OHSOFAST

Alright, first, no OBX bashing. I got a good deal and got them REAL quick. (I'm an impatient person, overnight delvery is sometimes too slow)

Okay, so the OBX headers don't match up to the ports on my engine. I know this is nothing new, but I'm wondering why?!!?!

I know that this increases the air velocity, however, this must also increase air turbulance.

Has anyone ported out there OBX headers to better match the engine ports?

I'm thinking about doing this prior to installation, but fear that this may have more negative effects than positive.

Anyone have any ideas as to what I should do? (meaning leave them be or port them....NOT sell them and buy Comptech)

Thanks!!!

Nashua_Night_Hawk

do you have pics? you can port them as big as the pipe itself.

OHSOFAST

I was wondering if there was some method to OBX's maddness for making the header runner inlets so small....

I can get you some pics....hang on....and thanks!

Would it be worth my time porting them?

Nashua_Night_Hawk

The stone headers are 2mm smaller too. However, thay are port matched to the pipes. Smooth ports outlet means better flow and less noise!

OHSOFAST

The front headers are used (less than 1 month), the rear ones were new (that's how I bought them-I was told that the rear were replaced by OBX due to a warranty issue and never installed as the previous owner just bought some Comptech's rather than wait-I would have done the same thing too). So I can send you pics of the front to show the difference as the used ones show the build up on the flange and highlight the diameter difference.

Interested? You may have to adjust the balance/contrast.... And if so....where do I send them?

Also, what are the benefits of the pipe diameter not matching the engine ports? I know the Comptechs match, but why not OBX or Stone?

Would that turbulance cause any performance issues or possibiliy hurt the engine? Just curious.....

Nashua_Night_Hawk

Sent them to nashua_night_hawk@yahoo.com and let me know.

Smaller is not all the time bad, it means you get better torque at lower rpms, bigger ports means higher gains at hi rpms and no gains at lower rpms.

OHSOFAST

In advance, thanks for your insight....

I can port the flange opening diameter up, but don't know how far to really go....

scalbert

The port is smaller because the OBX was designed for the AV6 originally. But due to the similarities of the J series motor they fit just fine.

The size is not the concern, it is the step which occurs. You never want a hard edge in any flow path. Use a factory exhaust manifold gasket and taper the flange port to fit. This should yield the best results. An hour with a grinder and you should be good to go.

scalbert

You might want to rethink you statements or reasoning.

Piping diameter does plan a role in how and where power is produced. But we are talking about having a hard flush edge in the way of a larger exhaust port. That is never better at any point in the rev band. Had the flange port been tapered there might there might be an argument, albeit minimal IMO.