I just bought a 1990 IROC-Z and I want to install a true dual exhaust system with turndowns before the rear axle. Is this possible? I can't find anyone with this setup on this car. Any suggestions?

 

it is possible but not terribly easy. what size pipes you planning to run? and, there is vertually no place for a full sized muffler under the mid-section of the car. run some of those 4" round mufflers and you might be able to work something out

 

I want to run a true three inch system. I have had a few older muscle cars in the past with three inch exhaust. I really liked the sound. Anybody have any suggestions?

 

Grab some Hedman longtubes, they'll make running duals much easier. It's possible to run duals with shorties (I speak from experience) but difficult. You will then need to get pipe bent to go down along the driveshaft tunnel then mount the mufflers right before the turndowns at the axle. I would reccomend a 4" round design muffler such as a Dynomax Bullet or a Moroso Spiral muffler. The hardest thing really though is finding a shop that will mandrel bend 3" pipe for duals (I couldn't find anybody in town to bend my pipe so I cut and welded the pipe to fit myself. I even went to some shops and they said duals couldn't even be run on my car...)

 

I know how you feel. The week I got my 90 I went all OVER the place looking for someone that would do true duals on my car and everyone told me it isn't possible. Major lie, they just don't want to do all the work it takes. I had to settle with a Flowmaster 40 series. Yes, it is very hard. I'm getting ready to do duals side-exiting myself. I don't think Kfoley could have said it any better. Listen to him!

Bruce (90RS305)

 

I wish it was possible to run dual pipes (2.5"-3") with 2 converters and 2 Flowmaster 40 Series with the tips exiting like stock on these cars and still have some kind of clearance.

 

It IS possible! Not only have I seen it, I've seen it pass emitions! No lie. It was on a 87-88 IROC (don't remember exact year, he didn't have it for long) but yeah it was on there. It'd take me a whole forum to explain how it was in there...

Bruce (90RS305)

 

Explain!! That must've sounded good.

 

Ohh goodness yes it did. Made me friggin' jealous as hell. Especially cuz' I had JUST gotten my RS with a 305! I must say, it DID have quite a few bends in it, which made it more restrictive than you would prefer, but it DID make the car quite a bit quicker. Basically both pipes followed the passenger side (stock exhaust rout) and had the 2 cats for the most part right where the single one is located. From there its a strait shot back to the axle, up and over, then back down. As for the mufflers, its hard to explain, but they were next to each other, but offset. I'd have to show a picture and I'm far from artistic. Then, instead of pipes strait out the back, he opted for the stock look and had them angle down just out of sight like it would look off the assembly line. As far as part numbers, pipe sizes, and all that good stuff, I have no clue. I was too busy drooling when he was telling me. :hail:

Bruce (90RS305)

 

What size pipe?? Mandrel?? Sounds like he basically ran the exhaust the stock way with 2 pipes next to each other, 2 converters in the normal location, straight to the back and over the axle, but how the mufflers were you gotta explain better. Next to each other how?? He still had clearance with this??

 

Please explain the layout of the mufflers if you could. I will then try to find an exhaust shop to do it. I really want a three inch dual setup on my 1990 Iroc.

 

If you go with the setup he's talking about it'll be pretty tight to fit two 3" pipes over the axle. It's been done before, but it's pretty tight in there.

 

It does depend if you have SFC. Ir you have them in they might have to come out. The spacing and the size of the pipes will detrimine if that has to happen. If you don't have SFC them you will be able to put the duals in, but its a lot of work, if your having someone do it it can be expensive.

The first thing you have to do too is get the right muffler set up. If you try to start out with pipes and shape them then you will run into a big problem. I think that flow master has something but i am not sure on that. when you get done you also should work on your chip. This will improve your power, gas milage ect.

 

Gah the mufflers are hard to explain without drawing them, and I know even if I did I wouldn't do them any justice. They were offset, meaning one was more toward the front on the driver side and then the other was toward the back on the pass. side. Does that make sense? The pipe sticking down on the pass. side did a wierd loop back to make it out that way, that I could not explain, didn't get a good look at it. As for pipe sizes and all that stuff, finish reading my last post all the way through...

Bruce (90RS305)

 

mine comes off my header collectors, goes around the transmission crossmember, through my SSM lift bar cross member (basically following the trans tunnel) and under the rear axle, and exits through 2 flowtech warlocks in basically the stock location, its all 3" tubing

 

hey, you got anymore pics of that dual setup? ever have any problems with it going under the axle?

 

i have a few pics, but thats really the only one where you can see anything.....

never had a problem yet with the pipes being under the axle, they dont hit or anything.

its tight for clearance near the tranny xmember, and it has bottomed out before....but i have original struts in the front still, and the tubing is 3"....my brothers car has the same setup with 2-1/2" tubing, and his has never hit before

 

lol that looks NOTHING like the setup that the IROC I am talking about had. That one is MUCH less restrictive, and with a 383 I bet that sounds #$%^@ awesome!

Bruce (90RS305)

 

it does sound pretty mean, and it is basically zero restriction, as when i have run the car with exhaust open, it doesnt pick up any speed in the traps.

with cats, you could probably get through emissions as well....my brother has cats on that setup, with 2=1/2" pipe

 

What I'm more than likely going to do before I retry my quest for true dual is get 17's in the front and 18's on the rear tires to give me a more aggressive look AND give me a lil' extra clearance. I want 3"....

 

I have the answer!!!!!!!

You may not like it but I have it.

1. On dual cat cars the floor board is raised right in front of the passengers seat.

So, do the same to the drivers floor pan. Now you have room for cats.

2. The rear foot well are not needed by most.

Cut the Faulkers out. Actually you can raise them about 4" and this will make for plenty room for mufflers.

3. Install new true duals!!!!



WAAAAHHHH LAAAAAAA

PRESTO, MAJIC it's done.............

 

Are you really gonna need dual 3" though?? Dual 2 1/2 is really good to around 12.0 or better.

 

that depends vastly on the engine

 

Yeah, for my 305 the 2 1/2" would work best but soon I should be getting my 383 (I hope I hope I hope) so I figure cut down on backpressure!

 

heres some pics of the exhaust out of the car....

 

more...

 

Cool. Did you guys do that yourselves or did a shop do it??

 

a shop did it for me last year.....there is actually a huge pipe bender right inside that door...but im not any good at bending tubing, we use it for some special jobs.

like the posts that hold up the safety fence at loudon speedway in NH....we make those, they have a huge sweeping bend on the end of them, but i cant do complex exhaust stuff lol.

 

How much was that exhaust and what size is it??

 

its 3" and i dont know how much it would cost......i did a small fence, job for the guy, and he did my exhaust.....quid pro quo style......i think he said it would have been like a 500 dollar job or so, for all the custom work.

you can get the mufflers from summit, i forget what i paid for them....they are flowtech warlocks

 

WOW that looks totally sweet! I bet that sounds monsterous with the cut-outs removed! $500 huh? He willing to mass-produce?

 

i did it with 3" and an h-pipe and ive got a pic, i just do not know how to get it on the post.... so if some one would say how or ask i will email it pm it or post it or something

 

dur.....geee, george i figured it out disregard the previous post by me.... :lala:
p.s. sorry for the horrific size i do not know how to reduce it

 

1989rs...do you have any ground clearance issues with your setup? who did the piping? and, are those dynomax(?) 4" rounds or which ones are they? i like it.

 

yes they are dynomax mufflers, the 4" round ones they are 3"in/out x 12" and i did have clearance issues until i turned up those clamps, they were the lowest part of the whole system(the only part that scrapes)unless it is a severe curb with that
done...i have about 3 1/2=4" somewhere around there, which is enough for me i can get over speedbumps fine. and on top of that, the whole system, i did myself, for less than $160.00

 

i can't really tell from that pic....is the h-pipe bent like the pics above or is it straight back?

 

i believe it is tilted somewhat , if thats what you mean, otherwise....im confused:lala:

 

i just mean, are your pipes bent to go under and around stuff like 383's are in the pictures he posted above? or are your pipes straight?

 

they are straight, i did not use a single bend, with the exception of hedman x-tensions to go under the car, (very simple)

 

it almost seems too easy

 

it was (almost).... too easy, it only took about 3 hours to do the whole system

 

a guy near here was bending exhaust for a living and he owned a 86 Iroc with an under the hood blower,and wanted real dual....so he did a side by side all the way to the rear and he did it where the stock would normally go and he said he'd never do it again because of all the work involved but it did sound good,But my Camaro I put Edelbrock headers with 3" pipe to the muffler and 2-1/2"
exit to the rear and mine sounded sweet but it cost me like 6-700
to do it.... but it was a bolt on system and was slick!

 

it only cost me $160.00 for my whole setup and it sounds like nothing else

 

Hey 1989rs.......could u get some more pics of that exhaust system? I am probably going to do the same system you have. And what size of tires do you have...want to make sure I wont have clearance problems. And what kind of headers do you have and could you get a sound clip of your exhaust.....rally intersted in making this. Thanks alot man!

 

1989rs, how bad did that system hurt your ground clearance? and please get some more pictures. im very interested in doing that to my car.

 

I dont think he is on these forums anymoreb/c his last post was like 2 years ago. Has anyone else done what 1989rs did to his car? i am very interested in dong it.....it almost seems to easy.

 

oops, i didnt even notice that! but yeah, whos got a simular setup like what he had?

 

m66nova has almost the same setup...go to the dual exhaust picture thread. Maby someone should ask him about how to make it...although it does look like he has a ben in the front going up by the headers.