Geez...sorry to hear of the disappointing results MM. It must be rather frustrating to have gone through with all of that to only lose 10+ @ the wheel :/ . But that is the problem when it comes to maximizing exhaust design. It's quite a black art (like aerodynamics on F1 cars), so no matter how much calculating or guesstimating you do, it doesn't mean much until the car is put on the dyno for the result to speak for itself.

A dyno graph would definitely be quite helpful to understand the situation, and see what happened to the powerband. Because 309rwhp seems quite weak, when you consider that ~ 300 has often been achieved on a dynojet with just a good catback, Art pipes, intake and a tune (although that's not taking into much account possible variance in dyno calibration). My theory would be that with the higher flowing headers (larger primaries and much more efficient collector than the Stillen shorties), the Y-merge on the TDX V2 might possibly create a much more powerful reversion affect, which would be quite detrimental to the Hp gains in the higher RPM's. That's just my opinion...and I'm by no means an expert (although very few genuinally are IMO) on this subject.

To me, swapping the TDX for the AAM or Amuse system probably wouldn't be all that beneficial...if it even is. Although the shorter overall pipe length of the AAM single would be going in the right direction, yould still be dealing with a 3" pipe which I feel would be a fair bit of a hindrance at 360+ hp at the flywheel. A well designed custom 3.5" single (what Sg motorsports and Fontana nissan run on their NA VQ's ) would likely be ideal. Another option would be to have a custom mid section made for the TDX V2. A 2.5" dual mid section with a nice flowing X-pipe would also likely be quite a nice approach to remove the current bottleneck in order to realize the true potential of the new headers.

I was hoping to get somewhere with modding my HR by now, but decided to spend $6k on a daily driver so I could park the Z and gut it..so unfortunately I haven't been able to do some of the interesting exhaust/intake stuff I had planned for my HR. But with time it will happen. Just wanted to say thanks for leading the way at least

 

How is 3" exhaust a restriction when people with F/I can make 600 with it? I think y-pipe design (where/how it merges) plays a larger role than the catback diameter.

 

Well, you could likely make 1000 hp thru a single 3" pipe if the combustion process is powerful enough lol. But just because you could achieve such a number doesn't mean the 3" exhaust would be extremely restrictive at that point...in the end robbing a lot potential power. I've seen a pretty clear trend where significant higher end gains have been made on NA cars when going from 3" to 3.5" when power levels start approaching ~360hp per 3" pipe.

 

The testing already done on the 350 has shown that after the y-pipe merge, there is nothing to gain/lose at 3 inches until you pass 600 brake.

As the 'back pressure' goes, it's scavaging, and the testing shows it was nothing once you got to the y-pipe merge.

 

That post makes zero sense

Anyways compare apples to apples. NA vs NA

Can't compare FI exhaust flow vs NA flow

Look at the set up SG had as I posted before. They have the highest NA powers and they have custom exhaust they built. So duh. MM try and replicate what they had. Or start with the 3" single that you have and see what happens.

 

I think you're confusing me with screamer.

 

A single 3" pipe will cost a lot of horsepower at 600hp...don't care who says what on that....there's just too much evidence and results out there to argue otherwise.

Piping after the Y-pipe is not what I have issue with on the TDX V2 in this case. The dual piping that exits the muffler after the Y-pipe, is 2.5" transitioning into 3", which should reasonably support just about the most extreme NA VQ out there.

However, I will reiterate that I feel the single 3" y-pipe/section (it's more like
A restrictive x-pipe IMO) on the TDX V2 is what could be causing a bit of a bottle neck with the Hp levels MM'08 is floating around. My theory is that with the previous setup he had (stillen shorties/ art pipes), the gases that were exiting the combustion chamber were more gradually able to be stalled/slowed prior to the y-pipe merge/bottle neck (which is dual 2.5" into a single 3"), which would have reduced the turbulence and back pressure at that particular point, in comparison to with the PPE LT's. Again this is just a bit of speculation on my part...I think a dyno graph is needed though to really get a better idea though.

 

Right, and what was proven was that going wider closer to the engine was detrimental to the output Vs slow necking it up.

However, i've no idea about a blown system.

 

Sorry for the long wait guys. I just got back from SA in my Z and HOLY FUUUUU!!!!!! Car is still friggin strong as hell. Oh and what does it sound like??? The answer to that my friends is SEX. Feels as torquey as I left it and pulls up top really hard. It's unbelievable that the car lost power. I love it!!!

 

Yea, but more importantly, at what power levels and with what modifications was this testing done? Certainly it wasn't on MM's application or an HR with the equivelent mods and power potential (once optimized).

I'd also imagine that if the testing was done on a near stock VQ, the desired result was to produce a system with a most usable/maximized powerband for minor bolt on cars (say just intake, test pipes & tune). Not so much a system for all out flow, which would pay less attention to having such a small Y-pipe to improve scavenging in the lower RPM.

Also, I don't at all mean to put down Tony (Motordyne) and his product...as it's a beautiful piece in engineering, looks, and sound...I just don't think it's the ideal exhaust for where MM's HR is headed, now that he has the PPE LTH's on the car now. But it's hard to argue that with a lightly modded Z, the TDX V2 is a bad *** exhaust with about as good/usable gains as you'll see.

 

I just did a quick comparison of your latest graph (w/ PPE LT's) vs your previous 322rwhp graph (w/ the stillen shorties and ART pipes). The weather conditions actually seemed to favor the PPE LT dyno and I also noticed the long tubes seem to give you a slightly fatter torque curve in the mid RPM's (likely around where the RPM's fall into after a shift), so the car probably wouldn't feel much slower at all...especially since you tend to feel the Tq difference more (especially after shifting) in the lower rpms than up top. I'd still throw a fatter exhaust on it...but thats just me

I might end up trying the SFR equal lengths (in a quest for ultimate power 6k rpm +) on my HR in a couple of months. I would then mate that up to a pretty trick 3.5" single, which would then branch out with a 1-3 collector into 2 2.5" Burns mufflers (to at least have some type of noise reduction) with the 3rd 2.5" pipe not having any muffler whatsoever. These 3 pipes would then exit in a triangle shape "^" that would be cut into the bumper just below the license plate enclosure...just below the floor pan. It would be fairly costly, but at the same time unique and done right the first time I feel/hope lol.

It probably sounds like I'm dreaming some type of fairytale...but if you know me, I'm certainy not haha!

 

Is this done on the same dyno as before? I see the lowend dip is there on a HR as a DE just not as severe.

I still have my reducers if you want to try them out LMK. TerraS I have a extra set also if you want to try them out.

They reduce from 2.5 to 2in like ART pipes, but not as long and further down the exhaust path.

I'll repost the dyno before and after so you don't have look for it. One is untuned and the other is with a touch up tune.

Honestly they should have designed them like their 370z LTH which look almost identical to SG.

 

Same DYNO.

 

Still don't see a vid



Leaves

 

Ok ok guys what kind of video would you guys want to watch?

 

Start up. Idle for a few secs. Revs to redline. Flyby 1st-3rd and don't let off til you past camera

 

I can do that. Sounds like fun, only camera I have are my iPhone will that be fine?

 

Good day to peek back into my350z.com, I was curious how the long tubes would treat you, I wouldn't let people tell you how to do your car, you are kinda in uncharted territory with your car, I am willing to bet that a 3.5 inch would help, but what to do with the Y pipe I could not tell you. Like it has been said before, NA and FI are 2 different animals.

I wish your dyno sheet was in RPM's not MPH, but I would not be suprised if it is choking alittle, I hope you the best and your car is one of the few reasons I even visit this site anymore

 

Yea a buddy of mine shot one of my vids on one and it sounded good. Not the best but better than nothing

 

if you actually lost that much power you'd feel it. i have the exact same exhaust setup and it was definitely faster with the ppe's. i highly doubt its the tdx2... you really should have done a same day before and after if you wanted to know if you gained or not. id do a compression test if i lost that much. i cant see whats going on with your afr down below but it looks flat. is it the same value that it was before when u made 322rwhp? whats your injector duty cycle look like?