968 Cylinder Head

[colinham]

Will the 3.0 968 Cylinder head bolt on to the 944S2 engine or do you also need the inlet and exhaust manifolds from the 968 as well. I know you also need the 968 ECU wiring loom to provide the correct fuiling and ignition. Finally is there any company that provide a throttle body kit for the 3.0 engine that comes with its own management ECU set-up ?. Thanks Colin

 

[Neil Haughey]

Ninemeister I believe up around Warrington tried throttle bodies a couple of years back on a 968 but it doesn't work down to an inherent flaw in the cylinder head design.

 

[sawood12]

Kokeln have used individual throttle bodies in their race car.

 

[PJS917]

The inlet manifolds are quite different, I have never studied the outlets but I imagine they are different as the
exhausts are unique to each model.

There are a few people claiming to be playing around with throttle bodies in the states, and as Neil says 9m tried without good results, the ports on the 968 are very large and the design of them and the manifold do not aid ram effect into the cylinders. I too have looked into fitting throttle bodies onto the 968 but got scared at the costs.

 

[sawood12]

The problem with the 968 is that because it has variable cam timing the shape of your inlet manifold also needs to change to maximise the benefits of changing your cam timing. Because the 968 manifold is a fixed design it is a compromise. The Boxster/996/997/Caymen engines with variocam and variocam plus have a variable volume inlet manifold as well (a bit like varioram on the 993) that maximises the benefit of the variable cam timing.

 

[PJS917]

The manifold on the 968 has two paths 1 short 1 long that the airflow can take, it appears that it should
have a valve to change the airflow, as it is the air flows down both and mixes in the plenum chamber. Had there been a valve fitted it would be able to change the air flow charcteristics in line with the variocam.

The whole air intake on the 968 is a compromise, but like the Cayman Porsche marketing dept could not
allow another model upstage the 911 so the 68 was not tuned to the optimum. I have done some work on my 968 head and with unlimited funds I was assured with better inlet airflow significant improvement in power gains could be made. The outlet side is already very good.

 

[sawood12]

Good stuff Peter, good to hear about people who are actually rolling their sleeves up and trying things out.

Back on topic - I don't think the 968 head can bolt straight onto an S2 block. If it can phsysically bolt on, you'd have to do so much work around the engine to get it working so you may as well drop a complete 968 engine and ECU in there.

 

[PJS917]

I had come to the same conclusion, the best way to fit a 968 head into a 944 will be to fit an entire 968 engine in it,
and 9m have done that in the past.

 

[zcacogp]

How much more oomph, in the real world, will a 968 engine deliver over a 944S2 engine? The 968 lumps are not reputed to deliver their full 250 horses, but what about mid-range torque as well?


Oli.

 

[PJS917]

The 968 has noticeably more mid range torque, which makes them easier to drive on a daily basis. To get similar performance out of the S2 you have to work it harder and there are times when coupled with the different gear ratios the 68 leaves the S2 wanting.

I don't think many 968's produced the full compliment of German horses, however a good re-map and a little work can certainly improve things, with comparatively little work I got mine up to just over 250 horses. (More work on the bottom end still to come[][][]) The S2 engine arguably is easier to mod as it does not have the DM flywheel or the variocam. But in stock form the 968 engine has more torque when you need it.

 

[sawood12]

I'd have thought the variocam would be a desirable feature for eeking more horses out of the engine. I'm sure it is the same as with the Civic VTec engines and the Toyota VVT engines that the cam timing is compromised towards improved fuel consumption and emissions rather than power and torque. I'd like to see a 968 engine with new pistons to decrease compression ratio with a big turbo. I'd imagine it could be made to work quite well with stand alone EMS so you can play tunes with the cam timing.