nikasil cylinder corrosion unleaded fuel

[bede]

Nikasil Cylinders Corrosion. I was speaking to a well known BMW race mechenic here in Aus Tuesday & he told me that unleaded fuel is very unfriendly & corrosive to Nikasil cylinders.Has anybody else heard about this & if so is there an additive to help Cheers

[Bill Verburg]

I remember that when BMW came out w/ the aluminum V8 in the 540 they had to replace a bunch of engines because of that issue. I believe it was specific to the metallurgy they used and has not been reported to be an issue w/ 911s

[criv911]

Bill's right, the problem was with the process they used. It was in some way different then Mahle's. Oddly enough they went to alusil cylinder wall and haven't had a problem. Therefore what Porsche can do BMW can't and vise-versa. Ok all you metalurgical engineers out there please explain!

[criv911]

Bill's right, the problem was with the process they used. It was in some way different then Mahle's. Oddly enough they went to alusil cylinder wall and haven't had a problem. Therefore what Porsche can do BMW can't and vise-versa. Ok all you metalurgical engineers out there please explain!

[cnavarro]

I get this question all the time. There are many ways you can screw up the nikasil process- Too thin, too thick, contaminated slurry, inproperly prepped bore... Many of which can lead to poor adhesion, but usually it can be caught at time of honing. I have never seen any of our cylinders damaged by unleaded gas or E10. There is a science to the plating process and every time I have made a change of alloy, I usually supply a cylinder or two for them to practice on to get the process just right and for their destructive testing to measure adhesion of the plating to the cylinder walls.

[RickM]

Right on with the way the cylinders were manufactured.

This plagued the 93-95 1/2 4.0L BMW V8s, including the 740s.

Apparently the sulfur content in US gasoline is higher than in ROW. This would lead to accelerated cylinder wear.

[bede]

I am pleased to hear this.My mate is a BMW nut & knows them well but does not know there was a difference in the 2 processes.Cheers