Pistons QSC 2,7

[Lapkritis]

I chose to use copper aerosol sealant (Permatex) for the joint between the head and cylinder in lieu of the CE ring. I used the same sealant between the heads and cam housings. No leaks to report.

No noticeable or detectable wear on the cylinders. I do not have plans to disassemble the engine at this time (famous last words).

When Henry says he experienced wear with similar but not identical cylinders he also states the engine ran too hot indicating improper or insufficient cooling. As many of us know, if you run an engine too hot it will tighten up and wear incredibly fast. I expect normal wear with sufficient cooling, proper fuel ratio tuning and modern oil formula lubrication.

[crummasel]

Hmm.. is that really a solution?
I was thinking about (if i really take them) putting them onto a lathe to produce a proper CE- ring notch...
How do you see no noticeable wear? Have you been disassembliing the engine before?
Great you took the callenge to test them!
Did you also measure to check piston to liner clearance? What has been the tolerance and what has been the tolerance field?
As to Henry they are not very consistent...

[Lapkritis]

Originally Posted by crummasel

Hmm.. is that really a solution?
I was thinking about (if i really take them) putting them onto a lathe to produce a proper CE- ring notch...
How do you see no noticeable wear? Have you been disassembliing the engine before?
Great you took the callenge to test them!
Did you also measure to check piston to liner clearance? What has been the tolerance and what has been the tolerance field?
As to Henry they are not very consistent...

Hello,

Yes, the cylinders were fully inspected by an ASE certified machinist with decades of experience. They are suitable without adjustment. The QSC pistons were not inspected as I used JE instead.

I haven't disassembled the engine since rebuild. Indicators of wear such as oil consumption, loss of power output, noise from slapping pistons nor smoke at any time from the exhaust are not present. Power output is good, engine consumes no oil and there is no smoke.

Originally Posted by Lapkritis

The results of precision measurements for the cylinder bores for the QSC 92mm cast iron jugs were all out .0007" to .0008" top to bottom. You may not notice if you slapped them in and ran them at 3.622" as the margin is not that bad at all.

JE pistons part number 261665 PORSCHE 911 2.7L 92mm 9.5:1 are sized 3.6205" with a manufacturer disclosed margin of error of +/- .0005". This means you can order off the shelf from JE pistons and precision hone the QSC off-the-shelf jug to fit.

I wouldn't recommend retrofitting the CE gasket on an iron cylinder. The CE gasket won't give the same benefit on a cylinder with lower thermal expansion rate. The copper aerosol ensures seal and better thermal transfer without changing the geometry of measurement.

If selecting JE pistons then you should have the piston sized by manufacturer to the cylinder as it is more economical than honing the cylinder to size which is more labor intensive.

[crummasel]

Thank you,

since the engine will basically stay original i will keep the pistons, i want also to keep the "bowl" for the CIS so the clearance values of the original kit would be interesting.

[Henry Schmidt]

Once again Andrew is confused about the information I have posted.
He continues to believe that all the information I post are observations from a singular engine project.
Unlike Andrew, we have observed data in 100+ cast iron Porsche engines. Including 356, 912 and 911 engine equipped with cast iron cylinders. We exchange data with other shops about aftermarket cylinder manufacturers and they have observed similar results in other air cooled application.
When comparing cast iron cylinder wear, we include all manufactures that we've had the opportunity to observed. Malhe, Empi, NPR, AA and QSC
Wear predictions on cylinders with softer cast iron are based on observation of multiple engines built by a plethora of builders.

It doesn't matter if the hardness test of the cylinders is performed with a rock and a chisel of an outside firm specializing in non-destructive critical analysis (which is who we used) if all you're concerned with is a side by side comparison.


Quick note to Andrew: you ask questions with the sole intent to flame any answer, so why would I bother to answer. You asked my professional opinion when you started your project and then set out to prove you knew better. Interesting twist

[Lapkritis]

Originally Posted by Henry Schmidt

Once again Andrew is confused about the information I have posted.
He continues to believe that all the information I post are observations from a singular engine project.
Unlike Andrew, we have observed data in 100+ cast iron Porsche engines. Including 356, 912 and 911 engine equipped with cast iron cylinders. We exchange data with other shops about aftermarket cylinder manufacturers and they have observed similar results in other air cooled application.
When comparing cast iron cylinder wear, we include all manufactures that we've had the opportunity to observed. Malhe, Empi, NPR, AA and QSC
Wear predictions on cylinders with softer cast iron are based on observation of multiple engines built by a plethora of builders.

It doesn't matter if the hardness test of the cylinders is performed with a rock and a chisel of an outside firm specializing in non-destructive critical analysis (which is who we used) if all you're concerned with is a side by side comparison.


Quick note to Andrew: you ask questions with the sole intent to flame any answer, so why would I bother to answer. You asked my professional opinion when you started your project and then set out to prove you knew better. Interesting twist

Zero confusion here. I understand the differences between the two test methods you've claimed from one set of results. I know exactly what you're trying to do here and it's popularly referred to as "befuddling with BS".

If you're taking creative liberties with claims of scientific testing and then claiming empirical evidence after being found out then... understandably I'm going to take everything you say with a grain of salt. Opinions are fine but don't prop them up with BS.

[crummasel]

I bump up the thread once again.
Any further experiences meanwhile?
Any further comments on the CE- ring delete?
Thanks,
Robert

[panama911]

Hi Robert,

I have no particular experience with QSC products - but IF you're going to use these cast iron cylinders, I would think it's a very good idea to machine CE-ring groves into them with a lathe as you suggested above.

Opposed to Andrews recommendation not to do it, it is my understanding that what you are building is essentially the same as a 2.4 T, a rather low performance engine just with a little more displacement (2.7).
Since you are in Germany, you probably won't be building a US-spec early thermal reactor engine either and as a 'housewifes' daily driver this engine will not see too much heat.

As you know, Porsche used the CE-ring on these (2.4 T) engines with cast iron barrels successfully without any known problems - this fact stands in strong opposition to Andrews pure speculation that it wouldn't work properly on cast iron cylinders.

If I was you, I would rely on what is known by experience (I know you have :-) combined with a portion of 'Gesunder Menschenverstand' - but certainly won't go into experiments with modern gasket alternatives like aerosol copper where there is no need to, especially if recommendations for these are based on theory and experience is limited to a single build which not even has been in long term use or disassembled once...

Just my $.02,
Arndt

[Lapkritis]

Originally Posted by panama911

.
... in strong opposition to Andrews pure speculation that it wouldn't work properly on cast iron cylinders.

Arndt,

You've misquoted me here. Please re-read my post. I never stated it wouldn't work properly.

Best Regards

[cgarr]

QSC "quality specialty components" must be good they have "quality" in their name?

[panama911]

Originally Posted by Lapkritis

Hello,
I wouldn't recommend retrofitting the CE gasket on an iron cylinder. The CE gasket won't give the same benefit on a cylinder with lower thermal expansion rate.

Andrew - how should we read this then?

I was trying to answer Robert's question RE fitting CE rings to these cylinders.
I recommended it to him, while you wouldn't (see quote above).

But please excuse me if I got it wrong - English is a foreign language to me.

So according to you, it wouldn't give the same benefit...
as what? ..as used on an Alusil cylinder? ..as aerosol copper?
(One thing's for sure: one cannot properly criticize an unsharp argument. mea culpa.)

However - I'd say it would give the same benefit on these QSCs as on earlier cast iron cylinders. I won't go any further into it, it was just my answer to Roberts question, who asked for further comments on CE ring delete.

Regards,
Arndt

[Lapkritis]

Originally Posted by panama911

So according to you, it wouldn't give the same benefit...
as what? ..as used on an Alusil cylinder? ..as aerosol copper?
(One thing's for sure: one cannot properly criticize an unsharp argument. mea culpa.)

Yes, the benefit would not be as great as a CE style gasket used on an aluminum cylinder with dilavar head studs...this combination of materials has the greatest thermal expansion and contraction.

For this specific inquiry for a grocery fetching, normally aspirated low HP car, I believe it would be a fools errand to bother dimensioning the iron cylinder for a proper channel and ring when the benefit is arguable. With that level of commitment to additional machine time, why not go for a full job and o-ring the head as well with a staggered diameter and a more modern designed, hand-fitted ring and a solid copper medium between head and cylinder? This level of machine work is more in line with a maximum competition level engine.

Steel fastener, cast iron cylinder and an adhesive sealant is a thoughtful design. I did work the numbers on thermal expansion previously and they were favorable to reduced relaxation.

The CE gaskets are prone to fatigue and flattening over time which may contribute to leaks... unlike an adhesive sealant that remains tacky.


A few notes on CE gaskets:

The purpose of a gasket would be to create a better seal and stop leaks. A couple factors come into play that challenge the integrity of the joint between the cylinder head and cylinder beyond the thermal expansion of the fastener relative to the cylinder. The mass of material between the cylinder wall and the wall of the CE channel is critical due to the temperature extremes the material is under. This is where the combustion occurs - the pressure and temperatures are highest in this area. With an overbore, you can compromise the integrity of the wall especially on aluminum.

The CE should be installed with the gap to the top of the engine; the lack of attention to this small detail is likely the cause of more slow oil leaks than we would believe.

[crummasel]

Hi there, and thank you Arndt (kennen wir uns aus dem Elferteam?) for giving the CE - gasket a closer consideration.
In fact i do believe that Andrews version might work (as long as everything is perfectly level) but since the application i am planning is a very very conservative one i tend to using the CE - rings as a no-brainer.
But Andrew: Good point, i will give the portion you mentioned a closer look, not in terms of potential heat transfer but simply for stability as it will lack another 1 mm of wall thickness assuming the usage of the std 2.7 CE ring. If that proves to be too narrow i'd rather machine a more usefull groove for a copper ring...
Machining is no stunt for me, fortunately i have got all facilities inhouse using them regularly as a compensation for my regular occupation. ;-)

[panama911]

So you're saying that they are simply not needed in this config? theoretically?

I guess for that theory to work, with aerosol copper as a sealant or some other sticky stuff for that matter, would require the heads to have a perfect surface?
So he's got to crank up the lathe anyways since we're talking about an old 2.7 beater?

Probably he's done with machining the cylinders before she's back with the groceries - remember, she's got to walk...
Besides, there might be reasons why someone wouldn't want to machine the heads too much.
But this also is plain theory and speculation - I don't know the engine and it's condition.

I think we both made our points - maybe someone else has an opinion on CE ring delete on an early 2.7 rebuild?

edit: oops... too late, Robert's already at it ;-) Ja Robert - man muss ja auch mal woanders lesen

[Lapkritis]

Yep, no use throwing crooked heads on anything regardless of the presence of a CE ring/NI resist ring or not. By the way, a CE ring won't save you from leaks with a warped head surface.

If fitting CE, ensure the gap is at the 12 o'clock position so oil isn't leaking out.

[crummasel]

Andrew, why 1200 and oil leaking?
What do you mean?
Thanks,
Robert

[Lapkritis]

With the gap in the CE ring at 6 o'clock (oil return tube side, visible from the bottom of the engine when installed) you will have a potential path out due to gravity. If you ensure the gap in the CE ring is at 12 o'clock (top of engine, under the fan shroud with engine installed) then the gap won't be in the path of puddling oil in the combustion chamber that may seep out.

[Henry Schmidt]

Originally Posted by Lapkritis

With the gap in the CE ring at 6 o'clock (oil return tube side, visible from the bottom of the engine when installed) you will have a potential path out due to gravity. If you ensure the gap in the CE ring is at 12 o'clock (top of engine, under the fan shroud with engine installed) then the gap won't be in the path of puddling oil in the combustion chamber that may seep out.

I'm not sure I understand the recommendation above.
The CE ring is a solid ring with no gap.

The issue with installing a CE ring on a 92mm cylinder is that only Porsche CE ring available for this application is the 2.7 (90mm) CE ring. The inside diameter of that CE ring is 94.5mm. (IMSM) By using this ring you compromise the inner sealing area of the cylinder.
Some 92mm RSR cylinders were made this way with poor longevity.
The other option is the manufacture a ring. We've done this with 98mm cylinders when an additional seal was desired.
CE rings are designed to control weeping and minor weeping has a very small effect on the overall enjoyment of the 6 six engine.

[Lapkritis]

Pretty straight forward concept. If you put in a ring to seal then make sure any gap is to the top. Porsche, aftermarket wire as I suggest or even piston rings. Mind your gaps orientation. Simple. Questions?

[panama911]

Originally Posted by Lapkritis

Yep, no use throwing crooked heads on anything regardless of the presence of a CE ring/NI resist ring or not. By the way, a CE ring won't save you from leaks with a warped head surface.

If fitting CE, ensure the gap is at the 12 o'clock position so oil isn't leaking out.

With the 2.7, I wouldn't expect warped heads - but heads with a pitted & worn surface...

BUT:

What I totally missed in this discussion was that we're talking about 92mm replacement cylinders, not 90mm... as Robert mentioned above he wanted to keep his original pistons...? (mea culpa again)

since the engine will basically stay original i will keep the pistons, i want also to keep the "bowl" for the CIS so the clearance values of the original kit would be interesting.