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-   V8 and V6 Transmissions / Driveline (6L80 / 6L50 / TR6060 / AY6) (http://www.camaro5.com/forums/forumdisplay.php?f=76)
-   -   SS Shift Point (http://www.camaro5.com/forums/showthread.php?t=15595)

PONYKILR 03-16-2009 12:39 PM

SS Shift Point
 
I've noticed on the SS gauge cluster that the tach is blue to about 6k, with a blue line crossing at about 6250 RPM, then it is red to 6600, then red hashed past that. I am fully aware that the red hashing at 6600 is redline, but what about the area between 6250 and 6600 that's red, and what about the blue line crossing at 6250??? My guess is that it may be the optimal RPM to shift at for the 6-speed... Any other guesses?

Sorry about there not being a pic for reference, but it's on the new camaro site listed below and it's the last picture in the set.

http://www.chevrolet.com/allnewcamaro/#camaro=photos

BowtieGuy 03-16-2009 12:45 PM

You may have something there.

c0rsa180 03-16-2009 01:48 PM

Thats a good question...will it have a shift light?

7CAMARO7 03-16-2009 01:49 PM

find out what the ls3 vette guys are shifting at... simple as that:) Seems to me gm makes the tach, rev limiter, and engine to where you shift within 250rpms of the limiter. So just shift like 250rpm before the red or like 6500

toehead93 03-16-2009 07:23 PM

Shifting at the highest rpm you can is not always the quickest. There is a point where the next gear will have more power than the gear you're currently in. Although the car may spin to 6,500rpm doesn't mean that shifting at 6,250 is the best shift point. Maybe someone can post a link to a chart to compare rpm to gear shift points.

7CAMARO7 03-16-2009 08:34 PM

you will never have more power in one gear than the other, your engine just has more leverage over the drivetrain in lower gears.

the rpms=power (as far as the engine is concerned) 6000rpms in first is no more or less hp than 6000 in 5th, there's just a difference in speed

I was only speaking from experience with my ls1. I used to shift at 5500 which is where the red dot dot dot starts and I used to get horrible track times. That was back when I didn't know any better. I learned from all the other guys to shift at 6000 on my car. I started kicking ass after that:)

Also did you guys ever notice how the 97-04 ls1 vettes always were spec'ed at more power than our F-bodies? I noticed also that the same engine in the vette was spec'ed to something like 345 or 350hp@6000rpms with 350tq@5600rpms or something like that. Well for the fbodies they said 325hp@5500rpms and 325tq@ 4500rpms.

Why would it be different for the same exact engine? ITS NOT! Just something for you new guys to think about.

I also agree that the highest rpm is not always the best, but if the ls2 and ls3 follow after the ls1 then it is...

zebra 03-16-2009 09:05 PM

Quote:

Originally Posted by 7CAMARO7 (Post 342504)
you will never have more power in one gear than the other, your engine just has more leverage over the drivetrain in lower gears.

the rpms=power (as far as the engine is concerned) 6000rpms in first is no more or less hp than 6000 in 5th, there's just a difference in speed

I was only speaking from experience with my ls1. I used to shift at 5500 which is where the red dot dot dot starts and I used to get horrible track times. That was back when I didn't know any better. I learned from all the other guys to shift at 6000 on my car. I started kicking ass after that:)

Also did you guys ever notice how the 97-04 ls1 vettes always were spec'ed at more power than our F-bodies? I noticed also that the same engine in the vette was spec'ed to something like 345 or 350hp@6000rpms with 350tq@5600rpms or something like that. Well for the fbodies they said 325hp@5500rpms and 325tq@ 4500rpms.

Why would it be different for the same exact engine? ITS NOT! Just something for you new guys to think about.

I also agree that the highest rpm is not always the best, but if the ls2 and ls3 follow after the ls1 then it is...

the difference in power ratings is all in the tuning. the LS3 in the vettes is rated at 436hp (with the exhaust package). we have the same engine, but due to differences between the two vehicles, they required slightly different tunings.

as for the shift points, it really depends on the gear you're going to. you want to shift to where the next gear puts you in the sweet spot of your power band. a taller gear will need to rev higher before you shift into it than a shorter gear. take my truck for example: during normal driving, my 2-3 shift is around 2500 (going from a 2.32 to 1.40) anything much less than that starts to bog if i'm accelerating. my 3-4 shift (1.40 to 1.00), however can easily accelerate at a 2000 rpm shift.

i know that example's a bit different than racing, but not much and the principle's the same. it all depends on where the next gear will put your engine speed. hope that helped

Xanthos 03-16-2009 09:47 PM

Quote:

Originally Posted by 7CAMARO7 (Post 342504)
you will never have more power in one gear than the other, your engine just has more leverage over the drivetrain in lower gears.

the rpms=power (as far as the engine is concerned) 6000rpms in first is no more or less hp than 6000 in 5th, there's just a difference in speed

I was only speaking from experience with my ls1. I used to shift at 5500 which is where the red dot dot dot starts and I used to get horrible track times. That was back when I didn't know any better. I learned from all the other guys to shift at 6000 on my car. I started kicking ass after that:)

Also did you guys ever notice how the 97-04 ls1 vettes always were spec'ed at more power than our F-bodies? I noticed also that the same engine in the vette was spec'ed to something like 345 or 350hp@6000rpms with 350tq@5600rpms or something like that. Well for the fbodies they said 325hp@5500rpms and 325tq@ 4500rpms.

Why would it be different for the same exact engine? ITS NOT! Just something for you new guys to think about.

I also agree that the highest rpm is not always the best, but if the ls2 and ls3 follow after the ls1 then it is...

The bolded statement is not true.


Mathematically speaking, if (when x = current gears ration, y = next gears ratio, R = redline, and T = torque)

http://wolflord88.googlepages.com/equation1.JPG

than you'll need to short-shift.
- Xanthos

zebra 03-16-2009 09:49 PM

Quote:

Originally Posted by XanthosV6 (Post 342764)
The bolded statement is not true.


Mathematically speaking, if (when x = current gears ration, y = next gears ratio, R = redline, and T = torque)

(T @ R * y ) * y
x > 1
(T @ R) * x

than you'll need to short-shift.
- Xanthos

great explanation... for DGthe3!

care to tell us normal guys what that means?!

Xanthos 03-16-2009 10:16 PM

Quote:

Originally Posted by zebra (Post 342772)
great explanation... for DGthe3!

care to tell us normal guys what that means?!

Heh. I put in a picture so you can see the equation better.


Basically what it means is that if you divide the new gear ratio by the old gear ratio, and multiply that by the ratio of the flywheel torque at the new RPM divided by the flywheel torque at the redline, and get a number greater than one, you need to short shift at the highest RPM where that number would be 1 or lower.

For example. An electric motor has the following torque curve.

http://wolflord88.googlepages.com/theoreticalmotor.JPG

and a 2 speed transmission, with first gear being a straight 1:1 gear and the second being a 0.5:1 "overdrive" gear.

At the 10,000 RPM "redline" in first gear, the motor would be producing a net 2 ft*lbs at the wheel. But at 5,000 RPM after the shift, it will be making 3.5 ft * lbs. Meaning there is a point where you could have short shifted for a larger net "power under the curve."

Heres a visual representation of this.

http://wolflord88.googlepages.com/theoreticalmotor2.JPG

As you can see, the total area under the curve is higher in the short shifted instance than it is when you shifted at the redline - because while the curves are nearly identical, for that split second after you shifted (leading up to when you WOULD have shifted) you have more power.

This happens very rarely with modern transmissions (once you have a lot of gears to play with you can prevent this pretty easily), but it is a theoretical possibilty, especially once you start modding.
- Xanthos

69 Hugger 03-16-2009 10:28 PM

1 Attachment(s)
:hitcomputer::hitcomputer: :popcorn:

ucla1ove3 03-18-2009 12:49 AM

english is appreciated on this forum lol

Gentry78 03-18-2009 07:48 AM

xanthos you must do alot of work with some type of motor or engine, or way to much free time to do research lol:respekt:

cuz im like :iono: kinda

Scott@Bjorn3D 03-18-2009 07:59 AM

1 Attachment(s)
No that is not right, jeez here it is.

PONYKILR 03-18-2009 08:36 AM

In the world of Engineering, graphs are useless without axis titles. Just something we're told non-stop...

Xanthos 03-19-2009 12:46 AM

Quote:

Originally Posted by PONYKILR (Post 345246)
In the world of Engineering, graphs are useless without axis titles. Just something we're told non-stop...

Graphs are only useless without axis titles if the title is something less obvious. I titled mine both as Blank vs. Blank - its pretty much the same thing as an axis title. And the titles really don't matter in this case because I pulled the numbers out of my butt to illustrate a point anyway. The exact figures don't matter.

I'm not an engineer, though - I'm a physics major. :thumbsup:
- Xanthos

P.S. - And by the way, I just do way too much research. :thumbsup:

Although I do have some mechanical experience.

New2010CamaroLover 03-19-2009 12:58 AM

Wow this thread gives me a headache... How about shift when it feels right, that's generally what most peopledo anyways cuz it's too difficult to look down while racing.

Camarino 03-19-2009 12:59 AM

i used to practce shifting in my friends Civic ( IT WAs THE ONLY CAR AVAILABLE 2 ME @ THE TIME WITH A MANUAL lol) and i used to do like grandpa used to listen to the engine wind out you'll hear it wanna go 2 the next gear, i realize this is probably a less affective way but i'd like o learn how differnet gears have different sweet spots (i thats true)

Silver Streak 03-19-2009 04:19 AM

Every gear should have its own sweet spot, and as far as what XanthosV6 said :bangdesk::bonk::cry::iono: I definately agree! :sm0:


:headbang:

Milk 1027 03-19-2009 04:30 AM

Is it wrong that I actually understood that equation? :iono:


ugh. As far as I know I'm done with math classes and damn happy about it.:barf:

Camarino 03-19-2009 11:02 AM

I LOVE CARS!!!
I HATE MATH!!! PLZ DON'T PUT THEM TOGETHER !!! :suicide: LOL

THE EVIL TW1N 03-19-2009 07:41 PM

everygear SHOULD have a different rev limit/shif point, but judging by the other LS3's out there dyno's out there (stock), you will probably need to shift very close to redline (6500 rpm or so).

NightmareSS 03-19-2009 09:28 PM

Quote:

Originally Posted by PONYKILR (Post 341032)
I've noticed on the SS gauge cluster that the tach is blue to about 6k, with a blue line crossing at about 6250 RPM, then it is red to 6600, then red hashed past that. I am fully aware that the red hashing at 6600 is redline, but what about the area between 6250 and 6600 that's red, and what about the blue line crossing at 6250??? My guess is that it may be the optimal RPM to shift at for the 6-speed... Any other guesses
http://www.chevrolet.com/allnewcamaro/#camaro=photos

it would be like drag racing in need for speed! :burnrubber:

CynAgain 03-19-2009 10:31 PM

Quote:

Originally Posted by New2010CamaroLover (Post 347315)
Wow this thread gives me a headache... How about shift when it feels right, that's generally what most peopledo anyways cuz it's too difficult to look down while racing.

It doesn't give me a headache ~ I like to know what the recommendations are and the logic behind it, but for me it really comes down to the feel. That's why I opted for the stick.

Xanthos 03-19-2009 10:36 PM

Quote:

Originally Posted by CynAgain (Post 349789)
It doesn't give me a headache ~ I like to know what the recommendations are and the logic behind it, but for me it really comes down to the feel. That's why I opted for the stick.

And while this is a fine way to drive, its not the most efficient. The problem is that the gear your in doesn't give a hoot what the gear ratio will be after you shift - feel won't change based on the next gear, but will stay the same for every gear. So while you can feel when the engine wants to shift, you have to do the math and research to know when the transmission wants to shift.
- Xanthos


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