Re: Dual 2.5" exhaust??
[Re: 76dodgeboy]
#1333523
11/10/12 10:35 PM
11/10/12 10:35 PM
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Joined: Nov 2008
Posts: 1,491 Lethbridge, AB, Canada
dangina
pro stock
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pro stock
Joined: Nov 2008
Posts: 1,491
Lethbridge, AB, Canada
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Quote:
Is dual 2.5" exhaust to much for a stock 318 with headers and a 4bbl? 84 Chrysler 5th ave. Looking for best exhaust size for optimal fuel economy. Thanks
I'd stick with the 2 1/4"
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Re: Dual 2.5" exhaust??
[Re: 76dodgeboy]
#1333530
11/11/12 10:48 PM
11/11/12 10:48 PM
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Joined: Jan 2003
Posts: 3,472 Lubbock, TX
Erics5th
UsedtobeSatellite6
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UsedtobeSatellite6
Joined: Jan 2003
Posts: 3,472
Lubbock, TX
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I run a 2.5" system with a Flowmaster (yeah yeah)on my stock 5th with Edelbrock Performer and 1406 carb (on a low compression/stock cam 318). I think with headers on your stock engine, a large single system should be good. Personaly, I wouldn't even run headers on a stock engine, but its your car.
Eric
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Re: Dual 2.5" exhaust??
[Re: 76dodgeboy]
#1333539
11/13/12 01:28 AM
11/13/12 01:28 AM
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Joined: Jan 2008
Posts: 4,269 Canada
WO23Coronet
master
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master
Joined: Jan 2008
Posts: 4,269
Canada
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The back pressure thing I don't understand, IMO it's a bunch of nonsense, like how 15-20 years ago the common knowledge was that a turbo NEEDED back pressure to work properly which is BS. Back pressure makes an engine work harder, costing efficiency. And really, an engine turning ~2000 rpm at 20% throttle opening doesn't care if you have a single 2.5" or 3" or dual 2.5", you wouldn't have back pressure with any of them since you aren't flowing enough air/exhaust to max any of them out and it would be a wash from a mileage stand point IMO. Where you will notice it is when you do want to play (which you will) and get on it.
BTW, a single 3" pipe has less surface (7.065 sq in) than a dual 2 1/4" (7.95"), but the 3" has less boundary area than a dual 2 1/4" so it's probably a wash and they flow a similar amount of air. Remember, 250 hp Dakota RT's came with a single 3" system from the factory (along with the 98 and later rams, they may have 2 3/4" systems though)
Your exhaust guy may be feeding you a bit of a line about "back pressure" cause a lot of places don't like bending anything bigger than 2.5", go with the 3" single
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Re: Dual 2.5" exhaust??
[Re: 74RALLYE]
#1333541
11/13/12 03:48 AM
11/13/12 03:48 AM
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Joined: Aug 2006
Posts: 8,064 Iowa
76dodgeboy
OP
master
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OP
master
Joined: Aug 2006
Posts: 8,064
Iowa
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I don't mind loud exhaust. A Dakota Rt has more horsepower than a 1984 318. I don't know much if anything about backpressure. Magna flows site does say 2.5" duals are ok. The a-body kit comes with turbo mufflers which Im not positive I'll like. Im sure they have talked about backpressure on powerblock before or one of the car shows. I think Ill do some more research before I spend the cash. I still find it hard to believe there are no exhaust guys on here
Last edited by 76dodgeboy; 11/13/12 03:53 AM.
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