Those with kooks or ARH 2" headers..
Thread Starter
TECH Fanatic
iTrader: (18)
Joined: Oct 2004
Posts: 1,205
Likes: 0
From: Bay area, ca.
You want to increase flow and increase exhaust velocity. If you add more flow to what is needed, you'll slow the exhaust down and lose power. Ideally, you want to shrink your exhaust as it goes. The largest exhaust area is needed at the front of the exhaust because it's hottest so therefore its volume is greatest. As the exhaust cools, it condenses and takes up a lot less space. Therefore, running larger piping all the way back will limit velocity and add too much flow, hurting performance. If you have 2" headers and then funnel the gas into the reducers, the reducers will actually increase the velocity of the exhaust. This would benefit you if 3" exhaust provides enough flow at that point. It could be a good thing.
that's exactly the oposite of what you're saying. its getting bigger as it goes back, not smaller.
But then again I guess it's a Y setup, so it's different cause you're collecting two pipes into one.
Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
Nick @ ARH said they have an 8.90's car running 2inch headers with the 3 1/2 inch collectors that has a 3" 1/2 inch Y pipe that collects into a 4" I pipe. That's what he recommended me.
that's exactly the oposite of what you're saying. its getting bigger as it goes back, not smaller.
But then again I guess it's a Y setup, so it's different cause you're collecting two pipes into one.
that's exactly the oposite of what you're saying. its getting bigger as it goes back, not smaller.
But then again I guess it's a Y setup, so it's different cause you're collecting two pipes into one.
Necking down from two 3 1/2" collectors into a single 3" y-pipe would increase exhaust velocity, but a single 3" y-pipe will probably choke a car running 8.90's too much. If the car was running 11's or 12's, I'd be willing to bet necking down from 3 1/2" collectors into a 3" y-pipe would greatly benefit the car.
Necking down exhaust after the collectors is something you'd want to do more with true duals than a y-pipe. Y-pipes neck down automatically because you're jamming everything into a single I-pipe.
Closed ex-Sponsor Account
Joined: Sep 2008
Posts: 43
Likes: 0
jermzz, The set-up I described to you had a Y-pipe with 3-1/2" inlets that merged and collected to 3" at the y-pipe and had a 4" outlet. Do not underestimate how well this set-up works, particularly on a big cube application like yours that'll also see a 300 shot. This set-up is on quite a few 9 sec rides as well as a customer running 8.70's at 155 on spray. If you'd like to go over what we discussed yesterday in more detail, please feel free to call me or PM me your number and I'll reach you when it's convenient. Thanks.
Nick
Nick
Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
jermzz, The set-up I described to you had a Y-pipe with 3-1/2" inlets that merged and collected to 3" at the y-pipe and had a 4" outlet. Do not underestimate how well this set-up works, particularly on a big cube application like yours that'll also see a 300 shot. This set-up is on quite a few 9 sec rides as well as a customer running 8.70's at 155 on spray. If you'd like to go over what we discussed yesterday in more detail, please feel free to call me or PM me your number and I'll reach you when it's convenient. Thanks.
Nick
Nick
So, you're saying that 3" dual exhaust systems, with headers that have 3" collectors will actually kill power? And that its better to have a 3" collector, into a 3" y, that necks down to 2.5" x-pipe out the back (full exhaust)?
Closed ex-Sponsor Account
Joined: Aug 2008
Posts: 257
Likes: 0
The second part of your statement does'nt make sense you can't run a y and an x under the same car. most cars are different and require different things especially in max effort race cars. Lets say you have a true dual car with an x-pipe that needs a 1-3/4 primary header you would go 3" into the x-pipe and 2.5" out through the mufflers to the tails.The smaller diameter after the x-pipe will keep the velocity up of the cooler exhaust helping the overall scavenging of the motor
Lets say you have a true dual car with an x-pipe that needs a 1-3/4 primary header you would go 3" into the x-pipe and 2.5" out through the mufflers to the tails.The smaller diameter after the x-pipe will keep the velocity up of the cooler exhaust helping the overall scavenging of the motor
