader. Why not "run" the engine on 5 cylinders?

The readings that I posted are done at 200 to 300 rpm, starter speed, .If you do it by starting the engine you would be at 600, not to mention the inherent danger of a fire.
Harvey.

[svxistentialist]

Yes.

I am presuming there is only one pressure reader. Is there a reason why the engine can not run on 5 while one cylinder is being read? If so, explain what problem may be caused?

Joe

[svxistentialist]

Originally Posted by Crazy_pilot

I think (I've never done a pressure test, so this is only speculation on my part) that the goal is to get the piston to stop at top dead center to get an accurate reading. With no spark plugs and no compression on the other cylinders the starter has an easier time turning the motor to get where you want.

Thanks Chris.

That makes sense. With zero pressure at all the other 5 cylinders, the measurement at the cylinder under test will be more accurate. I suspect though, that the pressure gauge will only register the maximum pressure produced, so the TDC business is taken for granted.

Understood,

Ta,

Joe

[YourConfused]

Originally Posted by oab_au

The readings that I posted are done at 200 to 300 rpm, starter speed, .If you do it by starting the engine you would be at 600, not to mention the inherent danger of a fire.
Harvey.

Precisely, that's why all 6 plugs get removed, to allow the motor to spin freely.

[nextse7en]

This thread is taking a turn to the ridiculous.

With the throttle wide open:
171 to 206psi Standard.
142psi limit.
28psi difference between cyl.

Thanks Harvey.