TommyDeVito

Jonboy, I didn't do backflips over the speed Mr. Bias. Only mentioned that it has torque, which is good for passing. You ride the torque curve with your shifts, stay on boost, and yes, it has good passing power for what it is, and to me, better than a damn Civic, etc. Once you know the car's engine characteristics you know how to drive the thing. Stay on boost, stay in that torque curve (under the curve LOL) and the thing will move. Much different than a Civic and much less effort. And you claim that I'm wrong. LMAO. You don't understand +100 ft lbs, and you are saying it's the same as 128 Ft Lbs, that's all you had to say

You are the one going on and on about it like I said it's a fvcking 1/4 mile beast!
All I said was it had good torque values and good passing power and look at all this bs from you. I never mentioned most of what you said, never compared it to a sportscar but reading comprehension doesn't sound like your strong suit.

And you know what? If the car was a Honda you'd be going on and on about it. Look at those Honda engineers developing a Diesel, and look at the torque values, etc, etc. You are Mr. Bias on this forum. Look at your responses after people are dismissing Honda and mentioning other vehicles.

If you've driven it, a boosted Diesel, and you say you have, then maybe you need to learn how to drive because from your comments it doesn't sound you learned how to drive it. You drove it just like a Civic.

And either way, this is what I said and you acted like a 7 ft porn star with a 12" dick came all over your face.

Perhaps take off the Honda underoos, change the Honda sheets, and don't get so upset about other people dismissing Honda and their current offerings. You are Mr.-Defend-Honda-at-all-costs and a Hondapologist, actually the biggest Hondapologist. Honda doesn't make their similar cars with good torque, therefore it doesn't matter. We get it, what Honda says, does, is what you'll say. If they came out with a vacuum you'd be on and on about why it's better than Dyson when the numbers don't match up and proliferate on the subject ad nauseam.

Perhaps quit making a mountain out of a pile of shit in the yard or just show us the Honda stamped checks and be done with it.

JonBoy

You're wrong but you don't realize why and I don't have time to educate you. If you understood what differentiation is, and how that applies to hp and work, you'd stop talking, read up on the topic a bit and then come back and agree that you misspoke.

http://www.hotrod.com/techarticles/h...e/viewall.html

The last paragraph makes my point:

Guys, this is a very basic principle. You can argue all day long but because you don't truly understand how a 140 hp / 150 ft-lb car makes its power, and recognize the advantages and disadvantages of said car, you also don't realize why it's just as fast as a 140 hp / 300 ft-lb car (which also has advantages and disadvantages).

I've said it a bunch of times and I'll say it again - AREA UNDER THE CURVE is what matters. You probably don't even know what that means, or how it applies, but look it up and you'll see I'm right.

That's why HP (and not torque!)is the best indicator of the trap speed of a car in the 1/4 mile. It's the stronger correlation to how quickly a car accelerates.

This discussion also highlights why hybrid powertrains are so popular with cars now. You CAN effectively make a car with low-end torque and top-end power and INCREASE YOUR AREA UNDER THE CURVE. You can't do that with turbo or normally aspirated motors without compromising in some area and thus paying a penalty at some point.

JonBoy

What's hilarious is that you're claiming the TDI offers "decent passing power", as if that somehow is not available from Honda. Then you claim the TDI matches your driving style, which is fine, but in no way invalidates the use of a smaller, higher revving engine to achieve the same result.

I like the TDI. I'm glad you do too. As previously stated, I do wish Honda brought their diesels here, along with other manufacturers. I've been waiting on the Mazda 2.2 diesel for a while already. I just don't claim that they're faster, have better passing power or otherwise stomp all over the typical gasoline engines from other manufacturers in that area.

What's funny, Mr. "Unbiased", is that you have an issue with Honda that is the opposite of mine, but somehow, that's not a bias. Pot, kettle.

Dizings2k

First off, I don't appreciate your attempt to talk down to me in regards to the area under the curve comment. I know exactly what "area under the curve" is and why it is important. No need to attempt to insult me.

Forget horsepower. the same exact car with 150 tq and 300 tq will not accelerate the same. Once they are outside of their usable RPM peak torque range, yeah then horsepower comes into play. Floor it at 100mph with 140hp 150\300 tq and yeah I think the cars would accelerate the same, as they would both be working outside of their usable torque range. Floor it from a stop or somewhere where the engine isn't screaming and you're going to have that 300tq car run away from the 150.

This has been demonstrated over and over again with the supercharging vs turbocharging debate on this very site. Many videos are out there of same horsepower S2000's one supercharged (less torque) one turbo (more torque) and turbo pretty much always wins... not by a fender length or any amount of driver error.. car lengths. How do you explain that?

Dizings2k

IN A QUARTER MILE drag race... correct. Tom, and yourself at other points of your conversation are talking about usable daily driving power. Not a 1/4 mile at a time. Torque is a bigger factor in daily usable power. This is why some people don't like driving the S around town, stomp on it to merge on the highway in 4th or higher and the car does nothing. No torque, must be screaming to get into that horsepower area.

Elistan

You are mistaken. They will accelerate pretty much the same. If horsepower means nothing do you think a 140hp/300ftlb car will accelerate just the same as a 600hp/300ftlb car? No, of course not. I'll attempt to explain why from a physics standpoint.

Horsepower is not "completely dependent" on torque. Horsepower is dependent on torque and engine speed. You can exert a thousand pound-feet of torque on an engine but if it doesn't turn, the car doesn't move either and you're not generating any horsepower. So if when thinking about the acceleration of a car what we're really concerned about is both torque and engine speed, is there some sort of value we can use that represents this? Fortunately, there is - power. After all, hp = tq * revs.

So why does it work?

Considering the two engines above you mention, hopefully you realize they will have vastly different maximum engine speeds. To make things easier, I'll just assume that each has a perfectly flat torque curve. The 140/150 engine will generate its max power at 4900 rpm. The 140/300 engine will generate its max power much lower, at 2450 rpm. (Obviously if the engine with 300 lb-ft made that torque at 5000 rpm, we'd be talking about a completely different situation - a 285 hp engine.) It's not a coincidence that the engine with twice the torque but half the horsepower revs to half as many rpms.

Now I have to make another assumption - that the top speed in each gear is the same for both cars. That is, for example, 1st is good for 40 mph, 2nd is good for 60 mph, 3rd 90mph, etc. (This isn't always the case in the real world. Some cars have very short gears starting out to help things get going, other cars have so much power that a short first gear would be useless.) Given the very different max engine speeds of the two cars, they will of course have different gearing in the transmission. The 4900 rpm car will have an overall gearing (meaning transmission ratio times final drive ratio) in 1st of 9.125:1 with 255/45/17 tires to hit 40 mph. The 2450 rpm car, on the other hand, will have a 1st gear overall ratio of 4.5625. Again, it's not a coincidence that the car with half the revs will have gearing half as tall.

So what does that mean for the acceleration? At this point we get to talk about the whole F=ma thing. By having half as tall gearing as the the 140/150 car, the 140/300 has its torque as measured at the wheels halved by comparison. Meaning, at the wheels each car is producing the same amount of torque. We can use the tire diameter to convert the wheel rotational force into linear force, and knowing that each car is experiencing the same linear force and has the same mass, we know that they each will accelerate equally too. This would even hold true if each car was at highway speed in a 6th gear good for a top speed of 160 mph.

But what about in the real world? Well, in the real world, torque curves aren't perfectly flat therefore peak tq and hp numbers don't tell the whole story, and gearing and number of gears and tire size can differ greatly so we can't make direct comparisons on how the engine's rotational force translates into linear force via transmission, final drive and tires. And of course the mass of cars differs in the real world. Therefore there will be variations due to these reasons on how a 140/150 car and a 140/300 car accelerate - just like there will be minor variations on how a 140/150 and a different 140/150 car accelerate.

But generally, all you need to know to get a representative idea of a car's acceleration is its power to weight ratio, not its torque to weight ratio.

Dizings2k

And for the record, yes, I apologize and should have added "In most situations" to the statement that a higher torque car will out accelerate a lower torque car.

Dizings2k

Yes, I follow you on ALL of that... however, I am talking about the EXACT same car. Same gearing ratios (I know that example doesn't make sense as what happens in the real world is your example of halving the gear ratios) By your example, having the SAME gearing and therefore same top speeds in each gear, the higher torque car will get there faster... in *most* situations. Right?

Edit: Yes, I understand that power to weight is the best way to judge and compare cars acceleration.

Thanks for the huge explanation! slow day at work? yeah me too...

JonBoy

Sorry - your comments don't match your knowledge claim. Your questions show you don't understand the idea fully.

As previously stated, for any given speed range, one car will be faster than the other. However, across a broad range, they will be pretty much identical. Acceleration profiles will differ AT ANY GIVEN TIME but overall, they will, in fact, accelerate at roughly the same rate.

When you're doing races between S2000s, they're usually from a roll and the turbo car is fully spooled up. The disadvantage of longer spool times (and thus, less torque) at lower rpm has been effectively removed. The supercharged car has lost its advantage of building torque early on. Again, pretty simple. Run them both in the 1/4 mile and you'd see a much tighter race, assuming no anti-lag technology, etc, etc (ie, boost build-up at launch). Not necessarily equal but much closer (all other things equal).

If you read that full article (I assume you haven't, based on the question, since it was already answered in that article), you'll note that in racing (from a roll or on a road course where you rarely drop out of your "good" rev range), you are dealing only with a recurring rpm range (say, 5000-8500 rpm for an S2000), so you have to look at area under the curve for JUST THAT SECTION of the hp curve. That results in a turbo car car (especially a big-turbo car) having more area under the curve IN THAT PARTICULAR RPM RANGE as the torque is flat (and way higher) at that range, leading to more area under the curve. It gets to "ignore" its early weak engine characteristics and take full advantage of the big top end of the turbo. The supercharger, meanwhile, has a linear power curve that just builds consistently and thus, the top end is not exaggerated nearly as much. It'll lose every time.

Your example of a 140/300 vs a 140/150 is incorrect because you're not realizing engine characteristics behind those motors, typically. You can't make 140/300 without having a different type of engine (FI) or increasing displacement and reducing revs. Both generally reduce the rev range but regardless, knowing the relationship between hp and torque, the 140/300 car will make early torque and not rev as high or else will reduce in torque as the revs climb and thus probably flatten or drop in hp at the top end. The 140/150 car will rev higher to make up for the difference (by definition, it MUST rev higher to make the same power with less torque) and its torque curve will be much flatter, though not as high. That means a very linear acceleration curve, whereas the 150/300 car will almost certainly taper off in the top end (otherwise, it would make more hp), giving away the low-end advantage at the top end of the rev range.

Your example is pretty close to a TDI vs Civic argument and if you care to review my assumptions, you'll see they're correct. TDI is FI with a low redline. Civic revs higher to make up for it. The two cars have very similar 1/4 mile times and trap speeds (2010 Civic LX with 5MT is 16.1s @ 87mph, 2010 TDI with 6MT is 16.4s @ 84 mph).

Dizings2k

Right... so we are agreeing that the cars will accelerate differently at given speeds, I agree with that. Using those two cars as an example the quarter mile is the same, the story may be different before hand and different afterwards though.

So are we talking about quarter mile? Passing power? from a stop?

With the S2000's, it's frequently demonstrated that basically from 25mph on (turbo is limited traction due to torque), a turbo car will outrun a supercharged one in any situation.

And yes I understand the higher torque, lower rev, type engine characteristics perfectly.

What I'm trying to say is it is possible for a higher torque car to outrun a lower torque car in a given range because the horsepower hasn't come into play to catch the lower torque car up to the higher torque car... follow me? Whether that happen in 1/8 mile, passing, 1/4 mile, I didn't state. Just saying passing power say 50-80mph a higher torque car may be better for daily driving.