The Stovebolt Site Forums The Shop Area General Truck Talk exhaust changeover

I was in an accident on Saturday and my exhaust pipe got all messed up. I'm gonna have to weld on an end section, from about the muffler back. I figured I might as well change a bunch of stuff while I'm down there, right

I have a V8, and right now I have the Y-pipe that puts it down to a single exhaust. Is there any way to switch this over to a dual exhaust? I heard that if I wanted to do 2 pipes, I'd need a cat and muffler on each, but I'm new at this. Thanks for the help.

Hardy,

Can't speak for TX, but in Colorado, what you've heard is correct.

If you wanted to run a full true dual exhaust system, you would have to have two cats, two mufflers, and two tail-pipes.

One way around it, that you might consider is a "CAT-Back" exhaust system. In that case, they use the stock single pipe through the cat, and split the exhaust from there back.

While you won't see as much of a difference as you would on the full duals, it does make a pretty significant difference, when compared to stock. I did this on my 94 F-250 (460 CID) and it made a big difference. Sound real nice too.

I had Exhaust Pro's do the work, and if I remember correctly, with the mufflers, pipes, and stainless tips, I paid around $280.

Hope that helps.

HardyRestoration,

The best bet would be to go to your friendly muffler guy..he has all the answers. I don't think the '85 rigs had OBD1, so the system isn't "looking" at the converter (not sure on this). If Texas doesn't have yearly inspections or isn't California Smog Crazy, I don't know why another cat would be needed.

Leaving the converter intact is a smart move from an environmental standpoint, and if you are going with twice pipes, it wouldn't hurt to install another one. I think it would be a cost/environment decision. Each pipe would require a muffler, no question on this!

Stuart

Jed, what do you mean by "it does make a pretty significant difference, when compared to stock"

What kind of difference does it make? Power?

atomarc, that's a good idea, and I'm sure they have access to a lot of that stuff at better prices than buying it from a fancy place. Texas does have emissions testing every year - last year I had to install the cat and an A.I.R. pump even though the truck was not purchased with either, and has passed 19 years of inspections without one. That's what I get for going somewhere new...

Hardy,

Just did a search on OBD1 and it looks like GM started this protocol in '82. I am not familiar with your system..if it has an O2 sensor in front of the cat. The dual exhaust would probably result in minor power differences, but, with the proper muffler, could make the rig sound nicer. The muffler shop would be knowledgeable on the smog requirements...you don't want any hassles at inspection time!

Stuart

Hardy,

I can't quote any specifics on the performance differences, but if I recall, the exhaust system is attributed with approximately 10-15 additional horsepower on an average V-8.

I know that don't sound like much, but I can tell you the truck had improved acceleration and seemed to breath a whole lot better.

Since then, I've also added a K&N filter, and a PowerChips performance chip.

I pull a 27 foot 5th-wheel, and a 18.5 foot inboard boat, about 72 foot long and 12 or 13K lbs, at 5,000+ ft. elevation and can cruise 70+ mph all day long.

round here i don't think there is smog inspections really but if we did have them i'd be in a bit of trouble
Nate

OIC, I was!

Jed, thanks for the info!

I just realized when I went to lunch, my entire exhaust tip is GONE!!!

It must have punctured the tire? or something...

Eric,

Do I understand from your post above that you tow the trailer AND the boat at the same time???


Stuart

In Georgia you don't have to have catalytic converters, dual exhaust or not, if your vehicle didn't originally come with it. We ran duals with flowmasters on my sbc powered 52' and it greatly improved the sound and power.

you lucky georgians...dang

Highschool Hauler,

I think most states will let you get away w/out the cats. if the vehicle didn't originally come with one. Some of them get a little bit picky, if they know it's a later model engine, but alot will overlook it.

Same with safety equipment, or so I believe.

Atomarc,

You're understanding my post correctly. As I wrote, 94 F-250, 27ft. 5th wheel trailer, followed by a boat.

Together, the package is approx. 72 feet long, and the trucks pulling between 12-13K lbs. depending upon whether the tanks are full, what gear we've got etc.

Pulls easy as can be, don't even know it's back there. If the truck can fit, the trailer's just follow behind.

Only thing you gotta be careful of, is getting yourself into a situation where you have to back up. Good for about 10-15 feet at best. Anything further than that, and you're just flat out screwed.

Guys - I did some research and have found a good pair of cats on ebay for real cheap. My question is, are the cats there for the purpose of just protecting emissions, or are the cats there for the purpose of your engine not blowing up lol...exaggerating, of course... These cats are about 7 - 8 years old and are the universal cheap ones, and I want to make sure that I don't have to buy some MagnaFlow super fine cat for this to work.

Federal emmision laws are simple -- nothing may be changed in any way shape or form regardless of where you live. Fortunately enforcement of that standard is absolutely zero. The Feds allow each state to enforce the regs on its own terms. Some states enforcement are more picky than others (Calif & Colorado come to mind)It is safe to say that most states will have as a minimum requirement if they check a vehicle that it should have all factory installed equipment in place. That would mean that if you went to a dual exhaust you should add a second cat. Do that & I think you should be ok in all but the pickiest of states. I would be leary of installing used cats. It is illegal for a shop to even sell them. Cheap universal ones can be had for around $75each anyways. Not worth hasseling with the unknown factor in used ones. Whatever you do good luck with your project

Hardy,

They are there to make the rig smog legal. Aftermarket ones are usually sold based on the cubic inches of the engine. If you have a O2 sensor on yours, make sure the replacement converter has a fitting in it for this.

Are you indicating that the converters you are looking at are USED!! If that's what you are saying, I wouldn't buy them. These items are considered a consumable..they wear out!

Stuart

No no no, I never said they were used, they're just old ones that someone had. To check mine, doesn't the O2 sensor go in place either right in front of the cat (or behind, or both) and just looks like a tube going in there? If so, I don't think I have that on mine.

Ah!! now I understand. If you don't have an O2 sensor, you just leave the ports plugged and you are set. I don't know if these have a "shelf" life...they can't really be tested until they are on the rig, and that test is not truly definitive.

If they are cheap, the proper tube size, and they function correctly, you are in the money.

Stuart

Now I'm gonna have that song in my head lol

Alright then, thanks

steve,,,why not just sell it and buy an AD with duals on it Fred

If you run cats without an O2 sensor or any type of closed loop computer control they will burn out or plug up in short order. The mixture has to be precise going through the cats to keep them at exactly the right temperature. Too lean and they get too hot and melt, too rich and they plug up and foul. The O2 sensor tells the computer how to set the mixture. If your shop is telling you something else then you need to find a differant one.

Sorry, I assumed used when you said Ebay. my bad. 4ontheFloor is right about the closed loop issue. I assume (there I go again) this is on your 85 w/305 v8? Is it TBI or a feedback carb? If it is the feedback carb those were never real accurate to begin with & you could probably get away with just the 1 side O2 sensor providing feedback. If it's TBI it'll be a little more complicated.

Hardy,

After much searching I have come to the conclusion your rig has no computerized engine management system...it's dumb! You said in a earlier post you had put a new AIR pump on it. That should have been my clue. No O2 sensors, no nuthin. The converters won't melt or plug. Hope you got a great deal on them. Good luck.


Stuart

Mufflers...what ez mufflers senor,,, "we don need no stinkin mufflers".....hehehe