F5A engine parts

[Almost a Mini]

Can anyone confirm that F5A piston rings are 1.50mm thick? The ACL piston ring catalogue seems to say this. . .
The rings in my DOHC turbo F5A measure out at being 1.2mm thick. . .I guess that's not surprising for a higher performance engine. . .
The rest of the bottom end of the DOHC F5 seems to be identical to the local version - big end and main bearings are identical and the rods, crank and seals seem to be the same. It's really only the pistons that vary. I haven't had a good look at a piston from a local F5, but the turbo ones have cast-in fly cuts to clear the valves and are heavily dished to drop the compression (haven't measured the volume of the dish as yet).
This is a reeeaaaly long shot, but does any one know if there are manufacturers out there that do off the shelf performance pistons (either cast or forged) for F5's? I know Suzuki Sport do forged piston kits for the larger three-cylinders but the poor old F5 seems to be left off the list. . .

Thanks,
Pete in Perth

[Brayden]

I'd suggest that if you want hi-po forged pistons then sourcing them from a motorcycle place might be a good start.

Colin, being the guru of these things, might be able to help with some info.

[Colin]

from experience you will find that different manufacrures have different ring land sizes you
suzuki are one of the worst for changing things mid production
the easiest way is to replace pistons and rings togeather or mesure the ring lands with vernier callipers and pass the mesurements on to the spare part supplier.

[Almost a Mini]

Thanks guys.
I'm not sure that forged pistons are necessarily required - after all, Suzuki must have deemed cast postons to be capable of running 7psi of boost at 9,500rpm. . .having said that, if I could find something suitable, I'd certainly go for it.
On the subject of pistons, do high(er) performance engines generally run a higher piston-to-bore clearance? The pistons in my F5 aren't showing any appreciable wear and are still round. . .and the bores are just about perfect - round and still showing hone marks - however there is *considerable* sideways movement of the piston in the bore (I haven't measured the actual amount but it certainly appears more than in other engines I've dealt with). Is this just to allow for the extra heat that a turbo'd motor generated in the chambers?

Just out of interest as well. . .the big end bearings were showing some pretty interesting wear patterns - they were well worn all the way 'round their circumference *except* for the section immediately beneath the beam of the rod. Does that sound like the sort of wear that big (and probably excessive) revs would bring on?

Thanks,
Pete in Perth

[Colin]

pistons can handle heaps of boost (ceramic coating helps too) your main problem will be the big end bearings and con rods at your high rpm

[Almost a Mini]

pistons can handle heaps of boost (ceramic coating helps too) your main problem will be the big end bearings and con rods at your high rpm

Yeah, I must admit, I'm a bit worried about the rods - from all appearances they are the same as the Oz-spec SOHC F5 rods - which means they're pretty spindly little things.
However, I cant see much point in using absolutely massive revs in a turbo engine - especially one with a turbo as tiny as the RHB31 on the F5. . .by somewhere around 6500rpm it's run out of puff, so there's really no advantage in going much past that anyway.

I was planning on having the piston crowns and skirts as well as the valves and chambers ceramic coated providing I can find someone here in Perth that does the work. . .do you (Colin) know if 'old' pistons can be coated, or do you have to have new ones - I can imagine an old, oil/fuel/carbon impregnated piston would be all that good for bonding ceramic to. . .

Pete in Perth

[Colin]

bead blast the pistons they should ba able to be coated