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Discussion Starter · #1 ·
So I've seen lots of folks doing FMIC's and the hot side piping seems to be the biggest PITA of the project, mostly because of space limitations.

Now, most of the kits use 2.5" hot side piping, but the turbo outlet and CAP are 2" [except for the oval part of the CAP].

So my questions are:

1. Is there really any benefit to using 2.5" hot side piping since the turbo is 2"?

2. Would using 2" hot side piping help with space/fitment to the IC, where a 2">2.5" coupler would attach it to the FMIC?

Thanks guys :D
 

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I don't think you will gain any more air flow with a .5 of an inch difference.
 

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And this is based on your extensive experience with fluids?
lol I'm just saying if it's that much of a hassle for fitment/safety, an .5" isn't worth it. By all means if you wanna fit 2.5" do it but if your having a hard time does the benefits out way the hassle?
 

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lol I'm just saying if it's that much of a hassle for fitment/safety, an .5" isn't worth it. By all means if you wanna fit 2.5" do it but if your having a hard time does the benefits out way the hassle?
Not trying to be a dick, but he asked a legitimate question on the possible change in flow from a different diameter pipe. It is a significant difference. A 2.5" pipe will have an area roughly 160% larger than a 2" pipe. I'm really interested to know if that change will make a difference on the flow.
 

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Not trying to be a dick, but he asked a legitimate question on the possible change in flow from a different diameter pipe. It is a significant difference. A 2.5" pipe will have an area roughly 160% larger than a 2" pipe. I'm really interested to know if that change will make a difference on the flow.
I didn't think you were being a dick :D I really don't know, I'm no scientist or mechanic lol but I guess if we are just going for the largest diameter for air flow why aren't we boring out the throttle bodies while we are at it? I sure don't see those posts popping up every other thread :D
 

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i believe the basis of the question has to do with the turbo outlet size and the end of the CAP being only 2 inches, therefore its not a straight 2.5 inchs all the way to the FMIC so why is the 2.5 inch pipe used and not a 2 inch pipe.

It is obvious that a larger pipe will flow a lot more volume, but what are the effects of the lager pipe when there is a point in the piping that is slimmed down to 2 in and then opened back up to 2.5. This seems to be a legitimate question to me and something that I want to try to look into but I just dont know enough right now. As it has been said before there is really nothing that simple about fluid dynamics.
 

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Discussion Starter · #9 ·
i believe the basis of the question has to do with the turbo outlet size and the end of the CAP being only 2 inches, therefore its not a straight 2.5 inchs all the way to the FMIC so why is the 2.5 inch pipe used and not a 2 inch pipe.

It is obvious that a larger pipe will flow a lot more volume, but what are the effects of the lager pipe when there is a point in the piping that is slimmed down to 2 in and then opened back up to 2.5. This seems to be a legitimate question to me and something that I want to try to look into but I just dont know enough right now. As it has been said before there is really nothing that simple about fluid dynamics.
I could use a lager pipe right now ;)

I really am curious, because I don't see a real flow advantage since the turbo and much of the system is 2".

Also, if losing that extra .5" helps with fitment, I'm willing to lose a tiny bit of flow. I've heard doing the hot side on an 04 is a PITA even more so because of the AC, so I could use all the help I can get :D
 

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Discussion Starter · #14 ·
Hey, I'm in it for the beer. :beer::beer::beer::beer::beer: I don't want none of you two's shenanigans! :D
 

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Swedespeed, where a conversation about FMIC piping turns into a gay hook up :D
 

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No thank you :D
 

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So I've seen lots of folks doing FMIC's and the hot side piping seems to be the biggest PITA of the project, mostly because of space limitations.

Now, most of the kits use 2.5" hot side piping, but the turbo outlet and CAP are 2" [except for the oval part of the CAP].

So my questions are:

1. Is there really any benefit to using 2.5" hot side piping since the turbo is 2"?

2. Would using 2" hot side piping help with space/fitment to the IC, where a 2">2.5" coupler would attach it to the FMIC?

Thanks guys :D
Well this thread got off topic quickly...

I just did this install this weekend, and YES 2.0" piping would make this much easier, especially for a 2004/2005 with the large AC drier.

But remember that just because the turbo outlet is 2.0" and the charge pipe narrows to 2.0" doesn't mean that having a 2.0" charge pipe system will be as effective as a 2.5" charge pipe system. 2.5" gives you some wiggle room for power, and the wider diameter piping also allows the air to expand slightly and cool down.

I don't have any direct comparison between 2.0" and 2.5" piping, but 2.0" would be a lot easier to do, I just decided to stick with 2.5" because if I'm upgrading the intercooler I might as well upgrade the pipe diameter as well right?

Even at 55 degrees out tonight I noticed a definite increase in power and response with the intercooler and 2.5" charge piping...so it's hard to go wrong there...

By the way, with your AC drier, you will not be able to fit a straight 2.0" to 2.5" reducer, you'll have to fine a 90 degree 2.0" to 2.5" reducer if you go this way, and same for the drivers side, although that side has much more wiggle room.
 

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Discussion Starter · #20 ·
Thanks for the info!

IPD's new silicone charge pipe is 2.0" throughout, so I'm guessing there's not that much improvement with having a 2.5" charge pipe, otherwise I would think they would have gone that route. I also think db88's round pipe is 2" in diameter.

As far as cold side piping goes, I don't think you'd want to reduce it back to 2.0" after going through a 2.5" IC, as that would throttle the air, which isn't good for flow. If there's enough room to easily do 2.5" there, I would keep that the same.

Since I'll likely be doing this next year with a CXRacing kit, I think I'll try 2" charge pipe, 2" hot side, 2.5" cold side, and we'll see what happens from there. :D

Would still love to hear from folks on the issue.
 
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