Todays quandry.....HP vs Torque race 928 comparo
10-29-2011, 10:40 PM
#76
Rennlist Member
You're still talking corners only under ideal conditions and in racing that doesn't happen all the time.Alot of ifs in the above statement.There will be times when cars come to almost a halt and higher rpm motor out of its peak curve and the high rpm motor making hp on top won't get to its torque curve as fast.When out of the peak curve in 1st gear you're not going to be shifting lower to find the peak curve.Push in the clutch to rev it high the other higher torque car will be gone.
I agree with Icemans video and Carl with torque
I agree with Icemans video and Carl with torque
but, most all the higher reving engines have closer ratio gear boxes. to make an exclamation point to my point here, look at audi diesel R10. they used the same hP car with 2 x the torque of its predicesor. what it did was allow them to rev lower, and remove one of the gears. (5 speed vs 6 speed of the previous R8). both cars made similar lap times and really didnt have much of an advantage over one another or others with high strung engines)
watch my last race agaisnt the viper, i have a traffic situation in turn 5 at laguna on the 1st laps where I grap 2nd to keep in the power band and optomiz my exit acceleration at the slower speed. the wider HP curve does give you more range, but its not a huge differnce vs a hgh reving car.
Last edited by mark kibort; 10-30-2011 at 03:08 PM.
10-30-2011, 12:52 AM
#77
Burning Brakes
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Nice driving against the Viper.He sure is on the brakes early but pulls hard in the straights.
I looked at the Audi,wasn't sure if the race car version or street car which diesel that you meant the 500hp street cars?
http://www.topspeed.com/cars/audi/20...i-ar50502.html
730+ torque that was V12 twin turbo?Compared to newer R8 with V10 which isn't.
2014 maybe on the diesel but that was written back in 2008.
I looked at the Audi,wasn't sure if the race car version or street car which diesel that you meant the 500hp street cars?
http://www.topspeed.com/cars/audi/20...i-ar50502.html
730+ torque that was V12 twin turbo?Compared to newer R8 with V10 which isn't.
2014 maybe on the diesel but that was written back in 2008.
10-30-2011, 03:05 PM
#79
Rennlist Member
Nice driving against the Viper.He sure is on the brakes early but pulls hard in the straights.
I looked at the Audi,wasn't sure if the race car version or street car which diesel that you meant the 500hp street cars?
http://www.topspeed.com/cars/audi/20...i-ar50502.html
730+ torque that was V12 twin turbo?Compared to newer R8 with V10 which isn't.
2014 maybe on the diesel but that was written back in 2008.
I looked at the Audi,wasn't sure if the race car version or street car which diesel that you meant the 500hp street cars?
http://www.topspeed.com/cars/audi/20...i-ar50502.html
730+ torque that was V12 twin turbo?Compared to newer R8 with V10 which isn't.
2014 maybe on the diesel but that was written back in 2008.
cant find the turn 5 downshift in traffic , but i found the turn 3 which is usually 3rd gear too.
2:45 in to the race
I was talking about a same same comparison, which would be the audi R8 race car and the audi R10 race car. both near 650hp as the class allowed, but the diesel was 850ftlb of torque, and had a redline of about 5000rpm while the gas powered audi at the same hp was in the 10,000rpm range. (cant remember, might have been even higher so the torque would be proportionately less. so half or even less)
So, as basic summary,
The bottom line, it's HP that dictates or can be used, to determine a cars acceration potential, expecially when comparing two cars. ALSO , it's Torque that can determine this as well. HP has more information, thats it. you need HP to accelerate, to get a top speed, to push through aero drag or rolling friction. and torque is an integral part of this. torque is the twisting force, but when we are talking about what is found at the wheels (because that is only what counts) its better and more easily indicated by looking at HP at any vehicle speed. (only because it contains torque as well as engine RPM in one neat little package) . they are both in extricably tied together in HP ( torque and rpm). Hp is a rate of doing work, by definition. so , if you want to accelerate faster , you need to do work faster, (i.e. HP
) force changes with speed. infact, it goes down proportionately with speed.
THIS is why we use hp, becuase force at the rear wheels is illusive, and at the engine is useless. (unless you got a bunch more information to go along with it.
)
10-30-2011, 05:54 PM
#80
Nordschleife Master
"Nooooooooo"
And power=force * velocity
so...
a = (f * v) / (m * v)
Wait...
a = f/m
f = m * a
It's the law!
This is exactly why it is torque that accelerates the car!
People seem to forget the purposefulness of the transmission and final drive. Those step down the RPMs of the engine while stepping up the torque. This is why an F1 engine spinning at over 10000 RPMs but a low torque can accelerate the car so well: the tranny multiplies the torque while reducing the angular velocity.
10-30-2011, 06:42 PM
#81
Rennlist Member
No??? you just prove it right though!
Yes, F=ma, BUT again again again, its the F at the rear wheels
Its the value that you seek, but the best indicator is power at any same vehicle speed . incredibly useful when you are looking at comparing two cars performance . Go ahead and try and calculate who makes what "F" at any same vehicle speed. coming off a turn down a straight, in a headwind, etc etc.
same power, same foce at the rear wheels ITS THE LAW!!
Go ahead try it. with HP , all you need to know what engine speed you are at that vehicle speed and he who has greater HP wins. infact, its very easy to visually integrate who would have an advantage by comparing area under the curve for the speed range. Try that with a set of torque curves. you need to get tire diameters, gear ratios, etc etc. Its not easy. using HP is extremely easy and accurate.
F=ma
Acceleration=F/m
Acceleration= power/ (mass x velocity)
all truths! (simple newtonian identities!)
by the way glen , its : Gear boxes INCREASE ENGINE RPM, as it INCREASES torque. YOU HAD IT MIXED UP!
Yes, F=ma, BUT again again again, its the F at the rear wheels
Its the value that you seek, but the best indicator is power at any same vehicle speed . incredibly useful when you are looking at comparing two cars performance . Go ahead and try and calculate who makes what "F" at any same vehicle speed. coming off a turn down a straight, in a headwind, etc etc.
same power, same foce at the rear wheels ITS THE LAW!!
Go ahead try it. with HP , all you need to know what engine speed you are at that vehicle speed and he who has greater HP wins. infact, its very easy to visually integrate who would have an advantage by comparing area under the curve for the speed range. Try that with a set of torque curves. you need to get tire diameters, gear ratios, etc etc. Its not easy. using HP is extremely easy and accurate.
F=ma
Acceleration=F/m
Acceleration= power/ (mass x velocity)
all truths! (simple newtonian identities!)
by the way glen , its : Gear boxes INCREASE ENGINE RPM, as it INCREASES torque. YOU HAD IT MIXED UP!
Darth Vader says:
"Nooooooooo"
And power=force * velocity
so...
a = (f * v) / (m * v)
Wait...
a = f/m
f = m * a
It's the law!
This is exactly why it is torque that accelerates the car!
People seem to forget the purposefulness of the transmission and final drive. Those step down the RPMs of the engine while stepping up the torque. This is why an F1 engine spinning at over 10000 RPMs but a low torque can accelerate the car so well: the tranny multiplies the torque while reducing the angular velocity.
"Nooooooooo"
And power=force * velocity
so...
a = (f * v) / (m * v)
Wait...
a = f/m
f = m * a
It's the law!
This is exactly why it is torque that accelerates the car!
People seem to forget the purposefulness of the transmission and final drive. Those step down the RPMs of the engine while stepping up the torque. This is why an F1 engine spinning at over 10000 RPMs but a low torque can accelerate the car so well: the tranny multiplies the torque while reducing the angular velocity.
10-30-2011, 09:15 PM
#82
Burning Brakes
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Thanks!
cant find the turn 5 downshift in traffic , but i found the turn 3 which is usually 3rd gear too.
2:45 in to the race
http://www.youtube.com/watch?v=f_oYdmDLCLQ
I was talking about a same same comparison, which would be the audi R8 race car and the audi R10 race car. both near 650hp as the class allowed, but the diesel was 850ftlb of torque, and had a redline of about 5000rpm while the gas powered audi at the same hp was in the 10,000rpm range. (cant remember, might have been even higher so the torque would be proportionately less. so half or even less)
So, as basic summary,
The bottom line, it's HP that dictates or can be used, to determine a cars acceration potential, expecially when comparing two cars. ALSO , it's Torque that can determine this as well. HP has more information, thats it. you need HP to accelerate, to get a top speed, to push through aero drag or rolling friction. and torque is an integral part of this. torque is the twisting force, but when we are talking about what is found at the wheels (because that is only what counts) its better and more easily indicated by looking at HP at any vehicle speed. (only because it contains torque as well as engine RPM in one neat little package) . they are both in extricably tied together in HP ( torque and rpm). Hp is a rate of doing work, by definition. so , if you want to accelerate faster , you need to do work faster, (i.e. HP )
force changes with speed. infact, it goes down proportionately with speed.
THIS is why we use hp, becuase force at the rear wheels is illusive, and at the engine is useless. (unless you got a bunch more information to go along with it. )
cant find the turn 5 downshift in traffic , but i found the turn 3 which is usually 3rd gear too.
2:45 in to the race
http://www.youtube.com/watch?v=f_oYdmDLCLQ
I was talking about a same same comparison, which would be the audi R8 race car and the audi R10 race car. both near 650hp as the class allowed, but the diesel was 850ftlb of torque, and had a redline of about 5000rpm while the gas powered audi at the same hp was in the 10,000rpm range. (cant remember, might have been even higher so the torque would be proportionately less. so half or even less)
So, as basic summary,
The bottom line, it's HP that dictates or can be used, to determine a cars acceration potential, expecially when comparing two cars. ALSO , it's Torque that can determine this as well. HP has more information, thats it. you need HP to accelerate, to get a top speed, to push through aero drag or rolling friction. and torque is an integral part of this. torque is the twisting force, but when we are talking about what is found at the wheels (because that is only what counts) its better and more easily indicated by looking at HP at any vehicle speed. (only because it contains torque as well as engine RPM in one neat little package) . they are both in extricably tied together in HP ( torque and rpm). Hp is a rate of doing work, by definition. so , if you want to accelerate faster , you need to do work faster, (i.e. HP
) force changes with speed. infact, it goes down proportionately with speed.
THIS is why we use hp, becuase force at the rear wheels is illusive, and at the engine is useless. (unless you got a bunch more information to go along with it.
)Installed in the same car it ran slower than the other lower hp motor they had in it.Going by HP alone may be easily indicated like you said but it doesn't always mean a faster ET.
10-30-2011, 09:25 PM
#83
Nordschleife Master
I had it right, Mark.
F = ma
It's the law!
Making it more complicated is unnecessary.
Eschew obfuscation!
10-31-2011, 12:18 AM
#84
Rennlist Member
The gear box steps down the RPMs of the engine to a lower RPM at the rear axle. (Except for true "drive" 1:1 and OD gears.) This increases the torque on the axle compared to the engine by precisely the same ratio. (save frictional losses).
I had it right, Mark.
F = ma
It's the law!
Making it more complicated is unnecessary.
Eschew obfuscation!
I had it right, Mark.
F = ma
It's the law!
Making it more complicated is unnecessary.
Eschew obfuscation!
quite the contrary Glen, HP makes a comparison MUCH more simple. either you have more hp coming off a turn or down or straight or you dont. The "F" in F=ma, is a little more difficult to extract and compare. give me a couple of HP curves and gear spacing and ill tell you shift points and who has an advantage. YOU would have to take a lot more time to figure out any comparison . you cant even visualize anomolies with a torque curve, that you can with HP curves. why, becuase HP just contains more information. its that simple.
acceleration = power/(mass x velocity) its the law too!
10-31-2011, 12:20 AM
#85
Rennlist Member
On the guys that helped me with that stroker motor years ago I have seen a motor that they sqweezed alittle more hp out of for their Superstock drag car.
Installed in the same car it ran slower than the other lower hp motor they had in it.Going by HP alone may be easily indicated like you said but it doesn't always mean a faster ET.
Installed in the same car it ran slower than the other lower hp motor they had in it.Going by HP alone may be easily indicated like you said but it doesn't always mean a faster ET.
.
10-31-2011, 01:11 AM
#87
Burning Brakes
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This is a good page to show most of what was talked about
http://www.epi-eng.com/piston_engine...e.htm#equation
Here is what it said
Think of it another way: In cars of equal weight, a 2-liter twin-cam engine that makes 300 HP at 8000 RPM (197 lb-ft) and 400 HP at 10,000 RPM (210 lb-ft) will get you out of a corner just as well as a 5-liter engine that makes 300 HP at 4000 RPM (394 lb-ft) and 400 HP at 5000 RPM (420 lb-ft). In fact, in cars of equal weight, the smaller engine will probably race BETTER because it's much lighter, therefore puts less weight on the front end. AND, in reality, the car with the lighter 2-liter engine will likely weigh less than the big V8-powered car, so will be a better race car for several reasons
After reading it,for road racing its time to trade in your 928 5 liter for a modified Cosworth Vega lol
2 liter dual overhead cam.
The Cosworth Vega 122 CID engine is a 1,994 cc (121.7 cu in) inline-four featuring a die cast aluminum alloy cylinder and case assembly and a Type 356 aluminum alloy, 16-valve cylinder head with double overhead camshafts (DOHC), designed in conjunction with English engineering company Cosworth. The camshafts are held in a removable cam-carrier which also serves as a guide for the valve lifters. Each camshaft is supported by five bearings and is turned by individual cam gears on the front end. The two overhead camshafts are driven, along with the water pump and fan, by a fiberglass cord reinforced neoprene rubber belt, much like the Vega 140 cu in engine. Below the cam carrier is a 16-valve cylinder head constructed of an aluminum alloy using sintered iron valve seats and iron cast valve seats. Sturdy forged aluminum pistons and heat-treated forged steel crankshaft and connecting rods reveal racing ancestry; assure high performance durability.
Can't wait to see Mark in his new Vega soon
http://www.epi-eng.com/piston_engine...e.htm#equation
Here is what it said
Think of it another way: In cars of equal weight, a 2-liter twin-cam engine that makes 300 HP at 8000 RPM (197 lb-ft) and 400 HP at 10,000 RPM (210 lb-ft) will get you out of a corner just as well as a 5-liter engine that makes 300 HP at 4000 RPM (394 lb-ft) and 400 HP at 5000 RPM (420 lb-ft). In fact, in cars of equal weight, the smaller engine will probably race BETTER because it's much lighter, therefore puts less weight on the front end. AND, in reality, the car with the lighter 2-liter engine will likely weigh less than the big V8-powered car, so will be a better race car for several reasons
After reading it,for road racing its time to trade in your 928 5 liter for a modified Cosworth Vega lol
2 liter dual overhead cam.
The Cosworth Vega 122 CID engine is a 1,994 cc (121.7 cu in) inline-four featuring a die cast aluminum alloy cylinder and case assembly and a Type 356 aluminum alloy, 16-valve cylinder head with double overhead camshafts (DOHC), designed in conjunction with English engineering company Cosworth. The camshafts are held in a removable cam-carrier which also serves as a guide for the valve lifters. Each camshaft is supported by five bearings and is turned by individual cam gears on the front end. The two overhead camshafts are driven, along with the water pump and fan, by a fiberglass cord reinforced neoprene rubber belt, much like the Vega 140 cu in engine. Below the cam carrier is a 16-valve cylinder head constructed of an aluminum alloy using sintered iron valve seats and iron cast valve seats. Sturdy forged aluminum pistons and heat-treated forged steel crankshaft and connecting rods reveal racing ancestry; assure high performance durability.
Can't wait to see Mark in his new Vega soon
10-31-2011, 02:26 AM
#89
Rennlist Member
Best case for our cars is to have constant power output. We all try, but never really get there, but get close after we start moving and you have wide HP range and a close ration gear box . since acceleration is proportioal to power (acceleration = power/(mass x velocity), then acceleration will go down proportionally with speed. (and so does rear wheel forces). (ignoring aero losses and friction)
since acceleration is proportioal to power (acceleration = power/(mass x velocity), then acceleration will go down proportionally with speed. (and so does rear wheel forces). (ignoring aero losses and friction)
10-31-2011, 02:38 AM
#90
Rennlist Member
This is a good page to show most of what was talked about
http://www.epi-eng.com/piston_engine...e.htm#equation
Here is what it said
Think of it another way: In cars of equal weight, a 2-liter twin-cam engine that makes 300 HP at 8000 RPM (197 lb-ft) and 400 HP at 10,000 RPM (210 lb-ft) will get you out of a corner just as well as a 5-liter engine that makes 300 HP at 4000 RPM (394 lb-ft) and 400 HP at 5000 RPM (420 lb-ft). In fact, in cars of equal weight, the smaller engine will probably race BETTER because it's much lighter, therefore puts less weight on the front end. AND, in reality, the car with the lighter 2-liter engine will likely weigh less than the big V8-powered car, so will be a better race car for several reasons
After reading it,for road racing its time to trade in your 928 5 liter for a modified Cosworth Vega lol
2 liter dual overhead cam.
Can't wait to see Mark in his new Vega soon
http://www.epi-eng.com/piston_engine...e.htm#equation
Here is what it said
Think of it another way: In cars of equal weight, a 2-liter twin-cam engine that makes 300 HP at 8000 RPM (197 lb-ft) and 400 HP at 10,000 RPM (210 lb-ft) will get you out of a corner just as well as a 5-liter engine that makes 300 HP at 4000 RPM (394 lb-ft) and 400 HP at 5000 RPM (420 lb-ft). In fact, in cars of equal weight, the smaller engine will probably race BETTER because it's much lighter, therefore puts less weight on the front end. AND, in reality, the car with the lighter 2-liter engine will likely weigh less than the big V8-powered car, so will be a better race car for several reasons
After reading it,for road racing its time to trade in your 928 5 liter for a modified Cosworth Vega lol
2 liter dual overhead cam.
Can't wait to see Mark in his new Vega soon
Yep, dead on right again. however, sometimes having the heavier weight in the front can help high speed turn in.
related to this racing comparison. we had RX7 build that got close to mopping up the field . He used an LS1 that was a little pumped up
, and it was lightning fast. although, he did have a little problem with blowing motors at the end of a season! the power of the 928engine is pretty adaquate for racing. we just need some lighter chassis! but, there is no substitute for 500rwhp, and thats what it takes to win our races now. (although i think i could do it with 450rwhp
) anyway, with all the series going to expensive slicks, higher HP/weight cars, everyone in the grass roots world is just getting priced out of the game.
