# best intake/exhaust pipe size?



## nacho_nissan (Jun 12, 2003)

the title says it all. one of my friends needs help with what size of pipe we need for his homemade intake and exhaust(ka24). i was thinking a 2.5" intake, and 2.5" exhaust? thanx for the help peeps. 

nacho


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## Gsolo (Sep 11, 2003)

nacho_nissan said:


> the title says it all. one of my friends needs help with what size of pipe we need for his homemade intake and exhaust(ka24). i was thinking a 2.5" intake, and 2.5" exhaust? thanx for the help peeps.
> 
> nacho


do you want high rpm peak horse or low rpm grunt torque??


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## nacho_nissan (Jun 12, 2003)

eh, can you gimme the combo for each? then i'd let him know which is for high end or low torque. thank you!


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## Gsolo (Sep 11, 2003)

well i can't give you specific...but general rule of thumb small side for both will give good torque...like 2" tailpipe and usually just stock, maybe a tad bigger than stock but with a venturi effect. for high end you need a lot of air in and a lot out....and i can't say for sure what to do for the ka....


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## KA24Tech (Feb 2, 2004)

I think the stock exhaust pipe is 2" so I think that a 2 and 1/4" with a good performance muffler would make the better all around system although a 2 and 1/2" would not be too detrimental to performance since the manifold is still stock. Make sure that you use a resonator if you don't use a high flow cat or else it maybe a bit loud. 
The intake can be just about any size, within reason, as long as it is as big as the throttle body or the mass air flow meter.

Troy


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## Gsolo (Sep 11, 2003)

KA24Tech said:


> I think the stock exhaust pipe is 2" so I think that a 2 and 1/4" with a good performance muffler would make the better all around system although a 2 and 1/2" would not be too detrimental to performance since the manifold is still stock. Make sure that you use a resonator if you don't use a high flow cat or else it maybe a bit loud.
> The intake can be just about any size, within reason, as long as it is as big as the throttle body or the mass air flow meter.
> 
> Troy


logic would reason 2 1/4 would be perfect if intake was smoothed out and increased. 2 1/2 exhuast would be just a tad to much... granted great peak horsepower but you have to get there before you can use it. 

just my idea...do a nice smooth intake to the throttle body (and same size as throttle body) and a good air filter (none of this foam shit) and have a horn style inlet...i don't know if it's been proven but the horn can smooth intake and deliver smoother torque curve. if you don't have a horn oh well...i don't think it makes a huge difference...but theres a reason for sure why chevy has always used it.


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