down south jeep
Newbie
Joined: Mar 2010
Posts: 24
Likes: 0
From: Peterborough, On
Year: 1997
Model: Cherokee
Engine: 4.0
Nice build so far!
not so sure about that... here is a good link explaining a lot about a different way of breaking engine in : http://mototuneusa.com/break_in_secrets.htm you might need to enter your email adress but I NEVER received junk from him, here is what is site is saying :
sorry just taught I shared this info with you. Nice build keep us posted with lots of pictures
Nowadays, the piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber.
If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of
PSI (Pounds Per Square Inch) of combustion pressure ??
Of course it can't.
How Do Rings Seal Against Tremendous Combustion Pressure ??
From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into
the cylinder surface, to seal the combustion pressure as well as possible.
The Problem With "Easy Break In" ...
The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run.
There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!
If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.
If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of
PSI (Pounds Per Square Inch) of combustion pressure ??
Of course it can't.
How Do Rings Seal Against Tremendous Combustion Pressure ??
From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into
the cylinder surface, to seal the combustion pressure as well as possible.
The Problem With "Easy Break In" ...
The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run.
There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!
If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.
sorry just taught I shared this info with you. Nice build keep us posted with lots of pictures
Thread Starter
CF Veteran
Joined: Sep 2009
Posts: 1,152
Likes: 2
From: louisiana
Year: 1994
Model: Cherokee
Engine: 2.5L
thanks yea ive read the same thing before. but i chose not to go that root and just take it easy because the first new motor i did that with it ended up shattering a piston. and the company i bought it from preruns them before they ship them out so i figured they run it through the rpms during the test run
Thread Starter
CF Veteran
Joined: Sep 2009
Posts: 1,152
Likes: 2
From: louisiana
Year: 1994
Model: Cherokee
Engine: 2.5L
today i got bored and went buy some fog lights to use in the back bumper. first i cut a whole in my bumper to put the lights in
then my dad had this stuff layin around
so i put it to use!
then welded it in and ground it down
repeated on the other side
mounted the light in there
slapped some paint on it and put it back on the jeep and wahlah!
oh and i also put this kick *** sticker on it today!
then my dad had this stuff layin around
so i put it to use!
then welded it in and ground it down
repeated on the other side
mounted the light in there
slapped some paint on it and put it back on the jeep and wahlah!
oh and i also put this kick *** sticker on it today!
Senior Member
Joined: Jan 2010
Posts: 846
Likes: 0
From: South Louisiana
Year: 1990
Model: Cherokee
Engine: 4.0
Thread Starter
CF Veteran
Joined: Sep 2009
Posts: 1,152
Likes: 2
From: louisiana
Year: 1994
Model: Cherokee
Engine: 2.5L
