I would like to know the volume of the factory 85 gt cat...i would like to gutt it out, or replace it with a resonator. The vibrant ultra quiet is about 400+ ci.. if no ci info, then what are the w/h/l measurements? I'm going for a deep blub, blub, blub, instead off the ga, ga, ga, ga... I want to keep it simple, nothing major. Noooooooooooooo droning and low audibles.
To the OP... Sorry. Can't help with specifics, but lots of guys replace the cat with a glasspack of the same length. When I had my V6, I replaced the cat with a test pipe, and ran an Ocelot system. Sounded great!
I replaced my converter and downpipe with a straight pipe that I made. The rest of the exhaust was stock. The straight pipe made the exhaust sound a bit louder; not a major difference but it was louder. But after a few years with the straight pipe I could no longer stand the stench of the non catalyzed exhaust. So I made another intermediate pipe with a Magnaflow 53004 converter. This new converter had almost no impact on the sound of the exhaust (idle, cruise, or WOT) or the performance of the car, but it did clean up the exhaust coming out of the tailpipes. Now I can start the Fiero in my garage and let it run for a couple minutes without stinking up the place.
If you need to replace the cat, put a new factory replacement on.
If you want a "deep glub glub glub" sound, swap in an SBC.
If you want a quiet exhaust, then use a stock design cat, and replace the muffler with an OE style that is quiet, and repair any leaks that may exist in the system.
A stock exhaust can actually be pretty quiet. I once looked at a Fiero about 10-11 years ago, that I didn't buy because it was too quiet.
Replacing any single point of the system is unlikely to result in what you want in terms of exhaust sound.
Ok thanks for all the info! I have another related question: Can you change the tone of the exhaust note by increasing the volume (ci) of the system? For instance....if I throw a couple resonators on and increase the diameter cat-back?....or am I on the wrong trail? I like the idea of glass pack for the semi-quiet idle, but strong punch of wot action! I do most my driving at highway speed, so I don't want droning at all. Keep in mmind, I haven't even driven the car yet...i'm just anticipating....
I appreciate the videos. I noticed a difference in sounds between the two...it seemed like the idle was more refined in the second video, while wot was similar. Thanks.
Ok thanks for all the info! I have another related question: Can you change the tone of the exhaust note by increasing the volume (ci) of the system? For instance....if I throw a couple resonators on and increase the diameter cat-back?....or am I on the wrong trail? I like the idea of glass pack for the semi-quiet idle, but strong punch of wot action! I do most my driving at highway speed, so I don't want droning at all. Keep in mmind, I haven't even driven the car yet...i'm just anticipating....
An SBC is a small block chevy. You're not going to get the V8 glub glub glub burble sound without a V8. Changing the diameter of the exhaust will change the tone, but also will affect performance. Too large an exhaust will give you a "deeper" tone, but the engine will also not perform as well, as the exhaust gases slow down when they expand to fill a larger area. Hollowing out a cat will actually result in worse performance, as the exhaust will expand too much in the cat. You're better off installing a new cat, than just hollowing the old one out. The Fiero's engine control system is also less efficient than modern systems, so there will be unburned fuel in the exhaust gases, especially if using a camshaft with overlap.
Ok. Thanks. I'm not interested in motor swaps, or internal hd upgrades....sooooo I'll keep it straight and simple with a cat replacement and factory spec exhaust....for now. I AM, however, interested in REFINEMENTS that will update and create efficiency....
Ok. Thanks. I'm not interested in motor swaps, or internal hd upgrades....sooooo I'll keep it straight and simple with a cat replacement and factory spec exhaust....for now. I AM, however, interested in REFINEMENTS that will update and create efficiency....
Short of a drivetrain swap, you won't get much, if anything, out of little mods. Some larger mods may get some useful results, depend on what you're trying to get, and what you're working with. Granted a Gen I/II SBC won't get you any gain in efficiency, even if you did put one in.