.I have been doing work to find the best exhaust system at the lowest price,below are tips to help less experienced fiero owners ,,Unfortunately my paper with all sizes & where to buy was thrown away,errrgg 1=almost any turbo muffler will improve performance. 2=for best performance the muffler has to mount in the stock location. 3=a performance cat will not hurt performance 4=a straight pipe is better for flow 5=It is easier to mount the muffler where the cat was ,but this hurts performance glasspacks are restrictive & hurt performance because of small entrance slots to packing,, hard to believe but true. 6=use a hack saw to cut out cat,save the most pipe you can,cut past the welds .with 2 new blades this goes quickly 7=file down the slag & welds .smooth to correct form of pipe . 8=use extreme care to save every inch,every millimetre of the pipe that runs from the cat to muffler ,,the B pipe 9=you need a 22 inch pipe to replace the Cat.auto parts store do not have this length pipe in stock.this is the A pipe 10=Advance auto carries an 18 inch pipe that will work if you use 2 adapters the stock pipe is 2 inch use an adapter that necks down as the first adapter . 11= the 2nd adapter will fit inside the B pipe 12= Of course you can weld it all together 13 =If you weld pipes together,, do not weld it all to make removal easier 14= the most difficult hook up is at the B pipe to muffler connection 15=use the stock springs to mount muffler remove original sprin hooks 16=use L brackets as replacements for original spring brackets 17=use muffler clamps as spring holders ,drill holes in clamps 18 =if you saved muffler spring holders by chisel off or cutting off weld to new muffler,,metal is thin so this is expert stuff. 19=buy eye bolts & small turnbuckles from hard ware store to pull/ajust springs and pressure 20=use dynomax ,magna flow,flowmaster,hooker aero, almost any turbo will improve performance 21= for duke & stock 2.8 60o up to 125 horsepower use dynomax 17730 2 inch inlet & outlet. 22=For 3.1,,3.4 V6 & modified 2.8 V6 use #17733 dynomax,, the 17733 has a 21/2 inlet & outlet ,,In my corespondence with dynomax techs this is best up to 190 horsepower 23= if you have limited wrench skills use the thrush turbo muffler from summit racing equipment (fast shipping) summit/thrush#WLK17702 a bit noisy under acceleration. I will finish this in another section ,, the mounting of the new turbo muffler is not fun,very time consumming I will cover some therory in short understandable SIMPLE terms & try to find correct specs for adapters to ease install .. this is worth it for the duke
[This message has been edited by uhlanstan (edited 04-24-2011).]
I know you have great faith in the published articles extolling the virtues of the Turbo Mufflers, but, Stan, I can tell you that I tried one on the Fiero and it cost torque and power. I replaced it with a Magnaflow and reversed the effect. The Magnaflow is, like the glass pack, a perforated pipe with stainless mesh behind the holes.
I have a turbo muffler sitting. It ain't worth the amount I paid for it.
Arn
IP: Logged
02:55 PM
Isolde Member
Posts: 2504 From: North Logan, Utah, USA Registered: May 2008
I first tried "turbo" mufflers on my '71 Camaro. It had a mild 350, with dual 2.25" pipes. Not happy, I cut those muffs open, and made them very much like the DynoMax "Super Turbo", which was louder, but only made the car a tenth quicker at the track. Cutouts found me another 3.5 tenths. Fast forward through years of Cherry Bombs, to the late '80s. Borla was all the news, and beat Flowmaster in every test. So I bought a pair of Borlas. I was happy with them. On that car, they were a tenth slower than cutouts. I've tried Supertrapps with the expected results: the more discs you add, the louder it gets, and the quicker you get. I have finally found a good use for chambered muffs, like Flowmaster, but it's nothing applicable to a Fiero. A single 2.5" straight pipe is no restriction at the 260 crankshaft HP level.
IP: Logged
03:31 PM
Racing_Master Member
Posts: 1460 From: Hooksett, NH, USA Registered: Nov 2007
I know you have great faith in the published articles extolling the virtues of the Turbo Mufflers, but, Stan, I can tell you that I tried one on the Fiero and it cost torque and power. I replaced it with a Magnaflow and reversed the effect. The Magnaflow is, like the glass pack, a perforated pipe with stainless mesh behind the holes.
I have a turbo muffler sitting. It ain't worth the amount I paid for it.
Arn
What turbo muffler? Just wondering so I stay away :P
Also for performance exhaust, it is not just "straight is better" and "glasspacks suck" because both of those... are false <_<. a GOOD performance exhaust actually creates a vacuum at the engine, to suck the exhaust out of the cylinder, and increasing velocity of the intake, to fully evacuate all exhaust and create more power. a straight dump right off of the manifold technically should (in rational thinking) produce the most power, however this is not the case, it actually removes power.
Designing a performance exhaust can be very very mathmatical and tricky. First of all you have to use fluid dynamics (Air is technically a fluid, as physics is concerned) to design a system that flows properly. Second, exhaust travels in pulses, not a straight stream, thus a frequency builds inside of the exhaust pipe. Tuning this frequency can enhance exhaust evacuation. X pipes, H pipes, and the like, also have a benifit in exhaust evacuation. 180 degree headers work very well also. if you time each pulse over one another next to the next pipe to get a pulse, it acts like if you blew over the top of a straw in a drink, it will suck the exhaust right out of it. X pipes work off of this theory however they do it per bank vs per cylinder. Header styles, types, exhaust length, muffler style, build, baffles, resonators, pipe steps, all of these have an effect on your exhaust. Articles in magazines generally simplify it for the general public. However people who build race cars do not look at a magazine to design an exhaust, they do math to tune a perfect exhaust for their exact engine the built. No two engines will react the same to the same exact exhaust/parts/ECM tune
one last thing, Magnaflow I believe has an x pipe in dual in dual out setups, even if its a glasspack style, it has an X pipe inside to enhance exhaust evacuation.
BUT with just making your stock exhaust better, without too much work, a simple performance muffler (flowmaster, Magnaflow, Borla... etc) would work sufficiently to increase your tone and make you a bit faster. Its the cheap and easy way to make a good sounding exhaust. However, I wouldn't call it performance, just upgraded :P. The tips about cutting and leaving the welds are good, I diddnt do that but I had a nice bit of pipe to insert and stick weld in the cat's place. I left my stock muffler but I do plan on making a full performance exhaust at some time... I have no clue when :P
[This message has been edited by Racing_Master (edited 04-24-2011).]
What about no muffler at all? Go from downpipe to the free flow cat and straight out the tail. Buddy of mine did this for his LT1 install and it is not loud when you are not getting on the pedal, but when you mash it..... I think the deaf can hear it.
does the engine need some back pressure?
[This message has been edited by timgray (edited 04-24-2011).]
IP: Logged
09:23 PM
Racing_Master Member
Posts: 1460 From: Hooksett, NH, USA Registered: Nov 2007
engine NEEDING backpressure is a myth, just like charging/storing batteries on concrete is a myth. Race engines actually have negative backpressure, because their exhausts pull vacuum by the pulses of exhaust flow :P
..DID NOT EXPECT SO MANY REPLY SO SOON,,THANK YOU My post is partially based on Dyno comparison reports by Various hot rod,car craft magazines & my corespondence with various muffler tech support.. ..I also cut out articles on Dyno testing of various performance mufflers. this is aimed at the Fiero owner who will never pull the engine to build for performance,but performance builders can also use this.. Google the below
hotrod magazine muffler test carcraft magazine muffler test titantalk.com flow chart for a few mufflers
I understand that mounting the muffler at the cat location negates part of the power from a turbo muffler . the louder muffler always seems faster a properly mounted turbo will produce more horsepower than a straight pipe
there are not a lot of performance parts available for the stock Fiero engines If you port the stock exhaust manifolds doing a premo job,, port out the Y pipe & have fairly smooth piping flowing back to a turbo muffler ,you can gain 15 horsepower ,not much compared to a sbcV8 but a lot for the 2.8,3.1 & 3.4 V6.. ..most fiero owners will never have a truelo header,, a few will have a west coast fiero or Fiero store header,you need a free flowing muffler to take advantage of the headers or ported manifolds I pick the Dyno max turbo because it is quiet ,has a nice sound & is affordable,it sounds fantastic at 5000 rpm I use magazine Dyno test ,,I have no money for serious testing,,I do not have a Dyno nor the money for 50 dyno runs ..The mounting of the muffler in the stock location is a royal pain in the butt,the reason for this post.. you need pipe B to be as long as possible a few S hooks may help some people I eliminate the old spring mounts & the exhaust tailpipe tips the hardest match up is the pipe B to the muffler this connection should be welded,, this is the pipe from the rear of the cat to the muffler . Using the thrush turbo will make the install easier because it is short like the stock muffler .. mounting in cat location causes excessive heat to starter & fuel lines,,keep fuel line hose cool !! if you have a 3.1 ,,3.4 or modified 2.8 V6 use the dynomax turbo 17733,, this is the recomendation of dynomax for more horsepower & torque.. # 17733 21/2 inlet 21/2 outlet
for stock V6 or duke use dynomax #17730 2 in inlet ,,2 inch outlet
I would use the thrush turbo for a mounting in the old cat location ,,it gives a little bit more room for heat shield
[This message has been edited by uhlanstan (edited 04-24-2011).]
..With the more powerful 60o V6 ,, using the Dynomax #17733 should produce as much or more power than a straight pipe .. the physic involved is variable the highest performing exhaust system is not always the freest flowing..less back pressure does not always equate to the highest horse power system Simple explaination VALVE SHUTS= low pressure wave surf downstream when this surf wave hits a neck down ,it is reflected back up stream. NOW with proper design the wave returns to the exhaust valve JUST as it opens and there is a reduction in pressure ,,which pulls the new gases out of the chamber poorly design exhaust systems reduce power . a really good system will actually pull unburnt gas thru the ex valve and recram it back in . this is why I want you to neck down the pipe just past the donut ,,newbies do not worry about this.. A glass pack/ steel pack hurts performance ,,use a turbo,, even if you mount it between the starter and fuel tank it will help . .. the most important modification you can make to the stock Fiero V6 is to port the exhaust manifold ,,grind out the blockage & smooth down the welds . to really port a exhaust manifold you have to V port the very front weld to take the bluntness out of it & reach back inside and smooth the interior weld s you can not see,, not fun to do .. a good exhaust manifold port job is worth 8 horsepower ,,a fantastic port job will yeild 8 to 10 horse power actually its all VOODOO chicken choking to me ..
