Great write-up, but I am waiting for my free demo ride :eek: to handout your rep point. Anyway, what's next...engine tune? :tup:

From the video that almost sounds *too* loud, but I'll take your word that it's quiet while driving like a granny.

Umm, quick question...why did it take 3 hours to wrap the headers...thats like a 20 minute job...

I suspect beer was involved, but that's just me.

sounds like one of my jobs:icon18:

*shrug* I didn't do it; my mechanic did. I will say this though -- my mechanic is very meticulous. If something doesn't look perfect to him, he will undo everything and start over until it looks perfect. But to be honest, I will also say that time management isn't his strongest point. My guess is that the 3 hours included an undisclosed amount of 'distraction time'.

Would you guys like me to make a vid clip just driving around normal with my stereo playing? Would that help? You know, at one point in the clip as I'm about to turn onto a main road, my radar detector starts going off. I didn't change the volume setting of my V1 from prior to the header installation. So if you go back and play that bit, that might give you a better idea. It even continues beeping 1 or 2 times after I make the turn and go WOT again. Another thing you can listen for is my turn signal clicker. You can still hear it clearly even when the engine is under load. Now, our clicker isn't a loud one, so I think you can make an inference from that as well.

Underdrive pulley. Then a tune when UpRev releases their 370Z package.

semtex, you don't know me from Adam, but I've been following your posts.

I've got an 05 g35 sedan 6mt, with pretty much full n/a boltons. Other than the fact that my exhaust is raspy as hell(full test pipes instead of hfc's), your car sounds almost exactly the same as mine. Very familiar.

And to be honest, that disappoints me. I don't want to go too far off topic, but I've always wanted a v8 sound, and that nissan v6 will just never sound the way I want it to.

Regardless, I've gotta go off topic again, in another direction: I'm eager to see your dyno results. With full mods and a utec tuned by sharif, my car has gone 13.26@104mph on drag radials in the 1/4. Before your headers, and no tune, I believe you put down 306hp on sharif's dyno. That's sick. That's 60hp *more* to the ground than my car, on the same dyno. Props man.

^Thx dude. I will have updated dyno results by Wednesday afternoon/evening, including numbers from Sharif's dyno.

Dyno results
 

Okay, the dyno results are in, and they are um . . . somewhat confusing. I went and did dyno runs on both DynoJet and DynoDynamics just like I did last time.

Let's start with DynoJet.

This is the run I did last time, before I had the headers installed:
http://www.the370z.com/members/semte...d-321-3-dj.jpg

This is the run I did this morning, after installing the headers:
http://www.the370z.com/members/semte...09balanced.jpg
Kinda underwhelming, right? A max hp gain of 3.31, and a torque gain of 2.1 ft-lbs. I mean, at this point I was thinking "what a freakin waste of money!"

So then I make the drive over to Forged Performance to do a run on their DynoDynamics.

This is the previous run, prior to the headers:
http://www.the370z.com/members/semte...re-14-7whp.jpg

Now here's this morning's results. This first graph shows HP and A/F:
http://www.the370z.com/members/semte...209hpandaf.jpg

This one shows torque:
http://www.the370z.com/members/semte...9-042209tq.jpg

So . . . what to make of this? :confused:

On DynoDynamics, I get a gain of +10.8 hp, which certainly makes me feel better. But I get a small loss in torque instead of the small gain I got on DynoJet! I go from approx. 251 to 247 ft-lbs. And that's comparing peak to peak. The delta in the lower to mid rpm range is actually larger than just 4 ft-lbs (unfortunately Sharif partially obscured the lines with his logo).

I'm going to go out on a limb here and say that I don't really trust the DynoJet results. I say this because the shop with the DynoJet is really close to me, and I went and did the DJ run before the DD run, so I'm thinking that my engine wasn't adequately warmed up. Last time, I drove the 45 miles to Forged and did the DD run first, before driving back and hitting the DJ.

Well, the charts are there for you all to look at and draw your own conclusions. My own conclusion from these results is that if you've already done the intakes and HFCs and cat-back, the hp gain you'll get from the headers is either negligible, or at best modest (relative to what you'll get from the other components), and you'll either lose a little torque, or at best gain a negligible amount. Are the headers worth it once you factor in installation cost? I can't answer that for you -- it's an individual decision.

All in all, I have mixed feelings on this (based on the DD results). I like the HP gain. I like 317.2 a lot better than 306.4. But I'm not pleased about the loss of lower mid-range torque.

Hmm, confusing indeed. It makes no sense....how much driving did u do with the headers on before the dyno?

Are you sure that the low-rpm torque loss wasn't just from ramping the throttle in? On my DD run, I don't really trust any of the numbers under 3750 rpm or so as I'm pretty sure the engine wasn't solidly WOT until shortly before 4K. Even then, the way my torque doesn't really peak up until about 4250 is suspicious (this may have been lag between hitting WOT on the pedal and the engine really starting to breathe like WOT).

Given the data we have so far (including yours), I think it's fair to say that the headers aren't great bang per buck (and especially aren't good bang per installation hour), but I have a hard time believing we really lost torque on them given the graphs and the unknowns.

There's also the ECU consideration. The headers may provide better gains under good tuning (or not), we'll have to see.

About 3.5 days worth. A good mix of normal and hard driving, incl WOT runs up to 150mph.

Even if it was from ramping the throttle in, why would it show a loss? The throttle had to be ramped in the last time as well, right? I don't know. I'll tell you guys my driving impression so far though. I can notice the loss of torque on the low end. I mean, before the dyno, I kinda suspected it, but now I have confirmation. But paradoxically, it feels quicker once I really get into it, which I guess is where the hp gain comes into play. Sound wise, I'm still undecided as to whether I liked the way my car sounded before the headers vs. after. To be 100% honest, I do not feel that this was money well spent. I'm actually toying with the idea of having my stock headers put back in. But then that's another $750 out of my pocket, right? So I probably won't. Plus you're right about the tune. It'd be premature to rip these out until I see what a tune will do.

Semtex,

I wonder if you were to go to a single pipe exhaust whether you would regain some torque and hp?

http://i584.photobucket.com/albums/s...34b3_W1200.jpg

Hmm....this isn't at all what I wanted to hear. I guess the stock headers are the only good part of the stock design...

Things just got a little more complicated.

You know something though, I think I may have a suspicion about the cause of this. Switching to PM.