First Test Drive w/ Fabspeed Premuffler

arbita1 · arbita1's Garage

So after a lot of aggravation removing my old cat, I'm sorry to report I'm less than thrilled with my fabspeed premuffler.

Firstly, it's a bit throaty-er. However it's louder. I was hoping the sound wouldn't really change.

Secondly, my car seems to be running hotter. I thought it was supposed to run cooler with a premuffler?

Lastly I don't think I saw any performance gain. I figured my stock cat would have been clogged and at least the new premuffler would have brought back some lost hp. Maybe it wasn't as bad as I thought.

So, is something wrong. Should I just put my old cat back on???

James Brown · James Brown's Garage

Porsche does there homework, almost no backpressure from there cat's over there life . Now you need a Dansk sport muffler to go with that bypass.

nineball · 07-19-2010, 02:29 PM

i run a dansk premuffler on my 83SC and i had similar results - a little deeper, ever so slightly louder at anything under 2k, after 2k it sounds normal, no seat-of-the-pants dyno improvement. i have not noticed any change in the running temp though.

Oh Haha · 07-19-2010, 02:34 PM

You need to change the muffler to get a different tone.

Little to 0 HP gain but the sound will make you giggle like a school girl every time you press the gas pedal.

Obviously, many threads have been posted on what muffler is "best". I like my oddball Flo-Pro 1in-1out setup. Check them out and decide for yourself what you like.

KNS · 07-19-2010, 02:46 PM

It should at least be cooler on that side of the engine. I once measured the temp at the catalytic converter right after engine shut down and then compared that to the temp with the cat removed and the premuffler in place. There was a significant drop in temperature.

arbita1 · arbita1's Garage

In regards to sound...I already have a GHL 1 in/1 out that I was very happy with sound wise. It seemed to be the perfect volume. Now with the premuffler it's a touch louder than I'd like.

Quote:

Originally Posted by KNS

It should at least be cooler on that side of the engine. I once measured the temp at the catalytic converter right after engine shut down and then compared that to the temp with the cat removed and the premuffler in place. There was a significant drop in temperature.

After my test drive today, the temp needle was a little more than halfway between the 2nd and 3rd marks. It used to just go slightly past the 2nd mark. And when I got out the car, the whole area by the premuffler was very hot.

Could something be wrong?

Oh Haha · 07-19-2010, 02:56 PM

You may need to adjust the fuel/air mixture.

It may be running a bit lean which can cause hotter temps.

A gas analyzer is the best way to check.

tcar · 07-19-2010, 02:57 PM

Is your oxygen sensor hooked up? Did you maybe break a wire on it while you were working in that vicinity?

arbita1 · arbita1's Garage

Quote:

Originally Posted by Oh Haha

You may need to adjust the fuel/air mixture.

It may be running a bit lean which can cause hotter temps.

A gas analyzer is the best way to check.

Good point. I had it set to 3.3%. So I guess I should check it again. I imagine around 3.5% w/o O2 sensor hooked up should be good?

Quote:

Originally Posted by tcar

Is your oxygen sensor hooked up? Did you maybe break a wire on it while you were working in that vicinity?

I've had my O2 sensor disconnected because I'm not sure the lambda system is working properly and I haven't had a chance to go through it yet. So I figured I'd run it disconnected for the time being.