Boxster piston ring end gaps?

[Homeoboxter]

Originally Posted by maytag

Ohhh.... i'd probably back the bus up abit, if I were you. At least lay on the brake some...
If you're trying to do this even partially "right", you shouldn't be letting $100 worth of snap gauges and a caliper stop you. Take your time, do it right. You'll be glad you did.

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I do have a caliper and snap gauges, but those are useless to measure cylinder wear. For that you need a bore gauge, and you are right, they are actually much cheaper than I remembered, so I might go ahead and invest into buying one or just take the cases to a machine shop and get them measured. Still, I don`t know the tolerance values for the bore, not even sure if they were released by Porsche.

[Homeoboxter]

This would do it, for sure no machine shop would measure the wear and ovality for me for this much:
https://www.amazon.com/Blesiya-50-160mm-Cylinder-Internal-Measuring/dp/B07K59JPYH/ref=sr_1_8?s=industrial&ie=UTF8&qid=1547515233&sr=1-8&keywords=bore+gauge+metric

[Homeoboxter]

I still don`t know if the 2.5L and 2.7L piston rings are interchangable. Based on the dimensions (bore size and thickness) they should be identical. However, the sellers say the 2.7L rings won`t fit my 2.5L engine based on the catalog. Am I still missing something here? I already posted some info about the ring end gap measurements in my show&tell gallery and asked the same question there: http://986forum.com/forums/show-tell-gallery/73917-blue-boxster-resurrection-project.html
Perhaps more people read this thread and there`s somebody out there who has seen both of these engines apart and know the answer? Thanks!

[Ottomotion]

Dial the dealer?

Post up on Rennlist?

[marsheng]

The ring gap will seldom change down the bore. The ring wears and opens up the gap. If there is wear in the bore, you will feel a lip just above where the ring stops at the top. No step, bore ok.

[Homeoboxter]

Originally Posted by marsheng

The ring gap will seldom change down the bore. The ring wears and opens up the gap. If there is wear in the bore, you will feel a lip just above where the ring stops at the top. No step, bore ok.

Yeah, I checked that, I think the bores are fine, there`s no lip. It`s possible though that there`s some ovality, and the wear may be different along the bore due to the different piston speeds at different heights. So I`ll measure this just in case. BYprodriver also had a fair point when suggested that if the wear is substantial I may have a better seal with the original rings in the same position than with new ones. But most likely it`ll be fine with a fresh ring set once I find one. I think I`ll just go ahead and order a set for the 2.7 and send it back if it doesn`t fit, but I doubt that.

[marsheng]

Originally Posted by Homeoboxter

BYprodriver also had a fair point when suggested that if the wear is substantial I may have a better seal with the original rings in the same position than with new ones.

Rings can rotate during their life so there are no original ring positions. Always give a light hone before installing new or old rings to help bed them in. .

Cant find the link on running in a motor but if you are using old pistons, a few squirts on the accelerator with a back of is all that is required.

Have you ever see race cars do 10000 miles as slow speed to run them in ?

New pistons, new hone, 2 - 3 heat cycles and pedal to the floor.

Quite and old video of mine.

https://www.youtube.com/watch?v=PsEFKYULNDc

Cheers Wallace

[Homeoboxter]

Originally Posted by Ottomotion

Dial the dealer?

Post up on Rennlist?

Thanks Otto, the dealer is gonna tell me what the catalog says. I can try Rennlist, but mostly members there and here overlap, don`t they?