Was watching one of Dave’s (Monster engines) video’s where they were talking hone (cross hatching) patterns and diagnostic imaging next to his CNC machine - makes me wonder if some OEM’s are not rushing that process …
What works in production volumes and what works in a bespoke custom build shop can be quite different.
With the right equipment to precisely measure things and understand, a small shop dedicated to excellence can do amazing things (think F1, NASCAR, etc or perhaps Monster Engines
).
But often the small shops just lack those resources and can't rise to even what the OEMs do in mass production. It really depends on how the shop spends it capital and whether it sees the value of some VERY expensive measuring instruments.
For example, our measurement lab has a laser-based surface finish system that can give you surface resolution <0.1 micron and precisely give you all the Ra Rz etc values your heart desires. It can only scan I think like a 20mm length at a time (you are VERY zoomed into the surface), but nothing else provides quite such an understanding of surface texture and such.
This way the precise product of different honing patterns and crosshatch setups can be studied. Most people know about plateau honing. But how deep to the valleys between the plateaus need to be? How deep is deep enough? Too deep? How close together is too close? Too far? How flat does the top of the plateau need to be? How smooth?
That level of detail is where the magic of many of today's higher performers lies.
If you want to see how much it can matter, go find an old copy of one of the first Engine Masters shootouts where Lennart Bergquist's big block chevy won the competition (509CID rule). Lennart had the big block bore finish PERFECT. The teardown of the engine after the competition would defy anyone to prove the engine ever even ran. It was absolutely surgically clean after dozens of dyno pulls and lots of heat. But the pistons didn't even have a tan on them and the disassembled parts all looked nearly new. It was burning ALL of the fuel and NONE of the oil.
He spent a huge portion of his engine build time just tuning the bore finish and it paid off.
It's been ages since I read up on that build and contest, so you'll need to forgive my recollection, but I want to see that his winning surface finish was actually from using FLEX HONE brushes! I think he made his cross hatch from a 180 grit followed by a 400. I doubt he had all the instruments to precisely quantify his testing, it was more like just test and tune and assessing using the torque required to turn over the short block.
I remember that engine for some reason. It was special and so was he. ( I believe he has since passed?). 851hp from a 509 at only 6400rpm on pump gas is quite something. I can't find much other than the power results of that engine with a web search. Back in the day, PHR had a great write up with the pics of the impressive engine internals.
