Big exhaust + big power = BIG MONEY!

[Tim_K]

I was planning to buy a 3" mandrel bent exhaust system for my 89 Spirit 2.5 Turbo. Just waiting on the tax refund.

But between being unemployed for 2 weeks, having a stack of bills that gets bigger by the day, and other things that are drawing off cash before I even get it, I'm going to have to tighten up on my expenditures quite a bit.

So I'm trying to figure a way to get a good 3" cat-back system (without the cat) onto my Spirit.

Several local muffler shops say they can bend a 2-1/2" system, but we all know you need 3" for max power.

The one place that can bend 3" pipe charges $10 a foot to do it, and after spending close to $100 on a piece of pipe, it's still compression bent.

JC Whitney is no help either. Yes, they've got a good selection of mandrel bends, but everything in 3" is priced nearly DOUBLE what 2-1/2" pipe costs!

I need to find a cheap way out here.

I know, I know, "Speed's expensive, how fast you want to go?" applies, but I'm cheap AND nearly broke AND have a lead foot all at the same time.

Anyone got some good used 3" pipes from a Spirit, Shadow, or Daytona?

[guyd_15]

Go to a shop that sells parts for over the road trucks (Mack, Freightliner that kind of truck). Tell them you want 3" mandrel elbows and 3' pipe, ask to look in a catalog (I used the Donaldson brand, I think each 90 was around $10).
I think I have less than $40 USD in mine from the swingvalve to the rear bumper (I welded it up). The 3" swingvalve cost a bit more, oh well gotta have flow right? But I can't see a decent exhaust shop charging over a $100 to weld it together.
Guy Douglas

[scott_s]

I have been thinking about bigger than a 3". Why not 4" at least to the axle. Bigger is Better!! (for somethings)

[Frank]

bigger is not better. you will stall the gasses out of the turbo and the velocities will drop and you will get stagnation and lose performance.

engines and their surrounds have to work in harmony.

frank

[scott_s]

Then what about all the guys that do not run anything? I did not run anything for a couple days until I was able to get my system on. All I can say is WOW.

I have no experience with going to 4" myself but have read about a 10s car with a 4" downpipe. I imagine it was doing something good. I am familiar with going from stock to 3" and what that does. My 3" lightly modded (headwork) pulled about the same as a friend's moderately modded 2.5", with head work, a bigger turbo, IC etc. I believe the rule for turbo cars is the freer the exhaust the better. HP increases, gas mileage goes up.

I would do what guyd_15 suggested. I have a couple of other friends that found their mandrel bend pipe cheap that way.

[2Lebarons]

the problems with running "nothing at all" are clear....
as for 4" pipe, dont even think about it, unless your TD is in the 9`s.........
concerning fuel economy improvements....dont expect any.
despite what you may hear, even properly functioning stock exhaust systems dont hurt fuel economy...if they did, dont think for a second that the factory wouldnt have installed a bigger system.....

[Frank]

if you run nothing at all after the turbo, that is fine since the exhaust gases can disperse in all directions. A pipe directs flow so if you go to big, you stall the gases.

Yes you want to the exhaust as free flowing as possible, BUT not at the expense of sacrificing exhaust gas velocity. But that is a whole can of worms.

Frank

[scott_s]

I understand what you are saying. A 3" is plenty good for the stockish but the 4" would require the supporting upgrades to make it worth while. Just thought it might not be a bad idea from what I read. The other TD I read about, with the 4" , had the bigger turbo, IC, head, etc. so I imagine it was all set for it. Gus's pages mentioned the best muffler was the best, because it had a 4" pipe in the center. So I just went from there thinking if it was good for the muffler should be good for the whole system.

2Lebarons, perhaps you refer to no gas mileage increase going to the 4". I mentioned the gas mileage increase because, going from stock to 3" mine did and I just extrapolated that a 4" would as well. Going from stock to 3", I went from 27-29 to 33, with my last tank getting 34 and that was with most driving through the snow when my mileage usually goes in the tank, so to speak.

I just thought to put the idea out there to see what others thought. Now I know, thanks guys.

Sorry to go a little off topic Tim_K. Hope you are able to find the cheap mandrel bend pieces. I know a buddy that put a 2.5 on and after driving my car he is planning to put on a 3" exhaust.

[Tim_K]

I went to the muffler shop today that said they could bend me a 3 inch pipe. I had them put the car up on the lift, and I showed them what I wanted to do.

They said 3 inch would not clear between the spring and the gas tank. They handed me a piece of 3 inch pipe and I tried it myself. Yes, it's a pretty tight fit. And they say they can only make a bend every 8 inches in 3 inch pipe.

I told them I could buy mandrel bent pipes for the car. The ones from fwdperformance.com

So they ended up giving me a price of $150 just to get me out of there. They said they could do it in 2-1/2" but not 3".

So I'll probably end up buying the fwdperformance.com pipes just to keep the hassle to a minimum.

With what it would cost me to buy the mandrel bends from JC Whitney and then cut and fit them and get someone to MIG them together, it's not worth it.

I called a Freightliner truck store today, and they said they didn't have anything smaller than 4 inches.

[dwh4784]

Just do 3" out the side. Less pipe to buy, and less bends. Looks cool too.

[TurboShadowES]

or just exit under the car

when i get mine redone im gonna have them make me a 3in DP, then run it to right before my back axle and put a turn down on.

[scott_s]

I had the same problem as well. Even when I had the pipes from FWDP I still had 2 shops that said they were not magicans and it could not be done. The third shop did an excellent job.

Best of Luck

Quote:

Originally posted by Tim_K I went to the muffler shop today that said they could bend me a 3 inch pipe. I had them put the car up on the lift, and I showed them what I wanted to do. They said 3 inch would not clear between the spring and the gas tank. They handed me a piece of 3 inch pipe and I tried it myself. Yes, it's a pretty tight fit. And they say they can only make a bend every 8 inches in 3 inch pipe. I told them I could buy mandrel bent pipes for the car. The ones from fwdperformance.com So they ended up giving me a price of $150 just to get me out of there. They said they could do it in 2-1/2" but not 3". So I'll probably end up buying the fwdperformance.com pipes just to keep the hassle to a minimum. With what it would cost me to buy the mandrel bends from JC Whitney and then cut and fit them and get someone to MIG them together, it's not worth it. I called a Freightliner truck store today, and they said they didn't have anything smaller than 4 inches.

[Chris Faulk]

Quote:

Originally posted by dwh4784 Just do 3" out the side. Less pipe to buy, and less bends. Looks cool too.

And you'll kill youself with the noise...that or go deaf in your left ear. I know...I've done it all before.

I have a 2.5-inch FULL exhaust out the back and my cars runs just the same as the side-exit.

I will say that my turbo spools a SLIGHT bit slower...but I much prefer the sound my car has now...or rather lack thereof.

[dwh4784]

A friend of mine (GLHNSLHT2) has FULL 3" out the side with no muffler or cat just straight pipe. Personally I love the way it sounds.....even with the t-tops off its not like you're going deaf. Riding in the back seat of my friend's honda with a ricer muffler on the back is worse.

I did my own exhaust with mandrel bends for about $100+. I went with 2.5" and a dynomax super turbo muffler. Oops I for got to put the cat back in, maybe next time. A local shop , Baxters sold the bends for about $20 a piece and a ten foot length of tubing. If you can weld or know someone who can that will save you money. I also went to a muffler shop and bought a bunch of three bold flanges, so that if I need to I can remove the exhaust in sections. I also bought new hangers for about $3 a piece. My recommendation is to NOT drop the exhaust pipe on your head while under the car.