924Board.org

[bcblase]

So I was checking my exhaust system this past weekend - I had a small leak at the front of the cat. When I removed the exhaust, it snapped off at the front of the cat due to a bad weld.

The cat and muffler looks pretty new, it was a crappy weld that messed up the stock setup.

As a mostly track only car, should I just install a test pipe to replace the cat, or go whole hog with a 2-1/2" straight pipe all the way?

Do you really get any more power without a cat or muffler?

Opinions please.
_________________
1987 Porsche 924S - track toy
1986 Mercedes 190E 2.3-16v - autocross
2007 F-150 5.4L Lariat Supercrew - tow beast
1994 Volvo 850 Race Wagon - 24 Hours of Lemons Car
2001 BMW 325xi - daily driver

[Fifty50Plus]

Brad,
You will lose some mid range performance with less back pressure. More than you would gain with any straight pipe at higher rpms. Size and length of a straight pipe are critical to any improvements. Multiples of 29" from exhaust valves (@3500 RPM) is a place to start.
Chuck
_________________
1979 924 NA race car H-Prod SCCA
1982 924 NA race car - Sold
1981 924 Turbo sold
1982 924 Turbo sold
1972 911 E race car - traded for Cayenne Diesel
1975 914 1.8 Building for H-Prod SCCA

[joecitizennn]

If you straight pipe it you will have to change your engine management to match the increased air flow. Best to stick with the stock exhaust.
_________________
87 924s
88 924SE gone
447 hp cgt clone
87 924S gone
84 944 sold
83 944 sold
89 turbo S LSD, ABS etc
86 951 white rocket
85 944 sport everything.
84 944 sold.
87 944 sold

[dvalmont136]

I was reading a thread about this the other day:
http://www.924board.org/viewtopic.php?t=29552&highlight=
I think it kinda turns into a thread about something else; but I got the impression that losing the muffler/cat wasn't exactly a performance boost.
_________________
80 931 <RIP - Change your Timing Belt!>
88 924S Stock/Auto/SaratogaTop/WilksChip
12 FXT Touring
12 BMW E92 335i M-Sport

[bcblase]

Thanks - I remember that thread now. I think I answered my own question.

I'll probably just go with the 2.25" test pipe to replace the cat for now and see how it works out.

Brad
_________________
1987 Porsche 924S - track toy
1986 Mercedes 190E 2.3-16v - autocross
2007 F-150 5.4L Lariat Supercrew - tow beast
1994 Volvo 850 Race Wagon - 24 Hours of Lemons Car
2001 BMW 325xi - daily driver

[Porschejag]

I had a similar experience (exhaust pipe falling off whilst checking for leaks) with my little monster. Crawled underneath to see where exactly the obvious leakage was... and the damned thing broke off! I decided that I should go big (or go home) with a new exhaust system, so bought the massive 3" Exhaust system from Lindsey Racing. I opted to veer away from getting a cat, but got a Borla muffler. I was a young chap at the time (Still am, I suppose).

If'n I'm honest I would rethink my decision on the massive exhaust choice. Granted it looks incredible peering out from the back.. It was (or is) boarder-line annoying, ferociously loud. I did put the well-marketed "Pre-Muffler" that Lindsey offers to dampen the sound a bit, but to no avail, really. On a side note.. The actual driving experience hasn't change one bit. But! It's only annoying with the windows down.. driving on the highways or interstate.

If I were going to do it again.. I would definitely go with the stock exhaust. Especially on one that is intended to be a everyday driver. I'm not even sure this ranting about my somewhat poor decision belongs on this post, but whatever.

With all of that nonsensical rambling finished, I think you that you've made the right choice. Especially since your baby is mostly a track car.

[bcblase]

Good comments... definitely nice to hear some first hand experience.

The 2.25" test pipe is installed. The exhaust sounds a little louder, but I still have it up in the air in the garage.

Hopefully, I will be able to take it for a test drive this weekend, if we don't get flooded out.

Brad
_________________
1987 Porsche 924S - track toy
1986 Mercedes 190E 2.3-16v - autocross
2007 F-150 5.4L Lariat Supercrew - tow beast
1994 Volvo 850 Race Wagon - 24 Hours of Lemons Car
2001 BMW 325xi - daily driver

[joecitizennn]

I ran a test pipe on my 924S for a year or two, and under a load it kind of sounded like an old barge I rode on in mississippi. When I put a cat back on it sounded better.
_________________
87 924s
88 924SE gone
447 hp cgt clone
87 924S gone
84 944 sold
83 944 sold
89 turbo S LSD, ABS etc
86 951 white rocket
85 944 sport everything.
84 944 sold.
87 944 sold

[bcblase]

Yeah - it sounds kind of like a tug boat. I guess I'll get used to it.
_________________
1987 Porsche 924S - track toy
1986 Mercedes 190E 2.3-16v - autocross
2007 F-150 5.4L Lariat Supercrew - tow beast
1994 Volvo 850 Race Wagon - 24 Hours of Lemons Car
2001 BMW 325xi - daily driver

[joecitizennn]

you should pull out all stops and supercharge that baby.
_________________
87 924s
88 924SE gone
447 hp cgt clone
87 924S gone
84 944 sold
83 944 sold
89 turbo S LSD, ABS etc
86 951 white rocket
85 944 sport everything.
84 944 sold.
87 944 sold

[bcblase]

And how, exactly, would I do that on the cheap?

Maybe we should start a new thread?

I'm interested...
_________________
1987 Porsche 924S - track toy
1986 Mercedes 190E 2.3-16v - autocross
2007 F-150 5.4L Lariat Supercrew - tow beast
1994 Volvo 850 Race Wagon - 24 Hours of Lemons Car
2001 BMW 325xi - daily driver

[fennacf07]

See the following treads for exhaust treads on pelicans forum. They have a lot of good info in them.

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/12264-replacing-cat-glass-pack.html

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/538907-thrush-exhaust-project.html

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/543375-what-aftermarket-muffler-type-muffler-makes-these-cars-sound-good.html

[joecitizennn]