Ring Seating Isues

[1972_911T]

Is piston ring seating in re-ringed nikasil cylinders really an issue? I have read the other honing topics on this board and followed the scotch brite pad recomendation, I did however feal that with the cylinders been so hard that if anything the scotch brite had more of a polishing effect than a roughing effect on the present honing marks.

I have just been reading the following engine running in article posted on another pelican forum and this made me worry a bit as it claims modern engine honing is uneffective at sealing piston rings after the first 20 minutes of use.

http://www.mototuneusa.com/break_in_secrets.htm

Has anyone who re ringed nikasil cylinders without a machine shop carry out fresh honing had issues with piston ring seating?

[cstreit]

It depends as much on the ring material as the technique. I've built new engines that didn't seal right even with "standard" break-in techniques. Goetz rings are notoriously hard and I generally recommend just beating the piss out of an engine that has these installed.

As long as you have a decent surface you should be okay. I happen to agree with the guy in Mototune... don't baby it.

[ChrisBennet]

I don't I think the scotch brite pads actually remove any metal. I think they clean just remove the glaze to reveal the original honed surface.
-Chris

[1972_911T]

So what about seating the rings should I follow Waynes method of running it first for 20 minutes at 2000 rpm or should I follow that article in the link above and run it in on the road to get the higher combustion presures?

Steve

[cstreit]

The 2000RPM for 20 minutes procedure is for seating in new cams and rockers... If you haven't replaced them and they are installed the same way, it's not really necessary IMHO

[sammyg2]

IMO The 2000 rpm break-in is a hold over from the old days of hot-rodding V8s. It was to properly break in LIFTERS against the cam lobes. At that rpm they would have enough oil pressure to keep them lubricated and spinning in the bores. If the lifter stuck in the bore and didn't spin (lifters actually turn slightly every time the lobe hits them) they will flatten the lobe quickly.
2000 rpm might work well to bed in the bearings, but if installed corectly they shouldn't need to be bedded in.

Running an engine at 2000 rpm to break in rings does not make sense to me. IMO You would want to vary the vacuum and pressure on them to get them to develop the proper profile.
My personal opinion is to go out and run the engine relatively aggressively to seat rings, varying the throttle and load.

When I did my nikasil cylinders, I used scotchbrite and solvent.
The rings seated using the above method with no drama.

[john walker's workshop]

i run them fairly hard for 20 minutes or so. like moto. limited window of opportunity.

[cstreit]

John's on the mark there. The problem with that 20 minute run-in is that you only have so long to seat those suckers...

Run it hard, but also remember to allow the car to decellerate IN GEAR to generate those reverse pressures...

Do let the car warm up to operating temp before hammering it though!

[1972_911T]

Ok thanks for the advice guys, my biggest problem is that my car isnt really road worthy yet I want to overhaul the suspension before I take it out on the road, so should I wait untill all this is done before starting up my engine, rather than starting it up and running it on my drive?

Steve

[sammyg2]

If I had a freshly rebuilt engine, I would not start it and run it for more than a few minutes unless I could put a load on it.
Either in a car or on a dyno.
But that's just my opinion.

[iamchappy]

Getting on it right away does this mean redline pulls and back down, also wait for the engine to completely warm up how is this done right away, it takes awhile and many miles before my oil temps get to 180 by then it would be to late wouldn't it.

[sammyg2]

I would not take a fresh engine to redline.

My break in technique includes driving normally for about 5 minutes, then accelerating harder than normal but not acting like John Force. Drive it like you're in a hurry, but not like the cops are chasing you.
Occasional full throttle pulls in third up to around 5000, then let off for several seconds, then full throttle again, etc.
The cylinder pressure at full throttle and also the vacuum created from engine braking help the rings develop the correct profile when they tough the cylinder wall.
I just try not to keep it at a steady state for extended periods for the first few hundred miles or so.

Oh, and try to stay out of full boost, at least at first
If you must use it, turn it down a little for a while.

I'm intentionally staying out of the synthetic vs. conventional detergent vs. non-detergent oil debate.

That should start an interesting discussion

[patkeefe]

Thread back from the dead...

I basically ran my new engine as you guys have described. I have another thread on this. Loss of compression in 4-5-6. Definitelt not the cam timing, leakdown cold is blowing air past the rings, manifest in crankcase pressure; out the breather vent, and out the oil return tubes with the valve cover off. No leakage past the valves or head sealing surfaces. I can find no evidence of broken ring shrapnel, but sometimes that is hard to see.

I wonder if my rings seated? How does the T04B effect the ring seating?

I'm going to warm the engine now, and test it again.

[patkeefe]

Back from the dead again...
I just pulled 4-5-6 apart. Doesn't look like the rings seated. All the ring gaps migrated to the tops of the cylinders. No broken rings or cam timing issues, nor any sign of detonation. Engine has Goetze rings. I did indeed break it in hard..I did have 7 PSI boost for probably the first hour of runtime. I also had 25% leakdown in #4, and a few% in #5, the rest were zero leakdown WARM. #6 looks just like #4.

My problem is that this is the first Nikasil engine I ever built that I actually got to take apart again, so I don't have a lot of experience in identifying ring seating issues. As usual, I am open for suggestion.

Pat

[Henry Schmidt]

ScotchBrite with soap and hot water will generally increase the RA factor.
This would indicate that all the ScotchBrite does is clean the glaze from inside the cross hatching. If cross hatch is nonexistent, the cylinders are probably toast. But if they are still round and not tapered the cylinders should be diamond honed.

The way we break in cars is to run them a relatively low RPMs to set the timing and mixture (close is good) them drive them on the road, varying the RPMs between 2500 and 5000 for 40 min to an hour. Park the car and let it cool. Stone cold.
Then do it again.
After it cools for the second time perform an in depth tune.
For the next 500 miles or so limiting the RPMs to about 1000 RPMs from red line.
Adjust valves.
Break in should be complete.

[T77911S]

here is something i found on air plane engine break-in
lycoming engines
some aircraft owners and pilots who would prefer to use low power settings for cruise during the break-in period. This is not recommended. A good break-in requires that the piston rings expand sufficiently to seat with the cylinder walls during the engine break-in period. This seating of the ring with the cylinder wall will only occur when pressures inside the cylinder are great enough to cause expansion of the piston rings. Pressures in the cylinder only become great enough for a good break-in when power settings above 65% are used.

Full power for takeoff and climb during the break-in period is not harmful; it is beneficial

one more argument for high power settings during engine break-in. The use of low power settings does not expand the piston rings enough, and a film of oil is left on the cylinder walls. The high temperatures in the combustion chamber will oxidize this oil film so that it creates a condition commonly known as glazing of the cylinder walls. When this happens, the ring break-in process stops, and excessive oil consumption frequently occurs. The bad news is that extensive glazing can only be corrected by removing the cylinders and rehoning the walls