Best intake manifold and throttle body for motec'd 3.8 964?
 

Hi,

I have a 964 with 3.8 conversion, cams, motec'd bought as is but running stock 964 intake and throttle body. I have been recomended a 993 varioram manifold and throttle body but after reading 993 varioram thread it seems this may not offer much improvement. What should I run as a manifold and throttle body to release the potential of this motor?

There is no straight answer here because "it depends" on what you want to do and how you will use your car. If outright performance is all you want, then install a 9M Individual Throttle Body setup which will expand your usable power to 7800rpm depending on camshafts. You can install the varioram intake which will give a slightly more broad torque range over the standard plastic manifold, but will add weight in the wrong place. Your other option is to install a good camshaft with your plastic manifold and run the car. If you are primarily a street car, this is the option I'd choose.

Fortunately, with a MoTeC ECU, you can install any intake manifold and the ECU can be configured properly to run the resonance flap, varioram, or simple throttle body.

The rpm limit that your motor will run is the deciding factor.

If you have stock rods & Mahle pistons you should not run it above 7000rpm, therefore the black plastic resonance flap or the varioram manifold will be your only real choice. Of the two, the VR gives more from 2000-4000 and from 6200-7000 whereas the res flap version is stronger from 5000-6000rpm, but there is not much in it to make the change worthwhile. The dyno graph below shows the difference between a pair of identical 9m 993+2 engines with VR and non-VR manifolds.

If you fit a set of 9m or Carrillo rods with suitable 9m or similar forged pistons , you could then safely run the bottom end past 7000rpm. Add a matching set of 9m race cams, valve springs & ti retainers and you will get the performance of the 9m clubsport race engine - as shown in the second graph against a similar 3.8 964RS to your specification, both running 9m Motec conversions. On the strength of this performance we ended up rebuilding the other engine to Clubsport specifications which then gave these 964RS's the performance to match a 997GT3 in a straight line.

All that said, if you want to fit a set of 9m ITB's on your engine and keep the limit at 7000rpm, you will be a winner on the basis of throttle response, looks and sound.....

Thanks very much for the advice. So where to get the 9m throttle bodies, I assume this is ninemeister? Car has all strengthened components and cams and all so individual throttle bodies sounds the way to go. If car already has Motec, all I need is throttle bodies and several hours on the dyno I assume?

Yes, the 9m ITB set up above (pictured on the 993 engine in the back of a 3.2 Carrera) is available through Ninemeister. Where are you located?

Can you install a 9mm throttle body on a plastic 964 manifold without lots of other mods, and is it worth it? The engine is getting 993 headers and straight through exhaust to a muffler.

Colin, how much of a restriction will the 964 heads have on those numbers?