Exhaust Manifold - Unequal or Equal
11-28-2005, 03:11 AM
#1
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Car Info: 2004 Java Black Pearl Wrx
Exhaust Manifold - Unequal or Equal
Hey guys... I was thinking on getting my new exhaust manifold soon. I will have my car catless soon. I have a 2004 java black wrx. I prefer to get an unequal length manifold but I don't know which ones are which...can someone help? I know the cusco one is for low - midrange power and not top end but is equal length. ....anyways thanks for the help.
David
David
11-28-2005, 06:41 AM
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You might contact Gruppe-S to hear what's available and their recommendations.
Longer and narrower primary tubes for each cylinder makes more low end and mid-range torque. Conversely, shorter and bigger diameter primary tubes moves the power band higher in the rpm range. Equal length always ensures each cylinder has near identical power output but the limitations of routing the equal length tubes from both cylinder banks over to the right side of the chassis where the factory turbo and downpipe reside presents a much bigger problem than on inline fours or V-8 engines with true dual exhausts.
--
0==WW==0
"…axles of evil…" - george w. bush
Longer and narrower primary tubes for each cylinder makes more low end and mid-range torque. Conversely, shorter and bigger diameter primary tubes moves the power band higher in the rpm range. Equal length always ensures each cylinder has near identical power output but the limitations of routing the equal length tubes from both cylinder banks over to the right side of the chassis where the factory turbo and downpipe reside presents a much bigger problem than on inline fours or V-8 engines with true dual exhausts.
--
0==WW==0
"…axles of evil…" - george w. bush
11-30-2005, 10:50 PM
#3
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Originally Posted by LucidTrancer
I know the cusco one is for low - midrange power and not top end but is equal length. ....anyways thanks for the help.
David
David
I would suggest the Gruppe-s Header, ceramic coated, I have had mine for 8 months and love it, it makes good power.
Just keep in mind Unequal length is stock, boxer motor sound, equal length, with the wrong exhaust you will sound like Honda's revenge.
Cheers,
Austin
11-30-2005, 11:44 PM
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Not to mention that the Cusco piece(s) is big bucks! 
One shortcoming that is common to all of these headers is that even the equal length ones will not flow the same from cylinder to cylinder. When a bend is put in the tubing, the flow decreases. The old rule of thumb is that a sharp 90 degree elbow bend equals the flow restriction of an additional ten feet of the same diameter straight tubing! Smooth, flowing bends are the order of the day but the layout has to be compromised due to the flat four layout. Still, getting as close to equal length is better than not.
If I were to buy a header today, I would take WRX Rush's advice and experience and get the Gruppe-S V2 with Jet Hot coating to retain heat to spin that turbo up. In a turbo car, exhaust heat retention (expanding gases) means power.
At installation time, consider the probe location for an EGT (exhaust temperature gauge) if you plan to use one in the future.
--
0==WW==0
"…axles of evil…" - george w. bush
One shortcoming that is common to all of these headers is that even the equal length ones will not flow the same from cylinder to cylinder. When a bend is put in the tubing, the flow decreases. The old rule of thumb is that a sharp 90 degree elbow bend equals the flow restriction of an additional ten feet of the same diameter straight tubing! Smooth, flowing bends are the order of the day but the layout has to be compromised due to the flat four layout. Still, getting as close to equal length is better than not.
If I were to buy a header today, I would take WRX Rush's advice and experience and get the Gruppe-S V2 with Jet Hot coating to retain heat to spin that turbo up. In a turbo car, exhaust heat retention (expanding gases) means power.
At installation time, consider the probe location for an EGT (exhaust temperature gauge) if you plan to use one in the future.
--
0==WW==0
"…axles of evil…" - george w. bush
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