Gabed I have the invidia gemini on my car which is a 2.36 (60mm).

The collector outlet on the PPE is 2.5 so when it necks down to 2.36 at the collector it's not a smooth transition.

The reason why I said maybe my exhaust is the problem due to the tests SG did with a different exhaust see pg 5. (I should of researched)

My exhaust is smaller than the 2.5 tested.

https://my350z.com/forum/na-builds/3...-roadster.html

Trying to decide to get a custom 2.5 with a tuned x-pipe or 2.5-3in y-pipe exhaust.

The 2.5 they had used a h-pipe and Sasha said probably with a tuned x pipe it could of made more.

True about me already being tuned for headers compared to 512Z.

 

I believe that stepping down slightly at the collector is done intentionally to increase velocity, and actually flows more than keeping it 2.5" all the way through.

edit: If I remember correctly, it's because as the gasses exit the primaries and dump into the collector, you're moving from a smaller diameter to a much larger one, and the velocity plummets. Decreasing the diameter slightly around the collector venturi helps retain that velocity before it steps back up to a larger diameter.

 

That 60mm will most likely not help your case at all, but this brings up a good topic regarding the merge collector. The SGM one is a 2.25" tapering to 2.5", but yours is a 2.5". Another thing which may sound stupid but the PPE headers seems to be too symmetrical from side to side. Might be worth checking if they are trully equal length when comparing both sides, remember that the exhaust port layout is staggered from side to side making one side shorter by roughly 4". BTW, did you see those vhr dyno?

 

I understand that, but what I mean is the flange for my exhaust is smaller than the flange on my headers. So it goes instantly from 2.5 (63mm) to 2.36 (60mm) with no taper there is a lip from my exhaust flange where it transitions.



Gabed to be honest I don't think anyone can copy what SG did with their headers without paying.

I get what your saying about them being the same, but one side does have different bends from the other.

The stock cats and headers are from my car compared to their long tubes.




The collector is longer on the SG headers. The tubes merge earlier on SG's setup.

I'm just using what they did with their tests to confirm some things. I'm pretty sure people would not want SG headers if they posted major losses as their headers have shown with a crappy dual exhaust.

DE, RU, HR you need a free flowing 2.5in or 3in exhaust.

Getting close to what SG has done with half priced headers is good enough for me.

During SG's test they did confirm a little lowend loss 4-6tq below 4k, but with gains everywhere else

 

512Z not trying to take over your thread.

I hope the info in link I posted above helps you with what size exhaust you should mate to your MD XYZ.

 

Ohhhhh yeah, that changes things! Well, hopefully somebody else learned something, lol

On another note, it looks like the collector on the HR headers is further back from the ones for the 370z, meaning the design for the 370z is closer to SGM's.

Your PPE HR headers:


PPE 370z headers:


SGM headers:


And I guess for reference, the FI headers:


I remember Fast Intentions (I think it was them...apologies if not) coming out and stating that PPE "longtubes" weren't really longtubes b/c the primaries merged too soon (still well past an OEM setup, so who's to say what constitutes a longtube and what doesn't?)

At any rate, it is interesting to note. Has PPE said anything about why they changed the merge collector position with the HR vs the 370?

 

I noticed that also. I asked the same question they told me there was no room to do it that way. I think on the SG headers one of the primarys on the DS has a dent in it for clearance not sure though.

Also the step location is different the 370 and SG are almost the same closer to the heads. While the ours is further down.

At least the collectors are similar.

I remember FI was calling PPE's 370 headers mid-length and not true long tubes.

 

correct there are actually two dents on that same pipe. one to clear the trans and one to clear the steering rack.



u can see the dent on the top left in the pick. I remember when I first got them and I called up Sasha thinking they got damaged lol

 

512Z, any progress on the rest of your exhaust?

 

All done guys will be uploading this weekend

 

Nice can't wait to see what you did.

 

<iframe src="http://player.vimeo.com/video/38908861?title=0&amp;byline=0&amp;portrait=0" width="400" height="225" frameborder="0" webkitAllowFullScreen mozallowfullscreen allowFullScreen></iframe>

in the mean time you can hear what it sounds like its supper loud LOL

this is last weeks event and im the only BLUE Z at a 1:51

 

what exhaust did you go with? Nice vid!!

 

Sounds pretty good! Let us know what you went with!!

 

ok i went with a motordyne single shock wave the funky looking one and it sounds like this video but louder LOL so what we did is we kept the same single and chopped the end off and put a muffler in and its still loud loud but smoother sound.. no rasp

http://youtu.be/BV11dJ2VJK0

 

sounds pretty good, did you see any difference with the new exhaust in terms of power?

 

Do you plan on getting it re-tuned with your exhaust? I'm interested in your final power numbers. We need some flyby vids!! Don't leave us hanging, your the first to do this to an HR!

 

This dyno is showing a -40hp/tq difference from uprevs which you pulled 301?Both are dynojets right.

Car sounds good BTW.

 

why would you buy the MD single and cut the end off and re weld? Tony designed that exhaust for optimum performance. Why not just have a 3" pipe out to your choice muffler? Lot cheaper

 

Tony has cut the rear most portion and welded in a muffler himself. That's how I got mine from him. There's nothing wrong with doing the same yourself if it's done right.