New Mazda 'WIDE' (15B) Rotary 2007
#251
WWFSMD?
Join Date: Jul 2003
Location: Massachusetts, USA
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by hedgecore
My point is that you seem to be ignoring the assumptions of current technology...you're high HP, low torque motor works well, but there are limitations to how many gears can be efficiently implemented into a vehicle...in any 4-7speed transmission on a car engineered to pass crash tests and sold to consumers, torque is a desirable variable in determining a cars performance...
A well designed car will have an adequate and balanced amount of both based on it's design...
A well designed car will have an adequate and balanced amount of both based on it's design...
Originally Posted by hedgecore
P.S. I'm not trying to be a dick...i'm genuinely curious...how well versed are you in physics?
#252
WWFSMD?
Join Date: Jul 2003
Location: Massachusetts, USA
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by therm8
Perhaps not, but you seem to be implying that horsepower is doing all the work, when in fact it is not. Your points are all based on gearing, which is used to make better use of torque output to provide more work per time, and have no relevance to the points I am trying to make.
- force = mass * acceleration
- torque = force * distance
- work = force * distance
- power = work / time
- power = force * velocity = torque * angular velocity
- engine power * system efficiency = wheel power (this is a standard input/output relationship)
- wheel power = wheel torque * wheel speed
- engine power * system efficiency = wheel torque * wheel speed
- wheel torque = engine power * system efficiency / wheel speed
- Peak power isn't the only important attribute because we don't always drive at the RPM corresponding to it
- More torque is needed to make high power at low RPM
- Many drivers prefer not to have to shift a lot or to keep it in a high-RPM power band and there are some competitive situations when it's disadvantageous to have to shift a lot
- Wheel torque is proportional to engine torque in any fixed gear... this is why you don't accelerate harder in a fixed gear as your power increases with speed in a vehicle with a flat torque curve (which may be what usually gets people so confused about torque vs power)
I seem to remember there being an illustrative problem in my old physics text about a car accelerating up a hill against significant wind resistance (which is a cubic function, if memory serves). I'll be happy to dig it out and post it if anyone wants.
#253
Bummed, but bring on OU!
I gave up. You weren't understanding what I was trying to say. I wasn't understanding what you were trying to say. I was leaving gearing out of it and approaching it from the engine side. That is why I hate the hp vs tq discussions, because it is too complicated to argue effectively. Power is only more important as a concept, not as a physical analysis. That's why the units of horsepower and watts were invented, they provide a conceptually easier way of looking at work capability. When it comes to engines, however I still maintain that one is not more important than the other. Regardless my end of this discussion is now finished.
#255
Int'l Man of Mystery
Join Date: Jan 2004
Location: Central Florida
Posts: 3,651
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by globi
As I said SMGs and CVTs might not be accepted by everybody, but they wouldn't be used in racing if they were just better on paper.
I know what the mechanical differences are between a SMG/DSG and a manu-shift auto. I have the auto in my current car. I've played with the shifter. I don't like it. I've had the car 3 years. I still don't like it, can't get used to it. I've driven BMW's with it too. Full auto is just more comfortable. I hate the +/-. I LIKE clutching. I like to skip shift sometimes. You can't argue this... this is personal preference. And there are others who feel this way. You like SMG... so good... get one in your car. Just don't tell the manufacturers to drop regular manual transmissions in favor of SMG, because there are plenty of us who hate them.
See this post... https://www.rx8club.com/showpost.php...&postcount=154
Last edited by Japan8; 11-13-2005 at 08:01 PM.
#256
Originally Posted by Japan8
Just don't tell the manufacturers to drop regular manual transmissions in favor of SMG, because there are plenty of us who hate them.
(Actually DSG seems to have more potential than SMG, due to the double clutch system there's no need for a power interrupt at all.)
#257
WWFSMD?
Join Date: Jul 2003
Location: Massachusetts, USA
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by therm8
I gave up. You weren't understanding what I was trying to say. I wasn't understanding what you were trying to say. I was leaving gearing out of it and approaching it from the engine side (1). That is why I hate the hp vs tq discussions, because it is too complicated to argue effectively (2). Power is only more important as a concept, not as a physical analysis (3). That's why the units of horsepower and watts were invented, they provide a conceptually easier way of looking at work capability. When it comes to engines, however I still maintain that one is not more important than the other (4). Regardless my end of this discussion is now finished (5).
- You need to consider gearing (either directly or indirectly - through speed) when looking at an engine.
- Too complicated to argue effectively? This isn't philophy... I don't mean to sound arrogant, but either you understand it or you don't. If you don't, you can learn it if you choose to.
- Hogwash. Just because power is "calculated" doesn't mean that it's important only as a concept. In a sense, torque is also calculated (dynos have to be calibrated to measure force and multiply it by a distance).
- Please don't take this as an insult because that's not my intention, but you've misunderstood some key concepts. If you want to figure this stuff out, you have several choices:
- Google it (though you run the risk of finding misinformation).
- Read some physics/engineering texts.
- Ask a teacher/professor about it. Feel free to show them my posts (I'll be happy to elaborate on anything).
- On that note, sorry to everyone else for perpetuating this off-topic tangent. Also, thanks for the kind words globi.
#258
Deslock, your write ups have been thurough. But they will never support your generalized claims.
There are many variable that contribute to the characteristics of a sports car. Ignoring torque is foolish.
Would you drive a car that has a constant 10ft-lbs of torque that redlines at ~157,000RPM with a max 300HP?
No, no you wouldn't...
Would you drive a car that has a constant 300ft-lbs of torque that redlines at ~175RPM with a max of 10HP?
No, no you wouldn't...
An car that yeilds good performance can come in different flavors...and current engineering doesn't give us any clear "Best way" of doing things. The smart engine designers know the limitations of their resources and abilities...these limitations are defined by the realities of things outside of you simplistic text-book explinations.
These two things are tied together...neither is nay more important than the other.
The best production cars on earth have engines that neglect neither torque or HP.
HP is not more important than Torque...this statement is much to general to be true.
*BOTTOM LINE*
If forced to trade one for the other...there is no clear answer without taking many factors into consideration.
If Power was more important, then you could blindly use it as your answer in all cases.
There are many variable that contribute to the characteristics of a sports car. Ignoring torque is foolish.
Would you drive a car that has a constant 10ft-lbs of torque that redlines at ~157,000RPM with a max 300HP?
No, no you wouldn't...
Would you drive a car that has a constant 300ft-lbs of torque that redlines at ~175RPM with a max of 10HP?
No, no you wouldn't...
An car that yeilds good performance can come in different flavors...and current engineering doesn't give us any clear "Best way" of doing things. The smart engine designers know the limitations of their resources and abilities...these limitations are defined by the realities of things outside of you simplistic text-book explinations.
These two things are tied together...neither is nay more important than the other.
The best production cars on earth have engines that neglect neither torque or HP.
HP is not more important than Torque...this statement is much to general to be true.
*BOTTOM LINE*
If forced to trade one for the other...there is no clear answer without taking many factors into consideration.
If Power was more important, then you could blindly use it as your answer in all cases.
Last edited by hedgecore; 11-14-2005 at 10:57 AM.
#259
Int'l Man of Mystery
Join Date: Jan 2004
Location: Central Florida
Posts: 3,651
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by globi
No one said to get rid of manual transmissions. Auto, CVT, SMG and DSG has been an option so far and it will be an option in the future.
(Actually DSG seems to have more potential than SMG, due to the double clutch system there's no need for a power interrupt at all.)
(Actually DSG seems to have more potential than SMG, due to the double clutch system there's no need for a power interrupt at all.)
#260
Bummed, but bring on OU!
Originally Posted by Deslock
- You need to consider gearing (either directly or indirectly - through speed) when looking at an engine.
- Too complicated to argue effectively? This isn't philophy... I don't mean to sound arrogant, but either you understand it or you don't. If you don't, you can learn it if you choose to.
- Hogwash. Just because power is "calculated" doesn't mean that it's important only as a concept. In a sense, torque is also calculated (dynos have to be calibrated to measure force and multiply it by a distance).
- Please don't take this as an insult because that's not my intention, but you've misunderstood some key concepts. If you want to figure this stuff out, you have several choices:
- Google it (though you run the risk of finding misinformation).
- Read some physics/engineering texts.
- Ask a teacher/professor about it. Feel free to show them my posts (I'll be happy to elaborate on anything).
- On that note, sorry to everyone else for perpetuating this off-topic tangent. Also, thanks for the kind words globi.
1. gearing can be ignored in the original context of the discussion, since I was originally talking about 2 different engines for the same car. Therefore with the same gearing. The discussion got carried beyond that original context.
2. I don't feel I've misunderstood anything. I was just talking about a different aspect of the topic than you. When 2 people narrow their focus to different parts of the system, the topic cannot be discussed effectively.
3. In that case, everything is calculated. Since everything is calibrated to some prime standard.
4. I have a heavy background in physics. Newtonian to nuclear. But perhaps my internet arguement capabilities are not up to par enought to get my point across effectively.
No offense taken, and now let's get back to the topic at hand, if there is one any longer.
#261
WWFSMD?
Join Date: Jul 2003
Location: Massachusetts, USA
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by therm8
I guess I'm not done, since I must now defend myself...
1. gearing can be ignored in the original context of the discussion, since I was originally talking about 2 different engines for the same car. Therefore with the same gearing. The discussion got carried beyond that original context.(1)
2. I don't feel I've misunderstood anything. I was just talking about a different aspect of the topic than you. When 2 people narrow their focus to different parts of the system, the topic cannot be discussed effectively.(2)
3. In that case, everything is calculated. Since everything is calibrated to some prime standard.(3)
4. I have a heavy background in physics. Newtonian to nuclear. But perhaps my internet arguement capabilities are not up to par enought to get my point across effectively.(4)
No offense taken, and now let's get back to the topic at hand, if there is one any longer.
1. gearing can be ignored in the original context of the discussion, since I was originally talking about 2 different engines for the same car. Therefore with the same gearing. The discussion got carried beyond that original context.(1)
2. I don't feel I've misunderstood anything. I was just talking about a different aspect of the topic than you. When 2 people narrow their focus to different parts of the system, the topic cannot be discussed effectively.(2)
3. In that case, everything is calculated. Since everything is calibrated to some prime standard.(3)
4. I have a heavy background in physics. Newtonian to nuclear. But perhaps my internet arguement capabilities are not up to par enought to get my point across effectively.(4)
No offense taken, and now let's get back to the topic at hand, if there is one any longer.
- My original response to you was to your post containing, "Apply x torque for some amount of time and you get power." (see post 227). It's worth noting that even with two cars with identical gearing, you still must consider what that gearing is (post 254) because if the two engines have different redlines, there may be vehicle speeds at which the two cars are in different gears.
- It appears you have either misunderstood a few things or there are some typos in your posts. You wrote:
- "Apply x torque for some amount of time and you get power." (this is not necessarily true... if you apply torque at some angular speed and you get power... to be fair, when questioned about it you mentioned that your statement was elaborated on in a subsequent post, but what you wrote is still misleading, even in this context)
- "I was leaving gearing out of it and approaching it from the engine side." (if you're looking at acceleration, you really can't do that)
- "Power is only more important as a concept, not as a physical analysis." (this is false)
- My response was really for those who think power is esoteric because you don't "feel" it directly. In any fixed gear force at the wheels is *proportional* to engine torque, but you don't feel the engine torque directly either (it goes through the transmission first).
- My cousin is a brilliant guy with a physics PHD who is working on some pretty wild stuff (involving - I kid you not - teleportation). But if I asked him what makes a car accelerate, he probably wouldn't be able to explain it and would stumble over a few concepts as some have done in this thread. Then again, he's not a sports car enthusiast and he doesn't spend his free time in online torque vs power discussions.
Anyway, thanks for keeping it cordial.
#262
WWFSMD?
Join Date: Jul 2003
Location: Massachusetts, USA
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by hedgecore
Deslock, your write ups have been thurough. But they will never support your generalized claims.
There are many variable that contribute to the characteristics of a sports car. Ignoring torque is foolish (1).
Would you drive a car that has a constant 10ft-lbs of torque that redlines at ~157,000RPM with a max 300HP?
No, no you wouldn't...
Would you drive a car that has a constant 300ft-lbs of torque that redlines at ~175RPM with a max of 10HP?
No, no you wouldn't...(2)
An car that yeilds good performance can come in different flavors...and current engineering doesn't give us any clear "Best way" of doing things (3). The smart engine designers know the limitations of their resources and abilities...these limitations are defined by the realities of things outside of you simplistic text-book explinations (4).
These two things are tied together...neither is nay more important than the other.
The best production cars on earth have engines that neglect neither torque or HP.
HP is not more important than Torque...this statement is much to general to be true (5).
*BOTTOM LINE*
If forced to trade one for the other...there is no clear answer without taking many factors into consideration.
If Power was more important, then you could blindly use it as your answer in all cases (6).
There are many variable that contribute to the characteristics of a sports car. Ignoring torque is foolish (1).
Would you drive a car that has a constant 10ft-lbs of torque that redlines at ~157,000RPM with a max 300HP?
No, no you wouldn't...
Would you drive a car that has a constant 300ft-lbs of torque that redlines at ~175RPM with a max of 10HP?
No, no you wouldn't...(2)
An car that yeilds good performance can come in different flavors...and current engineering doesn't give us any clear "Best way" of doing things (3). The smart engine designers know the limitations of their resources and abilities...these limitations are defined by the realities of things outside of you simplistic text-book explinations (4).
These two things are tied together...neither is nay more important than the other.
The best production cars on earth have engines that neglect neither torque or HP.
HP is not more important than Torque...this statement is much to general to be true (5).
*BOTTOM LINE*
If forced to trade one for the other...there is no clear answer without taking many factors into consideration.
If Power was more important, then you could blindly use it as your answer in all cases (6).
- What generalized claims have I made that are unsupported by my write ups? I've qualified my statements and I have not advocated ignoring engine torque outright, but rather I've explained why power is ultimately more important.
- Obviously not. But what you wrote partly illustrates why power is more important. I would drive CarA with a constant 150 ftlbs that redlines at 10500 yielding ~300 hp peak hp rather than CarB that has a constant 300 ftlbs of torque with a peak 150 hp that redlines at 2600 RPM (since CarA will have more wheel torque in most situations).
- Often, engineering does provide a clear "best way" of doing things (depending on the application). There are always compromises, and for everyday sports car drivability that sometimes means lowering peak power in order to increase low-end power (usually done by increasing peak torque). I never wrote anything that suggested otherwise (and in fact touched on this in post 254).
- I believe I covered real world situations in my posts before. However, since you believe otherwise, please show me a real world example that my simplistic text-book explanations do not cover.
- I find it a little ironic that your beef with my posts is that I'm being too general with my claims when I thoroughly explained why power is more important while mentioning why torque also needs to be considered.
- Nonsense. Just because attributeA is more important than attributeB, doesn't mean we can ignore attributeB.
#263
Originally Posted by BaronVonBigmeat
I was wondering about the flame speeds for hydrogen and LNG simply because if they burn faster, then the disadvantage of a large combustion area becomes less meaningful...I would think.
http://www.wired.com/news/autotech/0,2554,69529,00.html
#264
Originally Posted by Deslock
- What generalized claims have I made that are unsupported by my write ups? I've qualified my statements and I have not advocated ignoring engine torque outright, but rather I've explained why power is ultimately more important.
- Obviously not. But what you wrote partly illustrates why power is more important. I would drive CarA with a constant 150 ftlbs that redlines at 10500 yielding ~300 hp peak hp rather than CarB that has a constant 300 ftlbs of torque with a peak 150 hp that redlines at 2600 RPM (since CarA will have more wheel torque in most situations).
- Often, engineering does provide a clear "best way" of doing things (depending on the application). There are always compromises, and for everyday sports car drivability that sometimes means lowering peak power in order to increase low-end power (usually done by increasing peak torque). I never wrote anything that suggested otherwise (and in fact touched on this in post 254).
- I believe I covered real world situations in my posts before. However, since you believe otherwise, please show me a real world example that my simplistic text-book explanations do not cover.
- I find it a little ironic that your beef with my posts is that I'm being too general with my claims when I thoroughly explained why power is more important while mentioning why torque also needs to be considered.
- Nonsense. Just because attributeA is more important than attributeB, doesn't mean we can ignore attributeB.
Perhaps we're misunderstanding eachother..
You said "That's why power is more important... it tells us how much mechanical advantage we can get from gearing. It's that simple."
More important how?
If you are saying it's the most important factor in determining where a driver shifts from one gear to another...then i agree. By maximising the shift points to contain the most area under a power curve for a given car...you will achieve the best performance.
Or if you are saying that at any given instant, power is more important in determining what behavior the car will have...i agree again.
These are both highly conditioned statements...
Last edited by hedgecore; 11-16-2005 at 02:04 PM.
#265
WWFSMD?
Join Date: Jul 2003
Location: Massachusetts, USA
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by hedgecore
You said "That's why power is more important... it tells us how much mechanical advantage we can get from gearing. It's that simple."
More important how?
More important how?
Oh wait, I suddenly get the joke... you've been yanking my chain this whole time, replying to my posts as if you hadn't read them, goading me to explain myself over and over. Wow, you had me going there for a while. Bravo!
#266
What we need is a better measure of a car's power-to-the-ground potential. I'd like to see a measurement that integrates (area under the curve) the actual wheel torque of a gear, starting at the rpm's you would land in that gear if shifting optimally, up to the point you would shift out of that gear (at max wheel torque). Average 2nd, 3rd, and 4th gears and you'd have a good measurement of how effectively the engine, gearbox, and differential can deliver power in the rpm ranges that matter most.
#267
Originally Posted by Deslock
Are you pulling my leg? I explained it in several posts, including the one you quoted above!
Oh wait, I suddenly get the joke... you've been yanking my chain this whole time, replying to my posts as if you hadn't read them, goading me to explain myself over and over. Wow, you had me going there for a while. Bravo!
Oh wait, I suddenly get the joke... you've been yanking my chain this whole time, replying to my posts as if you hadn't read them, goading me to explain myself over and over. Wow, you had me going there for a while. Bravo!
#268
Hmmm......
convert chemical energy to mechanical
vs.
convert chemical energy to mechanical to electrical to mechanical
Seem's pretty obvious which is more efficient. So I doubt the train idea is going anywhere, that is done simply to get max torque.
convert chemical energy to mechanical
vs.
convert chemical energy to mechanical to electrical to mechanical
Seem's pretty obvious which is more efficient. So I doubt the train idea is going anywhere, that is done simply to get max torque.
#271
direct injection in a rotary (or piston engine for that matter) has the potential to allow high compression forced induction with NO knock, meaning better low end, faster spooling and high reliability!
Also the direct injetion system allows for leaner overall mixtures by creating a bubble of rich mixture near the spark plugs and ultra lean combustion in low load , i.e, cruising and idleing (some gdi engines run 40~50:1 afr's). This means lower emmisions and higher mileage.
Also the direct injetion system allows for leaner overall mixtures by creating a bubble of rich mixture near the spark plugs and ultra lean combustion in low load , i.e, cruising and idleing (some gdi engines run 40~50:1 afr's). This means lower emmisions and higher mileage.
#273
Registered
iTrader: (2)
Originally Posted by pcimino
Doesn't really answer your question but suggests hydrogen injection could be a solution...
http://www.wired.com/news/autotech/0,2554,69529,00.html
http://www.wired.com/news/autotech/0,2554,69529,00.html
For us that would mean close to 2 miles per gallon minus the cost of the distilled water that a person would need to produce or buy in order for the system to be able to pull hydrogen from the water it needs it.
Second of all Murphy's law states that there has to be some loss of energy from the conversion, so there can't be 100% efficiency from the conversion.
Third the cost of the HFI systems cost $4,000 and $14,000, depending on the size of the vehicle.
How much gasoline can a person buy for $4,000? IF gasoline was $3 per gallon that $4,000 could buy 24,000 miles worth of gas, averaging 18 MPG. That does not include the cost of distilled water. In order to reach the savings point the car would have to be driven 240,000 miles. How many people keep thier vehicles that long?
Does it sound worth it?
Truck drivers put a lot of miles on a vehicle. Most run them into the ground, I have heard of trucks with 1 million miles on them that is why it is worth it for some of them to invest in these units.
#274
Registered
Would a 15B provide a chance to change the Renesis exhaust ports?
Ok, I know it has been a while for this thread, and I just scanned it looking for someone else's mention of this idea and didn't see it...
But if you are widening the rotors (not saying they will) but that would involve a redesign of the crank, correct? If you are doing that, why not widen the center plate and put larger exhaust ports in? Get rid of the siamese ports, and allows some real breathing on each rotor.
That, with the better air flow velocities from the larger rotor may change the power picture.
Would this correct the flow issues that RotaryGod brings up?
When I read through the thread it seems the assumption that the center plate would remain the same.
There may be other benefits of a larger center plate too... crank shaft bearing stability, cooling, whatever.
These are just the thoughts of an amateur waking up in the middle of the night...
But if you are widening the rotors (not saying they will) but that would involve a redesign of the crank, correct? If you are doing that, why not widen the center plate and put larger exhaust ports in? Get rid of the siamese ports, and allows some real breathing on each rotor.
That, with the better air flow velocities from the larger rotor may change the power picture.
Would this correct the flow issues that RotaryGod brings up?
When I read through the thread it seems the assumption that the center plate would remain the same.
There may be other benefits of a larger center plate too... crank shaft bearing stability, cooling, whatever.
These are just the thoughts of an amateur waking up in the middle of the night...
Last edited by jeffe19007; 01-06-2006 at 03:35 PM.
#275
RG says the port area on the side housings is tapped out. Making the center housing wider won't help with a surface-area challenge. I'm not exactly convinced that there is no more flow to be had from the existing port; I haven't seen any explaination or proof of that. The key stat. is how much surface area do the ports have? Also, wider rotors definitely means a new e-shaft.