3.5 litre twin plug engine

[Howard Lazarus]

This is what is presently keeping me awake at night, and distracting me at work during the day. Do any of you own one, or ever driven in a 911 with one? If so, what is/was it like? I am thinking of something special for one of my RGruppe cars, other than a 993 3.6L Varioram conversion. Thanks in advance for any insights!

[Mr9146]

Kurt has one in his red rocket. 3.5 w/slidevalve I believe.

[andyjboy]

Yes - this is Kurt Zimmerman's 3.5 litre twin-plug slide valve engine:



It's based on an '84 3.2 Carrera crankcase & contains many rare/trick parts including 906/910 cams, Bosch 935 twin-plug distributor, Andial slide-valve injection, RSR headers, 917 megaphones & mounting brkt, RSR lightweight flywheel & clutch, etc...

[Eric911S]

Hello: I have built and run 3.0,3.2,3.2 short stroke,3.4 engines. My personal favourite is the 3.2 short stroke. It just revs and pulls to 8000 rpm (do that with your 3.6). The torque is very close for the 3.2 and 3.4 but the 3.2 just seems to rev faster. All of these engines where used with gearboxs that have shorter gears and limited slips. If I was you I would sit down and figure out what you are going to use the car for then see if the torque is what you want or the high RPM. If you want the torque you may just drop in a 3.6 with PMO carbs and keep on grinning all the way to the bank. Good luck with your project and get some sleep. Thanks Eric

[p-thomas]

I have an MFI 3.5 in my '70 T. It is similar to Kurt's motor but lower compression pistons. Mine makes about 250hp compared to Kurts ~360hp. Honestly if it had much more torque it would be hard to drive fast in a narrow body car, it is a blast as is. Mine had an RSR distributor when i bought it but i sold it and bought a crankfire set-up and a bunch of other stuff. The MFI is a modified RS pump, bored out mag intakes and custom throttle bodies from Eurometrix.

[Paul Schooley]

Wowsers.....very nice car. You must be proud of the work you put into that.

[TRE Cup]

3.5 motor= torque galore! we've had a 3.5 mfi, 3.5 motec, 3.5 sds efi, and 3.5 cis pass thru our hands and all brought big smiles to our faces. Since all had cams in them, they seemed to be "quicker" feeling than the 964 3.6. Of course there were no back to back comparisons with any of the combinations so a properly set up 3.6 could be just as fast or faster too

[Howard Lazarus]

Thanks everyone for your input. I am very grateful!

Dave, my project will begin on a carburated 3.0 litre that presently has Weber 40 mm IDA's. I am thinking of stepping up to 46mm PMO's. What do you think?

[kenikh]

Honestly if it had much more torque it would be hard to drive fast in a narrow body car, it is a blast as is.

You could make more power with the same torque curve with higher CR pistons and a hotter cam. Oh the fun you would have...

[TRE Cup]

unless you get big compression into that 3 liter, the 46s will be a waste of money. You will end up choking them down to make them work well on the street. You need at least a 3.2 or larger to make use of the 46's in hot street trim
PMO carbs are great btw.