power gains with cat bypass pipes

[spongebob]

I'm not worried about loosing any torque as the engine is equipped with only two cats in many countries including Germany. Probably the powergain wont be noticable either. The main goal is to shave off some weight from the rear engine mounts which hopefully will reduce the annoying vibrations at cruising speed.( I know that the mounting height of the mufflers alters the characteristics of the vibrations)
If sound and throttle response is improved its a great plus.

[BYprodriver]

Originally Posted by spongebob

I'm not worried about loosing any torque as the engine is equipped with only two cats in many countries including Germany. Probably the powergain wont be noticable either. The main goal is to shave off some weight from the rear engine mounts which hopefully will reduce the annoying vibrations at cruising speed.( I know that the mounting height of the mufflers alters the characteristics of the vibrations)
If sound and throttle response is improved its a great plus.

Usually the cheapest way to dampen vibration is to ADD weight!

[Johnny Danger]

The secondary are completely superfluous . Its merely a case of Porsche having a "belt and suspenders" approach to emissions/OBDII compliance. They're like having an extra set of thumbs. Get rid of them !

[spongebob]

Originally Posted by Johnny Danger

The secondary are completely superfluous . Its merely a case of Porsche having a "belt and suspenders" approach to emissions/OBDII compliance. They're like having an extra set of thumbs. Get rid of them !

Had to google superfluous as im not really good at A.english but I think its the first set of cats that should go in the first place.Problem is that the O2 sensors are placed there. A ( Porsche) mechanic told me that they where only really efficient at startup and lower temperatures before the secondary set starts to work a minute later. This is also how the RoW cars are designed . When you look at the pre-cat they do not seem to approve a smooth flow through them.
But all the problems involved with getting rid of the first ones, broken bolts ,O2 sensors scares me a little bit.
Strange thing is that a lot of companies sell dirt cheap headers but are not able to supply a simple bypass pipe for that price.

[Johnny Danger]

Originally Posted by spongebob

Had to google superfluous as im not really good at A.english but I think its the first set of cats that should go in the first place.Problem is that the O2 sensors are placed there. A ( Porsche) mechanic told me that they where only really efficient at startup and lower temperatures before the secondary set starts to work a minute later. This is also how the RoW cars are designed . When you look at the pre-cat they do not seem to approve a smooth flow through them.
But all the problems involved with getting rid of the first ones, broken bolts ,O2 sensors scares me a little bit.
Strange thing is that a lot of companies sell dirt cheap headers but are not able to supply a simple bypass pipe for that price.

I agree with you in so far as the RoW design is concerned, to include how most "tuners" (especially the European ones) prefer to configure their exhaust systems. However, the difficulty that I first encountered was finding high quality cats with the appropriate cell count for my application. And, secondly, finding ones that had the correct design lay-out so that they could be incorporated mid-stream. Therefore, in order to simplify the process, I decided to stick with the principles of the oem design and improve upon it in ways previously mentioned. This approach ruled out the need to add "bungs", re-route O2 sensors and possibly have to re-program the ECU.
Moreover, this was a design that I noticed that some of the top European "tuners" were utilizing in their 987 exhaust programs.

[mts]

Here is a link to a thread I did a while back on before/after dynos with Fabspeed bypass pipes:

http://986forum.com/forums/showthread.php?t=18467&page=1&pp=20&highlight=fabspeed


The 25hp claim seems more than a bit excessive to me.

[spongebob]

Originally Posted by BYprodriver

Usually the cheapest way to dampen vibration is to ADD weight!

I agree but, changing the weight in either direction will change the freqency and amplitude of the vibrations hopefully out of the " critical rpm" that this engine seems to have. Also putting less load on the transmission mounts will give them more room to dampen the vibrations.
This is just my theories but the will be tested later when the white stuff on the ground is gone.