Thread: TECHNICAL FOOD FOR THOUGHT

I read it on the internet so it must be FACT, correct?

funny thing is .. didn't Nissan only recently come up with some variable stroke engine!

What was left out was this was apparently a **** take from a mechanic.

Originally Posted by loanrangie

What was left out was this was apparently a **** take from a mechanic.

Wow, that put it all in a different dimension again.
The bloke that wrote the original comment must have been joking, surely?

See Poe's law - Wikipedia

Originally Posted by JDNSW

See Poe's law - Wikipedia

Ohh, yes you are quite right I did forget to put the "winky" face on the post.
So here be it, although somewhat belated.

My understanding is that rods/pistons etc stretch a little at higher reves, ie reach higher into the top of the cylinder.

Read some advice years ago to occasionally taking the vehicle to higher speed (higher revs but not red line) to ameliorate the wear ridge, to keep the bore as uniform as possible along its length to cope with rev increases you may experience in normal stress use - this is when my Ford engine had been rebored and I was installing new rings - hope it's a good excuse when the constabulary pull me over for 'slowing time' as I take the D1 Tdi300 to 135kmph.

Piston ring - Wikipedia

When fitting new rings to a used engine, special "ridge dodger" rings are sometimes used for the top compression ring, to improve compression and oil consumption without reboring the cylinder. These have a small step of iron removed from the top section to avoid making contact with any wear ridge at the top of the cylinder, which could break a conventional ring. These are not widely recommended, however, as they are usually not required and may give inferior oil consumption. A more acceptable method is to remove the wear ridge with a "ridge reamer" tool before lightly honing the bore to accept new rings.

Originally Posted by workingonit

Read some advice years ago to occasionally taking the vehicle to higher speed (higher revs) to ameliorate the wear ridge (to keep the bore as uniform as possible along its length) - this is when my Ford engine had been rebored and I was installing new rings - hope it's a good excuse when the constabulary pull me over for 'slowing time' as I take the D1 Tdi300 to 135kmph.

Piston ring - Wikipedia

When fitting new rings to a used engine, special "ridge dodger" rings are sometimes used for the top compression ring, to improve compression and oil consumption without reboring the cylinder. These have a small step of iron removed from the top section to avoid making contact with any wear ridge at the top of the cylinder, which could break a conventional ring. These are not widely recommended, however, as they are usually not required and may give inferior oil consumption. A more acceptable method is to remove the wear ridge with a "ridge reamer" tool before lightly honing the bore to accept new rings.

I can appreciate the problem happening when new rings are fitted to an engine where the block has not been re-bored, the piston rings have not got the same profile as the old rings which have worn to match the bore wear.
I tend to think that if a piston ring breakages in an engine that has been treated as a Toorak tractor (not travelled much over 80 KPH) for a number of years and all of a sudden being redlined over and over again can be attributed to carbon build up (for want of a better name) rather than the actual ring hitting the unworn lip at the top of the bore, the built up carbon is the culprit that would cause the stressing to the piston rings, unless of course the engine has so much wear in either the big ends, piston pin or whatever.
For this to happen then the engine has well and truly reached its use by date which could maybe brings the argument about this subject to a finish.
However I'm sure other blokes would be able to expand on this theory of mine and of course are most welcome to.

Regards:-
Patrick M.