mmarshall

A lot of modern large trucks have what is called a Jake Brake, which helps keep things under control on a steep descent. It works through exhaust valves and diesel-engine compression. The nickname comes from the Jacobs Company, which pioneered the system.

Many decades ago, before the advent of modern vehicles, there was a turn-off station on the side of that mountain about halfway up (or down, depending on which way you were going), where vehicles could stop and allow overheating engines, transmissions, and brakes to cool off....then continue after a few minutes. A well there provided fresh, cool water for radiators if needed. In those days, primitive cooling systems and brakes just didn't have the capacity they do today.

Byprodrive

iTrader: (1)

To your point Mike, & I believe your intended point for this thread topic: I have always read that no matter which chrysler car tested, the 440ci 6-pack equipped engine was faster 0-60mph & 1/4 mile, than a 426ci street Hemi engine despite the Hemi's higher HP rating in stock trim. Why the engine was better tuned for Torque than Horsepower.

peteharvey

Sorry, there is no link. Just university physics, and general knowledge.
More information about flashlights/headlights can be found at www.candlepowerforums.com , then click on General Flashlight Discussions, or Flashlight Reviews...

mmarshall

The 440 6-pack was indeed a torque machine. One of my high school friends had a new purple 440 6-pack 1970 Challenger (how he paid for it was anybody's guess....I don't remember). It had so much torque that if you weren't really careful about popping the clutch (it was also the pistol-grip 4-speed MT), all it did was basically sit still for awhile and burn up the rear tires, going nowhere. Once the rear tires DID bite, however, it was so long to anybody next to you.

P.S.....in those days, you paid for that kind of performance. That gas hog got between 90 and 100 miles to a tank of some 20 gallons of super-premium 100-octane leaded gas.....some 4-6 miles per gallon when you went around showing off like that.

FrankReynoldsCPA

Did he have any issues with motor mounts?

That was a problem my dad had in the past with his Firebird...rev it too much and it was liable to snap a motor mount.

Toys4RJill

mmarshall, your claim that torque is more important that horsepower is bogus.

Please explain he following:

Land Cruiser 5.7 despite giving up almost 80 pounds feet of torque outperforms the 4.5 diesel in the same configuration (tranny, chassis, 4wd). The 5.7 has 100 more horses than the 4.5 while the 4.5 has 80 more pounds feet of torque. mmarshall, please explain and do not avoid it.

mmarshall

Depends on the driving conditions. Most American drivers (and the majority of those reading this thread will probably be Americans) tend to prefer throttle response at low RPMs, as opposed to many Europeans, who tend to wind out their powerplants more into the peak-HP range. Throttle response at low RPM is generally more of a torque function than HP.

Diesels, especially of the types used in trucks/SUVs, typically offer a lot of torque at very low RPMS, but often run out of breath and are more RPM-limited than their equivalent (or larger-displacement) gas engines having lower torque (in this case, as you note some 80 ft-lbs.) Given enough room to actually accelerate for some distance, gas engines sometimes outperform diesels due to RPM and torque-curve limitations.


BTW, I clearly noticed that with the Mercedes-Benz Bluetec V6 diesel the last time I reviewed one. Because of its excellent low-RPM torque, its response at low speeds, especuially in the lower gears, would firmly push you back in the seat. But, above about 3500-4000 RPM, its response weakened noticeably...and, from there, the gas-engined Mercedes equivalents felt stronger.

Och

iTrader: (3)

Its shocking how many people simply do not understand the relatively simple concepts of how torque and horse power works and their direct relation to each other. The whole argument of torque vs horse power is hilarious.

Hoovey689

iTrader: (16)

6-pages of it

Och

iTrader: (3)

Turbo diesels typically offer a lot of torque at very low RPMS (which also means that they are producing a lot of horse power at very low RPMS), but because they are turbo charged, that torque is not instant off the line. I drive a truck with Fords 6.0 powerstroke diesel that has buttloads of torque - and its a total dog off the line, until the turbo spools up. Therefore turbo diesels are not always suitable for offroad vehicles, where instant torque, coupled with low range gearing, is preferred. But, of course, old diesels engines with mechanical fuel injection could be completely submerged into water without having to worry about electronics. That is not the case with moderns diesels.

peteharvey

What happens here is that the diesel with 80 lbs-ft more torque will out-accelerate the petrol 5.7 off the mark!
However, the diesel has a very limited red line before "pinking" [engine mis-firing] occurs, hence its red line is limited to say 4,500 rpm, such that its maximum speed is a limited mph in first gear.

Now what happens with the 5.7 petrol with 80 lbs-ft less torque [but 100 bhp more power] is that initially the petrol is slower to take off, however by 4,500 rpm, the petrol engine has ignition advance etc, so it has much superior combustion control and efficiency, hence the petrol continues to rev all the way to about 6,000 rpm in the SAME first gear, WITHOUT changing up to the second gear, where such a gear change would cause a significant drop in torque, hence less acceleration.
It is from 4,500 rpm to 6,000 rpm in first gear where the 5.7 petrol will catch up to, and possibly even overtake the diesel, where the diesel has already changed to second gear, and the second gear has a considerable fall in torque, hence less acceleration.

In mathematics, we use what is known as "integrals" to measure the total surface area under the torque curve, and under the power curve.
It is not actually peak torque, nor peak power that counts, but it is actually the total surface area under the torque curve, and under the power curve that determines overall performance.

Notice how torque is very different to power?
Torque actually determines the acceleration, but torque will be limited by rpm speed.
Power is achieved by both a higher torque curve, and power is also be achieved by higher rpm speed limit [red line], esp in the case of the petrol engines, and even more so in racing cars.
Higher red lines means that we don't have to change up to the next gear early, where changing up to the next gear causes a rapid fall in torque, and a rapid fall in acceleration.
Second gear will still accelerate, but not as quickly as first gear, and so on.


Torque
Torque and power are different.
So it depends what we want.
If we want to accelerate quickly off the mark, then get an engine with bags of torque.
On the other hand, if we don't want to take off the mark that quickly, we can get a high powered revver, which uses an engine with a high red line, eg Formula 1 racing cars red line at nearly 20,000 rpm, and motorcycles have hi rpm red lines too, such that we hold onto each gear longer, before each up shift, to maximize the acceleration.

To get bags of torque, it depends firstly on the type of fuel we use. Just has steak has more calories than salads, some fuels have more MJ megajoules of energy than others.
Petrol and diesel actually have very similar energy per gram weight.
However, because diesel is denser [a heavier mass for the same volume], there is more grams of diesel, hence diesel has more energy per the same volume.
Fewer cylinders will also help to maximize torque because fewer cylinders has more thermal efficiency, and fewer cylinders have less friction, and fewer cylinders have longer strokes.
To get bags of torque, we also need more cubic capacity to burn more fuel for more energy, hence more torque.
Torque is also achieved by a longer stroke; the longer the stroke, the greater the torque. However, long strokes have a narrow bore diameter, and this severely restricts the size of the valve openings for gas flow, which restricts rpm red line.
Torque can also be increased by a supercharger or turbo charger which increases the amount of air, so that larger amounts of air/fuel mixture can be burnt, to yield more energy, hence more torque.


Power
Power can be achieved by using petrol, because the auto ignition temperature of petrol is 246 degrees Celsius vs 210 for diesel, petrol has higher red lines, to hold onto the each gear longer, for greater acceleration, before up shift.
Power is also achieved with capacity increase.
Power is achieved with multi-cylinders, which are smoother, so can rev higher.
Multi-cylinders also have greater surface area for larger valve openings.
Power can also be achieved by a big bore, for a large diameter cylinder, which gives room for larger valves that enable more rapid gas flow for higher rpm's.
Power can also be achieved by valve lift, where the larger the opening, the faster the gas can flow.
Multivalve engines use multiple intake and multiple exhaust valves, where each valve is smaller and lighter, so that they can open and close faster for higher rpm red lines.
Power is also achieved by valve advance timing.
Power is also achieved by precise control of fuel by indirect and direct injection.
Power is also achieved by ignition advance to also give higher rpm red lines.

Due to fuel type, fuel limit, and engine capacity regulations, Formula 1 cars maximum torque is severely limited [even stunted], such that Formula 1 cars must strive for higher rpm red lines to achieve their performance.
However, just as well that their torque is limited, because more torque would only result in wheel spin like a dragster.
Because motor cycles and Formula 1 cars have limited capacity and limited torque, the pulling force won't be that good, but just as well because motor cycle is relatively light, and the F1 carbon fibre chassis is only some 500 kg+ anyway.
Hi red lines do make a racket of noise, and the engine won't last that long either.


Grunter vs Revver
A "grunter" produces the torque.
A "revver" produces the power.
The performance is achieved in different ways.
A low rpm grunter could out accelerate a hi rpm revver - actually how much performance depends on the total surface area beneath the torque curve, or beneath the power curve.

At the end of the day, the low rpm grunter has fast take off, but a limited top speed.
Meanwhile, a hi rpm revver takes off initially more slowly, but then overtakes with a higher top speed in each gear.

Thus, the low rpm grunter is used in buses, trucks and commercial vehicles that pull a lot of weight, but don't need much speed.
While the high rpm revver is used in motor bikes and racing cars which pull little weight, but require high speeds.
The grunter is used to pull mass.
The revver is ussed to attain speed.
If the grunter is used to pull a light mass, it will accelerate very quickly, with severe wheel spin even, however the terminal speed will be very limited.

Due to its narrow rev range, that's why grunters eg trucks and buses often need much more gears in their tranny eg a 22 speed gearbox etc.


Marshall & Jill
I'm neutral.
I'm not backing Jill nor Marshall.
You could say they are both wrong, or you could say that they are both right, but in different ways.

Marshall sort of prefers a typical 5.0L V8 grunter with a 6,000 rpm redline, rather than Jill's small capacity multi-valve revver like a Honda Civic 1.6L DOHC VTEC with an 8,000 rpm redline.

However, it's all a matter of degree, and how much.
They are both right, but in different ways.
Preference really.

Because if we give Marshall, at one end, a monster torquey grunter extreme like a diesel large capacity typically truck engine that red lines at 2,200 rpm - that 2,200 rpm redline wouldn't be a joy to drive at all!
This engine could lift weight, great for fork lifts, bobcats and tractors etc, but it wouldn't have any speed.
This type of engine is relatively low on power.

On the other extreme, a typical power revving motor bike engine or F1 engine with a small capacity engine that red lines at 10,000 to 20,000 rpm is very quick, but it has no pulling power, is poor for towing, and it makes a lot of racket [noise], and on civilian streets, people will avoid revving past 6,000 rpm.

Balance and moderation is best for typical road family cars.
A 5.0 V8 torquey grunter vs a 1.6 DOHC multi-valve VTEC grunter etc.
In this case, where the difference in redline is only 6,000 rpm vs 8,000 rpm [not much difference], either designs could win.
The difference between 2,200 rpm and 20,000 rpm is nearly 10 fold; however, the difference between 6,000 rpm and 8,000 rpm is only 1.33 fold; hence very little difference.
Hence they are different in delivery, but relatively equal overall.
The quicker car actually depends on the total surface area under the torque and power curves.
Or, be more practical, and line them up on the drag strip, and drag them side by side.

Always remember, that ultimately, at the extreme, the tiny power revver with a 20,000 rpm redline will always ambush a monster torquey grunter with a 2,200 rpm redline.
However, the monster torquey grunter will out tow [greater towing capacity] the tiny power revver.
We cannot use a small capacity power revver to tow a boat or caravan.

Thus, a common real life situation of a 5.0 V8 6,000 rpm redline torquey grunter, versus a 2.0 multi-valve VTEC 8,000 rpm redline power revver - it is very debatable which is quicker in the straight line? Either could win.
However, at the extremes, a monster torque engine with a 2,200 rpm redline versus a small capacity multi-valve 20,000 rpm redline power revving engine, it is quite clear which can tow more weight, and which is faster.

There are also practical considerations.
If one is too lazy to rev the engine, or wishes to avoid noise and attention by keeping rpm's low, then the big 5.0 V8 torque monster is favored over the power revving small capacity multi-valve VTEC with an 8,000 rpm redline.
The V8 is also favored if one must tow trailers, boats, and caravans.
Meanwhile, the compact lightweight mighty mouse power revver is favored if one also wishes to have excellent fuel economy, handling and dynamics.


Road & Circuit Type
It also depends on road/circuit type.
A mountainous road would favor the V8 torque monster grunter.
A flat road will favor the mighty mouse power revver.

Large hi speed curves favor the power revver in two ways: (1) the hi powered revver has more engine speed, hence more overall speed, and (2) on top of that, the hi powered revver is often a small capacity lightweight engine, and this further enhances the handling and terminal speed around hi speed curves.

Small low speed twists and turns are tricky to determine who is quicker, because while the low speed torque monster grunter can blast out of corners, their typically much larger engine capacity, and hence mass, limits their overall handling and cornering speed...

Byprodrive

iTrader: (1)

Maybe he had a problem with his harmonic balancer. The early balancer was a 2 piece bolt together part designed in the late '50s. Pontiacs were heavy cars & therefore had high torque engines to provide good acceleration at low rpms. 67 Firebird was the 1st light (3000 lbs) Pontiac & 1st year for the higher torque & rpm 400ci engine. On my 67 400 bird the balancer failed & you could see the engine move while reving the engine. In 1968 the balancer was redesigned to a 1 piece design which lasted longer. I later installed a 455 HO engine & never had any problems with motor mounts, or Camaros either.

nipponbird

/http://frankgermano.wordpress.com/viktor-schauberger-the-repulsine/The piston engine is so overworked, it is just not real anymore. Or can one say the fire engine, what form it may take, internal combustion, steam or whatever. Isn't it time we move away from this primitive contraption. Why isn't an engine like the Schauberger engine not followed up or won't it work for the petroleum companies? One can just imagine the complete apocalypse it will cause the oil moguls and the geo-politicians, if something like the Schauberger engine (of course it needs further development) takes over. The irony is that the solution to have a renewable energy engine, complete safe to the environment and capable of unheard of power, is staring us right in the face.

Hoovey689

iTrader: (16)

very informative post peteharvey

peteharvey

Engines
Getting a bit off the topic, but I've never heard of the Schauberger engine, and it is still very difficult for me to understand how it works?

Presently, the internal combustion piston engine is still best.
It is simple, efficient, plenty of practical bottom end torque, and suited to fluctuating speeds in start/stop traffic.

The Felix Wankel rotary engine sounds good on paper, with fewer moving parts, and a smooth rotary motion.
However, in practice [if you've even actually driven a Mazda RX-7 or RX-8], the rotary is coarse to rev, poor in bottom end torque, and very thirsty, with relatively poor emissions too.
It's a good thing Mazda discontinued the rotary engine.

The electric motor is very good.
Simple, bags of true linear bottom end torque, operates well under fluctuating speeds of start/stop traffic, silky smooth, and very energy efficient, with superior pollution control.
However, just that battery breakthrough is required.
In future, hydrogen powered fuel cells may provide the answer here, and if so, the electric motor may replace the 100+ yr old internal combustion engine.



The gas turbine or turboshaft engine.
Has very good power for its engine size and weight, is very smooth, and great at hi speeds, and more suited to vehicles like aeroplanes that travel at constant speeds.
However, it is very inefficient, especially at low speeds, has poor low speed torque, and is not suited to being used with fluctuating speeds of start/stop traffic.

Turboprop.
Same as the gas turbine or turbo-shaft, but uses thrust from the propeller to drive, rather than the drive shaft powering through the wheels.
Propeller drive is better suited to air craft hi speed applications, than to low speed cars, with constantly fluctuating speeds.

Turbofan.
This is an intermediate between turboprop propeller and turbojet used on a fighter air craft like the FA-18 Hornets.

Turbojet.
Used on fighter air crafts like the FA-18 Hornets etc.
Uses jet propulsion, rather than air driven propeller.
Jet propulsion is much more efficient for high speed, and constant speed use, so no good for cars.

Rocket.
Rocket propulsion has almost no moving parts, and uses thrust for propulsion, but we must fuel up with both fuel and air, and once again much more efficient for hi speed and constant speed use, especially at hi altitudes where the air is very thin, or no air at all.


Suspension
Legs.
Legs are very good for all terrain use.
However, they are very inefficient for speed.

Wheels.
Presently, the humble wheel is still the best, although no air suspended ride, and certainly no travel over land and sea.

Air Suspension.
The air suspended hovercraft requires energy powered air for suspension, but air suspension does allow travel over both land and sea, and does give a smoother ride.
[Think of a hovercraft as a mini version of a helicopter].
However, fuel consumption just too high to suspend the vehicle by air, compared to the humble wheel.

Magnetic Levitation.
Gives a great ride, but presently requires railway tracks, such that travel will be limited.

Anti-gravity.
Sounds like it will deliver a smooth ride, and travel on all terrain, however the technology presently doesn't exist...