DAYUM! I didnt know our motors respond so well to nitrous. Do you have a build thread, id like to take a look at one of the fastest NA VQs out there.

 

Hey ds do u have base numbers from that same shop?? Or at least base number from another g35 auto??

 

Hi Derik,

If I can make a suggestion, try putting the ART pipes back on as a trouble shooting process to see if the low end RPM power comes back or not.

Depending on the results, it will tell you a lot about weather or not the loss is due to the long tubes or if something else going on. (Like the TB or ECU.)

Thank you for doing such a good comparative review.
Tony

 

I wish I could do that Tony not cheap to have them taken off then reinstall the ART pipes with my shortie headers.

The TB was changed out but the throttle still doesn't show 4v until 4k for some reason.

The headers outlet is 2.5 the invidia has 2.38 piping (60mm).

ART pipes low end torque prevents the lowend drop usually seen with cams once removed it can be seen.

Maybe it can be tuned out with more cam and ignition timing down low who knows.

I'm 5at.

There are alot of variables I like the added midrange but the lowend loss kills everything from a stop.

For comparison before the LTH if I ran 13.8 my trap would be around 101-102 with the LTH running the same time my trap is 105-106 with the same track conditions and 60ft.

The power is there just comes on too late so I'm playing catch-up.

 

No I don't I just have my 1st ever tune there compared to now on pg 4 runs 3 and 25. Run 3 was in 2009.

I haven't been stock since 3days after buying the car in Oct 03. I might go do a few pulls at the shop that installed the momentum headers so I have a dyno with stock manifolds and test pipes there on file.

 

Yes, it is a big project changing out headers.
Going from 2.5 to 2.38 will likely only affect top end if anything at all.
As for the TB, It doesn't appear to be the cause because the voltage plot is only ~0.1 voltage down out of 5V total. And the TB voltage change RPM doesn't correspond to the RPM change in the power curve.

It appears it may simply be a function of the long tubes resonance tuning but if there is any question as to what it may be, the only way to trouble shoot it is to go back to the pre condition for validation.

Its too bad changing out headers on this car is so difficult. Projects like yours (and mine) would be so much easier if we had just a little more room in the engine bay.

 

Tony you don't think the throttle position voltage can be a issue?

The voltage on a 6mt instantly goes to 4v+ at WOT mine doesn't do that until around 4200. The voltage shoots up to 3.9 and stays there until around 4200-4300 then it goes up to 4.12 and stays there that when the car takes off.

I'll take better pictures to explain later. Thanks for the advice on solving the issue.

I wish cipher showed percentage instead of voltage to be sure.

 

i really like this informative conversation going on..............nice to see people still putting time into this engine.

 

^werd

 

here is a nitrous run on the dyno 125 shot 3rd gear 30-100mph with the long tubes.

<iframe width="560" height="315" src="http://www.youtube.com/embed/b4eJALpBs84" frameborder="0" allowfullscreen></iframe>

 

I can't say for sure, but I don't think its the voltage.

Here is why.

1) 0.1V out of 5V is much too small to make that kind of a change on the curve. That's only a 2% variation of voltage.
2) The power curve delta is more than 2%.
3) Even if the TB is 2% closed, a 2% closure won't create any appreciable pressure drop across the TB valve unless the RPM's are high. But the RPM's were low.
4) The TB voltage goes to 5V at a different RPM than where the power curve shows recovery. If the power curve recovery RPM coincided with the voltage recovery RPM then it would suggest a correlation, but they don't. RPM of each event is different.
5) If you changed the TB and still get the same results, its not the TB.

Did you monitor the spark advance during the testing? If for some reason the knock sensor picked up some kind of noise it could pull back timing.

But for some reason, and I've seen the same type of effect before during my ART pipe experimentation, when I look at your power curve, it seems like its simply a signature of the acoustic resonance tuning. I did the same thing in the early stages of tuning the ART pipes. Some of my early ART pipe testing was actually much worse.

The only way to really know why you have a loss of low end TQ is to put it all back to the pre-test condition.... but I fully understand this is not something anyone would want to do unless they have lots of time and $$$ to burn.

 

Dsskyline, in your video posted above, is that the hesitation you're talking about? Looks like the car is punched, waits a second and then takes off.

 

Its getting NO2 squeezed in the video.

 

I will post some new vids on Sunday showing the hesitation. Tony can you open drf files? I have those from my runs.

I don't know if the spark advance was monitored. Just seems odd for the power to climb, drop, stay steady and then climb again.

I would feel better if it started low and then climbed instead of the blip of power at 3200. If power kept climbing from 3200 and leveled out to my current numbers would of been great.

Just trying the cheapest routes/options first before maybe switching back. 6mt would not have to deal with this since they can launch higher than the drop.

Actually it's cheaper for me to get a higher stall convertor than to revert back.

Tony on your tests did your drops look like mine a surge of power,drop, then a surge again?

Someone else suggested timing is being pulled down low for some reason or maybe add more cam timing down low.

 

Have you tried consulting PPE on this?

My headers should be shipping out in a day or two from them, but I won't know the results until spring when I bring the car out of winter storage. I plan to do cams as well, but more aggressive than the S1/S2. I'm also 6mt, can't forsee any issues.