cylinder finish issues

[MST0118]

So, just to be clear is it the consensus here that the Ra for new Nickies is similar enough to the Ra for new Mahle cylinders if purchased direct from LN Engineering for a 911 application regardless when purchased? Or does one have to confirm the appropriate Ra from LN in that situation as well?

[Neil Harvey]

You will find the LN cylinders match if not better the standard Mahle versions. The one thing you can count on is, Charles N makes very well made parts, understands what quality is and supplies such.

Give him a call and within minutes you will quickly see he knows what he is talking about. I have known him from many years, done very little business with him but we always have reason to discuss many engine issues.

We actually discussed this exact issue at PRI last years and came to the same conclusion, some people should stay well away from supplying parts they have no idea about.

[blue911rsr]

Just got a set back from millennium I gave the the size and the spec for Ra
They came back exactly the way I wanted them
You are the engine builder so don’t blame bad results on other people

[safe]

Originally Posted by blue911rsr

Just got a set back from millennium I gave the the size and the spec for Ra
They came back exactly the way I wanted them
You are the engine builder so don’t blame bad results on other people

Thats like ordering a set of wheels and you have to specify that they should be round....

The RA spec is specific for Nicasil not a 911, if you are in the business of doing Nicasil coating you have to know what you are doing AND have a quality control (the latter is probably whats lacking/missing altogether).

Did you check the RA of you cylinders?

[blue911rsr]

Originally Posted by safe

Thats like ordering a set of wheels and you have to specify that they should be round....

The RA spec is specific for Nicasil not a 911, if you are in the business of doing Nicasil coating you have to know what you are doing AND have a quality control (the latter is probably whats lacking/missing altogether).

Did you check the RA of you cylinders?

Sure did
These people handle hundreds of cylinders mostly non Porsche
So you have to be specific of what you want
I mark all my cylinders to make sure I get the same ones back
Tell them to check a number of things like hight and squareness
Top to bottom
If they are bad when they come back you have something to ***** about
And no it is not like ordering wheels
It like telling the waiter you want something to eat and he brings you a cheeseburger
Instead of a steak
You need to tell them what you want
The eyeballyo meter probably works for most of there work
😀

[KTL]

Anybody who's bought CP pistons should take note of the spec sheet that comes with them. Their sheet actually includes the cylinder surface roughness spec you need to relay to the plater, if you're having original Mahle cylinders re-plated. I don't have the sheet handy with me right now but i'll post a picture of it here when I get my hands on it at home.

As Neil said, the desired roughness is not just based on "hey plater, it's Nikasil so please establish roughness accordingly for that." It's the ring material that dictates your roughness value(s). Charles Navarro has shared some of this roughness data before

smoking newbuild

Excessive oil after rebuild

[cgarr]

The old eyeballs still work, he had it nailed but had to check it anyhow and it was spot on!!!

[KTL]

Nice time machine!!!!!!

[KTL]

Thanks to T Collins for reminding me to post the info from the CP pistons spec sheet. See pictures below

[MST0118]

Thanks for posting the CP specs but I think even relying on this could be problematic. For instance, the sheet recommends an RA of 10 to 12 for ductile moly rings but some builders might prefer to use softer rings with less tension, like certain Goetze rings used on Mahle pistons. I think under those circumstances, it’s probably recommended to go with the 4-6 RA as generally recommended above regardless of what CP generally states above.

I’d be interested to see what RA that LN uses for its Nickies when it sells a combo of pistons/cylinders and if it varies between Mahle, JE and CP. I suspect the RA would be close if not the same because LN probably tries to select the highest quality rings regardless of what piston is used but I could be wrong. I don’t the same knowledge of ring options like others here.

[KTL]

I didn’t mean to imply the CP specs are what everybody should follow, regardless of whether you’re using Mahle, Kolbenschmidt (KS), JE, CP, Omega, Neil’s pistons, or whatever other brand piston. The CP specs should be followed only if you’re running CP pistons with their CPN (nitrided) rings. The specs are specific to the type of rings being used from each piston maker, or more specifically, their chosen ring manufacturer

[Neil Harvey]

Be careful here. The honing specs by CP appear to be more general and I assume for steel lined blocks. It does make caution not to use Chrome for Nikasil, but the honing suggestions are not typical for Nikasil.

What is very good advice given is the note to make sure of the expertise of the shop doing the work.
This disqualifies the third party supplier named often in this thread. Best to use a shop that knows what is required or go direct to the palter of your choice and tell them what you need.

[VFR750]

It took me Three top ends to figure out the rings were never going to seat. A wasted 2015 season.

The cylinders were inspected and yes the honing cross hatch was too deep. The cylinders were replated with the specified Ra.

May 2016, the fourth top end, the Rings seated almost immediately.

Seems to me, this is too easy to fix, yet remains unfixable. No good reason.

Cost me $$$$ on the parts to keep cleaning and rebuilding.

Disappointed to hear this still happens.

[trond]

VFR; you should consider coming out and tell us who screwed up with your cylinders. This need to stop, I am shocked at the scale of this; how many have wasted time and money on buying unsuitable parts and it is allowed to continue. Hard to understand

[VFR750]

EBS was very good to me, they had the cylinder inspected, found the issue, and had Millennium re-plate them with a focus on a low Ra
So here is a history in pictures

You be the judge if the original Ra look too high to the untrained eye: March 2015, "new"




The rings never seated. and i did two more top-ends to chase the issue. ~400 miles per Qt. and smoke on every start. Disassembled in August 2015:


Still leaked so torn down the third time in November 2015:



This is when EBS took care of me and got the cylinder re-plated and specified a smoother finish. As an added bonus, the coated the piston skirts. All for free. Can you really tell the difference? Well, it mattered. Seated well, but still al little bit of blow-by causing some foaming of the oil. Overall >


Since I was getting pretty good with rebuilding my engine, i figured I'd swap in a bigger cam. This turned into an opportunity to re-ring again, with better.

Here is what they looked like in March 2018:



I used Scotch-brite and soapy water to refresh the cross hatching. Plus later I added the Total Seal dry lubricant prior to installing the pistons.


As of today, works really well. Leak-down late last year was 1-2% at 100psia, and compression 148-150 psia on all cylinders.

[VFR750]

I should be appreciated that in 2015 I beat the absolute c**p out of this engine to force sealing.
I did the 20 minute cam break in. Since i did (3) build in 5 months, I had the opportunity to use: SAE 30, VR1, Joe Gibbs , Lucas break in oil, Lucas hot rod oil. Really made no differnece. Many WOT 3000 to 7000 rpm runs and long down hill compression braking. Ring refused to seat. The leakage during the decelleration created some really loud backfires (BANG), and fouled the plugs and the engine would slowly idle and stall. I can document those too.....

In March-May 2016 when I rebuilt the engine for the 4th time, I decided to use Lucas break-in oil (I had the cam refinished for other reasons) And went with JG DT-50 20W-50 oil. In October 2017, I blew a RMS on a really cold track day (15-20F??)

I rebuilt the 5th time(this time for the FUN OF IT!) with a new DC40 cam. Used Lucas break-in oil then switched to only Mobil 1 15W-50 since then. BTW, drove the car 250 miles after this rebuild, and went to Thompson Motor Speedway for a track day. Hammered it after only 250 mile of "break in". All good now.

[VFR750]

Finally
With the Goetze rings I always had a little bit of oil foaming. Early (2015) on there would be a vapor cloud coming from the oil fill.

The Total Seal rings, I tried in 2015, that did not happen, but they did not seat either.

I went back to Goetze in March 2016 (free set of rings from EBS!) still had a little bit of foaming.

Went back to Total Seal May 2018, (with the 2-pc second ring) and aeration of the oil pretty much stopped.

I recommend the Total Seal rings, with the dry-film lubricant.

[KNIGHTRACE]

Updated results, no improvements

[Glenfield]

Seems this has become a generic thread on cylinder finish. Pls slap me this July 4 if not.

I’ve had 95mm Mahle cylinders replated to 6Ra. From what I gathered then and since, that was for Goetz rings. Engine builder wants to use Mahle rings. My concern is Mahle rings may be a different substrate and require different specs on roughness? Would greatly appreciate a steer before it goes back together.

Below quote was very helpful KTL.

Originally Posted by KTL

Anybody who's bought CP pistons should take note of the spec sheet that comes with them. Their sheet actually includes the cylinder surface roughness spec you need to relay to the plater, if you're having original Mahle cylinders re-plated. I don't have the sheet handy with me right now but i'll post a picture of it here when I get my hands on it at home.

As Neil said, the desired roughness is not just based on "hey plater, it's Nikasil so please establish roughness accordingly for that." It's the ring material that dictates your roughness value(s). Charles Navarro has shared some of this roughness data before

smoking newbuild

Excessive oil after rebuild

[KNIGHTRACE]

Many of the older rings were cast and more forgiving than newer hardened steel rings. Not sure of your question Glenfield. I am not trying to be negative, we're having issues and I am not calling out names. I am in need of a solution but I am VERY VERY close...... William Knight