I got my hands on a set of '07 350Z exhaust manifolds, which look a lot like Nismo or similar shorty headers. I ordered a set of test pipes for an HR engine so that the flanges will all line up with the OEM Y pipe. I plan to install these in the next couple of weeks. I will also be running some JWT cams by the fall. I have a 3" AAM exhaust installed. I have a UTEC to tune the AFR, so that won't be an issue. Has anyone tried running this setup, that is, HR headers on a DE engine?

 

Don't see it gaining a ton of power over stock DE manifolds, but it's gotta be better slightly.

Is there any room for improvement while you have them off? Smooth the inside of the collectors or ports or something?

 

The only company making a header for the HR is Stillen. The consensus on the HR threads is that an aftermarket short tube header is a waste of time, since the OEM header is already pretty optimized and has equal length primaries.

There isn't much to improve on in terms of porting. The welds could be smoother, but it seems like a waste of effort to try and grind them down. It could make things worse, too.

I won't have access to a dyno, but I should be able to tell by the fuel maps where power is gained or lost. When the mixture goes lean, that indicates a more efficient flow of air. I added a lot of fuel when the ehaust went on, so I know it helped.

I expect a shift in the powerband and most of the 15 hp claimed by Nismo and Stillen units. Hopefully I can get it done next week and share the results. The dyno will have to wait until the cams go in.

 

Keep us posted. You'll be the first and I'm very curious because it's something I've been considering too.

 

interested in results... sub'd

 

the hassle it is to install them, isn't worth it IMO

 

I don't really understand the point of doing this, unless the HR oem headers are better in quality and gains than the many aftermarket options available for DE (Crawford, SG LG, Nismo, Tomei, etc.)...

 

Probably the biggest advantage IMO is that they're OEM design and quality. The piping is beefy and thick to retain heat (ideal for exhaust components) and reduce noise and they'll bolt up with no clearance or quality control problems. The headers also have heat shields to keep underhood temps down. Finally, they've been designed and throughly tested by Nissan. They've got access to bench equipment that none of these other aftermarket companies have access too except for maybe Nismo.

 

Here is a thread with some good information about it:

https://my350z.com/forum/intake-exha...changable.html

 

I am doing this for two reasons:
1. The headers were free, and I can do the labor.
2. I will be installing JWT cams, and believe that the cams will respond better to headers than the cast manifolds.

Strike one so far. I got in test pipes for an HR motor and the flange on the passenger side test pipe didn't match up with the header. I think it is a fluke (flange welded on backwards), so they are sending me a new set.

I grinded the welds down a little on the inside of the headers to smooth the flow. I doubt that it will weaken them enough to cause a problem, but you never know. They were pretty intrusive inside the primaries. I debated doing a heat wrap, but settled on just using heat shielding on the fuel line, etc. as seen in Goth Chick's header DIY.

 

The test pipes came back from CNT racing and they fit fine. I will work on the install tomorrow. We shall find out if this works. I'm sure OEM headers are a good bit cheaper than Nismo ones. Pics will be posted so you can see the difference.

 

Alright. Here's the old vs. the new:


You will see, as I found out the hard way, that the studs on the middle pipe don't line up. After much swearing and knashing of teeth, I noticed that the studs could be removed and located on the opposite holes. I called a buddy to explain the best way to remove the studs, as only one of them would come loose with a vise grip. I put two nuts on the stud and tightened them against each other. Then I loosened the stud by twisting the nut on the inside. I got the studs swapped out and everything fit fine!



The test pipes will also mate up properly. I spent about 8 hours so far. It will probably take a few more sessions to get everything bolted up and running, then off to tune the UTEC.

Big thumbsup to Gothchick for listing the tools needed. I wondered why I would need 1/4" drive tools. As suggested, I picked up a 1/4 swivel, extensions, and rachet. Good call. Those ratcheting box end wrenches were also pretty handy.

 

Good Progress man!

Thanks some of us are interested and would like to see the results.

Keep it up!

 

Great thread! Information like this is valuable to the community.

 

Yeah, from my time working on these cars, you need small tools to make it work. Either that or tiny japanese hands.

 

When you're done, let us know what you had to remove to get the headers in. I'm curious if the passenger side water pipe or the steering drive needed to be removed/disconnected.

 

You have to remove the hard water pipe on the passenger side. It helps to remove the one on the driver's side, but I don't know if it's entirely necessary. The steering linkage has to come out. It's kind of tough. Loosen both bolts, wedge a screwdriver in the lower end, and push the knuckle up on the shaft, which will allow the bottom end to come free. Mark both ends with different looking marks so you can figure out which end is which.

I also had to unscrew a big bracket behind the alternator that holds a few hoses in place to get to the front header nuts. I put heat shielding on the fuel lines, a wiring harness, and the A/C line. I will post some pics when I get the time. Doing this stuff before work makes it difficult to post up progress.

Here's the good news. The collector end of the new headers are much larger than the old ones. The old diameter was 1.7" and the new is over 2", maybe close to 2.5". That's a lot more flow. I will post pics in a couple days. Both headers are on and torqued, and the steering knuckle is back on. Tomorrow I have to spend some time with the family, but I hope to get the test pipes and O2 sensors on. The job isn't that hard, just tedious. If you have to remove the studs, it's a pain. Two of mine were frozen up really bad. Smooth sailing from here on though!

 

Quick update on this:

I was going to top off the last of the coolant and start her up this morning. Then I noticed some coolant leaking from where the hard coolant pipe on the drivers side was leaking where it mates to the block. So I had to tear it down and redo it with some RTV on the joint. Tomorrow it should be good to go. Who knows why or how Nissan managed to make this connection without a gasket? Pretty frustrating, and the coolant puddle got all over my tools.

I also noticed that my factory Y pipe has inlets that are 2.1" in diameter. That screws up the stepping in the whole exhaust system, so I expect to not see all the benefits from this setup quite yet. I ordered an XYZ pipe from Motordyne, but they are out of stock at the moment.

One other thing: Remember that the newer Z's have a sort of wideband O2 sensor vs. the narrow band ones on the earlier models. I re-used the '03 sensors.

 

I love the gains on headers. With a tune and some headers I pull alot of hr's and plenty de's at the track. On a hurt motor I pulled 265 heat soaked later we got 273 with cylinder 3 and 6 filled with oil on the plugs. I based at 234 maybe 240 with all bolt ons headers, exhaust, intake and stock recalled oil burner I pulled from my batch of recalls. I'm curious to see how these work for you. Good luck and greets pics showing the difference I always wondered.

 

Cool. With a Pop Charger, Kinetix V+ intake and HFC's, and an AAM 3" single exhaust (tuned with a UTEC) I was at 250 whp and nearly 250 tq. The torque was tabletop flat at 250 from 2000 rpm to about 5000 rpm, so I'm hoping not to lose too much in the low rev range. This thing pulls like a freight train already, but I am having trouble pulling on 240 SXs with SR20DET's on the straights. The 240 guys always comment on my torque because it kicks their *** until their boost comes on. I will get it all dyno'd in the fall sometime after the cams go in and possibly a flywheel.

Pics tomorrow! I'll be off work.