944S2 vs 968 engine - Page 1 - Porsche General - PistonHeads UK

Ok to explain this you need to have an understanding of how camshaft timing works (Valve timing is dictated by the cam). In simple terms a cam with a small amount of lift helps bottom end and mid range power of an engine at the expense of top end. If you rev this engine hard it wont be at its most efficient. An engine with a high lift cam acts like a race engine inefficient at low revs but comes alive at high revs producing great top end power. All non variable valve engines run a camshaft timing that is a compromise betwean these two extremes. A variable valve engine acts in theory at least, as if it has more than one cam shaft timing. So therefore is more efficient through out its rev range. Hopefully benefitting power, economy and emisions. My appologies to any engineers out their I know this is a bit of an over simplification, but its the best way of discribing it that I could think of. PS. The S2 engine could produce the same top end power as the 968 it just needs a higher lift cam and the same size valves as the 68. But you wouldnt get the other benefits.

The variocam makes around 8bhp when actuated. The 968 has a higher compression that also adds power & the bigger valves of the 968 flow more at the low lift levels than the 944S2. However, imho, the 944S2 engine has a greater power potential at normal operating rpm than the 968, so given the right cams, intake and exhaust, it should make the same power as the 968.

Knowing that the valves of the latest S2 (MY91) are different to these of earlier S2, are they the same as the 968's ?

Don't know, sorry.

I think some of the very last cars were slightly tuned to 225bhp - maybe it was these that had different valves. My car is a '91 model with bridge spoiler but there is nothing to say it has more than the standard 211bhp...

As far as I know the late cars with 225 bhp are the UK-only 944 SE. I never saw one but I suppose they are just stock 91 models with a S pecial E quipment (M030, etc) and a special DME. Not sure they bothered modifying the engine only for this limited production run.

So is it possible to buy a special DME from an OPC?

Quite frankly Andy I would highly suggest you to keep your S2 as it is. I perfectly understand what you are looking for - more power - but you may find it not worth to modify your S2 beyond reason. If you want to go faster relatively cheaply and keep decent reliability buy a turbo. Unfortunately you will see running costs rocketing since turbo need much more fuel and by definition consume oil at an alarming rate. I have found my S2 to be more than up the job of travelling comfortably for endless journeys and it really is fast enough for overtaking Euroboxes of all sorts. I do not need a faster car. Roads and legislation do not allow to go much faster and I doubt I will ever come across a car that provides such an excellent pleasure per pound ratio and although I have had it for nearly two years I know it will be heart-wrenching to see it go when I need to sell it. Do like me - save money until you can afford building a 3l turbo or if you are afraid of putting your hands in the oil get yourself another car. Sad but true

I totally agree with you Thom I love my car and it is certainly adequate in terms of performance (I think you can detect the imminent use of the word 'but' here can't you ) but (there you go) I want more. It's such a great car it deserves more power. I don't like turbos though - I like an unstressed engine with sharp throttle response and a flat torque curve, one of the reasons I went for the S2 in the first place. I also don't like highly tuned engines, the most I'd want is 100bhp/litre normally aspirated. If I wanted forced induction it would be from a supercharger. Still interested in putting a 928 V8 in a 944 though

Although I have had the opportunity to drive various examples of 944 turbo (both 220 and 250 bhp) I do not like it as well and - as you exactly point it - they suffer from uncomfortable lag, BUT ( ) if equipped with Guru racing chips I can tell you the lag nearly disappears. Below 3000 revs it feels like an S2 and above it feels like no other thing on earth. It even feels faster than a Turbo Cup. Just do not give up on turbos so quickly ; take the time to have a look at many different cars before taking a decision.

Yes I know that you can use a 'boost enhancer' to increase the boost earlier in the rev range which effectivly reduces the lag. But I still have problems with under bonnet temperatures, restricted exhaust flow and more stuff to go wrong. If 9M can get 300bhp from this new manifold then I'll almost certainly buy one, as long as the torque is increased in proportion. I don't care how much fuel it uses though - I've got a Peugeot 309 diesel if I want to save money on fuel

I will be very happy to read about it if you go for it

I was very tempted by the supercharger kit, but I can't be spending that sort of money on my car However this manifold does look promising and good value if it does as expected. What I really want is to design and build a light weight mid engine sports prototype with a flat-6. I wouldn't mind putting turbos on this as it'd be a road legal track car

I know the main difference between the engines is the variable valve timing, but I'm sure I've read somewhere that its mainly for economy and emissions rather than power output. So where does it get the extra 29bhp over the S2 engine? Is it just a new chip and a higher redline? I know 9M is hoping to get about 300bhp from the new quad throttle manifold, but is this figure for the 968 only? ie. the S2 might only make 271bhp?