How come G37 torque is low?
01-09-2009, 02:20 PM
#31
This is a great thread, shows how useful myg37.com can be - simple question that could have been blown off with quick answers was instead delved into with a lot of thought and educated speculations. Much thanks to the "Kahboom & Mal_TX" fountain of knowledge. I know I learned a lot. Thanks guyz!
I learned that our cars are bad a$$es.
myg37.com FTMFGDW!!!!
01-09-2009, 03:50 PM
#32
My point still remains... Torque IS NOT directly dependent upon rpm then as you just said. A consequence low ratios is high rpm's to obtain reasonable speeds, so yeah crudely it could be viewed in this manner. If your speaking of engineering mechanics and physics (which I am), there IS NO direct relation. Also.. How often do you see a "Normal car" churning out 19,000 rpm????
The reason an F1 cars engines is built to turn those kinds of rpm's is because the cars travel road courses and are constantly in the corners, and having such a high rpm allows for a super broad power band, thus the need for shifting is greatly reduced.
The reason an F1 cars engines is built to turn those kinds of rpm's is because the cars travel road courses and are constantly in the corners, and having such a high rpm allows for a super broad power band, thus the need for shifting is greatly reduced.
F1 engines turn high RPMs because they have displacement restrictions. There are multiple ways to increase power which all involve increasing the amount of air going into the engine (and thus the amount of fuel combusting).
1. More displacement. The engine sucks up more air per revolution.
2. More RPM. The engine sucks up air more times per unit of time.
3. Forced Induction. The engine is force fed air at higher than atmosphere pressures.
Because F1 engines are now allowed to use FI, and have displacement restrictions, the only option left is to increase RPM.
As I stated above, engines are limited to roughly 75 ft/lbs per liter of displacement (again, only a rule of thumb).
75 * 2.5 (displacement of F1 engine) * 19000 (rpm cap) / 5252 = 678.313, or 680 if significant digits come into play. This is VERY close to what current F1 engines actually output.
That would also indicate that they only output rougly 187.5 (75*2.5) ft/lb torque. (I'm sure in reality its probably a bit higher due to exotic materials)
As you stated above, Torque is related to RPM, but not dependant on RPM. Horsepower is a measurement of work over time; RPM is a time measurement, and torque is the work. Horsepower is dependant on Torque and RPM.
01-09-2009, 03:53 PM
#33
LOLs I dunno what size wheels you are thinking of, but when I think about normal cars running engines turning at 19,000 rpm, I think that better be some f-ing short gear ratios! 
Point being -- the higher the revs the shorter the gears can be, which means more torque at the wheels through multiplication. While you are (of course) stating facts, unless the car in question is rolling on quarter-sized wheels or is traveling at hundreds (thousands?) of MPH, a high rpm is going to mean a shorter gear ratio is in play. Especially when we are using the example of a 19,000 rpm F1 car.
Point being -- the higher the revs the shorter the gears can be, which means more torque at the wheels through multiplication. While you are (of course) stating facts, unless the car in question is rolling on quarter-sized wheels or is traveling at hundreds (thousands?) of MPH, a high rpm is going to mean a shorter gear ratio is in play. Especially when we are using the example of a 19,000 rpm F1 car.
Real world example:
G37's can easily spin the tires in 1st gear, but not 3rd. Why? 1st gear offers more torque multiplication (and thus, more power being put to the ground).
High RPM is, imo, superior to high displacement for multiple reasons. You can run at low rpm (if properly geared) with low output for economy. You can rev up only when you need power.
However, high RPM often requires exotic materials, and require the engine to be built specificaly for it. In addition, variable valve timing of some sort is REQUIRED (unless you want absolutely NO power low end), and emissions (and efficiency) will suffer at high RPM relative to a high displacement low RPM motor of similar output..
VTEC just kicked in, yo.
01-09-2009, 09:58 PM
#34
Registered User
Torque is heavily, but not completely displacement related (in the case of a NA engine)
F1 engines turn high RPMs because they have displacement restrictions. There are multiple ways to increase power which all involve increasing the amount of air going into the engine (and thus the amount of fuel combusting).
1. More displacement. The engine sucks up more air per revolution.
2. More RPM. The engine sucks up air more times per unit of time.
3. Forced Induction. The engine is force fed air at higher than atmosphere pressures.
Because F1 engines are now allowed to use FI, and have displacement restrictions, the only option left is to increase RPM.
As I stated above, engines are limited to roughly 75 ft/lbs per liter of displacement (again, only a rule of thumb).
75 * 2.5 (displacement of F1 engine) * 19000 (rpm cap) / 5252 = 678.313, or 680 if significant digits come into play. This is VERY close to what current F1 engines actually output.
That would also indicate that they only output rougly 187.5 (75*2.5) ft/lb torque. (I'm sure in reality its probably a bit higher due to exotic materials)
As you stated above, Torque is related to RPM, but not dependant on RPM. Horsepower is a measurement of work over time; RPM is a time measurement, and torque is the work. Horsepower is dependant on Torque and RPM.
F1 engines turn high RPMs because they have displacement restrictions. There are multiple ways to increase power which all involve increasing the amount of air going into the engine (and thus the amount of fuel combusting).
1. More displacement. The engine sucks up more air per revolution.
2. More RPM. The engine sucks up air more times per unit of time.
3. Forced Induction. The engine is force fed air at higher than atmosphere pressures.
Because F1 engines are now allowed to use FI, and have displacement restrictions, the only option left is to increase RPM.
As I stated above, engines are limited to roughly 75 ft/lbs per liter of displacement (again, only a rule of thumb).
75 * 2.5 (displacement of F1 engine) * 19000 (rpm cap) / 5252 = 678.313, or 680 if significant digits come into play. This is VERY close to what current F1 engines actually output.
That would also indicate that they only output rougly 187.5 (75*2.5) ft/lb torque. (I'm sure in reality its probably a bit higher due to exotic materials)
As you stated above, Torque is related to RPM, but not dependant on RPM. Horsepower is a measurement of work over time; RPM is a time measurement, and torque is the work. Horsepower is dependant on Torque and RPM.
Exactly. Torque is not dependent upon rpm. It is dependent on displacement and many other factors, but more so displacement than anything.
Fuel rate is also a way to control torque, this needs no explanation. Most engines reach max torque around 4000 rpm and start decreasing because optimal flow has been obtained and the engine essentially sufocates. One way to combat this is to use variable length tuned intake runners (as seen on Ferrari Enzo, Yamaha R6 & R1, and old F1). This runner length is actually varied dependent upon rpm. The incident wave (incoming charge air wave) has different wavelenghts at different rpms. As you vary the runner to match the rpm you vary this incident wavelenght and essentiall time the incident such that it "slams" more charge air into the combustion chamber. When the valve slams shut it creats a hammer shock effect. The incident wave is now a reflected wave. If the can match these natural frequencies the reflected wave has no effect upon the incident wave, thus the mass flow of the charge air is much greater than an engine without a variable lenght runner.
I wasnt going to turn this into an insane tech thread, but lets keep it going
, but not in that order, 
01-10-2009, 02:40 PM
#36
Exactly. Torque is not dependent upon rpm. It is dependent on displacement and many other factors, but more so displacement than anything.
Fuel rate is also a way to control torque, this needs no explanation. Most engines reach max torque around 4000 rpm and start decreasing because optimal flow has been obtained and the engine essentially sufocates. One way to combat this is to use variable length tuned intake runners (as seen on Ferrari Enzo, Yamaha R6 & R1, and old F1). This runner length is actually varied dependent upon rpm. The incident wave (incoming charge air wave) has different wavelenghts at different rpms. As you vary the runner to match the rpm you vary this incident wavelenght and essentiall time the incident such that it "slams" more charge air into the combustion chamber. When the valve slams shut it creats a hammer shock effect. The incident wave is now a reflected wave. If the can match these natural frequencies the reflected wave has no effect upon the incident wave, thus the mass flow of the charge air is much greater than an engine without a variable lenght runner.
I wasnt going to turn this into an insane tech thread, but lets keep it going
Fuel rate is also a way to control torque, this needs no explanation. Most engines reach max torque around 4000 rpm and start decreasing because optimal flow has been obtained and the engine essentially sufocates. One way to combat this is to use variable length tuned intake runners (as seen on Ferrari Enzo, Yamaha R6 & R1, and old F1). This runner length is actually varied dependent upon rpm. The incident wave (incoming charge air wave) has different wavelenghts at different rpms. As you vary the runner to match the rpm you vary this incident wavelenght and essentiall time the incident such that it "slams" more charge air into the combustion chamber. When the valve slams shut it creats a hammer shock effect. The incident wave is now a reflected wave. If the can match these natural frequencies the reflected wave has no effect upon the incident wave, thus the mass flow of the charge air is much greater than an engine without a variable lenght runner.
I wasnt going to turn this into an insane tech thread, but lets keep it going
What to discuss next... resonance, velocity stacks, timing, overlap, fluid dynamics... the list goes on and on.
Lets do FI (Fuel injection, not forced induction
) and DI (Direct Injection)Typically, fuel is mixed into the air going into the cylinder. This can occur via carburator or with fuel sprays (fuel injection). Direct injection is exactly what the name implies; instead of having the air/fuel pre-mixed before going into the cylinder, the fuel can be injected directly into the cylinder.
This can allow for ultra lean burns; the fuel can be specifically placed to prevent excessive heat build up, and output can be VERY finely adjusted. This is why DI engines typically have improved fuel economy versus their non-DI counterparts (DI engines also have to use "less extra" fuel to insure that all cylinders get adequate cooling via evaporation of fuel, and more importantly, to insure that a cylinder doesn't lean out; all of these add to the fuel efficiency advantages of DI). DI can also result in a "more complete" combustion; DI allows for a better distribution of fuel within the cylinder, allowing for more to be burned. Uneven distribution can lead to uneven combustion, resulting in (somewhat) unpredictable power and varying heat levels and flame front speeds within the cylinder itself, but heat management and burn speed are another topic in themselves. DI reduces these variables, allowing for more efficiency.
DI and FI does not increase the power an engine can make. They simply increase the efficiency of the engine by allowing for more complete burns.
I wish the big bore versions of the VQ had DI.... It may not give the VQ significantly more power, but it would definately add some MPG when not under WOT.
04-01-2009, 01:40 PM
#37
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This is the best HP/Tq thread I've ever read. Good info, technical without bordering on comlicated, and respectful. Any time I read a "why no 330/330 wtf?" thread from now on I will direct to this thread.
I need to buy a g37 soley so I can justify spending more time on this forum than driver. Good work guys.
I need to buy a g37 soley so I can justify spending more time on this forum than driver. Good work guys.
04-01-2009, 07:58 PM
#38
Man Mike is the one who taught me extra knowledge on the basics of my g37, he sold me the car too when he worked for Infiniti, if he'd give me an advice, I stfu and listen He knows what to do when you want to build your car to Fi or even general tech questions, hes the only enthusiast I know that personally knows all shops and competitors around and still is very fair on judging and not biased of either of them. Go Mike! My 2 cents
He knows what to do when you want to build your car to Fi or even general tech questions, hes the only enthusiast I know that personally knows all shops and competitors around and still is very fair on judging and not biased of either of them. Go Mike! My 2 cents
04-01-2009, 08:54 PM
#39
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Ehehe this is getting more technical and more in depth
What to discuss next... resonance, velocity stacks, timing, overlap, fluid dynamics... the list goes on and on.
Lets do FI (Fuel injection, not forced induction) and DI (Direct Injection)
Typically, fuel is mixed into the air going into the cylinder. This can occur via carburator or with fuel sprays (fuel injection). Direct injection is exactly what the name implies; instead of having the air/fuel pre-mixed before going into the cylinder, the fuel can be injected directly into the cylinder.
This can allow for ultra lean burns; the fuel can be specifically placed to prevent excessive heat build up, and output can be VERY finely adjusted. This is why DI engines typically have improved fuel economy versus their non-DI counterparts (DI engines also have to use "less extra" fuel to insure that all cylinders get adequate cooling via evaporation of fuel, and more importantly, to insure that a cylinder doesn't lean out; all of these add to the fuel efficiency advantages of DI). DI can also result in a "more complete" combustion; DI allows for a better distribution of fuel within the cylinder, allowing for more to be burned. Uneven distribution can lead to uneven combustion, resulting in (somewhat) unpredictable power and varying heat levels and flame front speeds within the cylinder itself, but heat management and burn speed are another topic in themselves. DI reduces these variables, allowing for more efficiency.
DI and FI does not increase the power an engine can make. They simply increase the efficiency of the engine by allowing for more complete burns.
I wish the big bore versions of the VQ had DI.... It may not give the VQ significantly more power, but it would definately add some MPG when not under WOT.
What to discuss next... resonance, velocity stacks, timing, overlap, fluid dynamics... the list goes on and on.
Lets do FI (Fuel injection, not forced induction
) and DI (Direct Injection)Typically, fuel is mixed into the air going into the cylinder. This can occur via carburator or with fuel sprays (fuel injection). Direct injection is exactly what the name implies; instead of having the air/fuel pre-mixed before going into the cylinder, the fuel can be injected directly into the cylinder.
This can allow for ultra lean burns; the fuel can be specifically placed to prevent excessive heat build up, and output can be VERY finely adjusted. This is why DI engines typically have improved fuel economy versus their non-DI counterparts (DI engines also have to use "less extra" fuel to insure that all cylinders get adequate cooling via evaporation of fuel, and more importantly, to insure that a cylinder doesn't lean out; all of these add to the fuel efficiency advantages of DI). DI can also result in a "more complete" combustion; DI allows for a better distribution of fuel within the cylinder, allowing for more to be burned. Uneven distribution can lead to uneven combustion, resulting in (somewhat) unpredictable power and varying heat levels and flame front speeds within the cylinder itself, but heat management and burn speed are another topic in themselves. DI reduces these variables, allowing for more efficiency.
DI and FI does not increase the power an engine can make. They simply increase the efficiency of the engine by allowing for more complete burns.
I wish the big bore versions of the VQ had DI.... It may not give the VQ significantly more power, but it would definately add some MPG when not under WOT.
Yes and no.
It does increase the efficiency of the engine, but as a result it would generally also increase power output as well, the efficiency increases, therefore you're producing closer to the ideal power output in the first place.
04-01-2009, 10:40 PM
#40
Registered User
Right on. Efficiency and power move in tandem with one another. Increasing efficiency or thermal efficiency means you are producing less waste heat and converting that heat to power. The general rule for IC engines is the rule of thirds. 1/3 makes to power output, 1/3 lost to waste heat, 1/3 lost in the coolant. IC engines are very inefficient, but inventions such as compound turboing dramatically increases thermal efficiency of IC engines.
10-09-2009, 11:04 AM
#42
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As mentioned above HP is torque multiplication.
If an engine produces more peak torque than another it does not necessarily mean that it has a better powerband or more torque throughout the RPMs.
Ex The new VQ produces the same "peak" torque as the older VQs. But everywhere else in the power band the newer VQ produces more torque. When you combine more torque with higher RPMs you get more horse power.
A much better way of rating an engine is via "power under the curve".
Don't put all your stock in peak numbers. Without looking at a dyno chart you might look at both numbers (peak tq and peak hp) to get a general idea of how the engine performs in real world conditions.
Another example to consider: The S2K produces a lot of peak hp but very little peak tq. Thus to meet it's best performance numbers you have to drop the clutch from higher RPMs. If you try to use the entire powerband you will have slower numbers as much of it includes a range of low torque X low RPMs which = low hp.
In summary torque and HP are directly related to each other. It's just that mags and reviews only report on "peak" numbers. You have to gage by the entire powerband.
If an engine produces more peak torque than another it does not necessarily mean that it has a better powerband or more torque throughout the RPMs.
Ex The new VQ produces the same "peak" torque as the older VQs. But everywhere else in the power band the newer VQ produces more torque. When you combine more torque with higher RPMs you get more horse power.
A much better way of rating an engine is via "power under the curve".
Don't put all your stock in peak numbers. Without looking at a dyno chart you might look at both numbers (peak tq and peak hp) to get a general idea of how the engine performs in real world conditions.
Another example to consider: The S2K produces a lot of peak hp but very little peak tq. Thus to meet it's best performance numbers you have to drop the clutch from higher RPMs. If you try to use the entire powerband you will have slower numbers as much of it includes a range of low torque X low RPMs which = low hp.
In summary torque and HP are directly related to each other. It's just that mags and reviews only report on "peak" numbers. You have to gage by the entire powerband.
10-09-2009, 11:23 AM
#43
From an old guy...
In the early 70's I was way into drag racing, as were many co-conspirators of mine. I raced and drove on the street a hemi that ran high 10's, it didn't have much low end torque, but, it had good HP and good gears.
In my experiance, on the street, low end torque wasn't an issue as I often didn't have much traction at launch anyway. And after all, how much time do you spend below 2,500 rpm?
The last rambling thought, from a really old guy... I got spanked more than once driving a 10 second street machine. I don't know what that is in 0-60, but, to be "fastest" today, I know you'd need more than that.
Please drive safely, especially on the street.
In the early 70's I was way into drag racing, as were many co-conspirators of mine. I raced and drove on the street a hemi that ran high 10's, it didn't have much low end torque, but, it had good HP and good gears.
In my experiance, on the street, low end torque wasn't an issue as I often didn't have much traction at launch anyway. And after all, how much time do you spend below 2,500 rpm?
The last rambling thought, from a really old guy... I got spanked more than once driving a 10 second street machine. I don't know what that is in 0-60, but, to be "fastest" today, I know you'd need more than that.
Please drive safely, especially on the street.
10-09-2009, 12:44 PM
#44
im pushing 280lbs of torque at the wheels after getting the cobb tuning acessport & professionally tunned. i can spin tires with ease, if i choose. and i drive an auto. the tune helps alot. i gained like 30 or 40lb feet of torque. are carsw never get wot, so if you can get around that. this motor has a nice amout of torque.
