pics of 3" exhaust on a 2nd gen bird
 

hi. i'm ready to purchase an exhaust system for my 72 firebird & am having trouble deciding which is the best way to go. looking at the pypes kits with dual mufflers but my dilema is do i get the 2.5" or 3"? so i'm looking for some input &/or pics of a 3" system on a early 2nd gen, or later years too. the engine could benefit from 3" & although its not a full time drag car i dont want to choke it out with 2.5". who is running 3" on their bird & what problems did you run into for clearance on the floor? i know the cross member can be an issue or the cross braces in the floor, & possibly the fitment of the tail pipes in the rear. the car is lower than stock but not excessive & the headers do hang a little lower than most due to their tube size.

i looked into doing a custom kit with 3" x pipe & 2.5" tail pipes but pypes doesnt make that easy if you want to order it that way, they make you pay full price via PY & charge shipping on top. yet summit & jegs has super low prices for the standard kits but pypes wont let them order just rear tailpipes. you'd think they would offer the custom kits for guys with higher hp engines or be somewhat competitive on the prices with the larger retailers they sell through, but apparently not. i am all for buying from PY but just cant justify $100 more compared to summit when on a tight budget. so its looking like if i want to have the better flowing exhaust for my car i need to buy the 3" kit, or piece it together to get the 2.5" tails & spend ~ $100 more.

engine dynoed at almost 520 hp with no tuning yet & i have plans for more power in the near future. pretty sure 2.5" will not be enough for this engine. pics & opinions would be a huge help...

400/467
stock e-heads
old faithfull roller cam
SD ported cast iron intake & cliff prepped q-jet
hooker s/c 2" headers
th-400 trans.

My son has Hooker 2" primary headers on his Big Block Chevy powered 1979 Camaro with a 3" exhaust system that is bent like the stock exhaust including the tail pipes. Not a lot of room back there by the shocks, leaf springs and shackels and the rear sway bar end links but it fits. 2 1/2" exhaust will have more clearance.:)

I would chose a well designed mandrel bent 2.5" system over a cobbled together combo. For a primary street car, there is nothing to gain but noise, weight, and clearance issues with a 3" system. See my performance sig below. 3" non-mandrel bent pipes from headers to 2.5" flowmaster (don't flow that well) mufflers, and 2.5 mandrel bent tail pipes (flowmaster brand ordered from Summit.) Even the crossflow systems will work to around 500 HP and no mufflers hanging under the car.

Interesting combo...e-heads with iron intake.

Cool.

nothing cobbled together, it's all mandrel bent stainless from pypes. it would basically be their 3" kit but with 2.5" tail pipes. its about a 75% street car, will see track time but mainly for fun & tuning. just figured the 3" x pipe would be worth while & for the price savings just get the whole kit if it fits well. i know there are lots of firebirds out there with 3" full exhaust, hoping for some pics of opinions to help me decide.

yes, not my first choice but i'm going to be running a formula hood & it's the only combo that will fit right. of course i could run a torker or tomahawk type intake but i want to use the q-jet for now since its mostly a street car.

intake was done by SD with their "stage 3" cnc port. opened plenum per cliff's design & then hogged out the runners & matched to the e-heads ports, very nice job on the intake & SD says it has supported up to 600hp on one of their builds. im at about 520 on a brand new engine with no tuning so i would like to do a 3" exhaust if its not too much of a hassle. or a 3' 2.5" hybrid.

Torque Tech 3" tailpipes fit great plenty of room. Downside they exit below bumper do not "correct" for a 78.
I'll see if I have pics at home.

You can always order 3 inch Pypes X crossover ,use cone reducers into good flowing 2.5 mufflers (I use Ultraflows)and order 2.5 flowmaster tailpipes...
I've ran almost 119mph with a similar setup..the smaller tailpipes help mellow out the exhaust note too.

skip: i dont like under the bumper pipes, correct or not, just dont really like the sound. i plan to have the pipes exit where the dual splitters do on a later t/a. pypes said you just cut the pipe after the hanger & re weld a straight piece angled to where you want it.

t/aman: thats kind of what im considering doing however the cone reducer isnt stainless like the rest of the system. i am planning on using the pypes race pro instead of the ultraflo's, the race pro's case is the same size for 2.5 & 3", they are 4" tall, the ultraflo's are 4.5" tall. so i save a little money with race pros & a little space. & at 3" they should flow just as good as the ultra's. then its just a matter of expanding the end of the 2.5" tails to fit inside the 3" muffler.

I have a 72' bird with dougs headers 1 7/8 primary. 3" pypes systems with 3" super 44 flowmaster mufflers ( 4"thick casing instead of 5" casing provides a little more ground clearance) I did the install in my garage with the jegs brand band clamps. Also have the dougs electric cut outs just to be fun or obnoxious. : ) Did not have any major issues.

3.5 Pypes X with 3" Ultra flos and 3" Torque tech tails..

The only way for a 3" at splitter location would be to cut and section (which I have plans to do) where it comes out at that last hanger kind of like the Pypes adapters for splitters on their 2.5". Also most commercial splitters for 3" are a 2/5 bumped to slide on a 3". A 3" SS 45 could be cut to make a real 3" splitter. Problem there is it gets real tight through there and the leaf spring to body area.

nice pics of the 3.5" x & 3" tails. looks like the x & mufflers fit "ok" but the t/t tails might be a problem if you run a sway bar which i intend to do, & they need center outlet mufflers, pypes mufflers for their kit are offset/offset. so i think the sway bar kills the t/t tails. but thanks for the pics.

mg12692: good to hear you installed that kit ok, can you post any pics?

skip: sounds like what pypes told me to do, they said just cut the tail after the last hanger, then reweld or clamp a straight piece to exit between the leafs & quarter panel. no adapter or sectioning was mentioned. & to be clear, i dont want the splitters, just a single fat pipe exiting in that location like in darby's pic.

if 3" pypes tailpipes will fit there i will just make it easy & buy the 3" kit, but 2.5" tails would be easier to do & probably a little quieter.

Here are side shots of the Torque Tech and a rear one. Fine with a sway bar.

looks good. are your mufflers center or offset outlet for the torque tech tails?

All 3"
Pic 1:Was like this for years never liked it..
Pic 2: hackd it off even and put some bends on i picked up from the pypes tent. Kinda cheezy but the kids liked it.
Pic 3: chop saw the bends... more subtle i guess. Kids liked em shooting out the side. It did sound quieter.
Pic4: ended up going this route

Looks good, Darby. eventually I'll probly just cuttem off like you did... it's just hard to uncut it later so I've been dragging my feet

uh, pic #4?

what i want to do with the tails whether i go 2.5" or 3", is to cut right after the rear most hanger then agling it to come down right where yours are in pic 3 but with a straight piece of pipe. so it will angle down just like the dual splitter tips for 78's. basicallly just like in darby's last pic. hopefully 3" pypes tails will let me do that.

I have offset inlets/center outlets. That is how my original 2.5 system was and the electric fuel pump is next to the frame rail where offset/offset would not work unless I moved it. I had to add about 3" between the two Torque TEch pieces to do it as they are set up for offset/offset. I have Dynomas Ultraflows on it now. Dr GasX 3" in front of them.

I really played with the 3" tailpipes under the Camaro when I had the tank and everything out and I really think at least on Torque Techs there is enough room between the spring and the body for a splitter to kick out.

Almost 4 inches of ground clearance with 2 1/2 dynomax and some saggy rear springs.


http://i1177.photobucket.com/albums/...psd5fc5794.jpg

thanks but i am looking for pics & info on a 3" exhaust with an x pipe & tailpipes.

I have a set of 3" tailpipes for sale in the F/S section. Aluminized. Off my 76 T/A when I was running that small of a system. ;)

Dunno.. Still not crazy about it..

X2 BTDT even more fun w/fat tires

i went with torqe Tech's 3.5" X to 3"tails
system is very nice
before that one had their 2.5 dual kit, again super easy to install and fit absolutely perfect

before that one, had it custom made at a good high end exhaust shop

I have run multiple 2.5" systems at 425-450HP at the wheels. Engine dyno 2.5" at the 540-560hp range. Flowmasters in most cases. I like the Flowmaster crossflow system. Sound is very unique for a Flowmaster. I would do 2.5" sys. with cutouts. Never put smaller tailpipes on a system.

interesting & good to know. can you comment on what you think your 450 rwhp would have done if it had 3" exhaust? thats my main concern here, will 2.5" hinder or limit the engine? even though its mostly a street car i do not want to choke this thing out, especially with possible future power increases. if i'm at ~520hp now with no tuning or possible upgrades, what happens when i hit 550-575? do i get to replace the $500 system with another $500 system? just trying to avoid that & get a system that will not hinder what i have currently & be able to support possible future increases.

as for the smaller tailpipes, what about the fact that the exhaust gases have cooled dramatically by the time they get to the tails & dont need as much diameter to flow adequetly. it's been commented on many times & even tested & proven at the track by jim hand.

my dilema is based on everything i read on this forum & others sources. if bigger exhaust is not required for higher hp, why does everyone say you need 3" at about 500hp & above. quite a few guys on this thread alone are running 3.5" off the headers into 3" mufflers & tails.

i'm curious why you say 2.5" is ok for 500+ & to "never put smaller tailpipes on a system" can you elaborate on that?

got any pics of your current system?

3" Pypes x-pipe with Race Pro mufflers and 3" tips on my 74. It does tuck up very nicely into the body.

Note: the left tailpipe was bent wrong, so we had to use an offset exit muffler on the left side to make it work. As the car was occupying a lift in my friend's shop, that was quicker fix than getting a new tailpipe. Hoping to fix it next year, along with some detail work on the undercarriage :o

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http://i120.photobucket.com/albums/o...4tower0059.jpg

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very nice! thanks for the pics. sure does tuck up there nicely for a 3" system.

did you buy the kit or piece it together? i dont see their hardware, just welds. what was the issue with the one tailpipe? did pypes send it to you bent wrong? as far as i know their kit & tails are made to use the off/off mufflers, not off/center like the right one in your pic. did they offer to help but you didnt have the time to wait? i'd be pretty upset if they send me a wrongly bent tailpipe!

this is the usual trouble spot, with the leafs, sway bar, fender and fat tires its a bit tight

i agree it can be tight back there, but from everyones pics it looks like the leaf to fender has plenty of room, & it clears the sway bar & tires... depending of course on what rims/tires one is using. mine will be 15x7 with 255/60's so it should be ok. my main concern was the 3" x pipe clearance.

My friend spent some time to make sure it tucked up. It won't without some effort :)

I bought the kit from one of their resellers, BSM Exhaust, and it came with the center exit mufflers. The tailpipe was pre-bent wrong as it would not clear the leaf spring with the center outlet muffler, hence the offset exit muffler. The right side fit like a glove. The kit had the wrong x-pipe also. BSM sent me the right one without making me send the old one back, which took up a few days. And when the tailpipe issue came up, I didn't want to tie up my friend's lift any longer (he did the whole job for free...), so I over-nighted a muffler from Jeg's to expedite the matter. I am sure either BSM or Pypes would have addressed it too, but I ran out of time. Or if he had a bender he could have shaped it to fit with the center exit muffler. He also decided to weld everything rather than use the clamps.

I am using 255/60-15 tires on the 7" honeys :)

I had that 2.5" crossflow system on my car. Did the drone when cruising bother you? My Pypes 3" is actually much quieter than the Flowmaster :p

How about posting track data with exhaust...my car mph's in the 118's with 3 inch PYPES X ,2.5 Ultraflows and 2.5 inch tailpipes.

If you have a really healthy exhaust system budget, you could get a system that uses oval shaped exhaust tubing. Spendy but very nice & helps keep a boatload of ground clearance

Built a stainless 3" system out of mandrel bends from Columbus River. Used 3" Ultra Flows w/o a crossover. Have had many compliments on the sound, will never have another car w/o a 3" system. Worth every penny and the extra effort.

I have tested a lot of complete exhaust systems on engine dynos and chassis dynos. Thats why I say what I say. All engines are different. To paint with a broad brush here and say it works for this guy or that guy is cool with me. So are you saying that hotter gasses take up more room than colder gasses? BTW, did I try to put smaller tail pipes on the dyno, no. Did I baseline with open headers and a collector extension, yes. Havnt seen a complete exhaust make more power than open headers. Have I done back pressure testing at multiple spots along a system, yes. I simply use this dyno info to jet accordingly, and say to myself " that system only sucked X of the top." I dont know why other people say what they say or do. I test in a controlled environment and use math and stuff. You guys do what you want to do. Most of the time your minds are already made up. I'll just stick to my book learnin'.

3.5" oval. Busch series Flowmasters.

not at this time, but i can try to take some this weekend if i am feeling better
the flu hit us pretty hard the last two weeks

yes, i am saying, based on numerous info & testing i have read from reputable sources, that hotter gasses expand more & therefore need bigger pipes compared to cooler gasses. makes sense to me & sounds like its based on facts of physics. are you saying that's wrong? nobody is saying a complete exhaust will make more power than open headers... where did that come from?

my reply to your initial post was simply asking for more info on your statement that a 2.5" exhaust is ok on 550+hp engines... i asked what a 3" would have done in comparison. please elaborate on that with "math & stuff" & "book learnin."

not sure why the negativity in your reply, "you guys do what you want to do. most the time your minds are already made up." i wasn't doubting you, i was asking for more information based on your statements. sorry if that offended you.

thanks everyone for the help & pics.

Open header vs exhaust personal experience with 10.95 @ 124/6.91 @ 99.1 1/8 mile 3750 lbs car. initially had 3" head pipe and H pipe into 3" 2 chamber Flowmaster mufflers and 2.5 tail pipes(class requirement from previous class racing). Would loose 0.3 with exhaust hooked up compared to dropping a 12" section in the collector headpipes.Tailpipes were getting thin so we dropped entire exahust system with a tranny swap. Took to track and dialed in with new tranny/convertor and got the 1/8 mile times. Added a 3" Dr Gax X Ultraflow 3", 3" Torque Tech tailpipes and even with all that additional weight the car ran identical 1/8 times. So that car ran identical even adding a little weight open headers to exhaust system.

Theoretically with the same number of air molecules hot air will displace more volume than the same amount of molecules at a lower temp because the molecules are moving around more with more "gaps" between them. Same with a liquid having more volume at a higher temp than a lower temp.Thermodynamics and how a thermometer (non digital) works. So theoretically cooler exhaust should displace less volume and could ue a smaller pipe to keep the same velocity as hotter gas. Probably some formula you could figure.How much I can't tell you, or if it would be enough that a 2.5" woul dbe OK vs a 3" can't tell you either, and I would keep a system the same pipe diamter

The pipes system looks real similar to my Dr Gax X and Torque Tech tail pipe system.

The relationship between pressure, volume, and temperature of a gas is most simply decribed by the Ideal Gas Law; PV = nRT, where P is the absolute pressure of the gas, V is the volume of the gas, n is the amount of substance of gas (measured in moles), T is the absolute temperature of the gas and R is the ideal, or universal, gas constant. If you increase the temp, you increase the product of the pressure and volume. Bottom line, if the volume remains the same (as in a car's exhaust system), if you increase the temp, you proportionally increase the volume as "n" and "R" are, for all intents and purposes, constants in this scenario.

Had the exact same result as Skip on a Nova. Same 3" full system exits behind the tire, Flowmaster Super 40's. System is built with flanges, took out the sections ahead of the mufflers 11.86/111.68 full exhaust, 11.63/114.88 open. I was stunned, I made my 1st pass down a dragstrip in 1960, and seeing a 3+ mph increase on a system that I felt was very efficient was jaw dropping.

Have a couple 9" bullet mufflers I'm going to put on the Catalina in the spring, that and an aluminum flywheel might be just enough to get by an old friend who has a max wedge 63 Plymouth that outruns me by about 3 tenths.

Wrote a lenthly dissertation in responce to 78w72. Lost the data before I could post. Tired now. Not offended. Do your own testing. Forums are for advise not fact. Including my own. You got some pix. Not a big deal here. Take it or leave it. Its the internet. Just here to help. Posting my experiences.

I also went with a side exit oval tube exhaust system. I purchased mine from Ram Air Restorations. The system is their UXO-30 universal oval tube side exit exhaust system with 3" diameter tubes, X-pipe, and dual Spintech Sportsman series mufflers ($749.00 plus shipping). It's also available in 3.5" if you prefer. My 1978 Trans Am is lowered just over two inches from stock, and I have plenty of clearance between the exhaust and road. Being the non-conformist I am, I wanted something unlike any 2nd gen Firebird out there. The look and sound is unreal! Just another option to consider...

http://www.ramairrestoration.com/pon...th-x-over.html

"...if you increase the temp, you proportionally increase the volume"

I should add, if you decrease the temp of the gasses (as they cool passing thorugh the exhaust system), they proportionally decrease in volume. The big question is "how much do they cool...and how fast"? Factors that affect this are: surface area (larger diameter pipe and/or mufflers, the ambient temperature, the velocity of air passing over the pipe, fuel mixture, and timing. There are other factors that affect the rate, but are less influencial.

no hard feelings. i appreciate the help & advice... some of it just sounded kind of negative, or like you were mad for some reason & i wasn't sure where all that came from.... :confused: & it seemed like you were doubting or questioning some of what was reiterated about hot exhaust gases &/or using smaller tails. all backed up by tests at the track, & others even used math & science & stuff to support it. & yes forums are for advice, but that advice should usually be based on some type of fact. no?

t/a525: that ram air system looks very nice, i've "heard of" spintechs but never actually heard them. however at $749 + s/h they are way out of my budget.

based on the info & pics here i have decided to go with the 3" pypes system. any other info, advice or pics are welcome though.

thanks again!

tpssonic. That is the big question. The dyno loops at 200rpm per second from 2500-6000 tend to get the whole exhaust system pretty toasty. Most of the exhaust is pretty straight untill you put the multiple bends after the muffs. Inducing some restriction. Airspeed under the car helps cool, I'm sure. The Westech Dyno rooms are pretty "windy". Next time if time permits I would like to install 3" inch tails on a 2.5" system. Maybe create some extra "pull" on the gas column.

I should add, if you decrease the temp of the gasses (as they cool passing thorugh the exhaust system), they proportionally decrease in volume. The big question is "how much do they cool...and how fast"? Factors that affect this are: surface area (larger diameter pipe and/or mufflers, the ambient temperature, the velocity of air passing over the pipe, fuel mixture, and timing. There are other factors that affect the rate, but are less influencial.


That was my comment on hard to figure how much without an A vs B trial.

Another factor often overlooked in the whole equation is header tube diameter. Too big can decrease the velocity into the exhaust system and even my 2 chamber Flowmasters caused reversion until I dropped to a smaller tube size. This also decreased the open header to exhaust system difference on that motor.