I've had an OBX header sitting in my garage for a few months now. I want to put it on before Jan comes back to Detroit, so I was re-reading all the OBX header install info and noticed something odd...

The primary tubes of my header are smaller where they go into the Head plate than most of the ones I've seen here. I was able to find a picture in the galleries of what mine looks like: (ignore the flex joint - mine still has the normal donut gasket. I'm just concerned with the primary/plate interface)




Most of the OBX headers I've seen here keep a constant diameter all the way to the plate and do not go through it. In the header pictured above, as well as the one I have, the collectors are "crimped" and fit INTO the holes in the head flange....

What's up with this?

Are the new OBX headers better or worse than the old ones?

Is this a cost savings? Does it have a negative effect on the perfromance of the part?

I don't see how adding four extra crimping steps to the manufacturing proccess could save money - unless it allows for less fixturing when welding the systems...

I know, "you get what you pay for," but the OBX header seemed like it was an exception to this rule.

I'm now wondering if I should even bother with it...

 

You're right, that is weird & I haven't seen that before. I'd probably skip it all together & just go with the RMW header. Sooooooo....why'd you decide to take a picture of your header sitting on a toilet?

 

"I was able to find a picture in the galleries of what mine looks like"

No RMW for a while... once I'm out of warrantee, I'd like to go all out with the Head, cam, full exahust and whatever other goodies Jan has created by then. Trying to stay pretty minimal on the mods for now.

 

can it also be used as a plunger?

 

Not my picture.

Thanks for the help though.

 

I have not seen that configuration before. I suspect that there was a batch of tubing which was cut wrong and rather than scrap it out, this configuration was "cluged" together. The Quality Control of the OBX is spotty. To some extent you don't get what you don't pay for. When I put on the OBX, Jan's headers were not available.

I have the OBX and it works OK. However, I did take a file to the flange to make it flat, and took care to polish the area in which the "donut" gasket sits, to extend its life. The stud holes and gasket do not align perfectly either.

Never the less, I managed to eke out 239 hp. with the help of Jan's head and tune, using the OBX. See my gallery.

By far, the best bang for the buck after the pulley is the head and tune from Jan.

 

I don't know anything about header design, but on SpeedTV during one of the F1 races they did a tech special on red bull reanult's custom headers and where the pipes joined the flange it had the same crimped look to them.

 

Could be for anti-reversion

 

I was under the impression that they did that because of problems with the welds interfering with the bolt heads. FWIW, mine looks the same, and it's sitting in the corner, still uninstalled.

 

I saw that also,awesome bent metal!
- I'm a huge F1 fan.

 

Come on guys,what's with all the lonely,homeless headers.Install...install...install!
OBX is better than stock.
-I too have plans in the very near future for stem to stern RMWization.

 

Strange, my OBX is not that way. I'm wondering if its really smaller? or is it that those tubes are the same size as before and the other tubes are slightly larger? I'd question if they really made the flange ports smaller. please compare them to the stock system when removed.

At this juncture, I'd ensure that the flange matches up well w/ th exhaust ports and install.

 

I believe anti-reversion is where the header/flange has a larger diameter than the outlet port of the head. If exhaust gasses try to go back into the head, the relatively smaller exhaust port obstructs the entry of the exhaust gasses into the head. This OBX appears to have the reverse, if in fact the diameter of the manifold flange is smaller than the ports in the cylinder head. If that is in fact the case, the header obstructs the expulsion of exhaust gasses.

I believe the OBX is a copycat header and little or no engineering is used in its design. Therefore, I don't think the configuration has anything to do with what works or doesn't work, except possibly for what fits and does not fit.

 

What's the difference between installing an ebay aftermarket header that likely won't make more than 5 HP and a fully engineered header that will probably make 3x that .

I too once had an OBX (Which became a restriction shortly after installing it). It definitely didn't look like that!

 

The original or old style OBX was much better then there current design and Q/C. Although it was not a power gain header if you matched it up with a good exhaust system you can get more then only 5 hp out of it. For its time it was adequate. And a good price for the budget performer.But nothing beats a good developed header !

 

What's Jan's headers running thes day's... I have an old style OBX still in the box.

 

I'm not sure that the old is better than the one pictured. I think we would need to understand if the tubing sizes were changed. About power gain, it is a 4-2-1 design which is more of a mid range design than top end. From testing, the OBX has not given big HP numbers but has given better TQ gains. Dollars per hp/tq gains and here the OBX delivers making it like you point out a good budget performer.

I think its the right addition for a level 1 MOD'ed car and its the wrong addition if your seeking to join the 10,000.00 club.

 

Mine looks just like that. I believe the ports on the head are the same size as the neck down. The obx is a great header. I am very very conservative on what you call the "butt dyno" and I felt noticable gains in the midrange with mine. If you want to spend $1200 plus on a header that "may" give a few more horsepower feel free, but for the best deal, the obx is the best bang for the buck.

 

yep

 

I just picked up mine from littlehand and it doesnt look like that in the least. I will take a pic in a few.

 

How about spending it on a header that's actually been dyno tested to make 10-12 whp?

I had an OBX header. I pulled 212 whp with that header and an invidia exhaust, and 231 whp with the RMW Race Exhaust (Header-back). Sounds like it works to me?

 

The whole factor you have to work in is the cost. Unfortunately, not everyone has US$2000 to spend on the exhaust. FWIW when I spoke to Jan he told me that it is quite a good header for the money that you spend on it.

 

First its the marriage of parts that maximize gains. An important difference here is that the RMW header is designed to go w/ the RMW head (matched and larger ports) where the OBX is designed for stock ports. Considering the level of your mods, there are too many variables for one to claim the HP difference just to the header/exhaust. It could very well be that the gains came from the head (and the re-tune) and the header/exhaust just allowed those gains to come through. Would this header/exhaust work as well on a stock MCS engine? Probably not since Jan is designing all of his parts around his head.

I'll say it again - the OBX header is a good choice for a level 1 Mod'ed car and there are better options for the 10,000 club.

For me the two are not comparable.

 

True and correct. If you apply dollar per HP/TQ gained, the OBX is a worthy consideration. Are there headers that produce more HP/TQ, yes but at 5 times the price. Jan is coming out w/ a street header and it will be interesting to see at what price point he can deliver this header.

Many that are knowledgeable will tell you that the OBX is not the absolute best but a very nice header for what you pay.

It all goes back to ones engine development plans.

 

While I agree that gains will be much greater with a properly designed head, you're still going to gain a LOT more power with a header that has long primaries. The whole exhaust is expensive, but if you already have a cat-back and you're just looking for a header, you can still use the RMW header. The OBX is going to provide minimal gains.

I had one guys! Both stock and with a head... The power that was gained was only in the mid range (Under 5 HP). I actually lost low end torque and top end HP (tested on the dyno, not with my own perceptions).

For everyone that says they felt the difference afterwards, you're not going to feel a 5 HP difference . Placebo effect to the max.

I agree, if you have plans to sit tight at a pulley, intake, and cat back for the life of the car, the OBX works fine. If you plan on ever getting a head, or going further down the upgrade path, wait, and see what Jan comes up with for his "Street" header (Unless you don't mind wasting $300-$600 on the OBX + install).