Nikasil Cylinders

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Vigilant1

Well-Known Member
The cylinders I have received (all previous 4, and the last 12 which I could make a 2 sets of 4 from, 4 I sent back as un-usable due to defects in the cylinder wall or wrong length) are all steel lined.....the lining is only about 0.035" thick, so it doesn't make much difference to the weight.
View attachment 112220
Tipseynipper,
- That's quite a flaw in the wall of the cylinder (top photo). From a die bit that escaped the collet? Do you think it went through the steel liner?
- How long ago was your most recent purchase of these steel-lined cylinders from QVC QSC? Were they marketed as Nikasil cylinders?
- You've gotten good service since you bought and sorted them (to get some acceptable ones). Aside from weight, is there any advantage over regular steel cylinders? (Lower CHTs, etc?). One of the claimed advantages of Nikasil is their immunity to internal rust (a big issue for those that don't fly frequently). These steel liners wouldn"t be of much help there.

- Even with the differential thermal expansion of AL and steel and their bimetallic corrosion potential, you haven't had a problem related to that?

Thanks, sorry for the interrogation.

Mark

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Tipsynipper

Member
- That's quite a flaw in the wall of the cylinder (top photo). From a die bit that escaped the collet?
It is porosity in the steel liner.
Do you think it went through the steel liner?
Don't know.
- How long ago was your most recent purchase of these steel-lined cylinders from QVC QSC?
Purchased in Dec' 2020.
Were they marketed as Nikasil cylinders?
Yes
- You've gotten good service since you bought and sorted them (to get some acceptable ones). Aside from weight, is there any advantage over regular steel cylinders? (Lower CHTs, etc?).
Just to re-iterate: These photos are of the ones I bought in 2020, the other ones bought about 10 years ago were all of acceptable quality. No differences noted in Oil temp' or CHTs, but I did not run with Cast Iron cylinders before the QSC ones, so I don't have any data to compare with.
One of the claimed advantages of Nikasil is their immunity to internal rust (a big issue for those that don't fly frequently). These steel liners wouldn't be of much help there.
Agreed. Any VW (or any engine) that is not flown regularly should have some sort of temporary corrosion inhibition protocol......such as a corrosion inhibitor injected into the cylinders, or Tennis Ball with a cuttout for the ex' stub and filled with corrosion inhibitor placed over the ex' stubs. Corrosion X or ACF50 are very good. It is also worth supplementing your oil with a product such as Camguard ( CamGuard LAS Aerospace Ltd ). Do not fall into the trap of thinking that ground running or turning the engine over by hand from time to time will help.....it will make matters worse.

- Even with the differential thermal expansion of AL and steel and their bimetallic corrosion potential, you haven't had a problem related to that?
I used a lower torque value for the cylinder heads, I can't remember what it was, and need to review my maintenance info' folder to find it. I sold the a/c about 7 years ago, and have not had the heads off since, or seen it. However, I am in contact with the new owner, who has not had the need to remove the heads.

This photo shows the top of another cylinder that I sent back, it shows (at the bottom of the photo) where the steel liner is so thin that it has flaked away from the alloy. This cylinder had been bored offset so that one side of the liner was thinner than the other.

BrunoTheBear

Member
Did the test today with a magnet. It does stick lightly to the inner surface of the cylinder.
But this is normal as Nikasil coating contains Nickel, which is a magnetic metal (as steel).
I ckecked on ROTAX 912 cylinder (also aluminum Nikasil cylinder) and the magnet stick to the inner surface the same way.
As far as the cylinder height is concerned, they all fall close to 112.5mm except one which is closer to 112.8mm (?!)... guess I'll need to adjust the cylinder shims to get everything well aligned !!

Tipsynipper

Member
OMG! Yes, it will stick to a Nikasil cylinder wall (I tried it on a LN Nickie).......apologies. However, I am still very doubtful as to whether they are Nicasil, as the liner is quite visible on the QSC cylinders.
Yes, the only way to do it is to juggle the shims to get the cylinders level with the 'head, or use different copper top gaskets.......0.012" or 0.3mm is the same difference on the cyl's I sent back to QSC.

Bill-Higdon

Well-Known Member
OMG! Yes, it will stick to a Nikasil cylinder wall (I tried it on a LN Nickie).......apologies. However, I am still very doubtful as to whether they are Nicasil, as the liner is quite visible on the QSC cylinders.
Yes, the only way to do it is to juggle the shims to get the cylinders level with the 'head, or use different copper top gaskets.......0.012" or 0.3mm is the same difference on the cyl's I sent back to QSC.
Probably the best none destructive test to see if they're nickle or not would be XRF (X-ray fluorescence - Wikipedia) some scrap yards have hand held XRF units to test aluminum and other alloys

Daleandee

Well-Known Member
Seen this on Sonex Builders. I post it here for reference ...

Re: Replacing Nikasil Cylinders
by sonex1084 » Fri Jun 25, 2021 10:30 pm

Hi Scott, You probably chose the nikasil cylinders for the same reason I did, the lighter weight. Like you I also read the good, bad, and ugly comments about the cylinders. Some folks had a really bad experience with them while others have been using them for several hundred hours and haven't had a problem. I had the cylinders. so I was determined to use them.

I am currently in the phase 1 flight testing phase, so the engine doesn't have a lot of time yet. The first 10 hours were great. Engine temps were coming down and power was excellent. I was really happy. The engine was breaking in nicely. Then I began to notice a problem. My oil/air separator is not plumbed back to the engine. It collects oil like a catch can. After an hour flight I began draining 2 to 4 ounces of oil from the oil separator. At the 10 hour mark I re-torqued the heads and was surprised at how much I had to turn each nut to tighten them to the proper torque. I flew for a few more hours in case the oil loss through the breather was just a break-in issue. Then I did a leak-down test and found air was escaping through the breather tube on two cylinders. I didn't test the other two after the result of the first two.

I decided to remove the heads and cylinders to have a look. I found the cylinders were glazed and scored. I had heard that some nikasil owners found their cylinders had started to mushroom at the heads. They also were surprised by the amount they had to re-torque the heads. Luckily, mine were not mushroomed to where it was difficult to remove the the cylinders from the heads. There wasn't that much time on the engine, so I really don't know if that would have been a problem for me. Now, I don't know if my problems were because of flaws in the nikasil cylinders or because of my flaws in the break-in process. Sonex no longer sells nikasil cylinders so I have no choice but to replace them with steel. The representative I spoke with at Sonex recommended not using nikasil.

This info probably doesn't help you much to determine if you should switch. I read about the possible problems and still wanted to try the nikasil. I just had to try them and hope I was one of the builders who didn't have a problem. But then again, maybe the issue was mine and not the cylinders.

Good luck and have fun on your first flight. I'm looking forward to hearing about it.

Matt
Matt McKee
Sgt USMC
SGT Raleigh Police Dept
FO GoJet Airlines
Retired Old Man
Sonex 1084

osprey220

Member
Hi Guys,

Just to remind - not all Nikasil coated cylinders are the same. They basically fall into two categories: 1) cast (cheap), and 2) forged/CNC'ed (expensive).

Generally, the cheap cast cyclinders are made by QSC and have been resold by Sonex before even they decided QSC was trouble. Cheap cast cylinders are too soft and just dont work. Additionally, they have poor process and QC on the coating itself - leading to bubbling and flaking.
I have never heard of a happy cast aluminum cylinder experience on the VW.

The forged/CNC'ed cylinders may be had from Scott Casler (Hummel Engines - about $1,500 per set of 4 Home | hummel , or LN Engineering for a delightful$3,800 per set of 4. VW Type 1 - Aircooled Nickies - Products

I have never heard of bad experience with the forged aluminum and nikasil coated cylinders. They are now a standard technology in all high performance engines where weight is a factor. Indeed, most motorcycle engines are made this way now. The Zipper Big Bore kit for the Rotax 912 uses LN Engineering cylinders and to the best of my knowledge they have had no cylinder problems (though they have had a lot of other problems due to producing more HP than the engine was designed for).

Owen