10.5:1 Pistons and EFI

[flatspin911]

I'd like to use the 98 mm JE 10.5:1 High dome pistons on a 3.0L with the 3.2Carrera Intake. I also have a Webcam 120/104. I plan to use ported 3.0L twin plug heads.

This piston / cam combo is promoted as a carb or MFI combination however I wonder how it would work with the 3.2 Carrera intake.

My purpose is to build a higher hp Fuel injected motor based on the 3.0L case.

Anyone have some experience with this combo?

[cowfly911]

This thread may interest you. I am consider a piston change as well...

Intake suggestions for 3.0 with Electromotive FI

[flatspin911]

Excellent thread and sub threads - thanks!

What I'm trying to understand is more about the relationship between the intake, piston domes and cam timing.

[JohnJL]

I did exactly what you did with DR20 cams and got ~235HP and a flat torque curve with power to 6800rpm.

[Steve@Rennsport]

You are going to have some trouble using that intake with those aggressive cams.

Common-plenum intake manifolds do NOT like cams that have much duration or overlap as that causes a lot of reversion that makes for very poor idle and drivability below 3K-4K.

If you like those cams (I do), you should use an ITB system of some kind.

[cnavarro]

I would like to point out that JE has come out with a whole new line of Porsche specific forgings to address the issues some have had with them over the last decade, which I am told, is basically now just like a piston from CP. They were introduced this year at PRI & SEMA.

[Steve@Rennsport]

Hi Charles:

LOL,..Only time (and a lot of race miles) will tell if they are any more durable than their previous offerings.

[304065]

And you'll hear it here first, on the Pelican Engine Rebuild Forum!

(shameless plug)

[cnavarro]

I still swear part of the problem is probably as a result of the expansion of the 2618 forging outpacing the Mahle cylinder and possibly too how the pistons are cammed. The few cases of wripped-out wrist pin bosses sure look like the piston siezed in the bore or was in the process of doing so, but you know as well as I do, that it's hard to make heads or tales of anything once that happens. Knock on wood, I have yet to date have a single JE come apart in a Nickies cylinder, and i'd be willing to bet if I tally it up there are somewhere well over 1000+ sets in circulation with a JE piston in them.

[JohnJL]

Flatspin,
tried responding to your mail but got rejected returns...here's the info you asked for...

Hi,

I used 10.5:1 JE pistons (which cc'd out to 11.2:1!!!) Twin plugs Alu 3.2 intake Have used both Adaptronic and Megasquirt ECUs.
DC20 cams
K&N intake for a cummins 7.4l diesel
Twin triple-channel Haltech ignitors
Twin Ford EDIS-6 coilpacks
SC fuel pump (4 sale, replacing with higher-output series pumps for supercharged setup)
26lb accell injectors (for sale, I am replacing with 55lb for the supercharged setup)
Edelbrock rising-rate FPR Flowmaster 80 2-in2-out Bursch headers

Anything else I can help with?

[flatspin911]

Thanks JohnJL

I'm not familiar with DC20 cams? Are they similar to 964? SC? Webcam 20/21? What are the specs of this cam?

I'd like to use MSII - I see you used this and switched to Adaptronic? What is you experience with the MS?

[Jeff Alton]

They are similar to the 20/21. If you use a 12/104 you need carbs or ITB's.

Cheers

[JohnJL]

I had trouble getting the ignition signal correct on the MS2. I am sure it is operator error. I switched to Adaptronic because the designer and manufacturer lives 10 minutes away and even with his installation and tuning support it cost 15% of what Motec would have cost.

[sjf911]

I am running 98mm with twin plugged carrera heads, intake, and throttle body. The carrera head is a better match for the intake due to the orientation of the injector. Porting out the 3.0 heads doesn't leave a lot of room on one side of the intake port for the manifold to mate to. You will need ITB's for any cam with greater overlap. I am very happy with my 964 setup. 230RWHP on the first attempt at wot tunning on the dyno. Max torque is a little high at 5000RPM but is very flat to redline.

[cstreit]

Originally Posted by cnavarro

I still swear part of the problem is probably as a result of the expansion of the 2618 forging outpacing the Mahle cylinder and possibly too how the pistons are cammed. The few cases of wripped-out wrist pin bosses sure look like the piston siezed in the bore or was in the process of doing so, but you know as well as I do, that it's hard to make heads or tales of anything once that happens. Knock on wood, I have yet to date have a single JE come apart in a Nickies cylinder, and i'd be willing to bet if I tally it up there are somewhere well over 1000+ sets in circulation with a JE piston in them.

FWIW after two seasons with this combination, one of which running too lean a fuel mixture due to a calibration issue (14.2 avg) mine are holding up well (JE with Nickies). I was suprised at how little piston skirt abrasion I saw on this setup compared to the JE/Mahle combo's I've seen...

[flatspin911]

Steve

Are you using the 3.2 Carrera intake or the 964 Carrera intake? 3.2 Carrera Heads?
The 98mm Pistons/cylinders: Mahle 10.1:1 CIS dome style or JE 10.5:1 high dome? What cylinders did you used - Mahle? Nickies? Carrera bored and replated?

[canada911]

I love the 120/104 cams. I have them in a 3.4 (98mm Mahle 9.7:1) with PMO 50mm carbs (still working on off idle transition). The low rpm power is not all that great, but not bad either - above 4500 rpm it is a great deal of fun. A light 2400 lb 1970 shell makes for 12.5 second 1/4 mile times @ 118 mph. 60 foot time was poor as you can imagine.

Have fun.

[sjf911]

Originally Posted by flatspin911

Steve

Are you using the 3.2 Carrera intake or the 964 Carrera intake? 3.2 Carrera Heads?
The 98mm Pistons/cylinders: Mahle 10.1:1 CIS dome style or JE 10.5:1 high dome? What cylinders did you used - Mahle? Nickies? Carrera bored and replated?

3.2 heads, intake, throttle body, and fuel rails. JE pistons, nickies, and 964 cams ala Camgrinder.

[ChrisBennet]

Originally Posted by cnavarro

I would like to point out that JE has come out with a whole new line of Porsche specific forgings to address the issues some have had with them over the last decade, which I am told, is basically now just like a piston from CP. They were introduced this year at PRI & SEMA.

Forgive my ignorance, who is "CP"?
thanks,
-Chris

[cnavarro]

CP Pistons is a member of the Pankyl Group - Pankyl makes Porsche's Ti rods :-)

http://cppistons.com/