Bought OBX-R exhaust header, had some trouble but it's working now - RX8Club.com



Series I Aftermarket Performance Modifications Discussion of power adding modifications
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Old 06-18-2013, 03:54 AM   #1  
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Bought OBX-R exhaust header, had some trouble but it's working now

So I just gutted the cat on my car, and was looking to finish off my exhaust system with a header. Seems like the major headers offered were these:

OBX-R header - $185

M2 performance - $195

Racing beat - $536

AutoEXE- $2080 (not a typo...)

The m2 header looks like a copy of the racing beat one, so the real life difference between those two is most likely negligible. I went with the OBX header because it looks like the plate with the bolt flanges is much stronger than the m2/rb, and the OBX one looks like it is closer to having equal-length piping, an attempt at emulating the AutoEXE one. It is also made out of the same type of steel.


Installing it is much harder than I thought it would be. Last time I had to take the header off I had the motor out of the car on my engine stand, which made it real easy haha. You have to jack up the car as far as you can and put jackstands on all 4 corners to get enough clearance to get to most of this stuff. I took off my cat/resonator first; I removed the front bolts from the header, but just took the nuts off the rear studs so that I didn't have to take the whole thing off, and it saves me from having to deal with that rubber hanger. Then I had to take the motor mount completely off, which involved jacking up the motor from the oil pan with a block of wood so that the bottom of the mount can get out between the header and the subframe. From here I could easily get to the three top header nuts with a 2' long extension, wobbly adapter, and 14mm socket. The bottom 3 nuts were completely unobstructed. (remember to loosen the o2 sensor before pulling all the header nuts off, cause it's hard to get enough torque on the wrench when the header can move around). With the nuts and sensor off, a flatblade screwdriver popped the header off the studs and it slid right out.

Putting the new header in didn't go as smoothly as it should have. First, the carbon/kevlar gasket wasn't cut right, and didn't line up with the ports and holes for the secondary air injection. I had to cut it so that it matched up better. Then, when I tried to put the header on, it wouldn't sit flush with the irons and gasket. The flanges for the bottom 3 bolts protruded down too much, and were getting caught on the bolt right above the oil pan that holds the rotor housings and irons together. I had to pull it off and grind down those flanges for it to clear, taking off about 1-2 mm of material on all 3 flanges. I installed the header which went decently, except I couldn't seem to get the header bolts quite tight enough, especially the bottom ones. I just reefed on them as hard as possible and hoped it wouldnt be a problem. Reinstall the motor mount, re-attach the cat and the o2 sensors, and it was ready to start. Immediately you could hear a horrible exhaust leak, so we crawled under the car and revved it to try to find where it was leaking from, and couldn't really see anything. We figured it was leaking out of the bottom of the header, as those nuts didn't really feel like they were completely tight. Let it cool down, then tightened those bottom bolts as much as we could. restart the car, and it still is leaking, but not nearly as bad. I figured it was driveable as long as I didn't go crazy with it. Drove to work the next day and put it up on a lift to get a better view and try to find the leak, when I saw it. I hadn't ground down those flanges enough, and they were getting caught on a little lip on the sides of the rotor housings. Today I repeated the whole uninstall/reinstall process, grinding another 2mm of material off those flanges. The gasket had been destroyed by the bit of driving I did with the leak, so I had to use a stock metal gasket. The ports on the OBX header are the same size as the exhaust ports on the irons, but the stock header has bigger rectangles on the pipes than the engine does, so the gasket is designed for having a bigger port size on the exhaust pipes. I'm hoping it will hold up.

It took me about 5 hours to do the header the first time because of the grinding and fitting and frozen bolts. Today it only took me about 3 hours with the extra grinding, but I didn't get any help with it this time. Amazing how much having experience helps. With a whole bunch of those flanges ground off, it went on fine and reassembed no problem. I didn't get a CEL, it doesn't sound like it is leaking anymore, it is louder, and it sounds different. I'd say it makes the car about 30% louder, and the pitch is deeper especially below 3k rpm.

I'll update as I start driving around more on it, but I took it out for a test drive today and it seems to be pretty great. Seems like the exhaust flows a bit better, and it sounds nicer. Apparently it also makes the flames better, but I can't see the flames I am making
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Bought OBX-R exhaust header, had some trouble but it's working now-img_20130613_162806_556.jpg   Bought OBX-R exhaust header, had some trouble but it's working now-img_20130617_131946_907.jpg   Bought OBX-R exhaust header, had some trouble but it's working now-img_20130617_131644_676.jpg   Bought OBX-R exhaust header, had some trouble but it's working now-img_20130617_140347_315.jpg   Bought OBX-R exhaust header, had some trouble but it's working now-img_20130617_140425_019.jpg  

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Old 06-18-2013, 06:15 AM   #2  
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what i always found interesting about the RB design is how they have interchanged the center and rear exhaust port compared to other headers. Not sure if there is a purpose to that, but it is something that you dont see replicated by the "M2" (which is basically an ebay replica).

I have heard a ton of issues regarding the OBX header and fitment, but for the price i guess you cannot really complain.
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Old 06-18-2013, 07:42 AM   #3  
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AutoExe Clarification

Congrats on your purchase and I hope it meets all your expectations. I did want to clarify the AutoExe price as I am the sole authorized distributor for AutoExe in the US. I am currently selling at $1400 (I know, not even in the ball park with the Chinese stuff). The quality of design and materials of the AutoExe unit is on a different level. I know the debate over the benefit of a header on a renesis too well and we also consider Dollar/hp ratio, however, Check it out: AutoExe:???????

Sorry for the thread jack .

Paul.
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Old 06-19-2013, 03:08 AM   #4  
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Thanks for clarifying Mazmart, I just saw the price on the first couple websites in google and saw it was way out of my budget so I stopped looking at it. It does appear to be on a whole different level quality-wise, but at least an extra $1200 for the 1-2 hp that it gives you over any other header?

So far the OBX header is doing well, it changes the sound quite a bit for the better. So far it's hard to tell the difference performace-wise, but it feels like the rpm response it better in the higher rpms. Maybe slightly more power, but I'm not expecting much from any header. For costing only $200 I consider it a success! I might upgrade to the RB header at some point if I have the money and can't think of anything better to spend it on.

Does anyone know exactly what makes the RB header's port swapping different than the conventional design? Is it superior in any way, or is it just their take on how it should work? Seems like equal-length would be the most desirable configuration, as the exhaust pulses from each rotor wouldn't be colliding where the pipes converge. (assuming the timing makes the rotors evenly alternate exhaust pulses, but I'm actually not sure if that's how it is)
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Old 06-19-2013, 03:48 AM   #5  
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I think the main reasoning behind Racing Beat putting the center port runner on the top side is mainly for the oxygen sensor. A lot of these headers have the O2 sensor configured in a way that it would mostly get hit by exhaust coming out of only one rotor, where as the Racing Beat one sees exhaust gasses from both rotors more equally. What effect does this have on performance? No idea. But if one of the rotors leans out or starts running too rich, it seems to me that the computer is more likely to see it with the racing beat header.
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Old 06-19-2013, 06:25 AM   #6  
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That's a good point in the case of the OBX, but I know most of the other cheapies have the o2 bung right at the merge collector.
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Old 06-22-2013, 06:34 PM   #7  
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I have a AutoExe unit I found on Yahoo Japan. Fitment is perfect, welds are beautiful, and gives a nice tone change to the exhaust.

I had a hoist when installing, I couldnt imagine doing it without one lol
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