I think you need to re-read the article...

 

Nope, i think you need to tell me why, perhaps i didn't write my comment clearly enough?

 

The point you're missing is that lower gears have a higher torque multiplier (I think the article just refers to them as gear ratios). So there is an advantage to staying in a lower gear. You basically want to shift gears once the torque from the higher gear starts to equal the torque from the lower gear (at the same speed). If the car manufacturer is smart they set redline roughly around that point for maximum acceleration.

According to the fictitious engine in the article the peak power is at about 5600 rpm but the optimal shift point looks to be more like 6400 rpm.

In other words, you do not necessarily want to shift once you hit peak horsepower because even though your power is starting to drop the lower gear is still providing more torque than the next higher gear, up to a certain point.

 

I'm not sure if I agree with the article 100% though...I think it's probably more beneficial to compare horsepower between gears rather than torque, but maybe someone with more knowledge can chime in there.

 

Riiight, so i'm not sure what you're saying i didn't comprehend...

The result is, you shift at a point where the torque in the next gear is at least as high as the torque you're at in the previous gear.

I was explaining that shifting past peak power makes no sense, you're already out of the torque band and you're now past the peak power, torque is required for change of acceleration, therefore, in the case of the OP, shifting past the peak power point is wrong and pointless.

 

Correct. This point usually happens to be once you've passed peak power in the lower gear, though.

This is kind of a contradiction with your first statement. If you shift right at peak power, every time, you are likely going into the higher gear at a point where the engine (and gear ratio) is giving you LESS torque than you had in the lower gear. So you'd have been better off staying in the lower gear longer as you'd have been making MORE torque (usually until redline. It's there for a reason.)

 

Depends on what gear you're in, so we're both right and wrong. In 1st to 2nd, for example, you're right, but in higher gears, the difference in ratios are much smaller.

 

Lol guys all i wanted to know is if my auto hr revs to 7500 rpm, which at this point i know is yes. In my earlier post i said that my tuner increased my rev limit to 7500 rpm. I now realize that he didnt it was always set that way. I had read the car and driver article that said auto hr only rev to 6800. Which was an error on there part. My tuner never raised the rev limit he told me he did but im pretty sure he forgot. He can be forgetfule. I def appreciate everyones help.

 

Even so, you still don't want to shift right at peak power. That will make you slower regardless of the difference of the next ratio because you are throwing away the torque multiplier advantage you get from being in the lower gear.

The only reason you would want to shift at or near peak power would be if your powerband dropped off like a rock, which doesn't happen on most cars (the HR Z included) except for a few exceptions. My last car was a mazdaspeed 3, that car was the worst you could get as far as power dropoff was concerned. It hit max power at about 5500 rpm and you had to shift at around 5800 rpm since the power dropped off so badly.

 

Glad to hear you got it sorted out.

 

I have some questions, hope you guys an help me out.
350z. -2005 mods
V2 full vortech kit
kinetix intake pletnum
edge test pipes with resonators
full stillen 2.5 cat back exhaust.
now I'm about to upgrade the pulley to a 3.12 but I know my stock injectors will be max out so I decided to buy some 600cc, talk to the guy who's gonna tune my car he said he wants to tune it with uprev(Osiris) but my question is would my stock pump and the external fuel pump be enough.? I'm not planing on going over 400whp since my block is stock.

 

Do not lower it, and ride it out to the 7800. There are many perks to this, much of which (no offense, just my take reading your comments), you probably won't understand. I'm going to give you the best advise regarding your cel issue right here right now... Go to Osiris website, find a legit UpRev tuner, take them your car. They'll help you fix the issue and properly tune your car. If this guy tuned it to turn to 6800 rpm he doesn't know what he's going... I'm sorry tuning a car does not fix an issue already there, Osiris tells you this straight forward. Fix your issues, then tune it. These codes may or may not be directly from the test pipes. I can't remember what ones you had now but Motordyne art pipes shouldn't cause them, however! If you think that's the issue call Tony at Motordyne. He will walk you through trouble shooting and give you a final call on it. He is a ROCKET scientist who makes these parts, and is very hand on. That is if you have Motordyne art pipes.

 

,Thanks fore the advise, the issues i have been having have all been fixed at this point, no more cel light or boggy feeling ive also raised the rev limit back to 7500 rpm. My turner didnt tune the car to 6800 rpm., i had lowered the rev limit myself, at the time i read a car and driver article that said the automatic hr only rev to 6800 rpm. Actually i had read two articles that said that so i freaked out and lowered it. Its now back up to 7500 and running like a champ