So I got my dyno done and much to my surprise I was shifting just before redline which does not seem to be the best spot.



Looks like I need to be shifting at 7,100 RPM, not 7,400!!

 

your probably right, I would only use that extra 500rpm if i was track driving.

 

So maybe I'm just awful at reading dynos (good chance), but what did the motor put down (i'm assuming thats a stock motor, correct?)

 

300 WHP? Not stock if it's an HR

 

By looking at your graph I would be shifting at 6900 rpms. That's when your power starts to drop. You need to stay in the power range so she charges into the next gear so power is still going up. If you shift at redline you will get poor results. In my Z I shift at 6500 rpms my red line is set at 7200rpms

 

That's not the correct way to look at shift points. It's always dependent on how much of an RPM drop there is going from the lower gear to the higher gear. If going from 1st to 2nd, and theres a 2500rpm drop, you need to be making significantly more power 2500rpm lower, in the higher gear, than you do 2500rpm higher in the lower gear. 2500rpm was an arbitrary number, since the Z is geared a bit tighter than that, but I'm only using it to illustrate the theory.

The image illustrates it best, the amount of work the engine is capable of from 4500-5000rpm is less than the amount from 7000-7500rpm. The overall total area under the curve from shifting 500rpm sooner in our hypothetical scenario is less by short shifting.

TK

 

Not stock.

T_K:

I greatly appreciate your time and input! Keeping it in the powerband is key to keeping it moving. I do both drag and road racing so knowing the cars strengths is key to my improvement. After a review of your post I see that probably 7,275 would most likely be the optimal point for the shift. The RPM's seem to drop by about 1,750 per gear at a constant velocity (100 KM/H).

Thanks for all your input.

 

Best shift point is at the peak of the HP. I did some racing tonight and found higher trap speeds shifting my auto. I did shift once manually via triptronic going into 3rd @ 6,900 rpm where my peak is and it gained 1mph on the 1/8 trap speed to what I normally get when the car shifts itself around later 7,400.

Best shift point at peak HP.

 

I would have to disagree with you. I have been drag racing my HR for a little over a year now and from stock up to my current mod list my best times have always come from shifting right at redline. I managed a 13.2 which isnt bad but this guy is using the same shift point and he is running a 13.1 stock on a slipping clutch. Until someone can show timeslips with lower times I would stick with redline.

I will tell you from experience however that shifting any higher than 7500 (if you have the reflash) will slow you down.

https://my350z.com/forum/drag/394262...s-tonight.html

 

I'm just going by these.

stock 5A shifts
60' : 2.02
330:5.64
1/8:8.60
MPH:82.66

vs. 5A 1st-2nd + 2nd-3rd manual shift at the peak hp

60':2.19
330:5.86
1/8:8.80
MPH:83.49

if someone wants to analyze this.

 

No 2 runs are "exactly" identical. The trap difference was less than 1mph as well. That all falls within standard deviation.

TK

 

.

 

Shift at red line then next gear you have the power band.
If you shift at peak power band RPM in next gear will go too low.

 

you guys are right, it's just that the auto is different, since it drops at a set stall speed. I read that the optimum shift points vary for each gear. there's a a calculation for the ideal shift points, however if you're not doing the calculation, the redline is the closest to the ideal.

 

Holy sh*t, you have a few basic mods and you dynoed over 300WHP? WTF? The VQ35HR is some sort of miracle machine.

 

it was, but the VQ37HR is what's hot now. The 370z is coming. it may have 7speed transmission. Same types of mods on that thing will probably be about 330whp, a good difference backed by light weight, an easy 12second car.

 

it was, but the VQ37HR is what's hot now. The 370z is coming. it may have 7speed transmission. Same types of mods on that thing will probably gain about be about 330whp for the m/t, a good difference backed by light weight, an easy 12second car.