Exhaust: is it better to step up or keep the same diameter?
#1
Exhaust: is it better to step up or keep the same diameter?
Ok so thats my question...
Is it better to go from 2" header - 2.25" b-pipe - 2.36" axle back (ie stepping up)
or
2.25" header - 2.25" b-pipe - 2.25" axle back? (keeping the same diameter through out)
Is it better to go from 2" header - 2.25" b-pipe - 2.36" axle back (ie stepping up)
or
2.25" header - 2.25" b-pipe - 2.25" axle back? (keeping the same diameter through out)
#3
Honda-Tech Member
iTrader: (3)
Re: Exhaust: is it better to step up or keep the same diameter?
I would imagine that stepping up is better than nothing. Anything that reduces backpressure is good and the resistance of the exhaust is a function of length and diameter.
But if you've got options, just go full 2.5"
But if you've got options, just go full 2.5"
#4
Honda-Tech Member
Re: Exhaust: is it better to step up or keep the same diameter?
#5
Re: Exhaust: is it better to step up or keep the same diameter?
I thought 2.5" was overkill on the average Acura/Honda engine?
Lets face it, the average person modding these car's isn't doing much more then dropping it, I/H/E and MAYBE cams....from what i've read...60mm is even overkill for that
when i was driving around with no exhaust(cracked/disconnected) after the resonator...vs. now with a 2.25" Type R catback....the car *feels* much more peppy with an actual exhaust....back pressure is good...as long as its not too much
Lets face it, the average person modding these car's isn't doing much more then dropping it, I/H/E and MAYBE cams....from what i've read...60mm is even overkill for that
when i was driving around with no exhaust(cracked/disconnected) after the resonator...vs. now with a 2.25" Type R catback....the car *feels* much more peppy with an actual exhaust....back pressure is good...as long as its not too much
#6
Honda-Tech Member
iTrader: (3)
Re: Exhaust: is it better to step up or keep the same diameter?
The only real problem is the sound (and price). The idea that backpressure helps with power is just a myth. If you're sticking ONLY with boltons there may not be a big advantage of going above 60 mm, but if you're planning any engine building at all (ie cams) you'll be glad you went with 2.5"
A hidden advantage is that the best headers all have 2.5" collectors, so if you go 2.5" cat and catback you'll be able to mate with a 2.5" collector without stepping down. I'd bet that even with stock cams a car with a 2.5" replica header mated to a 2.5" exhaust will make better power than a car with a ITR-copy mated to a 60 mm or smaller exhaust.
A hidden advantage is that the best headers all have 2.5" collectors, so if you go 2.5" cat and catback you'll be able to mate with a 2.5" collector without stepping down. I'd bet that even with stock cams a car with a 2.5" replica header mated to a 2.5" exhaust will make better power than a car with a ITR-copy mated to a 60 mm or smaller exhaust.
#7
Honda-Tech Member
Re: Exhaust: is it better to step up or keep the same diameter?
I thought 2.5" was overkill on the average Acura/Honda engine?
Lets face it, the average person modding these car's isn't doing much more then dropping it, I/H/E and MAYBE cams....from what i've read...60mm is even overkill for that
when i was driving around with no exhaust(cracked/disconnected) after the resonator...vs. now with a 2.25" Type R catback....the car *feels* much more peppy with an actual exhaust....back pressure is good...as long as its not too much
Lets face it, the average person modding these car's isn't doing much more then dropping it, I/H/E and MAYBE cams....from what i've read...60mm is even overkill for that
when i was driving around with no exhaust(cracked/disconnected) after the resonator...vs. now with a 2.25" Type R catback....the car *feels* much more peppy with an actual exhaust....back pressure is good...as long as its not too much
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#8
Re: Exhaust: is it better to step up or keep the same diameter?
OK to be 100% honest...Right now my exhaust is a mixed mess...i'm waiting for parts to be delivered....BUT right this second i have a stock LS exhaust manifold, a High flow 2.25" carsounds cat(i'm 76% sure, its a long story), a stock Type R 2.25" b-pipe and a Stock 2" LS Axle back
Next weekend i should be installing a Type R 2.25" Axle back and a Greddy 4-2-1 header, which i believe has a 2" Collector
I'm trying to figure out if its worth buying a WS2 axle back which is 60mm...this was the reason for the first post....
If there are positive gains from stepping up exhaust vs keeping with the same diameter...i may buy the larger WS2 axleback...if not, i'm good to go
Next weekend i should be installing a Type R 2.25" Axle back and a Greddy 4-2-1 header, which i believe has a 2" Collector
I'm trying to figure out if its worth buying a WS2 axle back which is 60mm...this was the reason for the first post....
If there are positive gains from stepping up exhaust vs keeping with the same diameter...i may buy the larger WS2 axleback...if not, i'm good to go
#10
Honda-Tech Member
Re: Exhaust: is it better to step up or keep the same diameter?
There is no such thing as back pressure! Search if you don't believe me. When building an exhaust you will want to increase the exhaust gas flow velocity if staying N/A. and increase flow volume if going turbo. build accordingly. If you just want your car to sound loud, just get an axle back.
#11
Re: Exhaust: is it better to step up or keep the same diameter?
I thought exhaust design had more to do with Pulse width and size then just velocity
#12
Honda-Tech Member
iTrader: (3)
Re: Exhaust: is it better to step up or keep the same diameter?
I think you're splitting hairs at this point, especially since you've already got all your parts. Keep your header and enjoy it. If you ever start doing more engine work in the future, maybe you'll feel like getting a ful 2.5 - 3" exhaust then. That's what I would do (have done).
#13
Re: Exhaust: is it better to step up or keep the same diameter?
Only on racecars. On cars with mufflers, cats, and OTS headers, the pulses get broken up before they can have much of a scavenging effect, or so I've heard.
I think you're splitting hairs at this point, especially since you've already got all your parts. Keep your header and enjoy it. If you ever start doing more engine work in the future, maybe you'll feel like getting a ful 2.5 - 3" exhaust then. That's what I would do (have done).
I think you're splitting hairs at this point, especially since you've already got all your parts. Keep your header and enjoy it. If you ever start doing more engine work in the future, maybe you'll feel like getting a ful 2.5 - 3" exhaust then. That's what I would do (have done).
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