got a flex pipe in your exhaust system?
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fASTdONKEY
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got a flex pipe in your exhaust system?
does anybody have a flex pipe on their exhaust? if you do where is it located? i just wanted to know if anyone ever really had the need for one.... thanks for your time.... speed safely
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SingleCamSam
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erich wrote:Flex pipes are for transverse mounted engines.
Yeah sure, its not like our car engines don't receive shocks and vibrations through the exhaust system.
I am installing one in my downpipe, help keep the any extra loads created from the exhaust system off of the manifold considering how much load a turbocharger will already be placing on the manifold.
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C-Kwik
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A flex pipe or a swage connection is typical of FWD cars due to the way the engine moves under loads. But doesn't mean a RWD can't benefit from one. While there is not as much of a concern, it can depend on the exhaust set-up. Especially if the exhaust causes an exceptional stress on the manifold under load. But I would be more concerned with using one on the wastegate dumppipe than the exahust itself, unless you are using solid mounts on the exhaust.
Sure you don't need one and it probably won't hurt. Except that the inside of a flex-pipe is a bellows i.e. rippled. Look for some extra back pressure. Besides the stock exhaust hangars are designed to be able to absorb the stock engine movements. If your motor mounts are gone then you might get some exhaust clunking and perhaps break a downpipe if you're unlucky.
Flexpipes arent just for transverse mounted engines. If that were true then that would be saying that our motors dont move under load or under bumpy conditions. Alot of the reasons that manifold crack at the welds isnt just becasue of porr weld and heat. Its also becasue of the weight that turbo and downpipe put on it. When you go over bumps the whol exhaust moves too. thats a bunch of weight to put ont something with no flexability. Rev-hard even reccomends a flexpipe, and half of the guys with cracked rev-hards dont use them-but they still have cracks-go figure.
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C-Kwik
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Properly designed, most RWD cars will have little issue with needing to use a flex pipe on the main pipe. Any wastegate return pipe will see much more need for this as it cycles between expansion and contraction as the wastegate opens and closes. The main pipe will see temperature changes much slower since it will always have hot air going through it.
As far as the turbo's weight, unless the mani is exceptionally long, this shouldn't be an issue. With a typical short mani, the turbo sits very near where the mani is supported so there is less stress throughout. As far as the downpipe and exhaust weight, it should be properly supported by exhaust hangers. That's what holds the weight. Using flexible hangers helps to reduce stress as the engine and exhaust components move. If this is an issue you're doing something wrong.
As far as rev-hard manifolds, I said it before and I'll say it again. I have not heard one one person whose mani cracked that actually made provisions to reduce stress on the manifold. Cast iron manifolds in general are quite strong and are a great material for manifolds. The problems with the rev-had specifically is that the flange is one piece. The flange will see much less heat than the runners, so it will not expand as much. If you take a solid piece of cast iron and heat only one side up, it will crack. It's in fact so sensetive that repairing it requires the entire piece of cast iron must be heated to a certain temp then welded, then cooled over a long period of time. Separate the flanges, drill out the bolt holes to allow for expansion and remove cast flashings, particularly at stress points, and you should have a fairly worry free manifold.
As far as the turbo's weight, unless the mani is exceptionally long, this shouldn't be an issue. With a typical short mani, the turbo sits very near where the mani is supported so there is less stress throughout. As far as the downpipe and exhaust weight, it should be properly supported by exhaust hangers. That's what holds the weight. Using flexible hangers helps to reduce stress as the engine and exhaust components move. If this is an issue you're doing something wrong.
As far as rev-hard manifolds, I said it before and I'll say it again. I have not heard one one person whose mani cracked that actually made provisions to reduce stress on the manifold. Cast iron manifolds in general are quite strong and are a great material for manifolds. The problems with the rev-had specifically is that the flange is one piece. The flange will see much less heat than the runners, so it will not expand as much. If you take a solid piece of cast iron and heat only one side up, it will crack. It's in fact so sensetive that repairing it requires the entire piece of cast iron must be heated to a certain temp then welded, then cooled over a long period of time. Separate the flanges, drill out the bolt holes to allow for expansion and remove cast flashings, particularly at stress points, and you should have a fairly worry free manifold.
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Pornflakes
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Re: got a flex pipe in your exhaust system?
fASTdONKEY wrote:does anybody have a flex pipe on their exhaust? if you do where is it located? i just wanted to know if anyone ever really had the need for one.... thanks for your time.... speed safely
I always put one right after the down pipe, right before the cat converter (if there's one). Then I put another one in between the wastegate exhaust output and where it routes to the down pipe. This effectively "cushions" any engine movements.