Best Shift point ?

[chenc544]

http://lachlan.bluehaze.com.au/usa2001/vermont2001/05jul2001a/mvc-014f.jpg

 

 

Who is this Isaac Newton? THE Isaac Newton died in 1700's and he was buried in the Westminister Abbey with this monster statue as gravestone. He was never married either.

[Deer Killer]

Who is this Isaac Newton? THE Isaac Newton died in 1700's and he was buried in the Westminister Abbey with this monster statue as gravestone. He was never married either.

who knows, it's the first thing that came up in google, point made.. heh.

[bosco]

Hot Rod did a test on shift points years ago and came up with pretty much what DeerKiller is saying. one of the biggest issues with shift points is the gearing of the car. you want the engine to stay in the fat part of the torque curve when the shift is completed. if you fall below the middle of torque curve acceleration will suffer, if it is higher in torque curve same result. find out what your torque is at what rpm, then see were the engine drops when you shift in each gear. Hot Rod came up with 1st gear about 500 rpm over redline then 500 rpm each gear lower to keep engine in the meaty part of the torque curve. torque moves your ass, horsepower is the ability to do work. bosco

[bosco]

another way to look at it, torque gets you there, horsepower keeps you there. also no matter what engine in the world from your moms car to F1, all engines make the same hp and tq at 5250 rpms. ie 400 ft/lbs tq, 400hp. think about it in terms of acceleration. bosco

[Brady]

Hot Rod did a test on shift points years ago and came up with pretty much what DeerKiller is saying. one of the biggest issues with shift points is the gearing of the car. you want the engine to stay in the fat part of the torque curve when the shift is completed. if you fall below the middle of torque curve acceleration will suffer, if it is higher in torque curve same result. find out what your torque is at what rpm, then see were the engine drops when you shift in each gear. Hot Rod came up with 1st gear about 500 rpm over redline then 500 rpm each gear lower to keep engine in the meaty part of the torque curve. torque moves your ass, horsepower is the ability to do work. bosco

What you're saying is that to remain in max acceleration on a legacy, you want to keep the RPMs between about 3200 and 5000 rpm ... or the fattest part of the torque curve on a Legacy. Yes?

 

If so, that's not true.

 

For max acceleration you want to keep the car in the meat of the Power curve. Do the math, and show me how it is possible to be making more torque at the wheels in any other gear when you're at peak horse power in a given gear.

 

It's physical impossiblility. The time you will make the MOST torque at the wheels in our car ... and any car, is when you hit peak torque in first gear, after that, all your maximum torque at the wheels will be generated within the meatiest part of the powerband. It's math and physics at it's finest, but I'm sure Deerkiller will come in and say my math is wrong with nothing to back it up.

[Deer Killer]

I see no math. It usually involves algebraic symbols and signs, not flapping lips.

[Brady]

Dude, you've presented no mathematical proof to refute any of my claims.

 

You say "rpms cancel out" but that's not true.

 

Again, show me where where the car making 200 ft-lbs at 5252 rpm is less torque AT THE WHEELS than the car making 300 ft-lbs at 2626 rpm when the car is moving at the same speed. This is a simple show of if the car is accelerating faster in 1st or 2nd gear despite having less torque available.

 

Furthermore, build a car with a ton of horsepower way up high, and you'll be able to gear it in a manner that will smoke the hell out of a car with 3 times the torque only available way down low.

 

Two cars are driving 30 mph. One is making 300 hp, one is making 150 hp ... the wheels are moving at the same rate of speed.

 

Let's say that the wheels are turning at 409 rpm (or 30 mph for an LGT).

 

So the car making 300 hp is making 3844 ft-lbs of torque AT the wheels and the car making 150 hp is making 1922 ft-lbs. The car making 300 hp is going to accelerate faster. No, they're not necessarily in the same gear, and the engines aren't running at the same RPM, but that's why we have 5 gears, so we don't have to choose the gear where we're making the most torque. Instead we choose the gear where we're making the most POWER and we go faster.

 

You're so far out of this, it's embarassing to be engaged in this argument. And it saddens me that I have a degree in marketing, as it is painfully obvious that I should have just gotten a degree in engineering.

 

Go ahead, prove the math wrong. I challenge you.

[bosco]

brady if you read my post it stated you go over redline by 500 rpms in 1st gear, when you shift the rpms drop to the meat of the torque curve, 2nd gear you would shift 500 rpms earlier and so on. if you run your car to 5500 rpm and shift you are going under the torque curve in the next gear. nobody is saying don't go to redline. we're saying shifting at redline in each gear does not give max acceleration if the trans is geared wrong some trans are geared to do different things. i don't know anymore what you two guys are talking about now all the math and stuff. but what about traction, aero. ect.? bosco

[Brady]

I'm not saying go to redline either, I'm saying don't worry about the Torque curve, because if you say follow the meat of the torque curve, it has double meanings. Does it mean keep the engine reving in the meatiest section of the torque curve, or does it mean keep the wheels turning in the meatiest part of the torque curve. Well, if they mean the wheels, it will resemble more of a slope than a curve ... more like a bumpy slope and it will continue to trend downward because as you go faster, your wheels go faster, and the only thing that's going to create more torque to a wheel travelling at a faster rate of rotation is more power.

 

Now, if you look at the power curve of the engine, I know that on an LGT, it peaks around 5600 - 5800 rpm. The curve is fairly centered on that point. So, armed with that knowledge, I'll try to keep my rpm as closely centered around that area as possible. In the 1st -> 2nd shift, that means hitting redline first. In 2nd -> 3rd, the shift point is more like 6600 rpm, in 3rd -> 4th gear the shift might be closer to 6300, and 4th -> 5th might be around 6100. I'm not exactly sure where they are because I don't go doing 130 mph pulls all the time looking for optimal shift points, but if you know where the power matches up from gear to gear, you'll automatically know where you'll be able to put max torque down to the wheels.

 

Now, take an LGT with a bigger turbo in it and you might make peak power at 7000 rpm ... similar to the PDXTuning LGT. In that case, there's never a reason to shift below redline. Run it up to redline and shift every time.

[Deer Killer]

Dude, you've presented no mathematical proof to refute any of my claims.

 

You say "rpms cancel out" but that's not true.

 

Again, show me where where the car making 200 ft-lbs at 5252 rpm is less torque AT THE WHEELS than the car making 300 ft-lbs at 2626 rpm when the car is moving at the same speed. This is a simple show of if the car is accelerating faster in 1st or 2nd gear despite having less torque available.

This is not math, if you did math you'd be whipping out gear ratios and multiplication signs. In which case it would be obvious you are pulling numbers out of your ***

 

This is an equation:

 

1 = 1

 

This is more advanced:

2 = 1 + 1

 

See how that works?

 

This is called algebra:

 

x = 1

 

2 = 2x

 

2 = x + x

 

Make sense?

 

Here's another equation:

 

F = ma

 

Do you know what these letters stand for?

 

Let's try some more:

 

a = v/t

v = x/t

T = Fd

Tin/Tout=Rout/Rin

 

The above is every equation you need to calculate forward acceleration of a car, and therefore shift points. If you can't do it with the above, well... what shall I say... I don't see a P in there, do you? Sure you can make it, but it's called adding unneeded variables:

 

1*2 = 1*2

 

Does this look simplified? Oh look at what I can do

 

1 = 1

 

Isn't that better? What is the fundamental nature of this equation? That 1 equals 1? Or is it better to say that 1*2 = 1*2?

 

You're so far out of this, it's embarassing to be engaged in this argument. And it saddens me that I have a degree in marketing, as it is painfully obvious that I should have just gotten a degree in engineering.

The point is painfully obvious.

 

Go ahead, prove the math wrong. I challenge you.

Show me some math to prove wrong....

[Brady]

brady if you read my post it stated you go over redline by 500 rpms in 1st gear, when you shift the rpms drop to the meat of the torque curve, 2nd gear you would shift 500 rpms earlier and so on. if you run your car to 5500 rpm and shift you are going under the torque curve in the next gear.

That would only apply on a specific car with a specific transmission and a specific engine. That does not necessarily appy to the LGT

nobody is saying don't go to redline. we're saying shifting at redline in each gear does not give max acceleration if the trans is geared wrong some trans are geared to do different things.

I concur, my initial post about running to redline was more of a smart-ass remark to the initial question of "what's the best shift point" and not specifying for what purpose

i don't know anymore what you two guys are talking about now all the math and stuff. but what about traction, aero. ect.? bosco

Traction isn't much of an issue with our car running AWD, and really, once you get the car above about 10 mph, there's little hope of ever pulling the tires free as you'll never make enough torque to break traction. Traction is only overcome by torque ... or more specifically, torque transmitted to the wheels. So at least on dry pavement. Well, you can also break traction by turning, and then you can continue to spin the wheels, but your diffs won't be too happy with you!

 

Aerodynamics ... same thing ... only power is going to overcome more wind resistance, because more power equates to more torque applied at the wheels.

[Brady]

 

Show me some math to prove wrong....

That is math.

 

You show me any gear on the Legacy GT from 1st to 5th at peak horsepower and another gear you can shift to at the same speed where you will make more torque at the wheels.

 

You can't refute that ... it's a fact. You can't make more torqe at the wheels with less power.

 

If you can, please prove it to me. I would love to learn what it is that I'm doing wrong if I in fact am.

 

Prove this math wrong - even in gears on the Legacy. This is solid fundamental math. Show me that my numbers are wrong. Show me that the gear ratios are irrelevant. Show me that the Legacy defies this simple concept of physics.

 

Two cars are driving 30 mph. One is making 300 hp, one is making 150 hp ... the wheels are moving at the same rate of speed.

 

Let's say that the wheels are turning at 409 rpm (or 30 mph for an LGT).

 

So the car making 300 hp is making 3844 ft-lbs of torque AT the wheels and the car making 150 hp is making 1922 ft-lbs. The car making 300 hp is going to accelerate faster. No, they're not necessarily in the same gear, and the engines aren't running at the same RPM, but that's why we have 5 gears, so we don't have to choose the gear where we're making the most torque. Instead we choose the gear where we're making the most POWER and we go faster.

[Deer Killer]

That is math.

 

You show me any gear on the Legacy GT from 1st to 5th at peak horsepower and another gear you can shift to at the same speed where you will make more torque at the wheels.

 

You can't refute that ... it's a fact. You can't make more torqe at the wheels with less power.

 

If you can, please prove it to me. I would love to learn what it is that I'm doing wrong if I in fact am.

My argument with you is that you misunderstand the fundamental nature of what is going on at the engine and the transmission and what is happening to the car. You're complicating matters with absolutely no benefit to anyone, besides also being wrong in a number of regards. No one can feel power because it's not a force. You feel force, not energy, thus it is futile to try and use this to calculate shift points on an engine that even has variable torque and power output. Now you're backed into a corner arguing a different point than I am. I am telling you what you're saying above is irrelevant.

 

PS that's not math, that's jive talk.

[Brady]

Look at these shift points YOU linked to, and tell me if ANY of those shift points come close to where maximum torque is made on the LGT engine.

 

http://www.legacygt.com/forums/attachment.php?attachmentid=1265&d=1092964917

 

If you look at it, the shift points are where the power in one gear intersects with the same power amount of power in the succeeding gear. It is no where near the maximum torque produced in any given gear.

[Deer Killer]

No I'm not, read very carefully.

[Brady]

My argument with you is that you misunderstand the fundamental nature of what is going on at the engine and the transmission and what is happening to the car. You're complicating matters with absolutely no benefit to anyone, besides also being wrong in a number of regards. No one can feel power because it's not a force. You feel force, not energy, thus it is futile to try and use this to calculate shift points on an engine that even has variable torque and power output. Now you're backed into a corner arguing a different point than I am. I am telling you what you're saying above is irrelevant.

 

PS that's not math, that's jive talk.

Nope - look at the shift points. The shift points YOU linked to show that the engine is in the meat of its powerband. Not where it's making loads of torque.

 

It doesn't matter that the engine makes variable power and torque. If you had infinite gears and there was no consideration for time involved with shifting, you would just run the car at peak horsepower at all times and shift infinitely to maximize acceleration. If you had 100 gears and the same scenario with respect to shifting time, you'd keep the rpm VERY close to peak horsepower. How can you refute that? Why is it when you suddenly only have 5 gears you deviate from this fundamental principal? it only makes sense to avoid this if you have one gear, but then you're limited in speed by how fast your engine can rev compared to how tall or short that gear is.

[Brady]

No I'm not, read very carefully.

Either you're a stubborn idiot who can't admit he's wrong, or you're trolling. I truly can't decide which is the case anymore.

[Deer Killer]

Either you're a stubborn idiot who can't admit he's wrong, or you're trolling. I truly can't decide which is the case anymore.

Ugh.

 

Here is some stuff I've been playing with doing scalar turbo lag penalties. Mind you it's just playing with the numbers, but it's closer to the real world than the above.

[funkpelts]

I assume this is all regarding the manual transmission, but does anyone use the sport mode on the automatic? How do you like it? I don't think it is very sporty, but maybe it is just me.

[Brady]

Ugh.

 

Here is some stuff I've been playing with doing scalar turbo lag penalties. Mind you it's just playing with the numbers, but it's closer to the real world than the above.

That graph only shows wheel torque, but once again, if you look at where the engine is on those curves, it's still making more torque at the wheels when the car is making more horsepower in the previous gear. At no point can you choose max torque in any gear from 2-5 and be making more torque than is at least available at SOME point on the curve in the previous gear when the car is moving at the same speed.

[Deer Killer]

irrelevant to the legacy GT and shift points. You're arguing against a straw man.

 

The point of the graphs is that the shift point moves around in relation to a lot of things.

[Brady]

irrelevant to the legacy GT and shift points. You're arguing against a straw man.

 

The point of the graphs is that the shift point moves around in relation to a lot of things.

The beauty of my argument is that you can apply the same rule of chasing the power toward any combustion engine. It has to do with the way gear ratios interact, because no matter what the ratio is, the wheels are a constant. In a car with a tachometer, if you have a general understanding of where your powerband lies, and the relationships of the gears to one another, you'll be able to put the car in it's best position to accelerate. I know the engine makes more torque at about 3200 rpm, but I'm not going to run it down there unless I have to (1st - 2nd gear), because it's not going to put as much torque to the wheels.

 

Some cars make max power at red line ... their max torque might be well below the point where the gearing drops the RPM on each shift, but you'll still make more torque and acceleration at the wheels.

 

All I'm talking about is engine power and it's effect on acceleration. More power gives you the ability to make more wheel torque. If you don't have the transmission to take advantage of that ... that's a different issue.

 

After all, you could accelerate even faster than you do at 3200 rpm in 1st gear if you had gear below that one.

 

 

Now, if we were talking about electric motors, as you keep hinting is all I know about, since they don't really have variable power, it won't much matter where you shift ... the torque will always be applied equally at the wheels no matter what RPM you're running the electric motor at.

[Deer Killer]

All I'm talking about is engine power and it's effect on acceleration. More power gives you the ability to make more wheel torque. If you don't have the transmission to take advantage of that ... that's a different issue.

Great, welcome to the shift point thread on legacygt.com. A argument about hypothetical engine output vs acceleration is a straw man argument.

[Brady]

Great, welcome to the shift point thread on legacygt.com. A argument about hypothetical engine output vs acceleration is a straw man argument.

well, we do have the transmission to take advantage of it. It could be even better optimized.

 

maybe you just aren't getting what I'm saying, but if you try to look at it as a standpoint of power, you'll realize that whenever you pass a shift point, you're making more power when you shift. There is no optimized shift point where you shift to a new gear and make less power, but more torque. The gearing and the gear ratios are truly irrelevant. The torque at the wheels is ultimately what matters, and once you get the car going past 1st gear, the wheel torque will be made by power.

 

I don't even know how else to describe it for it to make sense to you since you obviously don't understand what I'm saying.

[Brady]

Great, welcome to the shift point thread on legacygt.com. A argument about hypothetical engine output vs acceleration is a straw man argument.

You know what. Screw it. Eat a bag, dude. I think you're a total idiot on this topic. I'm sure we agree.

 

I understand that wheel torque is all that matters when it comes to acceleration, but I'm more concerned with how one arrives at the wheel torque.