Pelican Parts Forums - 1-in 1-out vs 1-in 2-out

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- - 1-in 1-out vs 1-in 2-out (http://forums.pelicanparts.com/porsche-911-technical-forum/785386-1-1-out-vs-1-2-out.html)

Redridge, The Cat converter I chose was made by a quebec Canada firm called Maxspeed motorsports 1-855-466.2977. I chose a 100 cell Cat because I found that a pre muffler I had previously had quite an offensive smell (M&K) .The cat is of excellent quality, only 100 cell ...virtually free flow. Fab speed might have a similar product.
The muffler is produced by Monty mufflers, an Australian small SS MFG. that produces custom made mufflers for Porsches see Monty Mufflers - porsche mufflers stainless steel australia USA - hand, fabricated, heavy, gauge, 304, flanges. Monty has been doig this for the last 30 years and his products are a piece of art in quality and view.
The sound is second to none, reminds you of a nice v8 burble...I believe there is a u tube segment for a monty muffler....it is not cheap...probably about $1300...communicate with him by e mail...very honest and straight forward.
The Steve Wong chip was set for such a configuration with 91 octane. Talk to steve and explain all of the above...he used to recommend Monty in the past...
I hope this helps.

Quote:

Originally Posted by Craig T (Post 7792069)

Chip mapping is essential to a significant exhaust change on a stock CIS motor.

At Aase Motors the dyno runs have shown different CIS cars with stock motors can have varied dyno results from the same exhaust system. That's why we usually have Steve Wong in the dyno with us after we make an exhaust change (and I love your company to Steve;)) Steve can optimize accordingly. I changed to stepped SS headers on my stock 3.2 race car and saw no improvement. At the dyno SW tapped away on his laptop and picked up 12 HP by matching the chip to the new airflow.

Not to kick off another exhaust debate....But ;), the reality is...No exhaust is the silver bullet for our cars. To maximize performance, the exhaust must be matched to several factors, and not just intake port size, exhaust ports, cam, octane, compression, etc. Even condition and effectiveness of the CIS and remaining stock compression make a difference.

In the Porsche Owner's Club V3 race class (stock 3.2 but otherwise highly modified), guys spend thousands dyno testing different exhaust configurations just to get an extra 5-10HP....And it's usually a trade off...get it at the bottom, or get it at the top. No silver bullet.

That's odd, CIS cars don't have chips, injection is strictly controlled by the fuel distributor and ancillary devices, the ignition is controlled bu the vacuum and mechanical advance mechanisms is the distributor.

This system is much more difficult to tune for all configurations and rpm and throttle position

The first 911s w/ chip controlled engine management are the '84 Carrera 3.2s, these are relatively straight forward to tune for every possible configuration/rpm/throttle position w/i the systems parameters.

Quote:

Originally Posted by Bill Verburg (Post 7792728)

Bill, my mistake. I was referring to 84 and up 3.2's. I mistakenly called the system CIS (...but you knew that). My 3.0 SC is the CIS car, not my 3.2. I'll redact.

A cat or pre-muffler when combined with a single in single out main muffler will produce a nice note that is not too loud.
For the Carrera the pre-muffler / single in muffler combo performs as well as SSIs with a dual inlet muffler. The reason is primary tube ID sizing on the SSIs are a touch small for the 3.2L ports.