Building a catback out of PVC
11-09-2012, 09:38 AM
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Building a catback out of PVC
I'm sick of paying $250 odd dollars each time I want to dick around with my exhaust system. I can't weld, so what can I do?
Build it out of inflammable plastics, of course.
I propose that a good half of the existing steel exhaust system could be discarded in favour of a plastic replacement. A plastic exhaust should be lighter and cheaper to produce.
So all you have to do is cool the exhaust gases down. In fact, marine engines have used the wet exhaust systems for years. They suck seawater up, dump it into the tailpipe, and then eject the whole mess out of the back of the boat: mainly to reduce noise. I want to apply this concept to an automotive exhaust system. Injecting a mass of water into the exhaust would be no big deal; in fact automakers are already injecting urea solutions into the exhaust systems of clean diesel SUVs and trucks. Once the injected water has absorbed enough heat from the exhaust gases, they are no longer hot enough to harm plastics. So shortly after injecting water into the exhaust, you can sawzall off the steel piping and continue with a smaller, lighter plastic tailpipe.
So the significant difference between this exhaust and a marine or diesel exhaust is that we recapture the water. This can be done in such a huge variety of ways, that I haven't even settled on the best method yet. Absorbing or filtering the water out of the exhaust gas looks to be the easiest way. That's why I included a picture of a receiver/drier unit from an automotive A/C system. It could just as easily be a cyclonic filter or some sort of dessicant.
Anyway, the exhaust gases pass through, and the water is recollected and cooled - ready for use again. You wouldn't need a huge reservoir, just enough to account for the inevitable fact that the system won't be 100% efficient and you will consume some water. Here's a picture for an overview.
So to sum up, wet plastic exhausts:
-Have lower emissions
-Are quieter
-Are lighter
-Are cooler
-Won't rust
So I want to give it a crack this summer. It shouldn't be too hard to rig an injector up to the tailpipe and take some temperature readings. That will at least determine whether this project is feasible.
Thoughts?
Build it out of inflammable plastics, of course.
I propose that a good half of the existing steel exhaust system could be discarded in favour of a plastic replacement. A plastic exhaust should be lighter and cheaper to produce.
But wheels, that'd catch fire! Are you dumb?
So all you have to do is cool the exhaust gases down. In fact, marine engines have used the wet exhaust systems for years. They suck seawater up, dump it into the tailpipe, and then eject the whole mess out of the back of the boat: mainly to reduce noise. I want to apply this concept to an automotive exhaust system. Injecting a mass of water into the exhaust would be no big deal; in fact automakers are already injecting urea solutions into the exhaust systems of clean diesel SUVs and trucks. Once the injected water has absorbed enough heat from the exhaust gases, they are no longer hot enough to harm plastics. So shortly after injecting water into the exhaust, you can sawzall off the steel piping and continue with a smaller, lighter plastic tailpipe.
But wheels, you'd consume so much water! That's heavy!
So the significant difference between this exhaust and a marine or diesel exhaust is that we recapture the water. This can be done in such a huge variety of ways, that I haven't even settled on the best method yet. Absorbing or filtering the water out of the exhaust gas looks to be the easiest way. That's why I included a picture of a receiver/drier unit from an automotive A/C system. It could just as easily be a cyclonic filter or some sort of dessicant.
Anyway, the exhaust gases pass through, and the water is recollected and cooled - ready for use again. You wouldn't need a huge reservoir, just enough to account for the inevitable fact that the system won't be 100% efficient and you will consume some water. Here's a picture for an overview.
So to sum up, wet plastic exhausts:
-Have lower emissions
-Are quieter
-Are lighter
-Are cooler
-Won't rust
So I want to give it a crack this summer. It shouldn't be too hard to rig an injector up to the tailpipe and take some temperature readings. That will at least determine whether this project is feasible.
Thoughts?
11-09-2012, 01:02 PM
#3
Super Moderator
This is about as ridiculous as using an alternator spun by an electric motor to charge a battery to run the electric motor.
11-09-2012, 03:32 PM
#5
Super Moderator
This idea is stupid as . . .
Use the $250 and get a welder, then get j-bends and pipes from jegs or summit or somebody online and DIY. If the alternative to spending a few MORE hundred dollars is to have an additional tool and learning how to do something, I'm for it.
Use the $250 and get a welder, then get j-bends and pipes from jegs or summit or somebody online and DIY. If the alternative to spending a few MORE hundred dollars is to have an additional tool and learning how to do something, I'm for it.
11-09-2012, 11:29 PM
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If I have to be the hunchback of down under, so be it. But I really am going to at least test this concept on my existing steel exhaust.
The idea has been around for a while:
Although the marine ones need to have wacky dimensions for various reasons. All this is doing is removing energy from the exhaust gases; radiating heat silently means that there is simply less energy available for the exhaust to make noise. Who knows, I might not even need a muffler.
I swear that I'll do it.
The idea has been around for a while:
Although the marine ones need to have wacky dimensions for various reasons. All this is doing is removing energy from the exhaust gases; radiating heat silently means that there is simply less energy available for the exhaust to make noise. Who knows, I might not even need a muffler.
I swear that I'll do it.
