Cylinder Sleeve Clearances

[f1karting]

I am in the process of building up a 83 S3T with a target HP of about 280 and am planning to use Dartons nodular cast sleeves. The plan is to also have Darton machine o-ring grooves in the spigot end with the intent of completely eliminating the usual sealing issues. My question is.. what fitting clearances are ideal for cast liners in an alloy block? I measured some nikasil sleeves on an 88 and they appear to be about 0.002"... seems high to me. I would think closer to 0.0005 would be best in that case. However, I dont expect the cast-in-alloy clearances to be quite the same as nikasil.

Also.. any ideas on how to improve the sleeve stability at the top of the bore?

thx Jan

[USAndretti42]

You need to look at the different expansion of the alloy block and the steel or cast iron liner. They both run at the water temperature more or less, say 95 C and you measure the clearance at room temperature, say 15 C.

The aluminium expands by 24 millionths for every degree it heats up so you take the diameter of the hole, multiply it by the the temperature rise (80) and 24 and divide the answer by 1,000,000. Add this to the starting measurement. That should be the size of the hole at runing temperature.

Steel expands at about half the rate of aluminium so do the same for the nikasil liner but using 12 instead of 24 and see what you get. It will probably be a bit bigger than the hole in the block so it doesn't move about as the engine runs.

Then find the expansion rate of the liner you bought (the manufacturer will know or search it on the internet). Take the answer you got for the Nikasil liner expansion and work backwards, multiplying by 1,000,000 and dividing by 80 and the figure you found for your liner and take this figure off the size of the hot Nikasil liner you worked out. This will tell you what it should measure when cold. The difference between this and the block measurement is the clearance you should need.

I hope that's clear.

[WayneB]

I thought Tony Rudd was the only person who could have answered that post(then I realised he was dead) well done Trev....do you work for Lockheed-Martin?

[USAndretti42]

..do you work for Lockheed-Martin?

No, Wayne. I work a little further south, for Honda.

[f1karting]

Hi Trevor.. it makes sense to me. Is steel is exactly half that of aluminum?

The nikasil sleeve is actually an alloy sleeve with a nikasil coating on the bore. I am confused why they had 0.002" clearance even though the block and sleeve were both an aluminum alloy. If 0.002 is correct, then based on your theory, the early cast sleeves as used on the 83-86 910 engine may have been designed for 0.001". However, given the expansion rates of the components, neither sleeve would likely to be an interferance fit at 80C. Hence my question about the clearance spec and stability.

It would be nice to find out the technical data and blueprint specs on the liner to block fitment. But it seems likely lost with its designers. Perhaps Dartons engineers can enlighten me.

Do honda use a sleeve system on their engines? What is the practice on other performance engines using sleeves?

Thanks for your input.

Bibs.. I see you moved the thread. It was originally placed in the general chat to get better coverage since it is not a g-car only tech question... any chance you could link this thread to the other technical pages so I can get more feedback? Jan

[USAndretti42]

Thinking a bit more I was talking rubbish about the interference fit as the steel or iron would not expand more than the block so if the liner is a clearance for cold, it will have more clearance when hot.

The o-rings keep things in place. They are pretty incompressible when restrained by the grooves so the groove in the liner needs to stay reasonably close to the block. Clearance can't be too tight or the o-ring will get damaged when you put the liner in. 0.002" sounds about right