After a brief discussion about this in an earlier thread, and having searched around and found few answers, I'd like to ask for a difinitave answer on delivery pipes.
I have a '97 9-5 with the old-fashioned aluminium delivery pipe. It looks kind of like a drinking straw.
A lot of you have the newer, plastic delivery pipes.
Then there are those of you who have upgraded to bigger, shinier pipes.
Of these three options, including cost in the equation, is best?
Would it be worth my while buying the plastic pipe as an upgrade, or just going straight to a larger, shiny one?
you might get some benefit with the plastic pipe by avoiding heat soak from the down pipe, but I don't think there would be any benefit to going to a larger pipe than the plastic one. I was thinking about getting a bigger pipe and it seems like the consensus is that the bigger pipe is not any help unless you are running around 375hp or above. Also, to avoid heat soak in your aluminus stock pipe, you could wrap it with exhaust wrap if you don't feel like switching to the plastic pipe. good luck!
you might get some benefit with the plastic pipe by avoiding heat soak from the down pipe, but I don't think there would be any benefit to going to a larger pipe than the plastic one. I was thinking about getting a bigger pipe and it seems like the consensus is that the bigger pipe is not any help unless you are running around 375hp or above. Also, to avoid heat soak in your aluminus stock pipe, you could wrap it with exhaust wrap if you don't feel like switching to the plastic pipe. good luck!
There is no heat soak issue with plastic, steel, ally, inconel, silicone, carbon fibre etc. etc. high pressure boost pipes. The sheer air mass traveling through them and the speed at which it is traveling means 60 degrees ambient on the outside of the pipe has no effect on the air mass within the pipe as it is traveling so quickly under WOT conditions that its exposure to the surface on the inlet pipe is for such a short period of time little to no thermal transfer takes place outside of the boundary layer within the pipe.
Look at the coolant heated throttle body for a good example.
There is no heat soak issue with plastic, steel, ally, inconel, silicone, carbon fibre etc. etc. high pressure boost pipes. The sheer air mass traveling through them and the speed at which it is traveling means 60 degrees ambient on the outside of the pipe has no effect on the air mass within the pipe as it is traveling so quickly under WOT conditions that its exposure to the surface on the inlet pipe is for such a short period of time little to no thermal transfer takes place outside of the boundary layer within the pipe.
Look at the coolant heated throttle body for a good example.
I accept this point, but aren't we talking a lot more than 60 deg ambient temp inside the engine bay? This pipe basically runs up the side of the block and over the head. There's got to be some serious temps there. I can't touch this pipe of the engine's been on for more than 15 mins.
I accept this point, but aren't we talking a lot more than 60 deg ambient temp inside the engine bay? This pipe basically runs up the side of the block and over the head. There's got to be some serious temps there. I can't touch this pipe of the engine's been on for more than 15 mins.
Between pipe and block you may see what seems like crazy temps but there is an airgap in between which acts as an insulating layer between block and pipe and there will still be ambient air movement here. Ambient bay temp will still be circa 60 degrees though. Measure the different in CAT with different pipes and you'll see what I mean (Maplin or somewhere will do a thermocouple with an LCD display you can use).
There are bits of high pressure inlet air pipe on a Veryon that reach a surface temp of 93 degrees. CAT is still circa 37 in a 20 degree ambient though. A Megane 225 will show 87 degrees peak temp on its delivery pipe, 41 degrees CAT.
Put it like this measure the temp of your inlet manifold, throttle body and delivery pipe. See which one is the coolest.
Lets say you have a modified 9-5 consuming around 200CFM of air. That means that every second 3.3 cubic feet or 1 cubic metre of air move through its inlet tract. If you look at the size of the intake tract at various points you'll see what a short amount of time that air is actualy in there for.
If you're only interested in performance, just keep your stock pipes. The blingy stainless delivery pipes are good for show. You should notice no performance difference with any of them.
Looks don't particurlaly bother me - hence the lack of any external mods to my car.
I might exhaust wrap the stock pipe just to allay any of my irrational fears about heat. It's been said that it won't make much (any) difference, but stranger things have happened.
Plus, there's a lot to be said for witchcraft.
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