[MustGoFastR]

So, after all of the Injen testing was done at the 8/14 HFXA meet at Dave's, one of our new members, phamgiaj (we were also joined by BMWslayer. BOTH had black RWD FXs) wanted me to do G-Tech runs in his FX just for kicks. He DID request that I attempt to power brake launch on some of the runs (hold the brake and bring the RPMs up, then drop the brake) to see what, if anything, the ECU does. It had previously been discovered on the 350Z that if the ECU detected that the gas and brake were applied at the same time, it would cut power and that the work-around to this was to pull the stop lamp fuse. Anyway, here are the runs:

Stock RWD FX35 (1/4 tank):
-manual mode, standing start (release brake and floor gas)
1. 6.72
2. 6.83
3. 6.85

-manual mode power braking to 2800 RPM (it stopped there and wouldn't rev further with the brake applied):
1. 6.69
2. 6.68

-auto mode, standing start:
1. 6.95

-auto mode, power braking
1. 6.80

I've previously mentioned that I always get better results by shifting in manual mode (as shown here), but wanted to be thourough. At any rate, by power braking, the 0-60 time was reduces by .14 sec. :shock:

Now, apparently the ECU DOES intervene in that it won't allow it to rev past 2800 RPM (which happens to be the best RPM to launch from; that's where you start to hit the meat of the torque in the powerband), but it apparently DOES NOT cut power.

I'm not sure I would personally want to do this on a daily basis, but 12secZ of My350Z.com braket raced his HEAVILY modded and supercharged automatic 350Z (with no tranny mods) says he does it all the time (he has to pull his brake light fuse) and that the tranny can easliy handle it.

Interesting stuff... SO, if you happen to be sitting at a stoplight next to a car you want to race and think you might need that extra tenth and a half, go for it!

 

[MustGoFastR]

Oh, also, if you happen to compare these numbers to Dave's stock numbers, they are about .2 sec slower in 0-60. phamgiaj runs 87 octane, while Dave runs 93. Dave had also had his timing advanced 2 degrees the previous day. You can make your own speculations on this.

 

[jimsbmw]

MGFR

Thanks for the info, every little .1 seconds count.

Jim :greenjumpers:

 

[brnjug]

The stall of the converter may be thelimiting factor and not the ECU.

 

[MustGoFastR]

Possible.

 

[Golden Boy]

MGFR,

What RPM do you hit the slap shifter at? I have read that there is about a 300 rpm delay between hitting the shifter and the tranny actually shifting.

 

[Golden Boy]

[darn, hit send and then remembered I had another question ]

Also, was there any difference with the traction control turned on or off? Could that have anything to do with the ECU interfering?

 

[brnjug]

Slap shifter delay is 300-700rpm which isis so unreliable unless you get it modified to shift on demand. For a/b testing the automatic shifts are more repeatable and the manual for max performance.

Turning off VDC should not effect any other dynamic in the ECU espeially under WOT(wide open throttle)

 

[MustGoFastR]

I slap the shiftr at about 66-6800 (redline is 7200) and that puts me there pretty consistently. I would normally agree with the comment above, asside fromthe fact that I have always averaged better times using manual mode as opposed to auto.

I made all runs with VDC off, but it really doesn't come into play unless wheelspin is detected; then it'll slow you down.

 

[IssaFX]

I could be wrong since I didn't check but going from memory, our redline isn't that high unless one has the T/S ECU Flash (older one I think moved it to 7100rpm while the latest is 7200rpm). Either way, it's not available for the FX yet - just G's and Z's. Our redline stock for the FX35 is 6600???

 

[MustGoFastR]

Oops, you are correct. Redline looks to be 66 or 6700; I was going from memory (apparently not as good as yours) as well. That means I slap the shifter at about 6250 - 6300 rpm.

 

[particlefx]

Is the engine delivering peak at redline and starting to fall off, or does it continue to increase up until the rev-limiter?

 

[brnjug]

I went back to top of page and it should be noted that most torque converters benefit from flashing...do not bring it full up on the brake under power(which is in the neighborhood of 24-2500 rpm),BUT bring it up to say 12-1500 rpm (or maybe 2000) and allow the converter to flash to a stall much higher than you could achieve on simple power braking,typically 500 rpm higher than full power braking...test it and see which works best..typically flashing yields better results and builds less heat in the trans and motor.

45 's pull strong to 7100 in 3rd and that is why an even higher cut off would help them...cannot speak for the 35.

 

[MustGoFastR]

Well, depending on what you have under the hood, a stock VQ will deliver peak HP at 6250 rpm, the plenum alone raises that by 200 rpm and I'm not sure about the rest. Above this RPM, the HP does begin to fall off. I don't recall if the rev limiter is right AT redline or a bit above.

If you're getting at the idea that it might be best to hit the shift at the point of peak HP instead of timing it to shift at redline, I've tried it and it doesn't work.

 

[PhilP69]

Well, depending on what you have under the hood, a stock VQ will deliver peak HP at 6250 rpm, the plenum alone raises that by 200 rpm and I'm not sure about the rest. Above this RPM, the HP does begin to fall off. I don't recall if the rev limiter is right AT redline or a bit above.

If you're getting at the idea that it might be best to hit the shift at the point of peak HP instead of timing it to shift at redline, I've tried it and it doesn't work.

In general you want to shift after peak HP, because after it shifts, the RPM drops and so does HP until the RPM comes back up. The idea is to get the most "area under curve", where the average HP between the min and max RPM between shifts is the highest. It's possible figure out optimium shift points based on the power curve and RPM drops between shifts. It's also possible that the optimum shift points will be different for each gear.

Anyone know what all the gear ratios are for the FX tranny?

Phil

 

[kcrudup]

45 's pull strong to 7100 in 3rd

Yup- I was surprised today when pulling a power-pass that I'd hit the Rev Limiter in 3rd ... the engine still had more to go and I must have been at 105/110 at the time (someone should work out the max speed at the 6.9K rev limit for each gear).

I really trust the opinions of Q45Tech on FA- the guy knows more about Niss/Infi engines than anyone I've come across yet- but despite what he's saying about the rev limit being where it is for a (mostly longevity) reason, I also agree with 'Jug that it's not like we'd spend all day at 7.1K if we had it, but ****, since the motor's got it, let us have it!

Does anyone know where the Ques VK's limited?

 

[brnjug]

I similarly,enjoy Q45Tech posts,he is a bit conservative at times,but the critical piece here is the engineers at N/F have allowed some room...such as the +2 degrees advance for the ECU.If they wanted an absolute rev limit it would be so...instead they have allowed those who want to push it some room to do so.Clearly 7500 will not be permitted,but something like 7100 will,because the engineers permitted it,if you are willing to push it there.
Losing 100,000 miles of engine life is a statement without foundation,and I am sure that he knows that(especially with good oil and decent octane fuel).

 

[Sincity]

What am I doing wrong? I bought a used G-Tech Comp Pro from this guy who had a stroked/bored Z06 putting out 550HP. Do I need to recalibrate? The instructions says not to.

Anyway, my car has 1500 miles right now. I did 2 runs in AUTO mode and the best I can do is 8.47???? Temp was 105 and not sure of humidity (always dry in Vegas). Where I am is about 4k above sea level.

 

[MustGoFastR]

They're pretty idiot-proof. That actually sounds about right for that temp and elevation; those're performance killers for sure. Wait until you get a nice cold morning and try it again; you'll notice a BIG difference.

 

[AlexAtMyNismo]

Is the engine delivering peak at redline and starting to fall off, or does it continue to increase up until the rev-limiter?

This dyno sheet was from Jeff's Dyno, He owned the Copper Z on our homepage....... He had a good amount of work done, and his dyno shows him making power till aroun 6500rpm or so...... The VQ stock will make good power all the way till about 6200rpm.....

I would assume it is safe to say that if you push the car till about 6200rpm in gears 1-3, you will continue along your powerband and have a constant pull......

-Alex B.