Marc Shaw

According to a previous post by Adrian, it looks like a C4 is actually closer to 28% loss which puts me at 290 bhp at the flywheel.

Marc

kos11-12

298

cobalt

Wow that is power hungry. Time to drop all that weight and make it rwd think of the HP gain. Too bad it is so pricey to do on these cars.

sushisushi

just sell it and get a C2 if you need the power

I'm surprised at these power figures, are all these mods quite cheap relatively?

Marc Shaw

....or drop in a supercharger and get over 400.

Marc

BlueHeeler

A C2 will not be noticeably faster than a C4. What the C4 loses in drive train it makes up for in traction.

I was kidding before. I do not know the HP on my car. The budget mods on these motors are fairly limited. The Rennsport page does a good job explaining the situation:

Performance Enhancements

There are several things that can be done to improve engine power although not everything is cost effective. The 993’s especially, are very efficient engines that are quite well optimized as they are delivered from Porsche. Changes to these cars will be expensive and certain changes can make the car trigger "Check Engine" lights or difficult to pass emission tests.

The first thing that we recommend for all 3.6’s is a performance chip. This optimizes the ignition timing and fuel curves for more torque and throttle response at the cost of a narrower detonation margin. You must use 92 or better (pump) octane fuel in a "chipped" engine to prevent internal damage. This is the single most cost effective improvement that you can make. The 3.2 engines can benefit from the installation of a Mass-Airflow Sensor and larger Throttle Body. These are also quite expensive from a $$-per-HP perspective. SSI Heat exchangers and a good sport muffler will also help the 3.2.

The 89-94 C2/C4 Porsches has a fairly restrictive and heavy exhaust system that has room for improvement. Installing a bypass pipe and removing the final muffler will save some weight and helps the power somewhat. Although they have proven troublesome, the B&B headers and mufflers adds a little power albeit with more noise, especially inside the car. This setup would be for off-road only since the catalytic converter is eliminated. We also strongly recommend removing the tray under the engine in these cars since it seems to accelerate engine wear due to the contained heat. Here are some performance improvements for street driven cars:

http://www.rennsportsystems.com/engines%203.6-3.8.html

ilko

I wasn't. My car was supercharged

sushisushi

thanks for the info blue healer

Jimjacqmx5

I never bother looking at what they say in books. I used to have several books on MX5's (Miata's) that said there is no point doing valves or head work or exhausts as little gain could be made.
Funny thing is, when the racers did some head work, some bigger valves and a nice set of cams, bugger me, they nearly doubled their horsepower.

I suspect the same thing here. Most books say that little gain can be made as the oriinal design was so good, then how come with a few simple mods 964's are making 10-15% gains in power and with a bit of head work and some cams 350hp is not out of the question and not THAT costly.

I mean, intake $@100 (KN panel filter or EVOMS intake), chip $100 off ebay (accellracing UK), cup pipe $200max (Danske or Maxspeed motorsports in Canada), Dougherty 'cup' cams or slightly wilder 'DC21' camshafts $600, fitting 15 hours $1500.
That should give you around 310hp or 230kw. or a neat 25% power gain for $2500.

Obviously it would be nice to add some ARP rod bolts, stronger valve springs and do a port job as well, however the above set up with camshafts only pushes the power curve up 300rpm so you are still getting max power below 7000rpm or stock limit so you don't really need the extra strength and it will run on stock ecu.

And yeah, if you really want grunt without a full race engine and the associated machining costs, bolt on a blower kit.....

That said the rennsport advice is correct. I suspect most people here have an intake, chip or programmable ECU and an exhaust.
Depending on the individual car you should get somewhere between 200-210kw or a 25kw gain. Looking at pricing above this can be done for under a grand. For extra, you can you opt for a full headers/muffler system which is about $1800 and will give an extra 5-8kw over bypass setup or instead, get a 100 cell sports CAT to go with CUP pipe for only $400 and gain an extra 3-5kw, giving nearly the same power gain for $1400 less and keeping whole package under $1500.

Plenty of options but I still say the greatest gain for a 964 comes from suspension set up.

Cheyne

247 Whp with RSR style headers and Eurocup software, all wheel drive on a brand new Dynapack. 197 whp before modifications

wolv

<<< ooooooo, I like the sound of that.

<<< Is this the general practice of Rennlisters? Sounds like something to watch out for, mine has always been on.

Jimjacqmx5

I don't know of any 964 that still has the engine tray in place.
It's handy for catching oil drips from the through bolt leaks though!

meek

This is total conjecture ( I know, it's not you stating that, Blueheeler). Internet lore - copy and paste often enough and it becomes fact. So much posted up on this already, won't repeat it again.

Mine does, as do many of the UK cars I have seen. Depends on your local climate and what you believe?


Absolutely. So why don't C4s and C2s race in the same class? Because AWD gives an unfair advantage throughout a race season Well, if it rains it does

cobalt

Not true, the big problem when Porsche went to the 3.6 motor was excessive valve guide wear from added heat. Both the 964 and 993 suffer from this. If you don't have proper cooling and push the car hard (extensive DE) all the time you will have premature wear of the guides early on. Removing the under tray helps eliminate heat buildup. However, if you drive your car under normal operating conditions it shouldn't be an issue unless you sit in a lot of traffic on warm days especially with the A/C on. So it is based on some truth and is not just conjecture.

meek

Yes, you are absolutely right about heat-valve guide wear, but the issue is whether or not the undertray worsens/improves/does nothing to engine temp, which nobody has been able to prove/disprove as yet i.e. conjecture. I doubt anyone ever will. It probably traps heat at idle, but again, nobody has proved this. It is possible that it improves cooling at speed, but we don't know for sure. All we have is personal experience and mine is that my temp gauge acts in the same way at idle or at speed with the tray on or off; all UK weathers, all ambient temps, driven hard and fast and pootling along.

This is why I said 'so much posted on this already, won't repeat it again' - all this has been discussed and disagreed on before.