10.5:1 Pistons and EFI
 

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?

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

http://forums.pelicanparts.com/911-engine-rebuilding-forum/381867-intake-suggestions-3-0-electromotive-fi.html

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.

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

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.

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.

Hi Charles:

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

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

(shameless plug)

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.

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?

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?

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

Cheers

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.

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.

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...

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?

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.

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

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

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

http://cppistons.com/