from their lies you will know them.

[Billfz1]

Do you think an engine putting out 175 ft-lbs if torque would accelerate a Genesis very well?



Well, how about an engine putting out 1000 hp??? That would probably be quite fast, wouldn't it?


How about if the engine is the same???????????????


How about a gas turbine?


Hp is what accelerates a car and determines how fast it will go. Torque may make it easier to drive and reduce the number of gears if the torque stays pretty level over a wide rpm range, but hp gets you to the finish line first.

Well a gas turbine came within 2 laps of winning the Indy 500. If you have enough gear reduction you could use it to run your watch. You need both.
One of the things that could really improve the Genesis would be to lighten the car. That improves both acceleration and mileage.
Bill

 

[GenesisCaptain]

Here is the simple reality that is easy to forget: HP = Torque x RPM ÷ 5252

The nut is that torque and HP are basically the same. Not really, but they are mathematically bound. They are not independent of one another. So, what that means is that with the proper transmission gearing, two engines with different HP and torque curves can be made to perform the same. The engine, transmission, differential, wheel size-- final drive ratio-- must be considered as a whole, not just the engine by itself.

 

[forzza1]

From an Acura forum -- don't know how true the stats are --


Although the Genesis R-Spec has 429hp, its actual performance numbers aren't exactly that impressive relatively speaking. The TL 6MT is just a tenth of a second slower to 60mph and 1/4 mile. The $30k Accord 6MT on the other hand has the same trap speed at 103mph. A E550 4matic with 30 less hp carrying an extra 200lb is significantly faster (0-60mph in 4.3s thanks to launch, 1/4 mile at 12.8s@112mph, where the trap speed indicates its far superior actual power). Perhaps the 429hp in the Genesis stands for 429 hyundai power? Even a BMW 550i with 400hp is doing 0-60mph in 4.8s and 1/4 mile in 13.1s@109mph. There's also the Audi S6 with 420hp that does 0-60mph in 3.7s and 1/4 mile in 12.1s@115mph.

__________________

This it totally inaccurate. Trap speed for R Spec is 107mph+. Quarter mile is low 13. On a very good and sunny day a stock Acura TL will do a 100mph trap speed. Quarter mile on these cars is high 13. Same goes for Honda Accord (stock).

 

[GenesisCaptain]

This it totally inaccurate. Trap speed for R Spec is 107mph+. Quarter mile is low 13. On a very good and sunny day a stock Acura TL will do a 100mph trap speed. Quarter mile on these cars is high 13. Same goes for Honda Accord (stock).

Ditto. According to Car and Driver, the Acura TL is not anywhere in the ballpark of the Genesis. The TL is 5.7 seconds 0-60 and 14.4 seconds quarter mile at 99 MPH. The R-Spec is 5.1 seconds to 60 and 13.7 1/4 mile at 103 MPH.

Similarly, the 2013 Accord manual is 5.6 seconds to 60 and 14.0 seconds to the quarter mile at 103 MPH.

The E550 4Matic specs are legit: 4.3 0-60; 12.8 second quarter at 112 MPH.

So, the lesson is that the Acura forum grossly inflates Honda specs, but they are OK accurately quoting MB statistics. Acura fail.

 

[forzza1]

Ditto. According to Car and Driver, the Acura TL is not anywhere in the ballpark of the Genesis. The TL is 5.7 seconds 0-60 and 14.4 seconds quarter mile at 99 MPH. The R-Spec is 5.1 seconds to 60 and 13.7 1/4 mile at 103 MPH.

Similarly, the 2013 Accord manual is 5.6 seconds to 60 and 14.0 seconds to the quarter mile at 103 MPH.

The E550 4Matic specs are legit: 4.3 0-60; 12.8 second quarter at 112 MPH.

So, the lesson is that the Acura forum grossly inflates Honda specs, but they are OK accurately quoting MB statistics. Acura fail.

Agree. However you are a bit conservative on Genesis numbers. Quarter mile is anywhere between 13.1 to 13.3 seconds. Not long time ago one of the members of this forum run 13.2 sec 1/4 mile.
Also 4.8 sec 0-60 is more realistic.
From MT:
Even so, here is a Korean sedan as quick to 60 mph as a BMW 550i (4.8 seconds) and faster over a quarter-mile than a Ford Mustang V-6 (13.3 seconds at 107.1 mph vs. 13.7 sec @ 102.0 mph). It demolishes the 4.6's figure-eight time by nearly 1 second (26.3 seconds at 0.68 g) and consistently stops three feet shorter from 60 mph (109 feet). It also pulls an average 0.87 g on the skidpad (up from 0.86 g).

Read more: http://www.motortrend.com/roadtests/sedans/1107_2012_hyundai_genesis_5_0_r_spec_test/#ixzz2PAhcnOzh

 

[GenesisCaptain]

Agree. However you are a bit conservative on Genesis numbers.

All of the stats I cited came from C&D. I wanted to make sure that all the numbers came from the same source for consistency. The auto magazines tend to have their own procedures to generate some level of consistency, but they will not necessarily produce results that compare to other magazines. What are MT's numbers for the same set of cars?

For example, C&D clocked the 2011 BMW 550i at 4.8 seconds for the automatic and 5.1 seconds in the manual.

 

[forzza1]

All of the stats I cited came from C&D. I wanted to make sure that all the numbers came from the same source for consistency. The auto magazines tend to have their own procedures to generate some level of consistency, but they will not necessarily produce results that compare to other magazines. What are MT's numbers for the same set of cars?

For example, C&D clocked the 2011 BMW 550i at 4.8 seconds for the automatic and 5.1 seconds in the manual.

I understand and agree with your method.

MT has the following numbers:
2011 BMW 550i: 0-60 mph 4.8 sec Quarter mile 13.3 sec @ 106.9 mph

2012 Acura TL: 0-60 MPH 6.0-6.4 sec (MT est) - no 1/4 mile mentioned.

 

[the M5 beast]

Lets make this real simple.

H.P. = top speed

Torque = acceleration

0-60 and 1/4 miles times are effected by a lot of variables including but not limited to- H.P., torque, final gear ratio, trans ratio, weight, tire size, and shift times,

My M5 had 507 horse, 383 ft pds of torque and a top speed of 203 M.P.H. with a non forced induction motor. Stoplight to stoplight it is kind of a dog, but with a long distance or a rolling 30 MPH start if your not driving a Lambo or it's equal you don't stand a chance and they even have troubles taking it.

 

[stuofsci02]

Lets make this real simple.

H.P. = top speed

Torque = acceleration

This is not true... Once you are through the low RPM band (in 1st gear) which takes a fraction of a second acceleration is all about HP. If you are driving stick you can even avoid the low RPM band with a good launch.

When people think TQ for cars it is really that ability to have good pickup without needing to rev the car up.

If TQ = acceleration, then we should be using a diesel in cars we want to accelerate fast...

 

[gameday22]

Remember, you cannot have horsepower without torque, but you can have torque without horsepower!" It's called a dump truck.


Read more: http://www.hotrod.com/techarticles/hrdp_0401_torque_horsepower_guide/viewall.html#ixzz2PDXvy9ga

Enzo Ferrari was once quoted as saying "Horsepower sells cars, torque wins races". Obviously Mr. Ferrari believed that torque was most important of the two provided that both were present in sufficient amounts. With lots of turns, acceleration, and braking, torque wins hands down IF there is sufficient horsepower. Without the horsepower, diesel trucks would win auto races. Without torque, jet-powered cars would win all the races.


And as a bottom line none of it matters if you cant successfully put that force to the ground.

______________________________

Help support this site so it can continue supporting you!

 

[stuofsci02]

Remember, you cannot have horsepower without torque, but you can have torque without horsepower!" It's called a dump truck.


Read more: http://www.hotrod.com/techarticles/hrdp_0401_torque_horsepower_guide/viewall.html#ixzz2PDXvy9ga

Enzo Ferrari was once quoted as saying "Horsepower sells cars, torque wins races". Obviously Mr. Ferrari believed that torque was most important of the two provided that both were present in sufficient amounts. With lots of turns, acceleration, and braking, torque wins hands down IF there is sufficient horsepower. Without the horsepower, diesel trucks would win auto races. Without torque, jet-powered cars would win all the races.


And as a bottom line none of it matters if you cant successfully put that force to the ground.

To a certain extent this is true.. People buy based on HP but they drive TQ in normal day to day driving.

But if your concern is Max Acceleration with an internal combustion engine, then area under the HP curve in the operating RPM range is most important.

 

[427435]

What makes for a winning street or race car is a car with a broad hp curve---------------which requires a torque curve that has a high peak at a relatively low rpm. That characteristic, in engine circles, is called torque "backup."

From the basic HP formula of HP = torque x rpm/5252, one can see that if torque goes up 10% as rpm is reduced 10%, the hp stays constant-----which is a good thing.

On the other hand, a heavy duty industrial engine with high torque (say 1000 ft-lbs) at a low rpm (say 1000) is only making about 190 hp. If that torque drops to 500 ft-lbs at 1500 rpm, hp has dropped to 143------which is not so good.

An engine that makes lots of HP at a high rpm, that quickly falls on its face as the rpm is reduced is also not so good--------------unless you have lots of gears or a continuously variable drive train (snowmobile engines and drivetrains come to mind).

In the end, a good balance is needed----------especially in street machines.

 

[GenesisCaptain]

This is not true... Once you are through the low RPM band (in 1st gear) which takes a fraction of a second acceleration is all about HP. If you are driving stick you can even avoid the low RPM band with a good launch.

When people think TQ for cars it is really that ability to have good pickup without needing to rev the car up.

If TQ = acceleration, then we should be using a diesel in cars we want to accelerate fast...

The original post is accurate... A vehicle will always accelerate directly proportionally to the engine's torque curve. Always.

But, all of the other details about torque band, max RPM, transmission gearing, etc. confuse the topic.

 

[Potty_Pants]

What makes for a winning street or race car is a car with a broad hp curve---------------

Horsepower, torque, hood scoops or vinyl

Ask any racer, any real racer. It doesn't matter if you win by an inch or a mile; winning's winning.

ppp

 

[stuofsci02]

The original post is accurate... A vehicle will always accelerate directly proportionally to the engine's torque curve. Always.

Since HP = (TQ x RPM) / 5252 you are basically saying that water is wet..

You can say the exact same thing about HP, but it is far more accurate because it takes into account the power that the TQ is making..

You could have 500 ft-lbs of TQ at 1000 RPM, but if you don't make TQ at high RPM you are going to be slow...

 

[GenesisCaptain]

Since HP = (TQ x RPM) / 5252 you are basically saying that water is wet..

You can say the exact same thing about HP...

I stand by my original post. A vehicle will not accelerate directly proportionally to the HP curve-- there is a non-linear relationship between HP and torque. the M5 beast wrote that "H.P. = top speed; Torque = acceleration." You said that is not true in your response.

It is absolutely true. Torque is the thing that causes acceleration, not horsepower. Also, keep in mind that a dynamometer measures torque and calculates HP from torque. Torque is the real thing, HP is a derived value.

This does not take away from all of the other comments about HP = speed, RPM power bands, no torque at high RPM, etc. It is just that the fundamental physics of acceleration is based on torque, not HP.

 

[stuofsci02]

I stand by my original post. A vehicle will not accelerate directly proportionally to the HP curve-- there is a non-linear relationship between HP and torque. the M5 beast wrote that "H.P. = top speed; Torque = acceleration." You said that is not true in your response.

It is absolutely true. Torque is the thing that causes acceleration, not horsepower. Also, keep in mind that a dynamometer measures torque and calculates HP from torque. Torque is the real thing, HP is a derived value.

This does not take away from all of the other comments about HP = speed, RPM power bands, no torque at high RPM, etc. It is just that the fundamental physics of acceleration is based on torque, not HP.

I stand by my original statement.. I'm sorry, but TQ and acceleration are only related via HP.

In simple terms a car that makes 500 TQ but only 300 HP will be beaten in acceleration by a car that makes 500 HP and only 300 TQ assuming a realistic HP/TQ curve. All else being equal..

 

[Crusty Old Shellback]

stuofsci02,
I think your missing the Captians point.

You can not measure HP. It is a derivitive of measured torque divided by RPM's.

So even to say that TQ and acceleration are only related by HP is inaccurate. TQ is acceleration. The HP number is simply a product of TQ and RPM's.

The main problem is that everyone relates to HP even though they really don't understand it.

If you take a look at a dyno graph, you will see that HP and TQ curves will always cross at 5252 RPMs. Why? Because of the formula for calcualting HP = TQ/5252.

 

[GenesisCaptain]

I stand by my original statement.. I'm sorry, but TQ and acceleration are only related via HP.

I don't know what to say. Google it more, I guess. Torque is a real physical thing; HP is a man-made value, derived from torque. HP is helpful in understanding an engine's dynamics, but torque is the twisting force that causes acceleration.

Maybe this will help. An electric motor has torque at 0 RPM. So, consider a Prius, with its electric motor that produces about 295 ft-lbs of torque from 0 RPM to about 1,200 RPM. Guess what accelerates a Prius when the gasoline engine is off-- the torque of the electric motor, not the HP. It starts with 0 HP and gradually ramps up to 67 HP at 1,200 RPM. However the Prius accelerates quite nicely despite a total lack of HP at the bottom end.

The main problem is that everyone relates to HP even though they really don't understand it.

Crusty, you are dead-on. Here is a quote by an automotive journalist in Automobile Magazine about the Prius: "Powering the new Prius are a 78-horsepower, 1.5-liter four-cylinder engine and a 67-horsepower electric motor. The electric motor makes its horsepower from 1200 to about 1500 rpm, whereas the gasoline engine produces peak power at about 5000 rpm."

The statement is factually accurate, but it is an epic fail of explaining the car's power, and it truly misleads the readers. The electric motor's HP is irrelevant in that 1,200 to 1,500 range. What makes the Prius start from a dead stop is its massive torque from 0 RPM to 1,200. That is what the writer should have commented on, but saying the car has 11 HP at 200 RPM does not sound very convincing.

 

[427435]

Let's see if I can clarify this. The ONLY torque that matters in accelerating a car is the torque at the REAR WHEELS. That is determined by gearing as well as the engine.

How fast the car accelerates is determined by how fast the wheels can be spun at that torque-------------------------WHICH EQUALS HP!!!

Again, a gas turbine, that only generates 100 ft-lbs of torque, will accelerate a car rather rapidly because it is also turning 30,000 rpm and generating 570 hp.

OR:

Accelerating a car requires work to be done as a car at 50 mph has a lot more energy than a car at 25 mph. Work per unit time, by definition, is hp. You can accelerate a car from 25 to 50 mph with a low hp engine---------if you aren't in a hurry. The quicker you get from 25 mph to 50 mph, the more hp you will need in that engine.