Actual Horsepower Of '60s/'70s Muscle Cars

[Fleet 500]

Thank you for ignoring everything I've said.
The FAST racing group has ran at the track I work at, I've run thier races, I've seen what the cars can do, (high 10/very low 11 runs) with thier bias ply tires.

They run those times in spite of their bias ply tires.

Modern tires spin too. They aren't the ANSWER like you make them out to be.
MODERN RACE tires are a big improvement over the old tires.

Modern regular tires are also a big improvement over the old tires. I discovered that right away when I compared the two on my Dart.

[Fleet 500]

No it isn't.

But it's no more significant than RPM in terms of determining HORSEPOWER. And it is HORSEPOWER (and gear ratios) that dictates REAR WHEEL TORQUE at any given drive wheel speed. REAR WHEEL TORQUE, in turn, is what accelerates the vehicle.

For my '69 Cad: 525 lbs-ft torque at 3000 rpm, 2.94:1 axle ratio and 2.48:1 1st gear ratio... enough to easily break traction (with both old bias ply tires and modern radial tires; but easier to do with old bias ply tires).

I have owned SEVERAL modern-day performance cars. Every one of them was capable of spinning the tires in first gear once the clutch was full engaged.

My LS1 Camaro could spin them ALL THE AWAY through first and well into second.

When did I say that modern tires completely eliminate tire spin?
Here is a quote from a Car & Driver test of a '70 454 SS Chevelle (which ran a 13.81 sec @ 103.80 mph 1/4 mile):
(Compared with a '65 289 Cobra) "The Chevelle was decidedly more powerful, pushing its 3,885-lb bulk through the traps at 103.80 mph, but with 57.1% of its weight on the front wheels it just couldn't quite get a good enough bite on the asphalt to move out ahead of the Cobra."
Once again, tires being the limiting factor, not horsepower.

[Fleet 500]

Then a Toyota 2000 GT is great, isn't it?

For some, but not for me; I prefer muscle cars.

[Fleet 500]

2) MOST of the so called "muscle cars" yielded 60 to 100 MPH times and Trap Speeds that were no better than the Camry's.

Well, let's compare:
60-100 mph...

Camry------------------ 8.4 seconds (3.69 axle ratio)
'69 'Cuda 340----------- 8.5
'69 Coronet R/T 440----- 8.4 (with only 3.23 axle ratio)
'68 340 Dart------------ 8.5 (3.23 axle ratio)
'64 389 GTO------------ 8.3

Obviously, the Camry needs to use every bit of its (high) revs to run its time. While the '60s muscle cars ran those times practically loafing along!

Another:

40- 60 mph and 50-70 mph.

Camry (268 net hp, 3,490 lbs, 3.30:1 1st gear ratio, 3.69:1 axle ratio)
40-60----------- 2.6 secs
50-70----------- 2.9

'68 Dart GTS 340 (240? net hp, 3,305 lbs, 2.45:1 1st gear, 3.23 axle ratio)
40-60----------- 2.3
50-70----------- 2.8

The Camry probably makes more net hp and has a lower axle ratio and the Dart still wins! As I said before, I'll take the '60s cars! With real steel and looked like normal cars.

[Kitdy]

No it isn't.

But it's no more significant than RPM in terms of determining HORSEPOWER. And it is HORSEPOWER (and gear ratios) that dictates REAR WHEEL TORQUE at any given drive wheel speed. REAR WHEEL TORQUE, in turn, is what accelerates the vehicle.

You might understand that if you bothered to LEARN instead of DENY.

Horsepower v torque

ELEPHANT RACING Tech Topic, HP vs Torque

Yaw Power Products / Where Performance Meets Technology



I have owned SEVERAL modern-day performance cars. Every one of them was capable of spinning the tires in first gear once the clutch was full engaged.

My LS1 Camaro could spin them ALL THE AWAY through first and well into second.

All right, I have read the articles and am beginning to better understand the complex relationship between torque and horsepower. My questions then are these:

1. In a fixed gear ratio transmission, peak wheel torque, as per the example appears to occur at peak torque instead of peak horsepower. I notice however that the wheel speed is different, does this mean that in actuality there is somehow more torque at peak hp? I am really confused about this.

2. What is the advantage of lots of low end torque that comes form large displacement engines other than them needing less gears? Does a broader powerband mean that they will accelerate harder at lower rpms as horsepower will be higher? In a car with a CVT transmission, what is the benefit of a lot of low-down torque? I think a broader powerband is good as there is more torque to the wheels at lower rpm but am sorta unsure if a large displacement engine would be better than small displacement engine with the same peak horsepower.

3. Why aren't CVTs used in performance cars? Are they not capable of taking the high torque output of larger engines?

[Ferrer]

Kitdy I don't know about 1 or 2 but I think you're bang on with 3.

[Kitdy]

Kitdy I don't know about 1 or 2 but I think you're bang on with 3.

I don't quite understand CVT's benefits. The limited material that I have read about them implies they will allow for faster acceleration than comparable manual or automatic transmissions - but I thought that peak horsepower rpm was needed for max acceleration, and in a CVT gearbox, this would take a long time to get to. Am I completely oblivious to something here?

[Ferrer]

I don't quite understand CVT's benefits. The limited material that I have read about them implies they will allow for faster acceleration than comparable manual or automatic transmissions - but I thought that peak horsepower rpm was needed for max acceleration, and in a CVT gearbox, this would take a long time to get to. Am I completely oblivious to something here?

Well as far as I know a CVT allows you to have maximum acceleration constantly, should you need so, by sticking to the peak horsepower rpm.

It's theoretically a very good idea, a gearbox with infinite gear ratios.

[Kitdy]

Well as far as I know a CVT allows you to have maximum acceleration constantly, should you need so, by sticking to the peak horsepower rpm.

It's theoretically a very good idea, a gearbox with infinite gear ratios.

If this were true, the engine rpm would always be at redline, yes? This is not how they work so I think we are being deceived somehow by physics and our lack of understanding for mechanical systems. I have heard that CVTs offer maximum acceleration at all times as well but I am not sure exactly how this is possible as they are not revving at the engine at maximum rpm.

I've had a bit of a revelation - what I think CVTs may do is provide max torque at wheels for every possible rpm. This would make more sense, and the example seems to coincide with this reasoning, if memory serves.

EDIT: Ferrer, you wouldn't happen to know what an axle ratio is would you? I can only postulate. You are the only other person around this thread at this ungodly hour - for east coast North American that is.

On a purely comical level, I must point out that CVTs may not actually have an infinite set of gear ratios as space may be quantized - ie. space is made of tiny discrete chunks. That's for any physics buffs around here.

The word infinite is thrown around quite a lot these days.

[henk4]

Another:

40- 60 mph and 50-70 mph.

Camry (268 net hp, 3,490 lbs, 3.30:1 1st gear ratio, 3.69:1 axle ratio)
40-60----------- 2.6 secs
50-70----------- 2.9

'68 Dart GTS 340 (240? net hp, 3,305 lbs, 2.45:1 1st gear, 3.23 axle ratio)
40-60----------- 2.3
50-70----------- 2.8

The Camry probably makes more net hp and has a lower axle ratio and the Dart still wins! As I said before, I'll take the '60s cars! With real steel and looked like normal cars.

so why are you stupid? You quote in gear acceleration times for 40-60 and 50-70 and yet you give 1st gear drive for the two cars....think about that for a while, will you.

[jediali]

All right, I have read the articles and am beginning to better understand the complex relationship between torque and horsepower. My questions then are these:

1. In a fixed gear ratio transmission, peak wheel torque, as per the example appears to occur at peak torque instead of peak horsepower. I notice however that the wheel speed is different, does this mean that in actuality there is somehow more torque at peak hp? I am really confused about this.

2. What is the advantage of lots of low end torque that comes form large displacement engines other than them needing less gears? Does a broader powerband mean that they will accelerate harder at lower rpms as horsepower will be higher? In a car with a CVT transmission, what is the benefit of a lot of low-down torque? I think a broader powerband is good as there is more torque to the wheels at lower rpm but am sorta unsure if a large displacement engine would be better than small displacement engine with the same peak horsepower.

3. Why aren't CVTs used in performance cars? Are they not capable of taking the high torque output of larger engines?

1. Good question. Power is essentially a product of rpm and torque however it is also influened by efficencies, primarily mechanical in-efficiency which is usually 5-7% of power lost. This inneficiency is generated by cylinder wall friction (incrteases exponentially with rpm) and valvetrain loss (for example a pushrod engine has more moving heavy parts thus it needs stiffer valve springs which absorb more engine power).

So..while peak torque drops of at higher rpm (due mostly to less accurate gas exchange control) the higher rpm ensures power continues to increase until frictions, engine balance and valve timing limit operation.

2. Another good question. big engines consume more fuel because they have big cylinders which require more fuel to run (stoichiometric air/fuel ratio is 14.7:1) and high revving engines consume more fuel because more cylinder fills of fuel are burning in a period of time. Ideally you want a blend of both to maximise economy. There is the added benefit of low friction at low rpm. low end torque is fine but often sacrifices high end torque and it will have a low redline.

A good example is a LPT engine (LPT = low pressure turbo charger). This means that the light turbo spins up really easily at lower rpm thus providing better cylinder filling, therefore more torque at lower rpm, where you can cruise esier and minimise frictions ascociated with high rpm. My 1.8T is a good example of this. the 2.0TFSI is even better because it uses direct injection (this allows better compression ratio, therefore higher thermal efficiency extracting more power from fuel). This means that an LPT engine will likely have a better highway mpg but worse urban mpg than a non-turbo version.

3. You have already discussed 3. As far as i can see most manufacturers dont like CVTs because they cant handle torque and make driving less fun. But your theoretical point of view is fine.

[Ferrer]

If this were true, the engine rpm would always be at redline, yes? This is not how they work so I think we are being deceived somehow by physics and our lack of understanding for mechanical systems. I have heard that CVTs offer maximum acceleration at all times as well but I am not sure exactly how this is possible as they are not revving at the engine at maximum rpm.

I've had a bit of a revelation - what I think CVTs may do is provide max torque at wheels for every possible rpm. This would make more sense, and the example seems to coincide with this reasoning, if memory serves.

EDIT: Ferrer, you wouldn't happen to know what an axle ratio is would you? I can only postulate. You are the only other person around this thread at this ungodly hour - for east coast North American that is.

On a purely comical level, I must point out that CVTs may not actually have an infinite set of gear ratios as space may be quantized - ie. space is made of tiny discrete chunks. That's for any physics buffs around here.

The word infinite is thrown around quite a lot these days.

Well, CVTs aren't always at redline, it depends on the position of the accelerator. I you floor it the engine will go to redline, if you don't it won't.

To be honest I don't know much about the oily bits, you probably know much more than I do about this.

[henk4]

3. You have already discussed 3. As far as i can see most manufacturers dont like CVTs because they cant handle torque and make driving less fun. But your theoretical point of view is fine.

some may remember the DAF Formula III car that ran with an early version of their CVT (Variomatic as it was called by its inventors, the van Doorne brothers)

[jediali]

some may remember the DAF Formula III car that ran with an early version of their CVT (Variomatic as it was called by its inventors, the van Doorne brothers)

Interesting...was durability an issue? I wonder what them main reason CVTs arent more common then.

[Kitdy]

Well, CVTs aren't always at redline, it depends on the position of the accelerator. I you floor it the engine will go to redline, if you don't it won't.

To be honest I don't know much about the oily bits, you probably know much more than I do about this.

I was under the impression then that when you jammed on the throttle of a CVT car, it the rpms would ever so slowly creep up to the redline.