Mirror polishing?

Hello ladies and gents.

I am begining to assemble my bottom end of my 4g63 but there are a few things that have been bugging me before I begin to assemble it.

I have seen that engine machine shops use a micro polisher to polish the entire crankshafts and other components on the engines.

I have been considering actually mirror polishing my crank journals myself with some metal polish. Is there any .What I've effect from doing this ? Is it worth it ?

I am also considering polishing other components like my combustion chambers and the valves them selves.

Some advice on this would be appreciated

Thanks

Karim

Hi Karim, I would say that achieving a mirror finish on your engine components isn't going to be necessary and in most cases also won't give you any real advantage. Particularly as far as the combustion chamber and valves go, it's a good idea to smooth sharp edges as this can prevent hot spots, however actually achieving a mirror finish is unnecessary as (assuming you're running on gasoline based fuel) you'll end up with carbon build up on these surfaces after a short period of running anyway.

As for the crankshaft, there are companies that provide micro polishing services and this can be an advantage. In particular it reduces parasitic losses in the engine and can potentially result in a small increase in power. It should also put less heat into your engine oil. I don't know how realistic it is to achieve this sort of result in the home workshop though. For example I've linked to a crank manufacturer who offers micro polishing as a $750 USD option - http://winbergcrankshafts.com/index.php/winfinish-micro-polish/

Thanks for the reply Andre,

With regards to the crank polishing I was more refering to mirror polishing the journals of the crankshaft rather than smoothing out the casting marks on the webs ect.

Do you think this has a benefit with regards to the oil film in the journal clearance? The more I think about it, a smoother finish will cause the oil to flow, abit like water on a waxed car.

I don't know if that would be a good thing or not though as surely you want to keep the oil in the journals, that's why I am asking the question.

Thanks

Karim

Hi Karim, it certainly can't hurt and yes, there can be some potential benefit. It comes down to whether or not the juice is worth the squeeze here. It's likely to be difficult to achieve that sort of finish yourself and your alternative is to use a company specialising in super finishing which is going to add to your cost.

Ok, thanks for the reply Andre