SCM_Crash

LOL! Touche!

irun4cops

C5 z06's with taller c5 tall ratios installed, made it to 60 faster than the stock z06 trans because the car wasnt limited by power, it was limited by traction, so getting rid of a shift point made them quicker to 60

And 0-200 is an extreme situation where you are starting off at less than 1000rpm's for the first 60mph. Dont insult our intelligences with that kind of nonsense and try to imply that has any relevance to my comparisons.

0WildVettes

Did someone other than GM get the car I didn't hear about? Until then there are NO facts you are going to know about how the computer interacts with the engine because GM isn't going to release that info to the public.

Why would they?

irun4cops

requote my quote, i edited it

irun4cops

the only fact you have is that you may have heard a GM rep talk about something he hasnt the slightest clue about.

That was your only fact.

0WildVettes

I wasn't the one insulting people's intelligence. You said if someone has five gears they are going to get to 200 mph faster than someone with six. Implying ratios to be unimportant.

You completely ignore friction and drag which increases as you go faster. Having closer ratios makes it easier to accelerate because rpms don't drop as fast and HP being produced is also higher. This makes overcoming friction both ground and air easier.

A constantly variable transmission that adjusts immediately to the ideal ratio for any given speed and power level is ideal. There are actually some in testing right now.

If gears and ratios didn't matter then my C7 would have the same four speed in my 1971 Stingray.

The extra time required to shift a gear in a race to 200 mph is a laughable comparison. Why don't we argue the five speed driver shifts slower than the six speed driver?

If there was an auto transmission that could keep rpms at peak HP level from start to drag limit for HP that would be the car that won the race. The closer you get to being able to maintain peak HP constantly while driving the faster you are accelerating.

Your example of the C5Z is 100% accurate because the limiting factor is traction. It does not apply to your example of gears or ratios.

irun4cops

i didnt say 4 speed. I said 5 gears to 200 keeps it in power band enough, that the extra shift, if one had 6 gears, is negligible.

From a track standpoint, you also have less shifts, which means less moments of having to baby it under acceleration as you go from one gear to another exiting a curve. Less shifts... since there is plenty of power across the rev range.

HP is important as is torque. We have a ton of torque in this car, and it starts low rpm

torque propels upgraded diesel pickups down the drag strip faster than a vette, including trap speeds.

0WildVettes

Horsepower is a measure of Torque at a given RPM. To produce the fastest acceleration you must stay as close to peak HP as possible once overcoming the initial traction issue at launch. The more gears you have within reason the better able you are to accelerate.

Quick trivia question for you. How many gears do semi trucks have? Google it and get back to me.

irun4cops

let me give a couple examples for you to further wrap your head around...

if a vette had 800 peak torque at in the vacinity of 3000-4500 rpm... and then the curve fell down and crossed the HP curve, and the HP curve never exceeded 465... then in a drag race... one would want to keep the car between 3000-4500 rpm as often as possible. Meaning, you would want more gears to keep it in that window more often. The HP in this high torque window, will probably be next to nothing... but the car accelerates faster there than it will at 6500rpm with 465 hp. That is reality.

Inversely, if the car made 800hp, and only made 465 torque, and the hp came on from 5500 to 7000, then you would want to keep it in that window.

But when you have equal torque and equal HP across the majority of the rev range, something magical happens....

You have nearly the same power everywhere... it doesnt matter if you are running 4000rpm... or 6000rpm... the power is always there.

Therefore... adding more shift points, at some point... becomes counter productive in acceleration when you have a large window of power.

SCM_Crash

This is exactly correct. And this is also what makes electric cars so fast. They have 100% of their torque through the RPM range up to 5252 RPM where the HP is 100% to the max RPM of the motor.

irun4cops

i own a trucking company.

So lets be real here for a second... your pulling 100,000 lbs down the road... yes, you need more gears. You arent limited by traction. And you have the aerodynamics of a barn, and friction levels as high as pulling a plow.

You keep using extremes that are not relevant to the reality that exists to my comparison of 5 gears vs 6 when the power curve is literally flat on this car.

irun4cops

right, so if adding another gear to the car ensures that after up shifts, that you never fall below 5000rpm if you shifted the previous gear at 7000rpm

VS the situation where only having 5 gears on the way to 200 means you maybe fall down to 4500rpm on upshifts from 7000 instead... at 4500 there is still almost even power with 5000rpm... so you arent losing anything with a car that has a flat power curve if your gearing doesn't keep you above 5000rpm at all times. If the torque was slightly higher... youd want to be in lower rpms instead of the upper.

In this case it doesn't matter where you go... the power is the same throughout... and the 5 gears keep you in that power window... adding another one is negligible and only adds another shift point... that is an annoyance, especially in curves.

This principle applies, otherwise all cars would have 10 or more gears like a semi, every nascar, every drag car... everything.

You are dealing in absolutes and ignoring other important variables and you conclusions are not reality.

irun4cops

ill admit it might be a bit slower, but not by much. And the extra shifts are perceived annoying by the majority of the population

Regardless, the solution here is simple, if someone wants put all the gears in the trans into play, then run shorter gears in their rear diff... its all solved.

Chevy didnt mess up with the trans... people have been throwing a shorter gear in the rear diffs since the beginning car racing time, who have to achieve a high speed in a certain MPH range...

Then you sacrifice fuel economy and more shift lags. Its a several hundred for a new gear. You can make the money faster than complaining on corvette forum will ever cause chevy to regear their trans based on your whining.

Chevy didnt mess up, they just didnt take your vote over the 20:1 ratio of others who dont want that.

niels007

In a straight line, it doesn't make a lot of difference.

Default gears versus tightly spaced 6 gears with fast but not impossible shifts, I get to 180mph about 1 second faster with the more 'race like' gear ratios compared to the Z51 box.

zx10cobra

Wow genius. If the other comparison was a 6 speed and they shared all the same gear ratios except for the 7th, wouldn't that make it a 6spd in your argument?

glass slipper

It’s impossible for anyone to wrap their head around what you post because it doesn’t pass the BS test.

If a Vette had 800 LB-FT of torque from 3000-4500 RPM, the HP in that RPM band would be 457-685 HP with it crossing 465 HP at about 3053 RPM…obviously the HP exceeded 465 already before the torque curve crossed the HP curve at 5252 RPM. Let me remind you of the equation HP=T*RPM/5252. In addition, 457-685 HP in your mythical “high torque window” is obviously not “next to nothing”. With your mythical 3000-4500 RPM power band, a drop to 3000 RPM represents a drop of 33% which is more than the first three gears in the Z51 7-speed…why would you want more gears??? The car accelerates fastest when the average HP delivered to the rear wheels is at a maximum, it has nothing to do with torque alone…THAT is reality.

If the engine made 800 HP and only 465 LB-FT of torque in the range of 5500-7000 RPM, even if the 800 HP happens at 7000 RPM the torque will be 600 LB-FT. Again, it’s a very simple formula…HP=T*RPM/5252.
It’s also impossible to have equal torque across the majority of the rev range and equal HP across the rev range by definition with the HP formula above. There is nothing magical about your mythical scenario because it doesn’t exist except maybe in your head. You won’t have “nearly the same power everywhere”, there is a distinct power curve that has an increasing slope going towards peak HP and a decreasing slope after peak HP…power is not always there and there isn’t a “large window of power” thus the need for more gears.

Horsepower is a measure of the rate an engine can do work. Accelerating a given mass from one speed to another in a given time requires a certain amount of HP, you are increasing the kinetic energy of the vehicle and HP is what “adds” kinetic energy. At lower speeds, larger RPM gaps can be tolerated but as speed increases, the car will accelerate faster with more closely spaced gears that keeps RPM drops to a minimum. Large RPM drops at higher speeds has a very large impact on acceleration because it takes substantially more kinetic energy to go from 150 MPH to 160 MPH versus 0 MPH to 10 MPH. Remember KE=½mV². A 60 HP drop after a shift at lower speeds will not have nearly the effect of a 60 HP drop at higher speeds…remember acceleration is much less at 150 MPH and we’re looking at average HP to add kinetic energy. The time spent with a 60 HP deficit versus the same car with more closely spaced gears will manifest itself in the other car running away and hiding from you.

I’ll sum up the above…given equal cars and engines irrespective of the shapes of the torque or HP curves, he who puts the most average HP to the ground wins.

glass slipper

You should really verify info in others posts before stating "exactly correct"...his post was filled with BS.

BTW, electric motors have a torque curve too with max torque occurring at locked rotor and minimum torque occurring at rated RPM...it's not a straight line 100% torque. Most electric motors will never see 5252 RPM but max HP occurs at the rated RPM...I really have no idea what you're trying to say in that last sentence and I don't think you do either. So few people understand HP...

RedLS6

The above is completely incorrect .....

Rear wheel torque is what creates maximum acceleration, not engine torque. To generate maximum rear wheel torque, you need to keep the engine at the engine's horsepower peak, and not the engine's torque peak. Maximum rear wheel torque is created by the engine's maximum horsepower, and then gear reduction between the engine and the wheels.



.

TTRotary

More overdrives is the only way to add gears to the T-56 / Tremec which began life as a 4-speed trans. You are locked into a 1:00 4th spped because of the layshaft design, which makes the trans a direct-drive in it's old top gear. And GM is locked into this trans because it is the only one in a reasonable price range that can handle the torque of these big V-8s. So, yes, it is really a 4+3. Which happens to work very well in this case because of the amount of torque on tap.

0WildVettes

Glass you had me at hello.

After spending 35 minutes with a girl telling me I needed to replace her Iphone for free because the phone dropped and the glass broke and that should not have happened I have decided not to beat myself up over people that "know things" .

She said it was an inferior product and shouldn't have broken but refused to acknowledge Apple makes inferior products. Then compared a mechanical defect in her Dell Laptop that was replaced to a broken screen I told her the scenario was different because she didn't drop her laptop and break it.

She was a hairstylist by profession and robbed me of 35 minutes of my life. Man if we could eye for an eye time.

Anyway, thank you for attempting to clear up what I was saying.