# best intake/exhaust pipe size?



## ByReaL (Jul 5, 2004)

i have used the search function before making this topic, and i did it coz i id not cleared my self in this problem

we are talking about a 200SX RS 13 with a CA18DET engine
the stock inatke is 2" (50mm) and stock exhaust is 2" (50mm)

i read a lot on the net and as an upgrade for exhaust i saw that people used 
2.5" (63mm) pipe or 3" (75mm) pipe

as for intake i mesured the intake of the engine and he has 80mm, i'll also use a Z32 AFM wich has a 80 mm opening, and because of that i thought to make all the intake (except the turbo) with 80mm pipe

what i want to ask if there is a good ideea to have a 80mm intake (the FMIC will have also 80mm opening)?

second qestion is: should i go for 2.5" (63mm) exhaust, or should i go for 3" (75mm) even 80mm exhaust pipe?

i use the car for dayli driveing and once or twice per month i go racing 

what size of FMICr do u recomend me?

i thought at 600mmx300mmx100mm (24"x12"x4") with 80mm pipe conections


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## DaCheat (Nov 4, 2004)

First off, i will start with Exhaust, because of personal experience.
I have a 1991 240SX, stock engine and never been rebuilt.
i put straight stock pipes on my car (No Cat, No Resonator) Fart Cannon on the end, and i hate it!
My suggestion to you is, 2.5" Exhaust, High Performance Cat, and a Low Resistance Resonator (usually muffler shops sell 2.5" adapting round generic Resonators). When it comes to the Muffler, put whatever you think looks nice on your car, personaly I am building my system like this and putting a single 2.5" in, dual 3" out 5x7 oval magnaflow or vibrant exhaust on my car.

Also from personal experience, intakes, try to keep everything the same size, this will avoid headache's down the road. If the intake manifold, or throttle body has an 80mm opening, put a pipe on there that is the same size and adapt it on with silicon conectors. For a MAF, go with a MAF that also has a 80mm opening, 300ZX Z32, Or Cobra MAF's follow this.
Finish the other side of the MAF off with either an Air Filter or Cold Air Extension.
When it comes to an FMIC i'm not sure what kind of piping you would want to use there, but if i had to guess i would say keep it the same size as the rest of the intake setup. :thumbup:


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## ByReaL (Jul 5, 2004)

Any other opinions?

Untill now it seams that this 80mm (~3") intake and that 63mm (2.5") exhaust is a very good solution for that engine


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## Joel (Jun 11, 2003)

Its a turbo. Make the exhaust at least 3" from the turbo all the way back including either hi flow cat or just a replacement pipe.

As for the intake - the intake, hot pipe and cold pipe are all different. Usually the intake is between 2" and 3" depending on the AFM you are using or up to 5" for a MAP sensored car (no AFM to get in the way). Im still using the factory intake pipe and it works fine.
There is a lot of debate on the cold and hotpipe sizes. A lot of intercooler kits retain the factory hot pipe and use a 2.5" or 3" cold pipe to the throttle body. My personal setup is 3" polished stainless on both hot and cold pipe.


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## ByReaL (Jul 5, 2004)

ok then the intake seams good, as i think to it

about the exhaust will be only one problem the eqipmanet i have accest to can only shape pipe smaler then 2,5" so if i use 2 pipes to achive same aiflow as 3" pipe i think i'll have same performance

2 x 1,5" pipes the only problem will be to join them before the turbo


i have no cat

any other refernce on that?

if someone knows what will be the gain from a 3" compared to a 2.5" compared to stock (2")


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## Kato (Apr 21, 2004)

3" for both intake and exhaust...


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