Dry ring and cylinder break in. Why?

[mattcfish]

I know that this is what the current BMW manual recommends. Wash the cylinders with soap/water and apply a small amount of oil to the piston skirts only. Install dry. Does this go for iron liners as well?
This goes against all the old school rules. Can anyone explain the rational for this procedure? Is it to heat up the rings more quickly?
I'm building a new motor for my VW Vanagon and I'm contemplating trying this. The VW forums aren't warming up to the idea.

[Motorhead]

I do this will all my BMW and Harley motors and the reason is seating the rings

you can use the old oil if the motor if being rebuilt over the weekend or other short term from use to rebuild although fresh motor oil/filter will need be be changed just after the "run"

this method is faster and what I do after a 1 minute dry run build is run to 3000 rpm for "1" minute and I let it cool to cold

then I use it as I would any street bike or on the highways not higher than 70 Mph, but I would not hot rod it until I have 250/500 miles and I'm happy and had no problems during this period

oil changes come at just after, then 50 then 500 then regular periods there after fresh filters

inspect filters ofr any debris should just find nice fine gray metal in very very small amounts cleaner at the last oil change before regular periods

Red does 4100 miles and maybe uses or seeps .02 oz.......

also as the oil pump is very effecient even a dry motor is lubed and splashed after the first 4 turns

[Garnet]

I have tried both wet and dry methods on iron cylinders and not seen any different results.

I think that the most important thing is "seating" the rings early by getting a decent load on the engine ASAP, which is at times not that easy.

[vanzen]

Rings will seat quickly & thoroughly without oil to interfere with the process, eh ?
Works for me.

[Frog]

I know that this is what the current BMW manual recommends. Wash the cylinders with soap/water and apply a small amount of oil to the piston skirts only. Install dry. Does this go for iron liners as well?
This goes against all the old school rules. Can anyone explain the rational for this procedure? Is it to heat up the rings more quickly?
I'm building a new motor for my VW Vanagon and I'm contemplating trying this. The VW forums aren't warming up to the idea.

I just did this on my new top end on the slash five. More friction between the rings and the cylinder walls makes for a faster break in.

[melville]

Matt, you live in a wet place as do I. If the motor is to sit for any time longer than a day or two after you button it up until you fire it, a dry cylinder is going to rust up. I like the idea of the dry first firing, but so far I've been unable to have all my $#!+ together enough to pull it off. There's always some subsystem that I've got to rework/reengineer that makes it weeks at the minimum from longblock together to running in the vehicle.

What I've done with the VWs (and am doing/will do with the Airhead):

A light coating of oil on the cylinders, spread with fingers.

The usual reassembly and reinstallation

Crankcase filled with Brad Penn 30 weight Break-In Oil

If a new cam, 20 minutes at 2500 rpm (vehicle stationary), then drain crankcase and refill with Brad Penn 30 weight Break-In Oil. Adjust valves.

Then 100 miles of varying loads, usually someplace I can drive 30 seconds or so at up to 80% throttle and coast down under engine braking and repeat repeat repeat. Some call this the "Drive it like ya stole it" stage. From Bellingham, I'd probably use Rte 9 back and forth to Sedro Woolley.

Then drain crankcase and refill with you preferred oil. Adjust valves.

Then 1000 miles, change oil, adjust valves.

Then it's regular service intervals from there.

Good luck!

[mattcfish]

Matt, you live in a wet place as do I. If the motor is to sit for any time longer than a day or two after you button it up until you fire it, a dry cylinder is going to rust up. !

Tell me about it, last week my garage had an inch and a half of water all across it. I had to wade out to my bike.
I've gotten used to keeping everything on pallets.
I've read about spraying the iron bores with WD40 or penetrating oil to prevent the rust. It burns off in a flash so you are essentialy going dry.
When I'm done with the Wasserboxer I'll be putting my MI pistons and jugs on my R90.
It's amazing how many people sware by copious amounts of lubrication and others say they only go dry. I just want to do what's going to give me the best compression and least blow by. Maybe I'm on the wrong forum .
On another note, if I'm putting a used 336 cam in my bike, I can forget the 2500rpm idle...right?

[melville]

On another note, if I'm putting a used 336 cam in my bike, I can forget the 2500rpm idle...right?

Boy I dunno. Is it using the same lifters, in the same holes? That's the only way I skip cam break-in with VW stuff. It does occur to me that one wants a fan or two on the motor if leaving a running Airhead stationary for 20 minutes. VW, of course, have the fan built in.

I'm a little paranoid about cams and lifters. Since oils were reformulated in the late 90s, VW folk have learned the words "flat cam." I didn't think much of it, but a motor I built in 2004 dropped a valve seat in just 3500 miles. When I disassembled it, I thanked the valve seat for dropping, as I had a lobe and lifter starting to grind each other into dust. Looked like 350000 miles of wear!