Arrvaxx's quest for the 10s.

Arrvaxx

Yes, massive room for improvement. Which I expected having done this once.

Thanks for all the feedback. Validates my own thoughts on what needs focus. I think this Wednesday night I will try a few things including shifting in to second earlier. I think I might try shifting before recline. If I remember correctly my hp peaks at 6800 or 7000.

*Edit: Using the 91 octane tune numbers.*

- So my torque ramps fast and starts its gradual decline at 3500rpms.
- Torque and HP cross at 5250rpms.
- From 5500rpms to peak HP at 7250rpms the HP difference is only 10%. By redline I've lost that 10% and am back down to 5500rpm HP.

My thoughts on what this tells me...looking for validation or correction:

- If I launch at 3000rpms my torque is a full 100lbs less than 3500rpms. Launching at 3000rpms vs 3500rpms should help to keep the spin down. ?
- I should shift from 1st to 2nd at 5250rpms. Landing in 2nd should put me at peak torque. If the R-S3s are warm I won't spin in second.
- I should shift from 2nd to 3rd at 6500rpms which will land me at 5250rpms...right when HP overtakes torque.

Finally...4th. As I mentioned on Wednesday I ended the 1/4 mile just a tick shy of redline. I'm 'thinking' that I should shift from 4th to 5th at 7000rpms. At 7250 it drops like a stone so I think it would be better to shift earlier than later or risk the chance of shifting too late. I might even do it at 6500. But the car pulls sooooo hard in 4th it is hard to not let it have every moment it can there. But it has to be better to get the car in 5th sooner than shift 10' from the end or even worse hit the limiter and watch it suck out the power.

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phunk

If you are not spinning top of second or into third, then you want to take second gear all the way to redline. Dyno graphs are a little misleading... see, even though we call that graph "rear wheel power", it is NOT rear wheel power. That graph is ENGINE power as measured at the rear wheels. So it does not take into account gearing. It only takes into account drivetrain loss.

With the 370z stock final drive and transmission gears, first gears absolute ratio is 14.00. Second gears absolute ratio is 8.58, and third is 5.99.

Reference your dyno chart at any RPM you wish. Take the number either HP or TQ and multiply it by your absolute gear ratio. THAT is your power to the axles. When you do the math, you will find numbers that are insanely high in low gears. YUP! Imagine what 100fb lb of torque feels like when you tighten a lug nut with a torque wrench, and then try to imagine that amount of torque powering a honda civic to 14 second 1/4 miles... Then it will start to make sense. 100ft lb can only do that after its multiplied several times through gearing.

This is why, unless you are spinning the tires, you keep the car in the lower gear AS LONG AS YOU CAN!!! Power applied to the wheels in second gear is nearly cut in half from first gear. You loose like 25% from second to third, not as bad, but obviously very significant.

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Arrvaxx

Interesting. Thanks!

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