J-McDonald

I've thought for a while that my C2 cab sounded a little timid -- mostly fan whine and a little mechanical noise, but no exhaust note. So, after doing some research on this Board and checking the video/sound clips on www.fabspeed.com, I decided to go with the primary muffler bypass ("Cup" pipe), GIAC chip and cone air filter, all purchased from EVO Motorsports. [no affiliation with either Fabspeed or EVO].

I got the car back from the shop last Friday, and I have to say that I LOVE the effect of the mods -- both sound and feel. It now has a nice, low burble at idle and a stronger exhaust note under load, but it's not loud by any means -- cruising at highway speeds there is little or no additional sound. I was concerned after reading others' reports about the secondary muffler bypass making the car too loud (particularly when the top is down in a cab, like mine). I also didn't want the car to sound like a Mustang with a bad muffler -- all "rumble," no "howl." I read posts that, because the secondary muffler actually does most of the "muffling", the effect of the primary muffler bypass is much more subtle and results in a higher pitched exhaust note. These reports were supported by the Fabspeed video clips (one has cat bypass/primary muffler bypass, the other has cat bypass/secondary muffler bypass).

I haven't done any testing, but the car also feels faster -- it now has minimal hesitation at low rpms and pulls stronger throughout the range. Since all three changes were done at the same time, I can't attribute the effects among the mods. All in all, I highly recommend them.

Cheers!

joey bagadonuts

Congrats! I bought the EVO intake and chip, as well. I think you'll notice some extra zip as you overtake traffic in second gear. Throttle response is even sharper, at least, that's my impression.

Glad you liked it.

Rennen

Does a chip really accomplish much of anything in these NA power plants?

J-McDonald

I think it's mostly timing advance -- check out the dyno chart on http://www.evoms.com/porsche%20ec%20art.htm (go to "964"; then "tuning systems", then "level 2", then "DYNO" (towards the bottom))

Rennen

But timing advance only helps if you bump up the grade of your gasoline, right?

J-McDonald

The factory timing settings are very conservative -- although 91+ octane gas is recommended by the factory, the timing is set by the factory to allow the engine to run on 89 octane. The chip assumes a baseline of 91 octane. I'm still well within the parameters since I only use 93 octane in the car.

Rennen

I'm asking this stuff because I really don't know what level of technology the 964's have computer wise. I know that most current cars have knock sensors to back off or advance timing so that the car can maximize performance based on the grade of gasoline used. Do the 964s have this?

J-McDonald

Yes, 964's have knock sensors. If they sense detonation, the ECU will retard the timing to protect the engine.

Herbie

964 knock sensor system isn't sophisticated.

It has only a single point of action: advance is retarded by a fix great value (30° ?).

Modern cars take advantage from super gasoline (98oct) because their advance curve is recalculated according to better anti-detonant performances.

964 has only a simple protection to avoid problems with poor quality fuel and/or too hot cylinder heads.

Marc Shaw

Is this upgrade package from EVO Motorsports something a reasonably handy but non-mechanic could install themselves or would a more knowledgeable person (ie. mechanic) need to do it??

Thanks...Marc

Lorenfb

"964 knock sensor system isn't sophisticated.

It has only a single point of action: advance is retarded by a fix great value (30° ?)." - Herbie -

Not True!

The 964 engine uses 2 knock sensors and it's very sophisticated. The system retards
the timing in 3 degree increments to a max of 9. It then begins to advance the timing
in small increments when the knocking ends. With the use of the Hall sender, the system
can determine which cylinder is knocking and only retard timing for that cylinder.
Therefore, since the timing is set for max performance using knock sensors, most
performance chips cause more problems than good results for 964/993.

Check out the web site (www.andial.com) on the FAQ page Question #2, as the writeup
is most applicable to the 964 & 993 with knock sensors. Andial Porsche was/is the
Porsche Factory racing USA.

joey bagadonuts

Yes. Replacing the chip is a little tricky, though. There are two circuit boards which snap together and you need to pull them apart to swap chips. There's a "trick" to doing it which has been covered in previous posts (I think with pics). Try searching for more info but feel free to drop a line if you get stuck.

Go for it!

Pesty

mmmm those dual outlet fabspeed exhausts look good I take it I would need to moify the rear bumper in some way?
Can you get these in teh UK or would I have to import it?
and are teh exhausts easy to fit? I could handle the chip no probs but not sure about the exhaust sytem on this car.

sorry for the dumb questions

tonytaylor

Dual outlet exhausts are available inthe UK IIRC Design 911 have them. You can purchase a left quarter bumper with the exhaust cut out, 9M have them.

Remember that noise will increase which can be a problem for certain trackdays.

Marc Shaw

joey bagodonuts - looking back in the archives, I see that you did this after being unhappy with your drilled airbox. I think you did the cat bypass, not high flow cat.....Does it affect emissions? How does it sound compared to stock?? I'd like a "balanced" upgrade so a package looks tempting rather than random bits and pieces but I'd also like a little more exhaust note -- not boy-racer, just something so people give the car the respect it deserves!

Marc

p.s. thanks for the tip on the clear side covers -- on order already!