Question about when to shift when approaching redline
What's your point? Are you just trying to discredit the information?
Each line represents a range from 0? rpm to a redline of 6500 rpm for each given gear...thought that part was obvious. If you compare it to a dyno plot, you'll notice the shape of the curve looks hauntingly familiar.
Each line represents a range from 0? rpm to a redline of 6500 rpm for each given gear...thought that part was obvious. If you compare it to a dyno plot, you'll notice the shape of the curve looks hauntingly familiar.
Originally Posted by roast
rockinboy what you are describing is pretty close to being perfect. Although, #2 & #3 are pretty much a combined action, which instantly leads to #4. The only exception is that you might start to push the clutch a fraction of a second before you lift off the throttle, so you don't get any engine brake. It's best to push the clutch all the way(or as far as possible before engaging the next gear), and as fast as possible. You drop the clutch the instant you have engaged the next gear, before the rpm have had a chance to drop for an upshift revmatch. The extra power is sent to the wheels and the clutch is given a chance to grab. This is known as speedshifting, and it's the fastest way down the strip. It is only slightly stressful on your drivetrain, and nowhere near as bad as powershifting, but best of all it's faster.
so speed shifting is basically regular shifting on crack? there's nothing really different that's going on that I can see, correct me if i'm wrong please...
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Joined: May 2006
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From: sims, nc
Originally Posted by 350Zenophile
What's your point? Are you just trying to discredit the information?
Each line represents a range from 0? rpm to a redline of 6500 rpm for each given gear...thought that part was obvious. If you compare it to a dyno plot, you'll notice the shape of the curve looks hauntingly familiar.
Each line represents a range from 0? rpm to a redline of 6500 rpm for each given gear...thought that part was obvious. If you compare it to a dyno plot, you'll notice the shape of the curve looks hauntingly familiar.
Your confusing torque and power.
Your graph shows a relationship between speed, and torque, and how it is changes from one gear to another. It tells neither of us anything about a relationship between RPM, and power.
Power is the product of RPM and torque (HP = RPM X torque/5252) lower gears increase torque, and reduce output shaft RPM, and higher gears reduce torque and increase output shaft RPM. But since one variable inceases in direct proportion to the decrease of the other variable, the product is always the same.
The torque will be higher or lower, depending on what gear you choose. But HP will be the same. And regardless of the actual peak value, it will always occur at the same engine RPM.
bill
Originally Posted by bailey bill
The information is just fine, it just doesn't have anything to so with the discussion. It shows a relationship between torque and speed, not power and RPM.
Your confusing torque and power.
Your graph shows a relationship between speed, and torque, and how it is changes from one gear to another. It tells neither of us anything about a relationship between RPM, and power.
Power is the product of RPM and torque (HP = RPM X torque/5252) lower gears increase torque, and reduce output shaft RPM, and higher gears reduce torque and increase output shaft RPM. But since one variable inceases in direct proportion to the decrease of the other variable, the product is always the same.
The torque will be higher or lower, depending on what gear you choose. But HP will be the same. And regardless of the actual peak value, it will always occur at the same engine RPM.
Your confusing torque and power.
Your graph shows a relationship between speed, and torque, and how it is changes from one gear to another. It tells neither of us anything about a relationship between RPM, and power.
Power is the product of RPM and torque (HP = RPM X torque/5252) lower gears increase torque, and reduce output shaft RPM, and higher gears reduce torque and increase output shaft RPM. But since one variable inceases in direct proportion to the decrease of the other variable, the product is always the same.
The torque will be higher or lower, depending on what gear you choose. But HP will be the same. And regardless of the actual peak value, it will always occur at the same engine RPM.
This doesn't change my point that shifting at redline will accelerate the car faster than short shifting, which is what I thought the OP wanted to know 8 months ago when I originally made the post you are refuting.
If he wanted to know the physics behind it I would have pointed him here:
http://craig.backfire.ca/pages/autos/horsepower
The point being, even if the engine power will drop after 6,400rpm, holding the lower gear as long as possible and shifting just before the engine hits the rev limiter will generate the maximum acceleration.
Originally Posted by bailey bill
The information is just fine, it just doesn't have anything to so with the discussion. It shows a relationship between torque and speed, not power and RPM.
Your confusing torque and power.
Your graph shows a relationship between speed, and torque, and how it is changes from one gear to another. It tells neither of us anything about a relationship between RPM, and power.
Power is the product of RPM and torque (HP = RPM X torque/5252) lower gears increase torque, and reduce output shaft RPM, and higher gears reduce torque and increase output shaft RPM. But since one variable inceases in direct proportion to the decrease of the other variable, the product is always the same.
The torque will be higher or lower, depending on what gear you choose. But HP will be the same. And regardless of the actual peak value, it will always occur at the same engine RPM.
bill
Your confusing torque and power.
Your graph shows a relationship between speed, and torque, and how it is changes from one gear to another. It tells neither of us anything about a relationship between RPM, and power.
Power is the product of RPM and torque (HP = RPM X torque/5252) lower gears increase torque, and reduce output shaft RPM, and higher gears reduce torque and increase output shaft RPM. But since one variable inceases in direct proportion to the decrease of the other variable, the product is always the same.
The torque will be higher or lower, depending on what gear you choose. But HP will be the same. And regardless of the actual peak value, it will always occur at the same engine RPM.
bill
Last edited by davidv; Dec 29, 2006 at 02:39 PM.
Originally Posted by 350Zenophile
Wrong. Actual peak wheel power takes into consideration gear multiplication. I say actual b/c dynos are programmed to remove gear multiplication from the equation providing a standardized 1:1 ratio for comparison purposes. 5th gear in a 6spd is typically closest to being direct drive while each successively lower gear provides an increase in actual power to the wheels. Taking this into consideration, redline in 1st or 2nd gear will put more power to the pavement than the next gear shift up unless you have an abnormally sharp drop in power after peak. See attachment.
I think what he is trying to show you guys is that at 38-42mph in first gear you will have more power then shifting early and being at 38+mph in second gear. He is talking about usable power within each gear or taking every gear to its maximum mph. The car also has momentum and is still accelerating during the short period of time when the clutch goes in and out again, which is also another good reason to take every gear to right before redline because every increase in your mph will = being deeper in the power band for the next gear, thus having more power and acceleration. Hopefuly some of this made sense or someone else can come along and explain it better.
Originally Posted by davidv
How does that work out racing a real car in the real word. Post a time slip here: https://my350z.com/forum/showthread.php?t=23384
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Joined: May 2006
Posts: 1,100
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From: sims, nc
Originally Posted by 350Zenophile
Ahhh, I wasn't confused about anything but the point you were trying to make. I was using general language as most people do not distinguish between power and torque. If you want a graph that shows power in relation to RPM that is called a dyno plot. Do a search, there are tons on here.
They are 2 different variables,have different curves, and peak at 2 different points.
bill
Originally Posted by davidv
Thats some impressive technical stuff. Post a time slip here and lets see how it works: https://my350z.com/forum/showthread.php?t=233840
Originally Posted by davidv
How does that work out racing a real car in the real word. Post a time slip here: https://my350z.com/forum/showthread.php?t=23384
davidv's posts like that are always funny
Sense?
Originally Posted by Fingers
I think what he is trying to show you guys is that at 38-42mph in first gear you will have more power then shifting early and being at 38+mph in second gear. He is talking about usable power within each gear or taking every gear to its maximum mph. The car also has momentum and is still accelerating during the short period of time when the clutch goes in and out again, which is also another good reason to take every gear to right before redline because every increase in your mph will = being deeper in the power band for the next gear, thus having more power and acceleration. Hopefuly some of this made sense or someone else can come along and explain it better.
Originally Posted by bailey bill
A "dyno plot" overlays 2 curves, or graphs. One shows torque in relationship to RPM, and the other shows (horse)power in relationship to RPM.
They are 2 different variables,have different curves, and peak at 2 different points.
bill
They are 2 different variables,have different curves, and peak at 2 different points.
bill
Since you are so good at posting definitions, which plot shows the relationship between my disinterest and your ability to state the obvious?
Originally Posted by Fingers
I think what he is trying to show you guys is that at 38-42mph in first gear you will have more power then shifting early and being at 38+mph in second gear. He is talking about usable power within each gear or taking every gear to its maximum mph. The car also has momentum and is still accelerating during the short period of time when the clutch goes in and out again, which is also another good reason to take every gear to right before redline because every increase in your mph will = being deeper in the power band for the next gear, thus having more power and acceleration. Hopefuly some of this made sense or someone else can come along and explain it better.
Let's not let the human internal ear perception of acceleration or the speedometer needle going forward non stop as we up shift induce us in forgetting the laws of physics. Our perception is wrong, the speedometer needle is dragging behind the car's actual speed from it's own inertia (it barely catches up when we get back on power).
Originally Posted by 350Zenophile
My interest in this thread peaked 8 months ago.
Since you are so good at posting definitions, which plot shows the relationship between my disinterest and your ability to state the obvious?
Since you are so good at posting definitions, which plot shows the relationship between my disinterest and your ability to state the obvious?
Originally Posted by Fingers
Lol just wanted to let you know, before you hit me on that, mine will be in there as soon as I get a chance to go to track.
LOL. I race on weekends, and don't know all this technical stuff. In fact when I think too much, I screw up and those are my worst races. Looking forward to your time slips.
Last edited by davidv; Dec 29, 2006 at 08:30 PM.
Originally Posted by davidv
BTW I have seen your times. Nice driving.
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