Piston ring end gaps.

[EMWynne]

Continuing with the rebuild of my 2.5 M96/20 engine...I am now ready to install pistons 1/2/3...checked the ring gap with a piston to keep the ring square in the bores...all 6 top ring are between .014" & .016" I,m happy with those...BUT...all the second ring gaps are between .034" & .036"...normally they would be .002" larger than the top ring gap...these are new Mahle rings & my bores are very good condition wear wise...surely those 2nd ring gaps are much to wide for new rings...I,ve seen rings with less gap after 2 hundred thousand miles...anyone have the correct Porsche spec ring gaps.

[ike84]

Originally Posted by EMWynne

Continuing with the rebuild of my 2.5 M96/20 engine...I am now ready to install pistons 1/2/3...checked the ring gap with a piston to keep the ring square in the bores...all 6 top ring are between .014" & .016" I,m happy with those...BUT...all the second ring gaps are between .034" & .036"...normally they would be .002" larger than the top ring gap...these are new Mahle rings & my bores are very good condition wear wise...surely those 2nd ring gaps are much to wide for new rings...I,ve seen rings with less gap after 2 hundred thousand miles...anyone have the correct Porsche spec ring gaps.

I just checked the factory workshop manual, no specs listed there. Sorry dude.

Sent from my POCOPHONE F1 using Tapatalk

[EMWynne]

Thanks Ike...that seems to be the problem, none of the manuals give the specs because they did not expect the engines to be rebuilt...but people are rebuilding...you can now buy all the parts required...so somewhere there is the correct specs.

[Homeoboxter]

I replaced the rings in my 99 Boxster because the ring gaps were pretty large at the oil rings. Here you find some reference about the gaps of used rings versus the new set I used:
Blue boxster resurrection project

[Homeoboxter]

Oh, page #6 and #7.

[Quadcammer]

Thats definitely wrong. I aimed for 17 top, 18.5 2nd ring. .034...they sent you the wrong set

[EMWynne]

I have been chatting with my Porsche parts supplier & for those who said that 2.5 & 2.7 ring sets are different...he advised me THEY ARE NOT...all Mahle part number504-04-N0. standard...N1 for plus 0.010" & N2 for plus 0.020".

[Homeoboxter]

Originally Posted by EMWynne

I have been chatting with my Porsche parts supplier & for those who said that 2.5 & 2.7 ring sets are different...he advised me THEY ARE NOT...all Mahle part number504-04-N0. standard...N1 for plus 0.010" & N2 for plus 0.020".

Yes, I used 2.7 rings for my 2.5. The seller of course was convinced they won`t fit but I bought them anyway and they did. The stroke is different, the bore is the same.

[EMWynne]

I have just had an e-mail from the Senior Product Manager at Mahle...he quoted the ring gaps for piston ring set 504 40 N0 for Boxster 2,5/2.7cc engines as,
Top ring-0,15...0,35mm....006"-.014"

2nd ring-0,60-0,80mm....024"-.032"

oil control-0,50-0,75mm...020"-.030"

a very wide 2nd ring gap but they are correct.

My rings are still out of spec. brand new.

[EMWynne]

Homeoboxter, Where did you buy your ring set & do you have a part number...what did you set all your ring gaps to...because your car runs great with no problems...oil consumption etc.

[Homeoboxter]

Originally Posted by EMWynne

Homeoboxter, Where did you buy your ring set & do you have a part number...what did you set all your ring gaps to...because your car runs great with no problems...oil consumption etc.

It`s been two years now, but I believe I had bought these:
https://www.ebay.com/itm/PR1400-Porsche-Boxster-H6-2-7-Piston-Ring-Set-00-08-/164155998893

I didn`t touch the gaps, wasn`t necessary. Look at the build thread, i think I listed there what the gaps were like with the old and the new rings.