Postby Hasbeen » 15 Nov 2010 02:08
It probably depends on what you mean by over time Peter. Also my engines always ran on STP, which does not wipe off.
I used this technique in my Morgan +4, [TR3A engine]. I used the 1991cc engine for 3,000 miles of racing, & 12,000 miles road usage.
You could see a ring lip in the bore, but could not feel it, & could measure no wear in bores or pistons.
Rebuilt the thing with new liners & custom pistons to 2.24L, & did another 2,000 miles racing & 8,000 road, & could not measure any wear in those bores either.
Next owner crack tested [dye test at home first] the thing during a return to 1991cc about 20,000 miles later, & found the crank looked like a barbers poll, small cracks every where, but still no measurable wear.
My Ford Cosworth engine in the F11 Brabham did a little over 2,000 miles, [estimated no speedo], on a new block & had no wear at the end, although it had gone through 6 sets of Hepolite forged pistons, which used to crack between the skirt & the web.
The pistons were checked or replaced every 150 miles or so, & the rings lapped each time, so lapping had very little wear effect on the bores.
I have usually found any 20,000 miles engine has reasonably polished bores, with little sign of honing marks by that low mileage, so I don't think it matters much except while bedding in a new rebuild.
I really have no idea if my STP usage does anything today, with the good oils we have, but I'm not game to stop the habit of over 40 years experience. May be it helps.
Hasbeen
