I'm removing the cat. converter from my stock V-6 and am wondering where I can get a cat. delete pipe. I've checked around, can't find one on the web. Should I just measure and buy a length of pipe somewhere? Any ideas are appreciated. Thanks, Rich
The mesh or whatever inside the original cat on my 1988 Fiero Formula disintegrated many years ago, and as a replacement was unavailable (I'm in UK) my local workshop sourced a silencer (you call it a muffler?) of the right length and diameter which fitted the space, and installed that.
The car has run OK ever since, and passes the UK's "non-cat" emission tests. I think the brand-name of the replacement silencer/muffler was "Devil" or something similar.... but I suspect that other names and brands are available in the US which would fit.
just go to a custom muffler shop, tell them what you need, done in 10 min. if you don't want to bring the cat with you, just get the measurements and pipe diameter, larger or smaller than the original pipe and it will fit inside or outside the pipe.
Steve
------------------ Technology is great when it works, and one big pain in the ass when it doesn't
I got the right sized length of pipe at like an autozone, the Fiero Store's pipe is stainless I am pretty sure where one from autozone would not be. But yea you could go to virtually any exhaust shop and just ask for the right length and diameter pipe and some exhaust clamps, or weld it if you have a welder. I bet an exhaust shop could do all the work for you and include the pipe for under $100. At least all the places I have gone to before.
Going to a straight pipe at the CAT location is actually a negative performance option. The reason is not the flow. It is the length of the pipe from the Y to the muffler. That is over 6'. As soon as you get to 6' the pulses in the exhaust start tripping over each other and you lose your scavenging effect.
The best thing to do is to hollow out the CAT and put it back. It will behave like a resonator, and break up the exhaust pulses about 3' past the Y. This is a good idea and the cheapest option.
If you read up on exhaust design, you will run into this. Of course you should port the exhaust logs and the Y.
Originally posted by Arns85GT: Going to a straight pipe at the CAT location is actually a negative performance option. The reason is not the flow. It is the length of the pipe from the Y to the muffler. That is over 6'. As soon as you get to 6' the pulses in the exhaust start tripping over each other and you lose your scavenging effect.
I heard of this "six foot rule" before, but am curious about something. You said it's measured from the Y to the muffler inlet, right? So for example, if you have aftermarket headers where the Y is further downstream (the Y in the Trueleo headers is down by the O2 sensor), that would make the Y-to-muffler measurement shorter, yes? I ask, because in my setup the distance from the Y (in the Trueleo headers) to the muffler inlet is just under 6 feet.
Normally the measurement is right from the head. I am saying the Y because the Y changes the pulses a bit, but, if you measure from the rear port or the front port it also changes. If you want to be safe, measure from the head at the farthest port for your 6'.
The resonator cures all this. Be certain that the Trueleo setup falls under exactly the same rule. You need to measure the longest runner from the port to the first location in the exhaust which allows the pulse to dissipate. This distance is affected by the diameter of the pipe also, because the smaller 2" will flow faster than the larger 2.5" due to volume considerations. If I had a Trueleo (which I recommend anyone to buy and use) I would have either a muffler or resonator in the CAT position. BTW I know from experience that the Turbo Muffler design is not the one to use in the CAT position. It just doesn't promote flow. The Flowmaster is better in this application or the Spiraltech. Hope this helps
