We are primarily into racing, but because we've run into the problem over and over of not having parts available we've decided to start making them too. So we formed 2J-Racing to do both.

There is no decient header on the market for the QR25DE Nissan motor, and though we don't currently run a QR powered vehicle (we do have a B13 and a QR, harness, ECU, and electronics to do a swap).

I have a friend into drag racing who runs a high compression QR and JWT's new C1 camshafts that wanted a "real" header w/ a 3" collector per JWT's suggestion. This one will go on his car, but before it does, it'll get digitized (in the US by a US company) so we can tweak the different demensions based on feedback and dyno testing to dial it in. The math says the runner are too long, which is good. We can go too long and then go too short, and then try something inbetween to dial it in. Once it's digitized making dimater, length, and step changes will be a few clicks away.

I've done pipe work before for turbo set ups, intercoolers, and exhaust but never a header. Lucikly this was cake and nothing like I thought it would be. I "cheated" and used a prefabbed slip on collector for the first go to simplify things. We also have a slip on with runners that are 8 inches shorter. I put the runners parallel as soon as I could so swapping slip on collectors would be pretty painless for testing.

We are waiting on a run of alternator relocation and AC delete brackets so we can do a full race header with all of the primaries that come off of the head 6" before they turn down. Right now we have to clear the alternator. Everything is designed to work with a 3" head pipe that bolts to a 3" catback, because we think race first, and street is what we tow our cars to the track on

Any feedback is welcome.

What ID tubes are you using?  What's the redline of the engine?

What's the current length?  Running some very rough numbers without really knowing anything about the engine, I think a primary length of 18.375" (from exhaust valve to collector) will give a bump in the 5k-6k rev range.  Give or take a thousand   I'd be very interested in the resuts to see if the theory I'm working with is even close or not.  Though..... 27.5" might work pretty well too.  It looks like they're over 30" now?

Ah ok, you are running a slip collector and are going to cut shorter to tune it?  You should run the Burns bspec collector with the tuneable venturies to play with that as well.

once we get closer to something optimal it's something we'll consider refining.  But, until the induction side of the motor is improved upon, I don't think a header will produce spectacular gains. There is a less than ideal intake to exhaust ratio going on with the motor as it is. We're working on the head and intake too.... that's where the motor is going to come alive.

Schoenfeld slip ons, really cheap ($35), really easy to use and destroy and not feel bad about.

I finally finished up the mid pipe. We'll be at the dyno Tuesday to see what this thing does.

Posted By Mike Kojima on 03-19-2011 10:22 PM
Really eager to see what this does.

Me too.  I'm going to go with the shorter runner one.

Posted By Big J on 06-01-2011 09:27 AM
The shorter runners were up about 3-5hp and TQ over the longer runners, with both making pretty big gains TQ gains down low and 7-8hp gains up top over the ebay wonder flow headers he had used and tested previously. 

Ha, I guessed right!  There could probably be some more gains in tweaking either length and/or diameter, but getting a nice merge collector on their as opposed to your quick/cheap prototype version should give you a decent gain too.