Header Question
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Intermediate
Joined: Oct 2020
Posts: 42
Likes: 1
From: Texas
Header Question
I have a 2013 HD Limited my question is if I replace stock header pipes with V&H do I have to get the bike re-tuned or have to buy the module that is near $500? I am gathering that its not just an easy swap but a lot of extra **** that will be more expensive than I want to go.
Any help would be appreciated.
Any help would be appreciated.
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,158
Likes: 11,248
From: San Diego, CA
The general rule with twin cam engines;
They run lean from the factory due to EPA reasons, so even a tune on an OEM bike will offer better performance.... however,
If you change just the air cleaner or the exhaust, you don't NEED to retune, but a retune would be beneficial.
If you change both the air cleaner AND the exhaust, then a retune is wise, if not essential.
If you do more than a Stage 1 mod (air cleaner & exhaust) then a retune is mandatory for proper, safe operation.
What most people don't realize when they claim the the ECM will adjust for changes in the engine's air flow, is that only a portion of the OEM tune is closed loop (adjusted with O2 sensor feedback) and the other portion of the tune is open loop (no O2 sensor feedback or adjustments). The open loop portion is based solely off algorithms derived from the OEM components.
The closed loop portions of the tune are in the cruise/low load ranges of the tune. The open loop portions of the tune are in the high RPM/high load areas of the tune. This is done because the AFR in the high RPM/high load areas of the tune is generally outside the effective range of the OEM narrowband O2 sensors.
So if you have relatively normal riding habits, you should be fine. If you have aggressive or ride it like you stole habits, you are more likely to find yourself really lean in the open loop portions if you don't retune...
Personally, I've never left one of my bikes in OEM form, and I retune any time I change the airflow to the engine... IMHO, that is the safest and best way to deal with engine component changes.
Good luck with your decision...
They run lean from the factory due to EPA reasons, so even a tune on an OEM bike will offer better performance.... however,
If you change just the air cleaner or the exhaust, you don't NEED to retune, but a retune would be beneficial.
If you change both the air cleaner AND the exhaust, then a retune is wise, if not essential.
If you do more than a Stage 1 mod (air cleaner & exhaust) then a retune is mandatory for proper, safe operation.
What most people don't realize when they claim the the ECM will adjust for changes in the engine's air flow, is that only a portion of the OEM tune is closed loop (adjusted with O2 sensor feedback) and the other portion of the tune is open loop (no O2 sensor feedback or adjustments). The open loop portion is based solely off algorithms derived from the OEM components.
The closed loop portions of the tune are in the cruise/low load ranges of the tune. The open loop portions of the tune are in the high RPM/high load areas of the tune. This is done because the AFR in the high RPM/high load areas of the tune is generally outside the effective range of the OEM narrowband O2 sensors.
So if you have relatively normal riding habits, you should be fine. If you have aggressive or ride it like you stole habits, you are more likely to find yourself really lean in the open loop portions if you don't retune...
Personally, I've never left one of my bikes in OEM form, and I retune any time I change the airflow to the engine... IMHO, that is the safest and best way to deal with engine component changes.
Good luck with your decision...
Grand HDF Member
Joined: Jan 2017
Posts: 3,837
Likes: 1,430
From: NJ
Subscribing.
I'm in the same boat for my 107 M8. The stock header gets toasty! Not looking to throw a pile of Benjamin's at the problem either though. Stock A/C with V&H slip-ons and will probably remain that way.
I'm in the same boat for my 107 M8. The stock header gets toasty! Not looking to throw a pile of Benjamin's at the problem either though. Stock A/C with V&H slip-ons and will probably remain that way.
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,158
Likes: 11,248
From: San Diego, CA
The M8 engine is slightly different than the Twin Cam engine, in it's OEM airflow characteristics. I don't own, nor have I worked on an M8 engine, so I can't speak to specifics. I have read that the airflow characteristics are different, which will affect tuning questions.
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