OEM/GM Exhaust vs. Walker Exhaust

[MAC]

I need to buy a new exhaust from the catalytic converter back including mufflers. Walker sells a system which has a lifetime guarantee. I can buy it on ebay for $319, plus $44 shipping. I can buy a GM/OEM exhaust including both mufflers for about $500. The difference between the Walker and OEM is about $200.

Would anyone happen to know for sure if the OEM pipe is stainless steel on a '94 Eldorado? I'm sure the Walker is not stainless steel, instead it's aluminized. The rear hangers at the "Y" on my currently exhaust are missing. Must have broke off. It looks like it won't hurt to replace the pipe. My Eldo was a Florida car and I think the salt air took it's toll on the exhaust system. This is why I'm inclined just to replace it.

So between the OEM exhaust and Walker I tend to think spending the extra $200 is worth it?

[blue_eldo]

It has been my observation that the original factory exhausts on your vintage cadillac usually outlasts the rest of the car. Plenty of good exhausts in the salvage yards and from guys parting cars out. A couple of years ago a local engineering student was parting out a 95 Seville. I bought the entire exhaust, that he removed for $25! I installed it on a 4.9 Deville for the four tip effect. The system I took off the 94 was perfect as well.

Short trips and salty roads do the most damage.

[Bruce Nunnally]

That seems like a great price for the GM system; I would have expected it to be higher. I would vote for the GM system for $200 more just to avoid replacing the aluminized system a time or two, even if under warranty.

[Cadillac Jim]

My 1997 exhaust system is stainless steel, and I would expect that your 1994 Eldorado exhaust system would be identical to mine, except that you have the 4.9 and I have the Northstar. I would go to a good muffler shop and get stainless steel mufflers to your taste, clean up and re-use your existing tips and their Y-pipes (a major cost of the total system). If you need a cat, a Magnaflow direct-fit for $150 is here:

<a href="http://store.summitracing.com/egnsearch.asp?SearchType=Make&N=700+4294924760+4294908226+4294908221+115+4294923429" target="_blank">http://store.summitracing.com/egnsearch.as...+115+4294923429

</a>

If your muffler shop uses stainless steel welding and components, you will wind up with a better, cheaper system than the aluminized system, and quite comparable to cadillac OEM.

[MAC]

Thanks for the input. Just one other thing, my gas mileage is getting worse now that the mufflers need to be replaced. Does this sound possible. I believe I remember Guru saying that exhaust back pressure is needed and that low back pressure may throw off the computer.

[Ed Hall]

Yes, some back pressure is needed but I don't think there is anyway to have too little back pressure with just simply a muffler replacement or possibly even an exhaust system.

[MAC]

The latest with my situation is that the left side muffler came apart where the pipe meets the muffler. It didn't break apart due to rot, rather, the pipe actually fell out of the muffler. That said, it wasn't an OEM muffler. I didn't see what make it is, but obviously it's not good quality. Actually, both mufflers were replaced. I can see where the chrome tips were taken from the OEM mufflers and welded. Most likely it was brought to an exhaust shop. After removing the muffler I shook it and it's rotting from the inside--I can hear everything shaking around.

Well, I'm going to take Bruce's advice and buy GM/OEM because once it's fixed I don't want to deal with it again. I like blue eldos view about trying a salvage yard but I would have to work on fitting the pipe to the catalytic converter, which I really don't want to deal with.

[KHE]

The original mufflers on my '96 SLS are beginning to go bad and I contacted Brasingtons and was told the OEM exhaust is no longer available.

I now need to find some stainless mufflers that are quiet like the OEM mufflers.

[catmendo]

way off topic ... but I got to ask guys ...

" 72 Eld, 8.2 GMC Engine "

Blue ??? I had a 73 fat cat with a 472 CID motor ...

are you talking 8.2 litres here ??? and if so ...

I am confused, for that would be a huge motor ...

[Regis]

I'm on my 3rd or 4th Y-pipe and it has always had to be special ordered. It's not an in stock item I'm told... at least for the STS. Mac, I believe your Y-pipe hangers are just the simple donut style ones. About the cheapest hangers to replace ($.99). Jim is right in that the Y-pipe is the major expense so if it is fine then I would reuse it. My oem system, although rusty at the welds and joints, blew apart from the inside out. A lengthy period of short drives will accelerate this process.

[Texas Jim]

Yes, some back pressure is needed but I don't think there is anyway to have too little back pressure with just simply a muffler replacement or possibly even an exhaust system.

Ed,

I will have to disagree SLIGHTLY with this, with qualifications....

This happened on a Ford Taurus, so it may not apply to Cadillacs at all.

I bought a new 2002 Taurus, in Dec 2001.

Engine was the 3L, DOHC, 24 valve.

In the fall of 2002, I decided to put duals on it.

CUSTOM CATBACK system.

Factory exhaust was single.

The shop I took it to is well known in this area for high quality work.

I have known the owner for several years.

The factory system was ... both lead off pipes (2inch) come to a single cat... 2 inch pipe to a resonator... then about 2 inch (maybe 1 3/4) to the single muffler.

I wanted the resonator GONE... Install a HIGH FLOW cat with dual outlets and 2 1/2 inch pipe all the way back to dual mufflers mounted at the rear by the bumper.

He told me that was WAY TOO BIG of an exhaust system for that engine. There would be almost NO BACK PRESSURE and the computer wouldn't like it and it would probably have a bad DRONE at certain RPM's.

I insisted. That was what "I" wanted.

He tried to talk me out of it and almost refused to do it the way I wanted it done.

What I failed to take into consideration was,

"I" was thinking about what would work GOOD on a 6 to 8 litre engine... not thinking about

"Hey... THIS ONE is only THREE LITRE." 165 cubes NOT 425

After it was done, I started home with it. About 20 miles.

It had a drone, but I thought (at first) that it was live with it. (WRONG)

It also had NO TORQUE at lower RPM's and I do mean NO TORQUE.

It wouldn't even CHIRP the tires on slick asphault.

Not even if you held the brake, gassed it and then let off the brake.

It wouldn't really PULL till it passed 4000 RPM.

It would SCREAM at high RPM but was a TOTAL DOG at lower RPM.

I took it back after a few days...

I had to PAY to have a resonator put on it to kill the DRONE.

I (of course) had not kept the old resonator.

At his suggestion, went thru MULTIPLE battery dis-connects before getting the computer to go into RELEARN mode.

It was a LOT better after the computer relearn.

Still wasn't as strong in the first second or second and a half... coming off the line.

At about 2500 RPM... it WOKE UP.

From there to 6500, it was pretty stout.

For a 3L.

So, to summerize....

in my humble opinion...

you CAN have TOO LITTLE backpressure...

at least on SOME engines.

As I said at the beginning... this may not apply to Cadillac's at all...

Just thought I would throw in my (expensive) experience.

[Texas Jim]

way off topic ... but I got to ask guys ...

" 72 Eld, 8.2 GMC Engine "

Blue ??? I had a 73 fat cat with a 472 CID motor ...

are you talking 8.2 litres here ??? and if so ...

I am confused, for that would be a huge motor ...

What are you talking about?

No one has mentioned a 72 ElDorado with an 8.2 engine.

[Cadillac Jim]

way off topic ... but I got to ask guys ...

" 72 Eld, 8.2 GMC Engine "

Blue ??? I had a 73 fat cat with a 472 CID motor ...

are you talking 8.2 litres here ??? and if so ...

I am confused, for that would be a huge motor ...

The 500 cid engine was used from 1973 through 1976.

How much back pressure works for an engine depends on a lot of things, such as the camshaft, the head flow, and resonances in the intake and exhaust -- and whether the ECM has the right programs to deal with them.

Cadillacs in general don't have much back pressure. On a Northstar system, I would think that as long as you have a catalytic converter, you have enough. Someone here posted a video to demonstrate his pipes, and the video clearly showed that there were no mufflers at all behind the rear Y pipe. Perhaps he could let us know how is off-the-line torque worked out.

[KHE]

way off topic ... but I got to ask guys ...

" 72 Eld, 8.2 GMC Engine "

Blue ??? I had a 73 fat cat with a 472 CID motor ...

are you talking 8.2 litres here ??? and if so ...

I am confused, for that would be a huge motor ...

The 500 cid engine was used from 1973 through 1976.

Not quite right - the 500 engine was introduced in 1970 on the Eldorado. The 500 was a stroked 472 and was used exclusively in the Eldorado until the 1975 model year when all Cadillacs except the new Seville received the 500 engine. The 500 engine replaced the 472 engine for emission reasons.

[Ed Hall]

Yes, some back pressure is needed but I don't think there is anyway to have too little back pressure with just simply a muffler replacement or possibly even an exhaust system.

Ed,

I will have to disagree SLIGHTLY with this, with qualifications....

This happened on a Ford Taurus, so it may not apply to Cadillacs at all.

I bought a new 2002 Taurus, in Dec 2001.

Engine was the 3L, DOHC, 24 valve.

In the fall of 2002, I decided to put duals on it.

CUSTOM CATBACK system.

Factory exhaust was single.

So, to summerize....

in my humble opinion...

you CAN have TOO LITTLE backpressure...

at least on SOME engines.

As I said at the beginning... this may not apply to Cadillac's at all...

Just thought I would throw in my (expensive) experience.

Yes you're right that what applies to the Taurus doesn't apply to our Cadillacs. The choking point on our Cadillacs is the cross over pipe. You can go as free flowing as you want but that cross over pipe will always be the choking point. So far, I have not heard of anyone overcoming that limitation other than run a custom cross over pipe underneath the car. Someone did try it with their Northstar engine and it made significant power gains like in the +75 hp range.

[jking220]

Someone did try it with their Northstar engine and it made significant power gains like in the +75 hp range.

75 HP??? If theres 75 HP in it Ill be gettting a custom crossover made, Ive always wanted to.

[Texas Jim]

Someone did try it with their Northstar engine and it made significant power gains like in the +75 hp range.

75 HP??? If theres 75 HP in it Ill be gettting a custom crossover made, Ive always wanted to.

I was thinking THE EXACT SAME THING.

That would be money MUCH BETTER SPENT than trying to tune it for more power.

Will be using HPTuners Pro.

Which, by the way, is probably my next task. (Which now goes on hold while I investigate this)

[Ed Hall]

Someone did try it with their Northstar engine and it made significant power gains like in the +75 hp range.

75 HP??? If theres 75 HP in it Ill be gettting a custom crossover made, Ive always wanted to.

I was thinking THE EXACT SAME THING.

That would be money MUCH BETTER SPENT than trying to tune it for more power.

Will be using HPTuners Pro.

Which, by the way, is probably my next task. (Which now goes on hold while I investigate this)

The problem is the only way you can do it is to go under the oil pan which reduces ground clearance. It would be a nuisance to be constantly repairing this custom cross over when you accidentally smash it going over a speed bump.

[Texas Jim]

The problem is the only way you can do it is to go under the oil pan which reduces ground clearance. It would be a nuisance to be constantly repairing this custom cross over when you accidentally smash it going over a speed bump.

Very true... but I will be looking at the undercarriage the next time it is on a lift. Just to see if there is any way to do it. Maybe the underside of the new body style is a little different.

Hope... Hope... Hope...

[Cadillac Jim]

Innovation and unfettered imagination is the key here. The paradigm for transverse V8's is to use a dual 4-2-1 header into a collector, which is the cat in the Northstar but could be a resonator. To keep the lengths short so that the last torque peak is at 6000+ RPM, the only way around is right under the engine and then combine them in the front Y pipe as close as possible. Thus the squeeze for space in a transverse arrangement where the transmission is under the engine, as opposed to beside it.

The simplest solution would seem to be a rectangular or oval crossover pipe, should the additional width not cause clearance or interference issues. We all know that all the "low hanging fruit" in Northstar performance has been picked, and I would definitely consider an oval crossover pipe low-hanging fruit. If that was the solution we would have this in the original design, or at least in custom headers for the Northstar since 1993, but we don't. I would want someone who has done work in this area to comment on this, though.

In browsing the web for custom header solutions for transverse engines such as big-block Toronados and Eldorados, I have seen pipes that exit behind the fenders on each side. This would be a dual cat system, or with no cats a dual resonator system, with the header/cat tuned to provide that last horsepower peak just before redline. For a conservative look, you would want to keep the pipes inboard, but the idea of running the front bank out the right side and the rear bank out the left side strikes me as the magic bullet. At this point I would converge to a Y pipe to preserve low-end torque and everyday drivability and everything would be stock - or at least more "normal" - behind that.

This is a lot of work and may require some surgery on the underside, such as rerouting of brake and fuel lines. For 75 hp from the git-go I think it's worth a look.

[MAC]

Here's an update: I bought two Walker mufflers. They are pretty impressive looking and come with chrome tips. The left comes with the extension pipe and it's a bolt right on without any modification. The right, however, comes with some extension pipe down to the exhaust hanger flange, which is actually a good idea. Since the right stock muffler is welded on as part of OEM specs, the right side Walker muffler will require cutting the pipe near the hanger. I put the left side on tonight and it sounds good--like stock. I'll try to take pictures.

[KHE]

Here's an update: I bought two Walker mufflers. They are pretty impressive looking and come with chrome tips. The left comes with the extension pipe and it's a bolt right on without any modification. The right, however, comes with some extension pipe down to the exhaust hanger flange, which is actually a good idea. Since the right stock muffler is welded on as part of OEM specs, the right side Walker muffler will require cutting the pipe near the hanger. I put the left side on tonight and it sounds good--like stock. I'll try to take pictures.

Are they stainless steel or aluminized steel?

[MAC]

Here's an update: I bought two Walker mufflers. They are pretty impressive looking and come with chrome tips. The left comes with the extension pipe and it's a bolt right on without any modification. The right, however, comes with some extension pipe down to the exhaust hanger flange, which is actually a good idea. Since the right stock muffler is welded on as part of OEM specs, the right side Walker muffler will require cutting the pipe near the hanger. I put the left side on tonight and it sounds good--like stock. I'll try to take pictures.

Are they stainless steel or aluminized steel?

They're aluminized. But I must say it looks like a quality muffler--though only time will tell. The pipe is welded to the muffler and the muffler itself is pretty much the same size as OEM. The chromed tips look OEM--And I mean they're chromed, not simply polished steal. I'll take a couple of photos.