996 C4 tuning .......

Hello, i'm new to this site, and I don't own a porsche, it's my dad who's asked me to join and ask a few questions. you would all probably group me as a boy racer... lol. 1. CDA BMC enclosed induction. I've got one on my saxo engine, bit off topic, but thats where I've heard of them. They seem to be one of the best on the market within the engines I've come across. I know nothing about porsche engines. Could you advise me on the best enclosed induction kit on the market, and if the BMC is as good, or fits the engine for that matter. 2. exhaust. I am quite shocked at the price I've seen in one of my dad's porsche books for a performance exhaust, considering it is so small compared to a normal front engined car's. is the extra costs made up through the fabrication, as bending the pipes in such a small space may be costly ? Basically, my dad wants a performance exhaust, I would have thought a performance manifold, a sports, or de-cat, and performance back box are on the agenda, but again I'm not sure. 3. do you go down the cams, port/polish and remap route, or are the porsche heads and cams performance enough already ? thanks if you can give me anything on these, sorry about all the questions as well. lloyd emery

Porsche have tuned the 996 quite well. The standard engine is tuned for a reasonable compromise between power and torque to make it quick under real-world driving conditions. It also has to conform to emissions requirements and work with varying fuels, at sea level, up a mountain, in a desert and in arctic conditions. Since the fuel is pretty consistent here, we don't have any 3000m high roads and our weather is not excessively hot or cold, you can play about a bit. You could remap the engine, which would give some modest increase in power, maybe 10 or 15 bhp at a guess. You should be aware that Porsche offer their own performance upgrade, which costs 5K if ordered as an option when you buy the car, most likely more aftermarket due to the labour costs to fit it. This modifies the intake manifold, cams and the ECU. It gives you 23 bhp more. A rough rule of thumb is about £100 per bhp. More than this isf you want the factories offerings. Tuning Porsche's is more expensive than other cars, because there are not many simple tweaks. Most changes are measured in thousands of pounds, rather then hundreds. Everything is expensive, partly because it can be, but mostly because the parts have to be high quality and are only made in small numbers, so there is little economy of scale. The standard induction system employs dual length inlet tracts, and a resonance system (giving 3% if I remember rightly) improvement in cyclinder charging. There seems little point in changing this, and the only real improvement is through fitting a freer flowing air filter. The exhausts are all in thousands. That's just the way it is. You could replace the outlets with equal length headers, fit sport catalysts, etc. But you will start on a slippery slope that will cost a fortune, you will also push up the insurance, invalidate any warranty, exempt yourself from any goodwill claim and reduce the value of the car. Note that de-cat'ing the car makes it fail an MOT, will make the check engine light come on permanently on the dashboard and may cause problems for the engine management. Basically, I think tuning it is not really worth it. Fitting the lower/stiffer springs makes it feel more sporty, fitting the Porsche sports exhaust makes it sound more sporty, and a driving course will make you able to drive it faster/more safely. These three are more sensible. If you really want to go faster, changing for a GT3 or turbo is more sensible. Of course once you have a turbo the tuning potential is increased, since you can just up the boost and fit bigger turbos. However, note that you can spends 10's of thousands tuning the turbos. It is not a cheap game. Bear in mind that if you blow the engine up, I think it is 8-10K for a C2/4 engine, 18K (I believe) for a turbo engine, and I guess around 20K for a GT3 (due to the titanium con rods). Of course you have to be unfortunate to require a whole new engine, but labour costs mean that fixing a C2 engine can be more than replacing it. Edit: although this sounds high, it is a lot less than Ferrari or Lamborghini will charge you. The fewer cars that are sold, the more it costs you to do anything, even without deviating from standard. It is a different world to regular cars or Japanese tuning, although the most extreme 400 bhp Evos are getting into the same realms.

What about this lot? Any views? DMS FWIW, I've had engine management upgrades done by them on Beemer and Merc turbo diesels which have worked very well

DMS flatly refused to provide dyno results when I asked them to. Have since heard they don't even use one. Wouldn't want to fit a chip to my car that was developed by guesswork. Ian W

As I said, I've had DMS upgrades done to a BMW 530d and a Merc E320Cdi which have resulted in tangible increases in performance certainly in line with their power/torque claims although neither car was dyno'd. You do see tests of DMS upgraded cars turning up in magazines on a regular basis (rave reviews in Autocar recently) so I guess they know what they're doing. What I do think though is that it is much more difficult to achieve substantial performance increases with naturally aspirated engines so for that reason, I wont be taking my 996 to them