Mazda 6 Forums : Mazda 6 Forum / Mazda Atenza Forum - View Single Post - changing oil at 1000 mi?
View Single Post
post #70 of (permalink) Old 06-15-2007, 09:41 PM
Registered User
DennisW's Avatar
Join Date: Aug 2006
Location: NW Indiana
Posts: 2,661
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Thanks: 0
Thanked 14 Times in 12 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
I will also add the reason you want to vary your RPM's during break in, is to prevent the pistons "reaching" to the same spot in the cylinders, as this can create a small ridge in the cylinder that when the piston reaches past that point, the rings can chip.[/b]
Well in many years of building cars and engines I have to admit that's one I've never heard before.

If your pistons are reaching different points at TDC dependent on RPM you better find some connecting rods that aren't made out of rubber.
Sorry, but that's an absolute falsehood.

And eventually a ridge will form at the top of any cylinder bore, the top ring land on the piston isn't exactly at the top and in most engines the piston's TDC is slightly below the deck anyway. Add those tolerances together and you'll have a certain area at the top of the bore that the top compression ring will never reach to, thus forming a ridge as the rest of the bore below it wears from ring contact.

But trust me, they always travel the same distance in the bores.

"There are three easy ways of losing money - racing is the quickest, women the most pleasant, and the Stock Market the most certain."
DennisW is offline  
For the best viewing experience please update your browser to Google Chrome