Problem with my ring

[Taran Las]

Could anyone enlighten confused.gif me as to the benefit thumbsup.gif or downside thumbsdown.gif of running a Xflow (Cast pistons) without the 2nd compression ring. All opinions gratefully received. Anyone done this? How long might the engine last?

 

Thanks

 

Phil Owen

[cdg]

I was only discussing this the other day! Never done it, but if you don't mind more frequent rebuilds I think it's a great idea. Could give you an instant few bhp more as cast generally have thicker compression rings than forged. How about using a Total Seal top ring?

 

There are many high performance engines, from F1 to Superbike, that only use one compression ring.

 

Chris.

[Coose]

The only fear of using one ring in a two-ring piston is the ring-land between the two rings collapsing. This has been known to happen on Yamaha 2 stroke twins, but not sure how a x-flow would cope.

If you're racing the x-flow then I'd say go for forged, single ring pistons if available, but if it's just for road/track day use then surely keeping both rings to help reliability must make sense!?!

wink.gif

 

[Morls]

Cooose,

 

If I recall correctly this reccomendation comes from personal experience, but was it one of my LCs/TZRs or one of your LCs/TZRsquestion.gif

 

I'm sure I can remember shaking a spanny to get the piston bits outsad.gif, but was it an Allspeed, a Micron, Lomas, NK or Yamquestion.gif

 

Mark

[JP]

Ooops! Saw the title of the thread and thought you needed medical advice!

[Taran Las]

JP

 

Thought the title might catch people's eyetongue.gif

 

Thanks for all the thoughts on this - can't wait to hear Roger King and Oily's opinion.

 

Phil

 

Edited by - taran las on 4 Feb 2002 00:26:47

 

Edited by - taran las on 4 Feb 2002 10:13:08

[Taran Las]

Up to the top - cheeky I know.

 

Phil

[Roger King]

Don't do it!

 

Your are likely to suffer from premature piston failure, excessive blow-by and heavy oil consumption. This is especially relevant when using cast pistons.

 

We tried a similar thing about ten years ago, but we had special forged pistons made that were shorter and only had two ring grooves. The engine went well but was doing around 10 miles per pint of oil on the track. Surprisingly it didn't smoke, but following competitors complained that unburnt oil was coming out of the exhaust.

 

Engine failure was not long in coming, due to the oil reducing the octane of the fuel.

 

Following on from this, we made some more 2-ringers, but used special rings that were designed for the job and the pistons had several other modifications to suit the concept. This worked really well, with oil consumption only slightly worse than a standard engine. It could be considered a success, but was too specialised to be a serious production option on a Crossflow.

 

Unfortunately, with a Crossflow, you will never be able to take full advantage of the potential to reduce piston mass, because the crown design is inherently heavy.

 

If you do do it, I'd be interested in the results.

 

[Taran Las]

Thanks for that Rodger, I don't think I'll do it as I want a certain amount of reliability. It was a tight Welshmans attempt to gain a few horses for little money.

 

Regards

 

Phil Owen.

 

Edited by - taran las on 4 Feb 2002 12:54:58