When to shift for best acceleration??? intresting topic???
 

The 350z site is having a discussion on this. I found my answer years ago just by using common sense. They are having a problem with this subject.

You can have mods but if you shift at the wrong rpm, all those mods will not give you all they can.

Hint-highest/peak H.P. rpm.- redline-H.P./turq. rear gear ratio-and trans. gear ration. I think that's it.

I don't bother with a calculator to get exact, just a quick estimation works fine.

So when to shift to get the best acceleration??? using the hint stuff, maybe other stuff.

At some point I'll tell you what I know/think. Can't hurt you, only help.

You should shift at the absolute highest RPM you can. Any lower and when you pick up the next gear, you aren't making the power you could have otherwise

What if your car can rev to 9,000 rpm but highest H.P. is made at 7,000 rpm.
Shift at 9,000rpm?????

Plenty of people here have limiters at 8000, no extra power is made at 8000, but they do it so they can keep more power on in the next gear

You kind off got it:) but it's a bit more complicated when you use trans. gear ratios, H.P curve, top H.P. & highest redline. Like what if you make highest H.P. between 6k & 7k & you have your redline/peak rpm set at 9k.?

You were to fast :)

or what if they shift at the 8k rpm that you said & top H.P is at 6,500 rpm & the drop from gear to gear is from the 8k rpm shifting to 6,500 rpm. Is that ok???

really depends on the situation and what kind of racing you are doing

Unless your power drops off somewhere like 20-30% after peak, it'd be best to stay in as low a gear as possible since the lower gear ratio will put down more torque.

I guess I should have said going 1/4 & using 4 gears. Sorry. The first person DEpoint50 got it real close & very quickly. The only thing I had a problem with was "absolute highest RPM you can". That is not the case, but he does understand the drop of rpm after every shift. I'll give my answer on Monday. If anyone cares:) The other forum had a lot of problem with these basic stuff. So what's the point of spending thousand to mod a car for going quickly when one doesn't understand basic stuff like when to shift & why.

not much interest or a poor presentation by me-so I won't wait till monday
 

As we all know, after shifting the rpm drops. In order to get the max benefit, we need to keep the car's highest h.p the longest time in that drop. Example, if your highest h.p is at 7,000rpm then starts to drop, & because of your gearing(trans. & rear) it drops 2,000 rpm. You draw/pick a line from the dropped side & draw it to the other side (horizontal) where it starts getting going up to the highest h.p. Of course it should cover only 2,000rpm. You should now have THE MOST h.p the car makes in that 2,000 rpm space.

So highest h.p is at 7,000 rpm, shifting at 8,000 rpm & it drops to 6,000 rpm might do the trick. The reason I say might is because the h.p curve on the dyno chart might show that that will not have the most h.p in that range.

That is why I prefer a set up & tune that shows a long flat h.p. peak than a quick going up, then a quick drop. I'd prefer even lower top h.p if the top h.p stays longer(flat curve) but last longer!

Almost 3 years ago I made a youtube video of my shifting, where it clearly shows the drop. Just put my name andre12031948 & click.

Of course one should always consider the safety of shifting at high rpm. 07/08 HR's like mine, shifting at 7,500-7,600rpm is fine, I believe the 370 engine can be shifted safely at 8,000 rpm.

Oh yes, getting gears like 4:08's makes the drop smaller & brings the rpm back up much quicker. Result much more kick in the azz on the street & muck quicker times. My youtube video was made before I started heating my tires in water & had my 3:90 gears, not my 4:08's.

My subi had flat foot shifting. That plays too since shifts are lightning fast and rpms stay way higher then if you just shifted normal.

I just read my post & can see that what I wrote can be confusing to many people. Just pick/mark 2,000rpm(the drop) & put the peak h.p rpm(7,000rpm) someplace in the middle of that 2k drop where the,,,, oh, never mind. Seems I can't explain it clearly:(

:worthless:

lol jk i get what you're saying. Good read and thx!:tup:

I'll agree with Clint. If you are drag racing I would say shift at whatever point the next gear will put you closest to you peak torque. If you are road racing, you don't always want peak torque after a shift. Most times you want some engine braking and enough torque to exit safely, accurately, and wo throwing your butt out. In a straight line when you are not looking at your gauges(which you shouldn't be), just shift close to peak RPM. Debating wether you shift at 7800 RPM or 8000 RPM is pretty stupid and a unless you are racing a car some sponsors bought for you, I really doubt you can tell the difference between 200 RPM when you are going 90 MPH.

In my opinion and this is sure fire way to figure this out. Take your car to a dyno, get a few pulls in, then check your torque, horse power curves and where they start and drop, that will help tell you where you need to shift. You can even data log shifts on a dyno so you can see what your power does in a down and up shift.

I usuall shift around 6500 rpms plus or minus for whatever I might be doing, my stock clutch likes to cook when I shift at red line. (swapping to a South Bend stage 3 setup very soon)

Here is a dyno sheet from Z1 Motorsports with uprev, and off this I would shift around 6800 to 6900 rpms but you should get your own results with your car, also view it with smoothing off might help out as well.
http://www.z1motorsports.com/imageGa...370Z_uprev.jpg

this is my understanding-if someone knows better, I'll listen
 

When I drive on the street I shift between 2k & 3k max. When I drag race or would try my hand on a road track with curves & straight ways, or even a country road I drive this way.
Accelerating at the drag strip, according to this chart, which stops at 7.5 rpm, I would shift(power) at apx. 8k. so when it drops, it ends up someplace where the H.P is going up toward the peak. Same if I was on a straight way of a road track. Turq. is only a concern when I accelerate from a dead start, a slow roll, or after down shifting on a turn then accelerating. After I'm moving at a drag strip or a straight way of a road, I only pay attention at rpm to be at max H.P in the gear drop. When I'm moving, h.p. h.p. hp. is all I care about.

Actually, this chart shows me that it could use 4:08 gears or maybe shifting above 8k. My tune/chart has a long flat line from 6k to 7.5k.

I spent quite a bit of time putting this all together last fall. It falls into this topic pretty well I think.

Yes I am a bit of a nerd, lol. But if you care to look through it all you can actually determine through math and physics where you need to shift and how it affects your accelerations.

http://www.the370z.com/nissan-370z-g...readsheet.html

Raising the rev limiter to 8k has a nasty habit of grenading the oil pump.

Sooooo... For the 370Z, I was pretty right, shift at the dead last second you can, right? Lol

Pretty much. Peak HP is right about at redline, so shift there.

In any car, you will probably find that you should shift at the absolute highest RPM you safely can for maximum acceleration. Those of you looking at the dyno chart are not seeing the factor of gearing.

Even if the engine power at your high redline falls below the power you would land at in the next gear, the car will still accelerate faster in the lower gear.

You see.. these chassis dynos that we all use, despite what most understand, are actually measuring the *engine power* AT the wheels... not the *wheel power*. If you were to measure ACTUAL wheel power, you would see how ridiculously more power there is in lower gears then there is at higher gears... but since we are measuring engine power AT the wheels, we see little to no difference from one gear to another on the dyno minus the effects of altered engine load and driveline friction losses.

Shift as high as you can without hurting your engine and within logical reason. Do not skimp on the R's unless there is a solid mechanical or tuning related issue

Well, yeah. What the hell do you know about any of this anyway? :p

You're right, technically you would take a dyno chart and multiply it by the gear ratios for every gear. If you do that you will see that in 1st gear a car that peaks at 300hp on a dyno (assuming a 5th gear pull) will actually put down 1477hp (300*4.924). So you want to ride every gear for what its got to get the best acceleration. Because the next gear your now only at a peak power of 958, and so on and so forth.

:happydance:

I'll just leave this here........

http://i184.photobucket.com/albums/x...ps6a39da07.jpg


Car felt amazing with the 4.08 gears too.....

I stumbled on a post like 10 years ago, and I was able to locate it just now. I remembered this post because this guys method of explanation is able to clearly isolate the required facts to communicate the idea efficiently and is very easy to read. I would recommend reading all the posts from the OP in this thread, but at least read the very first post.

Gear ratios, final drives, and torque - Team Integra Forums - Team Integra

then after that, if you dont read the whole thread, look at just this one post on the following pages:

Team Integra Forums - Team Integra - View Single Post - Gear ratios, final drives, and torque

notice that at not a single point on the entire graph will you find a gear that is able to put more torque to the ground than a lower gear number, at any rpm/speed at all.

and for anyone surprised... YES stock hondas generate over 1500lb fts of torque in first gear. Guess what a stock 370z does!

Mechanical Advantage :)

So this thread has determined what everyone should have already known.

Rev to red line before you shift.

:facepalm:

Geez, it has already been determined no...... :p :shakes head:

I don't...

I don't understand what you're saying?

I said it first!!! Lol

I blame myself for not having a clear enough explanation
 

Simple
If you have completely stock car, shifting right before the redline, which is past the peak/highest h.p. the car produces is fine.

When you get moded & tuned, the peak h.p. redline, & turq & h.p power curve changes. You also want mods & tune that give you a longer steady flat top h.p. chart, instead of a quick up to the highest h.p peak & a quick fall. Even if that H.P. is higher!!!!

I can guarantee a twelve second 370z with only doing 3 things to the car.

If you know how to drive these 3 things will make the car quicker & faster than any other mods you do. N/A of course:)

1)Good tires for traction a must-The first 60' feet is where you lose or gain the most of your 1/4 mile run.
2)4:08 gearing-That makes the car get going quicker & gets quicker to the desired shifting point after each shift.
3) Its a two parter. Take off the power robbing cats & replace them with test pipes with a mandatory(because of the change) TUNE!! Don't forget to raise the redline.

Don't bother with intakes/exhaust or anything else. The car will be a twelve second car.

This part is not correct :) RPM drop between shifts is an agreement between the engine and transmission, and the car doesn't even need a differential installed to know exactly what the drop is.

I think you're right. The rest of the statement is correct.:tiphat:

This is bad advice. More than a few members have had oil pump failures due to raising the stock redline.

I never saw a post about that. Why would an oil pump fail???

Almost everyone who got a tune had their redline raised. That's a lot of people...

redline/peak H.P/ & H.P curve-When to shift?? :) intresting???
 

There's at least two guys that lost their motors from oil pump failure running a 8k rpm redline. Z Eliminator and somebody else. Sam at Gtm also strongly advised against a higher than stock redline. The internals of the oil pump come apart at that speed. There's a Nismo unit with hardened internals, but its pricey.

Most people don't take theirs to the track. That's where failures occur. How often is someone at 8k rpm on the street?

Out spins the ability of the oil gear. Probably cracks and breaks on the housing spinning to hard.

Any aftermarket higher flowing units?

That's exactly the issue. The Nismo unit is the only other one I know of. It's got a billet gear inside as opposed to ours, which I believe is sintered metal.

Very surprised. Sorry to hear that. I would think an N/A car would not need an after market fuel pump.

Oil pump. ;)

I believe that the lightweight crankshaft pulleys add to the problem of the oil pump failures. The lightweight pulleys change the harmonics on the end of the crankshaft. They set-up a vibration that can't be dampened out. Since the oil pump is driven off of the front end of the crankshaft. The vibration goes into the oil pump. breaking the gears in it. Dodge Hemi's have the same set-up almost. And there have been quite afew failures of the oil pump with the light weight pulleys on them too. :icon14: