Don Terrill’s Speed-Talk

Check this out and let me have your thoughts.
DV

Boring bar chatter? It seems to be an awfully consistent pattern.

That's my guess.

I think laser honed cylinders. What engine David?

roc wrote: ↑Tue Oct 10, 2017 4:59 pm I think laser honed cylinders. What engine David?

I think it is out of a Toyota truck with about 200 K on it.
DV

mitsubishi 4M40 diesel im guessing.

i have bored (and sleeved) a few of these, guessing some kind of induction hardening for the area of the bore that cops the most ring wear.

Looks just like the bores in some of the Duramax diesels where they are induction hardened as well.

Echoing what Dave McLain said. 6.6 Duramaxes look like that on the inside.

Mind you, that engine has Isuzu written all over it except on the truck's grille. So they must be doing something fancy for cylinder conditioning on the top inch or so.

the wierd pattern is induction hardening. its to prevent wear in the top portion of the cylinder.
As mentioned there is several manufactures doing this now to combat wear in lesser quality bore material

https://www.gehring.de/sites/default/fi ... -en-ww.pdf Looks a lot like this.

yes, I agree that is same as duramax, I've heard it called laser hardening. I assume it involves a laser, but I haven't seen them do it of course, so who knows. One thing for sure, it works. Very hard cylinder and minimal wear.

Interesting tech!

Induction hardening process, bout .100 deep. Check AERA bulletins. Does a nice job of keeping upper cylinder wear to a minimum. I've sleeved a few on Duramax engines to repair destroyed cylinders. I believe I used a Melling Performance sleeve.

Another vote for induction hardening. Getting more and more common on OE engines.

Its tough to believe that's really necessary in a diesel application because I've seen a lot of those with a ton of miles and really very little cylinder wall wear. Assuming a regular cast iron block was used in the 5.9 Cummins, 7.3 Ford etc.

Unless it is all about the reduction of emissions. Maybe to allow a lighter ring package instead of the keystone type of top ring..

I think it's a Toyota 1KZ or a 1KD.

They ALL look like that when you pull them down.
They're made like that.