Wondering which header would be the best ......assuming stock ITR with only a CAI right now ....but potentially in the future a couple more bolt-ons would be added if I knew I could eek out a little power after the Header (ie: intake manifold + throttle body + mild cams)
Two versions of the same header are offered, both with the same size output which I believe is 2.5"
Option 1 Step-up Piping Sizes (OD)
42mm - 45mm - 51mm
Option 2 Step-up Piping Sizes (OD)
45mm - 50mm - 55mm
Thoughts?
Will
which header of these two
Re: which header of these two
I think header choice and the combination of compromises is going to be very personal and changes over time.
I'd recommend planing to test and try until you find the one that fits your preferences. Try not to think of it as a one time purchase.
My general impressions(please correct if misrepresenting something) :
A header which increases max exhaust flow will typically trade low-mid range power for higher rpm @ hp peak
Moves power band higher, hp=tq x rpm so increasing rpm = more peak hp, even without a net power(total area under curve) increase.
At lower rpm gases are expelled with less frequency and pressure than at high rpm. Larger primaries allow the gasses to expand and slow so velocity is lost.
If you spend most of your time on the street in lower rpms you may experience a decrease in tq\hp. For example from a stop it may take longer to get to the power, unless you're launching at higher rpm.
Designs with more gentle bends will have better flow. Simply less restriction
4-2-1 header will generally have better high rpm flow
I think the idea is this helps maintain velocity when paired primaries are equal length and separated by 180* of camshaft timing, velocity is more even\constant?
Longer primaries tend to have higher max flow for N/A
I think this has to do with minimizing back-flow between primaries?
Shorter primaries seem to work better for superchargers
allows increase in diameter quickly to better handle higher pressure flow?
If running a cat (I hope you are) look for designs with anti-reversion built in
This limits the flow but cat is already doing that and will cause a push back on the exhaust flow so anti-reversion designs helps to limit this.
Other considerations:
ITR has a larger transmission brace than other model Integras, to stiffen the the transmission and motor. This can cause clearance issues for some exhausts that were designed for non-ITR models.
Ground clearance, depending on the sweep of the header you may have ground clearance issues.
Fan\Radiator\AC clearance can also be an issue with certain designs, larger radiators, and oem fan shrouds, both for installation of 1 piece designs and generally with movement of the motor (non-solid motor mounts).
Multi-piece designs commonly leak (and stink) to a degree, especially when cold.
Increased exhaust noise, while less significant than created from intake upgrades, a header will contribute to overall noise, especially when paired with high flow (less resonated\muffled) exhaust.
Lower mount\brace issues, (non-solid motor mounts?)I've seen many reports where welded brackets or even primary welds (if a lower bracket isn't used) will fail due to engine movement and repeated heat cycles. If using the lower brace the header should typically have a ball type gasket to help minimize issues. Proper alignment with exhaust and rubber hangers can also help.
Some (more) nit-picky items:
An aftermarket header won't hold\insulate exhaust gas heat as well. This means to some degree the gases will cool more and may not flow as readily. It also means you may be heating your engine bay and oil pan*. Heat wrap, ceramic coating, and other products like ZyCoat can help limit this but significantly increase time\cost and may decrease visual appeal.
*OEM cast manifolds once heat-soaked probably contribute as much or more to bay and oil pan temps.
An idea that I'm playing with is port matching and extrusion honing the OEM 96 spec. JDM manifold. Extrusion honing manifolds seems more common on older\muscle cars but some claim improves flow 25% on average, basically by polishing the entire length of the rough casting. This will also allow for use of OEM heat shields and should minimize issues with visual emissions inspections. A mostly cosmetic coating of ZyCoat should also help limit thermal conductivity. The OD of the JDM 96 spec. manifold is the same as the JDM 98 spec. header, still has anti reversion and many options for higher flow cat (or test pipe for track days). This won't deliver weight savings that a header would though.
I'd recommend planing to test and try until you find the one that fits your preferences. Try not to think of it as a one time purchase.
My general impressions(please correct if misrepresenting something) :
A header which increases max exhaust flow will typically trade low-mid range power for higher rpm @ hp peak
Moves power band higher, hp=tq x rpm so increasing rpm = more peak hp, even without a net power(total area under curve) increase.
At lower rpm gases are expelled with less frequency and pressure than at high rpm. Larger primaries allow the gasses to expand and slow so velocity is lost.
If you spend most of your time on the street in lower rpms you may experience a decrease in tq\hp. For example from a stop it may take longer to get to the power, unless you're launching at higher rpm.
Designs with more gentle bends will have better flow. Simply less restriction
4-2-1 header will generally have better high rpm flow
I think the idea is this helps maintain velocity when paired primaries are equal length and separated by 180* of camshaft timing, velocity is more even\constant?
Longer primaries tend to have higher max flow for N/A
I think this has to do with minimizing back-flow between primaries?
Shorter primaries seem to work better for superchargers
allows increase in diameter quickly to better handle higher pressure flow?
If running a cat (I hope you are) look for designs with anti-reversion built in
This limits the flow but cat is already doing that and will cause a push back on the exhaust flow so anti-reversion designs helps to limit this.
Other considerations:
ITR has a larger transmission brace than other model Integras, to stiffen the the transmission and motor. This can cause clearance issues for some exhausts that were designed for non-ITR models.
Ground clearance, depending on the sweep of the header you may have ground clearance issues.
Fan\Radiator\AC clearance can also be an issue with certain designs, larger radiators, and oem fan shrouds, both for installation of 1 piece designs and generally with movement of the motor (non-solid motor mounts).
Multi-piece designs commonly leak (and stink) to a degree, especially when cold.
Increased exhaust noise, while less significant than created from intake upgrades, a header will contribute to overall noise, especially when paired with high flow (less resonated\muffled) exhaust.
Lower mount\brace issues, (non-solid motor mounts?)I've seen many reports where welded brackets or even primary welds (if a lower bracket isn't used) will fail due to engine movement and repeated heat cycles. If using the lower brace the header should typically have a ball type gasket to help minimize issues. Proper alignment with exhaust and rubber hangers can also help.
Some (more) nit-picky items:
An aftermarket header won't hold\insulate exhaust gas heat as well. This means to some degree the gases will cool more and may not flow as readily. It also means you may be heating your engine bay and oil pan*. Heat wrap, ceramic coating, and other products like ZyCoat can help limit this but significantly increase time\cost and may decrease visual appeal.
*OEM cast manifolds once heat-soaked probably contribute as much or more to bay and oil pan temps.
An idea that I'm playing with is port matching and extrusion honing the OEM 96 spec. JDM manifold. Extrusion honing manifolds seems more common on older\muscle cars but some claim improves flow 25% on average, basically by polishing the entire length of the rough casting. This will also allow for use of OEM heat shields and should minimize issues with visual emissions inspections. A mostly cosmetic coating of ZyCoat should also help limit thermal conductivity. The OD of the JDM 96 spec. manifold is the same as the JDM 98 spec. header, still has anti reversion and many options for higher flow cat (or test pipe for track days). This won't deliver weight savings that a header would though.
Re: which header of these two
True info on header design and interreaction with everything else you have on/in the motor. IMO, I’d snag a Toda Replica from PLM. They flow well on stock/bolt-on motors, have great ground clearance, and are remarkably well made for the price tag. I’ve had 2 of them in the past and would buy again (the 2nd one took a tiny bit of grinding on the header flange).
Christian - Closet Honda fanboi in FL
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Dave7CDMTYPER
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Re: which header of these two
I have a T1R header brand new I'd sell you for less than new price. I originally ordered it a while ago but have since got another header or two that I like better. I think it's supposed to be pretty decent.
ITR CDM 01-1322
2001 GS-R
I have badge #00-1259 in hand.
2001 GS-R
I have badge #00-1259 in hand.
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