*Refer to clip below this paragraph first*
Umm,. . .here's a thought on that one. Okay, let's say that I've got
some air in a cylinder that is pressurized at 100 psi. Now, let's
say that I hook up a hose to that cylinder and try to inject air into
it. Now let's say that that cylinder only has a one-way valve on it.
Okay, now at what point in time would air from the hose start going
into the cylinder? 101 psi, right? BUT, that would drop the
pressure in the hose because air volume would be escaping, right, so
it would loose pressure in the hose. Well, that's basically what
happens when you do a compression check. The reason I crank it over
4 or 5 complete firing sequences is to get the maximum pressure in
the cylinder. You can't compress the air in the compression check
tool any more than what the pressure is in the piston cylinder. The
air would never go through the compression check's one-way valve if
it was not any higher pressure than the air on the other side of the
valve. That's why I say that when you only crank it over once you
have theoretically enlarged your combustion chamber area since you
are "bleeding" some volume out of it. Therefore, when the air has
more volume to go into, it will be of less pressure. So, you have to
keep on cranking it over to get it to bleed less and less pressure
off the cylinder until the pressure in the cylinder equals the
pressure in the compression check tool. At that point it will NOT
rise anymore. That is the TRUE pressure in the cylinder. Does all
this make sense to anybody?
- Rob Cobb 93 V8 LE 2wd
*Clip*
>>> <DesignTech@worldnet.att.net> 2/20/97, 04:32pm >>>
>AHHHHH!!!!!!!!!!
>that is how you do it
>you are recompressing already compressed air. in that case you can
>do it. i
>never did a compression test and i thought you only cranked it once.
>when
>your driving, all that the engine will compress to will be the
>theoretical
>value(about 135-140 psi) in that case you won't lose any power if
>you start
>out with 160 psi and drop to 145 psi cus no air will squeeze past
>the rings
>at either the engine with 160 psi or 145 psi. it doesn't leak until
>the
>pressure reackes the measured pressure and when you drive it won't
>go over
>140. therefore 140 psi is great and will run as good as an engine
>with
>200+psi
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