Torque vs. HP (formerly: Legacy GT turbo is 13.5 PSI??)
Suzuka Master
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From: Woodstock, GA
Originally Posted by fdl
you are just purely looking at numbers, your HP number will be a better indicator of how quickly your car will get through the 1/4 mile than torque will.
Again, as a general rule-of-thumb, HP is an indiactor or trap speed. Torque is an indicator of ET. You mention the time it takes to acheive a distance which is ET.
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From: Toronto
Originally Posted by scalbert
Can I ask how many engines you have built or how many times and what vehicles have taken you down the strip??
Again, as a general rule-of-thumb, HP is an indiactor or trap speed. Torque is an indicator of ET. You mention the time it takes to acheive a distance which is ET.
Again, as a general rule-of-thumb, HP is an indiactor or trap speed. Torque is an indicator of ET. You mention the time it takes to acheive a distance which is ET.
I think you are also confusing torque to the wheels (after gearing) to engine torque, because they are not the same. Let me give you another perspective. Assuming a relatively flat torque curve, the longer you can stay in a given the gear more torque to the wheels you will produce. Furthermore, the longer you stay in that gear the higher the rpms will go and the higher the HP (since we have a relatively flat torque curve). At some point, engine torque will be dropping so fast that even the increase of rpms is lowering HP, at this point we change gears. We want to stay as close to this PEAK HP as possible, because it means we are in the highest gear ratio passible and in turn applying the highest torque to the wheels possible.
Suzuka Master
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From: Woodstock, GA
Originally Posted by Dan Martin
I highly recommend everyone should read it or at very least, his conclusion at the end.
Taken from the article:
Unfortunately, *engine* torque does not tell you the full story. What matters is the torque *delivered to the tires*, including the effects of the transmission. We all know a car does not accelerate as hard in second gear at peak torque RPM as it does in first gear. The transmission amplifies or multiplies the torque coming from the engine by a factor equal to the gear ratio. So to determine how much the car is accelerating at a particular instant, you have to know both the torque output of the engine as well as the gear ratio.
Suzuka Master
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From: Woodstock, GA
Originally Posted by fdl
we shift at peak power, not peak torque for best straight line performance.
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From: Toronto
Originally Posted by scalbert
Not always, you will shift after peak power to get the best results in many cases. It all depends on the rate of decline of the torque curve.
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From: Toronto
What can I say scalbert, you and I have completely opposite opinions on this matter.
I have provided evidence to support my position from the creator of Cartest (acceleration software) and you still disagree. I guess we'll just have to agree to disagree then.
Edit: You replied in the time I was composing this message so I see we can reach a neutral ground. Yes gearing is important and I was trying to leave it out of the converstion to compare apples to apples.
I have provided evidence to support my position from the creator of Cartest (acceleration software) and you still disagree. I guess we'll just have to agree to disagree then.
Edit: You replied in the time I was composing this message so I see we can reach a neutral ground. Yes gearing is important and I was trying to leave it out of the converstion to compare apples to apples.
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From: Toronto
Originally Posted by Dan Martin
What can I say scalbert, you and I have completely opposite opinions on this matter.
I have provided evidence to support my position from the creator of Cartest (acceleration software) and you still disagree. I guess we'll just have to agree to disagree then.
Edit: You replied in the time I was composing this message so I see we can reach a neutral ground. Yes gearing is important and I was trying to leave it out of the converstion to compare apples to apples.
I have provided evidence to support my position from the creator of Cartest (acceleration software) and you still disagree. I guess we'll just have to agree to disagree then.
Edit: You replied in the time I was composing this message so I see we can reach a neutral ground. Yes gearing is important and I was trying to leave it out of the converstion to compare apples to apples.
he can keep shifting at peak torque and watching grandma pass him
Suzuka Master
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From: Woodstock, GA
Originally Posted by fdl
I think you are also confusing torque to the wheels (after gearing) to engine torque, because they are not the same. Let me give you another perspective. Assuming a relatively flat torque curve, the longer you can stay in a given the gear more torque to the wheels you will produce.
Just FYI and before we continue, you should know that I have designed and built one engine dyno, one transmission dyno and two jet engine dynos. I have a good understanding of the physics involved.
A WHP/WTQ plot will nearly mirror a CHP/CTQ plot but with different amplitudes. The crank numbers will be at a higher number. The wheel numbers are lower due to parasitic losses in the drivetrain.
You are also wrong in stating the following taken from above:
Originally Posted by fdl
Assuming a relatively flat torque curve, the longer you can stay in a given the gear more torque to the wheels you will produce.
Suzuka Master
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From: Woodstock, GA
Originally Posted by fdl
if torque declines and hp still increases you do NOT switch gears, because it will put you into a lower gear ratio and you will have less torque to the wheels when you dont have to.
Re-read what I stated, here it is again: It all depends on the rate of decline of the torque curve.
Is he a mechanic? If he is he needs to go back for some refresher courses.
Suzuka Master
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From: Woodstock, GA
Originally Posted by fdl
you guys need to go back to mechanic school. 
If you have half a clue you would understand these basic concepts. But it appears I am dealing with a toubled youth who attempts to argue just for the sake of it.
BTW, what car are you driving and how much power does it make??
Suzuka Master
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From: Woodstock, GA
Originally Posted by Dan Martin
Yes gearing is important and I was trying to leave it out of the converstion to compare apples to apples.
When gearing is taken out of the equation, you will accelerate quicker at the maximum torque. I don't think you disagree with that??
mod v. mod
+
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From: Toronto
Originally Posted by scalbert
I assume you are a bench racers. It certainly sounds that way.
It certainly sounds that way.hehe. maybe. anyways, i was just kidding around. its all good. Besides, I can;t argue with a Tool fan.
Suzuka Master
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From: Woodstock, GA
In addition, I have a bit of history making power in the J32A2 which is not talk and is proven:
https://acurazine.com/forums/search.php?searchid=7768
https://acurazine.com/forums/search.php?searchid=7768
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Photography Nerd
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From: Toronto
Originally Posted by scalbert
I guess I am confused as my original statements mentioned gearing.
When gearing is taken out of the equation, you will accelerate quicker at the maximum torque. I don't think you disagree with that??
When gearing is taken out of the equation, you will accelerate quicker at the maximum torque. I don't think you disagree with that??
From the article:
A car accelerates hardest with gearing selected to stay as close as possible to the engine *power* peak, subject to the traction capability of the tires.
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From: Toronto
guys again, i think we are confusing torque at the wheels (mutiplyed by gearing) vs torque at the crank.
Yes if you had 1 gear only, (take gearing out of the equation) you will accelrate hardest at peak torque. But when gears enter the equation you want to stay at the highest ratio possible the longest (i.e. maximize torque to the wheels) and to do this you want to stay as close to peak HP as possible. which is why HP is the better indicator.
Yes if you had 1 gear only, (take gearing out of the equation) you will accelrate hardest at peak torque. But when gears enter the equation you want to stay at the highest ratio possible the longest (i.e. maximize torque to the wheels) and to do this you want to stay as close to peak HP as possible. which is why HP is the better indicator.
Suzuka Master
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From: Woodstock, GA
Originally Posted by Dan Martin
From the article:
Taken from the article I provided:
The Case For Torque
Now, what does all this mean in carland?
First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same.
In contrast to a torque curve (and the matching pushback into your seat), horsepower rises rapidly with rpm, especially when torque values are also climbing. Horsepower will continue to climb, however, until well past the torque peak, and will continue to rise as engine speed climbs, until the torque curve really begins to plummet, faster than engine rpm is rising. However, as I said, horsepower has nothing to do with what a driver *feels*.
You don't believe all this?
Fine. Take your non turbo car (turbo lag muddles the results) to its torque peak in first gear, and punch it. Notice the belt in the back? Now take it to the power peak, and punch it. Notice that the belt in the back is a bit weaker? Fine. Can we go on, now? :-)
Now, what does all this mean in carland?
First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same.
In contrast to a torque curve (and the matching pushback into your seat), horsepower rises rapidly with rpm, especially when torque values are also climbing. Horsepower will continue to climb, however, until well past the torque peak, and will continue to rise as engine speed climbs, until the torque curve really begins to plummet, faster than engine rpm is rising. However, as I said, horsepower has nothing to do with what a driver *feels*.
You don't believe all this?
Fine. Take your non turbo car (turbo lag muddles the results) to its torque peak in first gear, and punch it. Notice the belt in the back? Now take it to the power peak, and punch it. Notice that the belt in the back is a bit weaker? Fine. Can we go on, now? :-)
Suzuka Master
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From: Woodstock, GA
Originally Posted by fdl
Yes if you had 1 gear only, (take gearing out of the equation) you will accelrate hardest at peak torque. But when gears enter the equation you want to stay at the highest ratio possible the longest (i.e. maximize torque to the wheels) and to do this you want to stay as close to peak HP as possible. which is why HP is the better indicator.
Moderator Alumnus
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From: Lenexa, KS
Originally Posted by scalbert
And your examples prove nothing because gearing is not considered. First of all, the ITR is not an acceleration monster. It only does OK and is designed for turning moreso than accelerating. F1 cars use low weight and aggressive gearing to acheive what they do as do most all purpose race cars.
Exactly my thoughts. Their examples are theoretical and based on infinite gear ratios on transmissions that don't exist. (there is no practical CVT tranmission made today)
F1 cars also have stellar aerodynamics (excluding downforce at 150+mph)
Suzuka Master
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From: Woodstock, GA
Originally Posted by fdl
ya scal, that is correct. But once gearing is in the picture HP becomes the better indicator. see my note above.
Gearing does play a big part in where the torque curve should be examined to determine the appropriate gear ratios. Your ideal gearing will be significantly different for a engine with the following numbers:
300HP @ 7000
300lb/ft @ 3000
versus
350HP @ 7500
250lb/ft @ 5000
There is no all encompassing statement. A better general concept would be the following:
When Torque/Gearing are focused on you get better off the line acceleration.
When HP/Gearing is focused on you get better at speed acceleration.
And anyone who has been drag racing knows that most of the race is made or lost in the first sixty feet.
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From: Toronto
aahh scab, i thought we reached a turning point here.
Those cars are fast because they have high HP, not engine torque. The fact that their torque rating is higher than HP is irrelevant. Its so simple, if you have HIGH torque, you HP will usually be high too, unless your engine only revs to like 3000 rpms and then you will be slow. Since HP = torque*rpm/5252 , high torque will mean high hp and in turn a fast car. I never disputed this.
So to recap, yes torque can make you fast, but so can rpms and gears which is why HP , taking more into consideration will give you a more accurate idea of a cars straight line performance. torque alone tells you less than HP.
Those cars are fast because they have high HP, not engine torque. The fact that their torque rating is higher than HP is irrelevant. Its so simple, if you have HIGH torque, you HP will usually be high too, unless your engine only revs to like 3000 rpms and then you will be slow. Since HP = torque*rpm/5252 , high torque will mean high hp and in turn a fast car. I never disputed this.
So to recap, yes torque can make you fast, but so can rpms and gears which is why HP , taking more into consideration will give you a more accurate idea of a cars straight line performance. torque alone tells you less than HP.
Suzuka Master
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From: Woodstock, GA
Originally Posted by fdl
aahh scab, i thought we reached a turning point here.
Those cars are fast because they have high HP, not engine torque. The fact that their torque rating is higher than HP is irrelevant. Its so simple, if you have HIGH torque, you HP will usually be high too, unless your engine only revs to like 3000 rpms and then you will be slow. Since HP = torque*rpm/5252 , high torque will mean high hp and in turn a fast car. I never disputed this.
So to recap, yes torque can make you fast, but so can rpms and gears which is why HP , taking more into consideration will give you a more accurate idea of a cars straight line performance. torque alone tells you less than HP.
Those cars are fast because they have high HP, not engine torque. The fact that their torque rating is higher than HP is irrelevant. Its so simple, if you have HIGH torque, you HP will usually be high too, unless your engine only revs to like 3000 rpms and then you will be slow. Since HP = torque*rpm/5252 , high torque will mean high hp and in turn a fast car. I never disputed this.
So to recap, yes torque can make you fast, but so can rpms and gears which is why HP , taking more into consideration will give you a more accurate idea of a cars straight line performance. torque alone tells you less than HP.
That, or it made well over 400 lb/ft turned only 4400 RPM and only had four gears. It also only trapped about 102 as well. Contrast that to my CL-S6 SC/IC which shoudl have easily ran the same ET if not better. But it would pass through the lights at over 10 MPH faster.
Point being, acceleration in a 1320' race is not about HP alone. The ET is very dependant on the torque made. Now take the two mentioned cars out on an open road and start from from say 60 MPH and there would be no contest; the CL-S6 SC/IC would obliterate the Typhoon.
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From: Toronto
Originally Posted by scalbert
Hrmm, my Typhoon ran a 13.2 and made only about 300 HP weighing in at about 4000 lbs. I guess it wasn't aware of your concepts.
That, or it made well over 400 lb/ft turned only 4400 RPM and only had four gears. It also only trapped about 102 as well. Contrast that to my CL-S6 SC/IC which shoudl have easily ran the same ET if not better. But it would pass through the lights at over 10 MPH faster.
Point being, acceleration in a 1320' race is not about HP alone. The ET is very dependant on the torque made. Now take the two mentioned cars out on an open road and start from from say 60 MPH and there would be no contest; the CL-S6 SC/IC would obliterate the Typhoon.
That, or it made well over 400 lb/ft turned only 4400 RPM and only had four gears. It also only trapped about 102 as well. Contrast that to my CL-S6 SC/IC which shoudl have easily ran the same ET if not better. But it would pass through the lights at over 10 MPH faster.
Point being, acceleration in a 1320' race is not about HP alone. The ET is very dependant on the torque made. Now take the two mentioned cars out on an open road and start from from say 60 MPH and there would be no contest; the CL-S6 SC/IC would obliterate the Typhoon.
I dont know what the exact specs on that truck are, but I bet you could get pretty much the same results had the engine been the same HP but less torque. Only place that high torque will help you is in first gear if you have the tires to hold it. Once you start rowing the gears, high torque, low torque wont matter if you can get the same HP out of the engine.
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From: Toronto
Yes gearing is very important because in the end, power to the wheels is the only thing that gets you down the track.
If Formula 1 cars could accelerate hardest at peak torque, there's no reason they'd have an engine that could spin up to 18,000 rpm. Spinning a small gear at 18,000 rpm produces a lot more power to the wheels than a larger gear spinning at the engine's maximum torque. In fact, an F1 engine produces maximum torque just above idle.
Same goes for Top Fuel drag cars. Why do they have a 9500rpm redline when peak torque is somewhere around 5000rpm?
In the case of your Typhoon scalbert, your truck produces a ton of horse power compared to other engines at the same rpm. If you could maintain the same amount of torque up to F1 rpms you'd be putting out 1400hp which would smoke any F1 engine available today.
If Formula 1 cars could accelerate hardest at peak torque, there's no reason they'd have an engine that could spin up to 18,000 rpm. Spinning a small gear at 18,000 rpm produces a lot more power to the wheels than a larger gear spinning at the engine's maximum torque. In fact, an F1 engine produces maximum torque just above idle.
Same goes for Top Fuel drag cars. Why do they have a 9500rpm redline when peak torque is somewhere around 5000rpm?
In the case of your Typhoon scalbert, your truck produces a ton of horse power compared to other engines at the same rpm. If you could maintain the same amount of torque up to F1 rpms you'd be putting out 1400hp which would smoke any F1 engine available today.
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From: Toronto
Originally Posted by scalbert
As a final note and I beleive this quote sums it up:
Repeat after me. "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*." :-)
Repeat after me. "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*." :-)
...and have higher HP.
high hp means higher torque at higher rpms. this is what I have been saying all along.
Suzuka Master
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From: Woodstock, GA
Originally Posted by fdl
I dont know what the exact specs on that truck are, but I bet you could get pretty much the same results had the engine been the same HP but less torque. Only place that high torque will help you is in first gear if you have the tires to hold it. Once you start rowing the gears, high torque, low torque wont matter if you can get the same HP out of the engine.
Torque got it moving out of the hole quickly and pulled it through to the end. It has relatively low HP numbers because the engine didn't turn very fast. After the 1 -> 2 shift it would drop to about 2500 RPM at which point it it was at peak torque.
Had the torque output been lower and the gearing been shortened it probably would have run similar times. It would have probably hit 4th which may have alloowed for similar times but gas mileage would have been crap in that heavey beast; worse than it was.
BTW, there was no rowing through gears, it was an automatic.
Suzuka Master
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From: Woodstock, GA
Originally Posted by Dan Martin
Yes gearing is very important because in the end, power to the wheels is the only thing that gets you down the track.
If Formula 1 cars could accelerate hardest at peak torque, there's no reason they'd have an engine that could spin up to 18,000 rpm. Spinning a small gear at 18,000 rpm produces a lot more power to the wheels than a larger gear spinning at the engine's maximum torque. In fact, an F1 engine produces maximum torque just above idle.
If Formula 1 cars could accelerate hardest at peak torque, there's no reason they'd have an engine that could spin up to 18,000 rpm. Spinning a small gear at 18,000 rpm produces a lot more power to the wheels than a larger gear spinning at the engine's maximum torque. In fact, an F1 engine produces maximum torque just above idle.
BTW, F1 cars idle at 8k RPM and make their peak torque higher than that. But they turn those high revs to take advantage of gearing. Because if you can turn it faster making the same torque, shorter gearing can be used and more power is put to the road (torque or HP, pick one and the RPM and you know the other.) with less weight associated with a larger engine.
Why is it you are referring to HP and torque as different value when HP is a subordinate of torque??