Which cam on 2,2E with high dome pistons ?

[71er E]

i´m on to rebuild my 2,2E with JE Pistons (high dome) and cylinders. Does anybody know if the "E"-cams will still work or do i have to change it to "S"-cams ?

Best greetings
Armin

[Flat6pac]

I would say the E cams would work because the S cams have longer duration and lift. The S cams will be closer to the pistons vs. the E cams at cam timing settings.
Bruce

[71er E]

Originally Posted by Flat6pac

I would say the E cams would work because the S cams have longer duration and lift. The S cams will be closer to the pistons vs. the E cams at cam timing settings.
Bruce

hmm i thought it´s vice versa. The "S"-cams should have shorter duration at same lift, or ?

[Grady Clay]

It is totally dependent on ‘which’ JE pistons you have.
Consult JE.

If the pistons are cut to fit the S-cam, then the E-cam will easily clear.

With aftermarket pistons, it is good (necessary) building practice to measure the actual piston-to-valve clearance with all the parts in place as they are to run.
This is also true for the piston-to-head clearance and the actual (measured) compression ratio (CR).

If these clearances are too close and contact is made, bad things happen to your new expensive parts.
Better safe (measured) than sorry.

Best,
Grady

[jpnovak]

Cam choice will depend on where you want peak power. E is more of a mid-range cam and S is more of a high-rpm cam.

Only you can decide how you want to change compared to your stock E when it comes to driving character. The Solex, Mod-E or similar cam would be my choice for a street car that just needs a little more pull at higher rpm.

The JE pistons should have deep enough valve pockets to clear whatever cam you want to use.

[bkreigsr]

'Mod S' from John Dougherty (user name camgrinder)
worth the wait

wake that puppy up!

Bill K

[Grady Clay]

I agree, these pistons look like they are cut for very large diameter valves and possibly high lift and duration cams.
My point is that you must know.

This looks like a very nice set of 84 mm (or are they 85 mm?) forged pistons and Biral cylinders.
The pistons appear to have unnecessarily large valve pockets.
There is a building principal to have the valve cut-out just ‘large enough’ and not give anything away by having them too large.

‘Giving something away’ is the trade off with CR and piston crown height.
The larger piston crown height raises the CR to the desired number.
The valve cut-out lowers the CR.
With a ‘too large’ valve cut-out, the piston crown height must be unnecessarily higher to get the proper CR.
High crown height is undesirable because it interferes with the flame travel during combustion.
This is particularly true with single plug engines. (Looking at these pistons, they would greatly benefit from twin ignition.)

What is the maximum size (diameter) valve that will fit in these valve cut-outs?
This should be about 1-2 mm larger than the 46 mm intake and 40 mm exhaust valves for your 2.2 engine.
Larger cut-out unnecessarily lowers the CR requiring an unnecessarily higher crown height.


Have you decided on what CR you intend to use?
That number is dependent on your use, access to high octane fuel and a number of other factors.
The CR is also dependent on your choice of cams.
You can effectively use higher CR with an S cam than with an E cam.


Does your 2.2E still have the MFI?
If so, it is undesirable to stray far from the 911E cams in the engine unless you change the space cam in the MFI pump.
The head intake ports, cams, throttle bodies and stacks are all size-matched to the space cam in the pump.
Carburetors are ‘smarter’ (just not as ‘cool’) and meter fuel in proportion to the air flow – whatever parts you use.
Well matched MFI produces more power and better over the entire rpm range.

I hope this helps.
Search the 911 Engine Rebuilding Forum. There has been a lot of this technical discussion.

Best,
Grady

[cmcfaul]

I have what looks like that exact set up in a 2.4 with both E cams and the Mod Solex (dc30). You are probably at a 9.5/1 CR

The e cams work nicely in this setup. They are matched to the MFI exactly and with the increased CR produce a noticeable increase in torque and HP. They do, however run out of breath at 7000 RPM's. I also burned a piston with this setup as temps got a bit hotter then I should have let them.

Recently I went to the DC30 (mod solex) grind. This is basically the e-cam with more lift. What it does is sacrifice some compression for VE (volumetric efficiency). For me this was desirable as I did not want to burn another piston.

The result of the DC 30 cam is a VERY smooth running engine that increases in HP all the way to 7300 rpm's and probably beyond. The down side is that the E MFI is not exactly tuned to this cam. I installed an air fuel meter to help get it dialed in and while close it is not perfect. I achieve optimal air fuel mixture at idle and 3/4 + throttle. I am rich at cruising speed 1/4/ - 1/2 throttle.

Both setups produce a car that is surprisingly quick.

Chris

73 911 E

[Flieger]

Originally Posted by 71er E

hmm i thought it´s vice versa. The "S"-cams should have shorter duration at same lift, or ?

No, S has more overlap, which is why the E cam has more midrange power but the S had more on top.

[71er E]

Thanks guys for these info. Please excuse my bad grammar. The engine has still it´s (overhauled) MFI. As i´m informed the space cam in the MFI is the same on an "E" and an "S".
This JE-pistons and cyl-set was sold over our german forum (on a acceptable price) so i decided to buy. Here are the specs:

84mm FORGED JE PISTON
BYRAL CYLINDERS,
COMPRESSION HEIGHT: 34.2mm (1.347")
PISTON TOP: 11.5mm (.453")
PISTON RINGS: TOP:1.5mm 2nd: 1.5mm OIL: 4mm

I want to keep the "E"-cams but i couldn´t find anything about the
clearance between the pistons and the valves when using the
original cams with these JE-pistons. On email requests which
i sent to JE, i got no response until now. I will unscrew my machine
and will measure it out but it would be helpful to know it if i´m in need
of some "S"-cams as they are kinda rare here in Germany.

[cmcfaul]

If your E cams have no wear, definitely keep them. A stock E car (especially with higher compression) is faster to 60 then an S. If you go with S cams you will need to have the MFI rebuilt with an S space cam. Your E cams with the higher compression pistons will be an awesome power plant. Mixing parts opens Pandora's box and your wallet.

Those JE pistons have nice deep valve pockets. I would be very surprised if you have clearance issues if they are from JE and designed for your application. JE makes two versions. A 9.5/1 and a 10.5/1 CR. 9.5 is as high as I would go with a single plug setup and E cams. Both with require high octane gas.

Good luck, you won't be disappointed.

Chris
73 911 E

[71er E]

Originally Posted by cmcfaul

If your E cams have no wear, definitely keep them. A stock E car (especially with higher compression) is faster to 60 then an S.

Hi Chris,

thanks for that. Exactly what i wanted to hear . I´ll get it on in the next weeks and will tell the result....

[Grady Clay]

Originally Posted by 71er E

The engine has still it´s (overhauled) MFI. As i´m informed the space cam in the MFI is the same on an "E" and an "S".

You are incorrectly (wrongly) informed.
The space cam in the MFI pump is very different between the 911E pump and the 911S pump.

Your 911E pump should be Bosch 0408 126 010, Porsche 911.110.221.00.
A 2.2 911S pump should be Bosch 0408 126 009, Porsche 911.110.222.00.
The difference is in both the space cam and the pump settings.

Any pump can be modified with another space cam and recalibrated for different engines.
However, the airflow characteristics of a given engine are ground (‘cast in stone’ so-to-speak) onto the space cam.
We are limited by a small choice of space cams when building a non-standard MFI engine.
If you stray too much from standard airflow characteristics, or use mismatched components (T pump with E cams for example), you run the serious risk of a too lean condition under unexpected conditions leading to a failure.

If you take a standard Porsche configured MFI engine, you can easily raise the CR and increase the displacement and adjust the MFI to compensate.
This is within the possibilities for MFI.


What are the JE part numbers for the pistons?

What are the (measured) piston-to-cylinder clearances?



By Google Translate:

Sie sind falsch (zu Unrecht) informiert.
Der Raum Nocken sind nicht dasselbe.
Der Raum-Cam in der MFI-Pumpe ist sehr unterschiedlich zwischen den 911E Pumpe und die Pumpe 911S.

Ihre 911E Pumpe sollte Bosch 0408 126 010, Porsche 911.110.221.00.
Ein 2,2 911S Pumpe sollte Bosch 0408 126 009, Porsche 911.110.222.00.
Der Unterschied ist sowohl im Raum Nocken und die Pumpe Einstellungen.

Jede Pumpe kann mit einem anderen Raum Cam modifiziert und neu kalibriert für verschiedene Motoren.
Allerdings sind die Luftströmung Eigenschaften einer Maschine Boden ("in Stein gemeißelt", so zu sprechen) auf den Raum-Cam.
Wir sind eine kleine Auswahl von Weltraum-Cams beim Bau eines Nicht-Standard-MFI-Motor begrenzt.
Wenn Sie zu viel von Standard Luftstrom Eigenschaften, Verwendung oder streunenden übereinstimmende Komponenten (T Pumpe mit E Nocken zum Beispiel), führen Sie die ernsthafte Gefahr einer zu mager Bedingung, unter unerwarteten Bedingungen führt zu einem Ausfall.

Wenn Sie ein Standard Porsche konfiguriert MFI Motor nehmen, können Sie leicht erhöhen CR und erhöhen die Verschiebung und stellen Sie die MFI zu kompensieren.
Dies ist im Rahmen der Möglichkeiten für MFI.


Was sind die JE Teilenummern für die Kolben?

Was sind die (gemessen) Kolben-to-Zylinder Freigaben?

Best,
Grady

[71er E]

Originally Posted by Grady Clay

What are the JE part numbers for the pistons?

What are the (measured) piston-to-cylinder clearances?

Grady seems that you´re right on the space cam. Thanks for
sharing your knowledge. The packages were the pistons and
cyl are stored do not have any number on it but the pistons do (pic).
I did not know that there is more than one piston-set for the 2,2´s

PS: You don´t have to use a translator...i do understand every single word....

[Steve@Rennsport]

Thats an 83mm piston. The number on the pin boss is the JE job number and if you contact them, they can provide CR & compression height.

Run them at .0025" clearance.

[Grady Clay]

Armin,

Here is the “Identify” page from the JE website:
How To Identify - JE Pistons




I don’t see a necessary number on your piston.



You should email JE with your image and ask for the specifications on these pistons.
euro@jepistons.com

Measure the diameter of the piston (to 0.01+ mm) to provide them that number.
Measure the piston-to-cylinder clearance and compare to Steve’s recommendation.


I am curious why these appear to be 83 mm.
A 2.2 should be 84 mm.
Are these a 3 mm over-bore on 80 mm (2.0) cylinders?

Please post an image of the head gasket surface on the cylinder (2.0 is a flat gasket, 2.2 is a CE ring).
My lame eyeball tells me the piston crown appear so high that they could be for the deeper 2.0 head and very high CR.


What is the engine number and the type number of your engine?
What are the casting numbers on either side of your crankcase (just below the oil return tubes)?

Best,
Grady

PS: Armin, the translation was an offer to be polite for our members who are not English as their first language.
We want to encourage others world-wide to participate in this Forum.
If a little Google Translate helps, great.
Most, world-wide can read 'Porsche technical' without translation and get the gist.
Anyone can post in their native language and include a Google (or other) translation to English.
Every Porsche enthusiast is welcome here and we all benefit.
G.

[71er E]

...now it´s becoming misterious. My engine is a 2,2E made in 05/1971.
I bought these pistons from a guy that imported a 2,0l 911 from California.
He told me that this set of cyl and pistons is not matching his engine and it
should match the 2,2l. I think we only will get a clear answer by asking JE directly.
Following pic shows my engine number. (Edit: me little stupid, that´s not the
engine nr. sorry)

[71er E]

Short news:
On my 5 emails to JE i got no response. The diameter of the pistons is app. 83,90 mm. I gave the set to my local Porsche mechanic for exact measuring and it seems that i can use this CP-Set with my E-cams.

Engine data: 2,2 E
Year/month: 1971/may
Engine nr: 621 1518

But there´s one question unanswered. Has anybody out there any data regarding cam-timing ? Should i use the factory-timing for the normal E-pistons ?

Any help would be appreciated.

[Grady Clay]

Armin,

As you noted, the picture is of the casting number.
With your May 1971 casting, the other half of the crankcase should be 901.101.102.3R.
Can you confirm?


Cam timing on a 2.2 911E (type 911/01 and 911/04) is:
Intake valve lift at TDC Overlap with 0.1 mm valve clearance - - - 3.00 mm to 3.30 mm with ‘desired value’ 3.15 mm.

Specs for the 901.105.181.00 (L, MFI) and 901.105.110.05 (R) cams are:
Intake lift 36.58 mm.
Exhaust lift 36.25 mm.
Intake opens 20° ATC.
Intake closes 34° ABC.
Exhaust opens 40° BBC.
Exhaust closes 6° BTC.


This afternoon I’ll call JE and ask why you got no response to your five emails.
I may have posted an incorrect (or not monitored) email address from their website.

It is critical that you know the CR, deck clearance and valve clearance.
Regardless of input from JE, any good builder will physically measure these critical numbers.
I would be particularly cautious given the pistons don’t have the markings noted in the JE website.

If, for some reason, you buy new pistons for your cylinders, send the cylinders to JE for accurate fitting piston size (you can specify the clearance).
You can also choose smaller valve pockets, more suitable for your valve size and 911E cams.
This allows for a lower piston crown (better flame travel) at the same compression ratio (CR).

Please post images of the tops of the cylinders where the head gasket sets.
It is not clear (to me) if these are for a 2.0 head or a 2.2/2.4 head.

What does the piston-to-cylinder clearance actually measure?
(Note Steve’s post above.)

Have you considered twin ignition for this engine?

Best,
Grady

[jluetjen]

71erE; When you get your engine back together I would also suggest that you get it dialed in on on a dyno. I've got a 2.0E with S pistons, which is similar to the configuration that you seem to have. The difference is that the 2.0's had smaller valves, a different combustion chamber shape and of-course a smaller bore. As cmcfaul alludes to, you'll need to adjust (ie. retard) your ignition timing some unless you want to burn through a piston. But too much will introduce a whole new set of problems. Essentially the window of acceptable timing will have shrunk since you're increasing the CR. It's best to know where you stand rather than guess and melt a piston as I have in the past.