Will header fit??

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jesparza602

New Member
Hi all,

I have a 91 si ef hatch with a jdm b16. I am looking to install a 4-1 header. What model vehicle am I looking to get my header for? Will a header for a 99-00 civic si work?? I was looking at one from Megan racing. I don't know if it will bolt right on without mods. I have no cat, there is a test pipe going to my muffler. Please help.

I recently bought the car and am new to this forum
I would also like to know typically when looking for bolt ons what vehicle type to search for since my hatch did not come with this engine. I don't know what will fit into this car
 
btw i do have a traction bar so I think this will help with rubbing against crossmember and I am not sure how to identify it its still 0BD0. thanks to anyone who can help
 
i dont know about the header...

but most 0bd0 vehicle have yellowish connectors. were 0bd1/2 have gray connectors.
 
i have ordered a megan 4-1 header. i assume it will fit since it is a for a 99-00 civic si. Although what am i to do about the two o2 sensors? My car is 0bd0. Help the noob please
 
The chassis is OBD0 or the engine is OBD0? The engine/ecu is all that matters. If it is OBD0, then all you need to do is use the 1 wire O2 sensor in the header. If the exhaust system has provisions for 2 O2 sensors, just cap off the second one.
 
The chassis is OBD0 or the engine is OBD0? The engine/ecu is all that matters. If it is OBD0, then all you need to do is use the 1 wire O2 sensor in the header. If the exhaust system has provisions for 2 O2 sensors, just cap off the second one.
You can't do that with obd0. obd0 reads the o2's in cylinders pairs. If you just use one, you'll throw a CEL for the other. Also, you can't just splice both o2 wires to one o2 sensor or you'll have one cylinder pair running rich and one cylinder pair running lean.

Either you can have an exhaust shop weld o2 bungs in the correct spots or find the HaSport header.
 
Waidaminit. I'm confyoozd. I thought they didn't have 2 o2's til OBD1...

Disregard! Disregard!
 
thanks for the help guys. I'm gonna have to have an exhaust shop weld the other o2 bung. It should be cheap too.
 
one other question though. does anybody know where on the header they should put the o2 bungs? Should they plug the one thats all the way at the cat/test pipe and weld two for each pair of cylinders?
 
nope the holes that are in it are in the right spots..
one up near the top nd one down by the cat
No, the holes are NOT in the correct spots.

They need to look like this...

61aecf13-b16f-463d-b540-ae33056ef4a7.jpg
 
OK well they look like that now on the stock exhaust manifold. On the header there is a sinle o2 bung right where it connects to my test pipe since i have no cat. My question is still, do I have to plug the one there and add two bungs, each corresponding to a pair of cylinders? If yes, what location is ideal or would my local exhaust/ muffler shop know where would be ok. thanks again for the help guys. I can't wait to install my header.
 
OK well they look like that now on the stock exhaust manifold. On the header there is a sinle o2 bung right where it connects to my test pipe since i have no cat. My question is still, do I have to plug the one there and add two bungs, each corresponding to a pair of cylinders? If yes, what location is ideal or would my local exhaust/ muffler shop know where would be ok. thanks again for the help guys. I can't wait to install my header.

If you look at the picture posted above, it tells you which cylinders to pair, and which ECU wire to connect them to. A 4-2-1 header would work better for this purpose, but if you insist on a 4-1 you'll have to put them both in the collector or connect C16 to cylinder 1 or 4 and C8 to cylinder 2 or 3.
 
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