Has anyone put a straight pipe on a fiero 2.8 before? Even just for a day? I want to hear the roar!!!

Yes, its been done. I wouldn't recommend it though as for starters, its illegal and second the motor was tuned with the extra bit of backpressure in place.

Hi Everyone,

My 87 V6 Fiero has a straight pipe instead of catalitic converter. The only muffler left is the back one. The sound is great but reasonable.

Check Youtube. I haven't seen a Fiero, but there are straightpiped 2.8's in other GM's. I personally like the sound of a 60*V6 with true duals

i have straight pipe....kinda.... i took out hte cat, put a 2 1/2" bullet muffler where the cat used to be, then its straight out the back from there, its a bit loud, but nothing excessive, honestly, i think at the last meet i went to, i wasnt the loudest car....

i replaced the cat with a piece of straight pipe and had a flowmaster muffler. sounded great. just for sh!ts and giggles i replaced the muffler with a glasspack. its only a little lounder. i acutally liked it better with the flowmaster

We only use straight pipes as it eliminates a restrictive fire hazard. You will improve mileage, and your engine compartment will be cooler. The only reason to keep that piece of rubbish is to satisfy state law but if you hollow out the CAT and keep it in place then you'll maintain the politically correct look. The the evil crooked bureaucrats will be happy!

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

The problem with a straight pipe is induced backpressure. When the pipe gets 6' long, the pulse times of the engine exhaust get out of sync and you actually lose hp. You need to break up the pulse before you get to 6'.

The sound is the other problem. The 2" pipe by itself does not sound great. The pipe is just a little too narrow for that nice rumble.

Now, if you shorten the pipe to say, 3' on each side and just point them down. Different story, but, pretty loud and definitely noticable by the local heat.

Arn

quote Originally posted by Arns85GT: The problem with a straight pipe is induced backpressure. When the pipe gets 6' long, the pulse times of the engine exhaust get out of sync and you actually lose hp. You need to break up the pulse before you get to 6'. The sound is the other problem. The 2" pipe by itself does not sound great. The pipe is just a little too narrow for that nice rumble. Now, if you shorten the pipe to say, 3' on each side and just point them down. Different story, but, pretty loud and definitely noticable by the local heat. Arn

Consider that you still have the muffler in place so there will be some back pressure. However, several years back Herb Adams dyno tested the 2.8L with the Fiero exhaust and with a straight pipe and didn't record any difference in horsepower.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

When my cat clogged up, I replaced it with a straight pipe, leaving only the OEM muffler. At idle, it sounded great. Not bad under throttle, but man, when you took your foot off the gas, especially if you were gearing it down to use engine braking, it sounded like a freaking UPS truck. I drove it like that for a while, but when I put a hi-flo cat back on, I think it sounds much better with a cat than without. It has a much smoother sound, and the hi-flo cats are a bit louder than the OEM ones, so it's still has a little more aggressive sound to it.

Now straight pipe only - I don't think that would sound good at all. You need something to tune the sound.

quote Originally posted by Dennis LaGrua: Consider that you still have the muffler in place so there will be some back pressure. However, several years back Herb Adams dyno tested the 2.8L with the Fiero exhaust and with a straight pipe and didn't record any difference in horsepower.

Good point. While the Fiero may not be considered powerful by today's standards, when it was new, it was quite a bit more powerful than the regular 2.8 V6. The 2.8 used in other GM cars only had about 110 HP, but the Fiero got bigger heads, bigger cam, etc. The 2.8 H.O. V6 started out in the Citation X-11 program in the early 80's and the L44 V6 in the Fiero was the culmination of that effort. It was as impressive for it's day as the current 3.6 DOHC is with 250HP.

Keep in mind in 1985 a V6 Fiero has 140 HP, and a LG4 V8 Trans Am had 155 HP. (and that was an improved LG4 - in '82 it only had 145 HP)

[This message has been edited by Formula88 (edited 10-10-2009).]

quote Originally posted by Dennis LaGrua: Consider that you still have the muffler in place so there will be some back pressure. However, several years back Herb Adams dyno tested the 2.8L with the Fiero exhaust and with a straight pipe and didn't record any difference in horsepower.

My muffler is a Magnaflow with no backpressure (back pressure is a hp killer) and my pipe T's before it gets to 6'.

As for Herb's tests, we do not know what pipe length he was working with. I have seen dyno figures that seem to conflict with his findings. That seems to say that the variables seem to be pretty extensive and therefore variable outcomes. However, the science doesn't change.

Arn

Wow Dennis I normally agree with most things you say when it comes to engine swaps or problems but your irrational hate of catalytic converters is pretty nuts.

Truth if theres no reason to do away with having a catalytic converter. They are not a restriction on your exhaust at all unless they are damaged and clogged from lack of replacement. Catalytic converters can actually be benificial to exhaust flow by keeping the exhaust gas warm which will help keep exhaust velocity up. Brand new replacement cats (non-oem) can be had for $50 which is nothing.

Theres no legitament good reason to remove a good working catalytic converter, that is unless your goal is a nasty smell from your cars exhaust.

iv always thought a CAT is a form of restriction to the exhaust. then people hollow them out to get rid of the restrction. im just thinking older style CATs. i dont know what the flow rates are with the new ones. im sure theres some restrction but probably not much that you will notice a difference if you removed it or not.