what creates torque??
Originally Posted by APeteSS
Nope, power is power. Output is the same no matter what the gearing is.
TECH Enthusiast
Joined: Jul 2005
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From: Herndon, VA
[QUOTE=H8 LUZN]Not nessecarily, Its the stroke that creates torque... a longer stroke means a larger moment arm is placed on the crankshaft given equal force of combustion.QUOTE]
I knew strokers really just added torque, and your answer crystalized the physics of it for me... thanks...
I knew strokers really just added torque, and your answer crystalized the physics of it for me... thanks...
Teching In
Joined: Feb 2006
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From: Bonaire, NA
Originally Posted by UMIRacing
Ok, here you go. Torque is created by pressure on top of the piston. This pressure is created by the expansion of the burning of the air fuel mixture. The piston moves downward and the connecting rod pushes on the crankshaft. The crankshaft then takes this motion and transmits it to the trans. The trans has different gears in it which multiply the torque. this torque is output to the rear end where it gets multiplied again. It then goes through the axle to the tire which takes multiplication away. The end result is the tire turns.
What a longer stroke does is two things, it multiplies the force created by the piston and it also increases piston displacement which increases its speed. This makes the air column fill the cylinder sooner in the RPM band.
You can also gain more torque by increasing piston diameter. Because you still have the same pressure on top of the piston, now you are taking advantage of more of it so it pushes the piston down faster. The downside to this is there is no multiplication.
The other way to increase torque is to increase air trapped in the chamber. This increases the air/fuel mass on the piston so there is more expansion which creates more pressure. This is how forced induction works.
You can also chemically supercharge an engine by the fuel. This is how Nitrous and any fuel that contains oxygen works. If the fuel used has oxygen, it can burn with less air in the chamber. This means there can be more fuel for more pressure. Fuel expands more than air, therefore you have more pressure.
As far as gearing a car goes, your engine still only makes x amount of torque and horsepower. Gearing cannot change the hp of the engine, it will however multiply the torque created. For instance, if your engine creates 400 lbft of torque, and you have a 2:1 final drive, your engine will "feel like" it has 800lbft of torque. If you change the gearing and you now have a 3:1 final drive, your car feels like it has 1200lbft of torque.
Gearing is the #1 way to make a car faster, well besides giggle gas. And if you were only interested in the 1/4 mile, you would gear your car such that in the highest gear you woul be 200rpm past the horsepower peak of the engine when crossing the finish line.
But this would pe totally impractical on the street, as you would need around a 5:1 final drive to achieve something like this. Also, the other problem you run into with gearing is over powering the tires. Remember, a tire can only handle so muchpower, and, if you go and increase the torque there is a great chance that you are not going to hook the car up so it will actually be slower.
I hope this helps.
What a longer stroke does is two things, it multiplies the force created by the piston and it also increases piston displacement which increases its speed. This makes the air column fill the cylinder sooner in the RPM band.
You can also gain more torque by increasing piston diameter. Because you still have the same pressure on top of the piston, now you are taking advantage of more of it so it pushes the piston down faster. The downside to this is there is no multiplication.
The other way to increase torque is to increase air trapped in the chamber. This increases the air/fuel mass on the piston so there is more expansion which creates more pressure. This is how forced induction works.
You can also chemically supercharge an engine by the fuel. This is how Nitrous and any fuel that contains oxygen works. If the fuel used has oxygen, it can burn with less air in the chamber. This means there can be more fuel for more pressure. Fuel expands more than air, therefore you have more pressure.
As far as gearing a car goes, your engine still only makes x amount of torque and horsepower. Gearing cannot change the hp of the engine, it will however multiply the torque created. For instance, if your engine creates 400 lbft of torque, and you have a 2:1 final drive, your engine will "feel like" it has 800lbft of torque. If you change the gearing and you now have a 3:1 final drive, your car feels like it has 1200lbft of torque.
Gearing is the #1 way to make a car faster, well besides giggle gas. And if you were only interested in the 1/4 mile, you would gear your car such that in the highest gear you woul be 200rpm past the horsepower peak of the engine when crossing the finish line.
But this would pe totally impractical on the street, as you would need around a 5:1 final drive to achieve something like this. Also, the other problem you run into with gearing is over powering the tires. Remember, a tire can only handle so muchpower, and, if you go and increase the torque there is a great chance that you are not going to hook the car up so it will actually be slower.
I hope this helps.
Torque and tires win races. If you can't stick, you will not go forward...... I always explain torque as the ability to start moving an object into motion. Make torque changes with cam, fuel mix, i.e. changing the "air/burn volume" in the cylinders.
Good post.
Thread Starter
12 Second Club
Joined: Jun 2005
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From: Orlando, Fl
I had forgotten but have now remembered what else I wanted to know. I guess when youre talking about multiplying the torque with like a 2:1 pr 3:1 or even 5:1 as mentioned above, those are theg ears in the tranny right? I was also wondering where I guess the drive gears come into it, like the 3:73's and 4:10's or stock 2:73's. Ive also always wondered why you have to have atleast 4.10's with the trex cam oor other larger cams, does this play into everything mentioned above?
ok, here is goes, engine makes 400ftlbs, 1st gear 3:1, rear gear 4.10.
Simple math works to this, 400 x 3 x 4.1 = 4920lbft
3.73 = 4476 lbft
Reason you need deeper gears with a larger cam is they need help down low and they can usually run upstairs better than a smaller cam. So, the gearing helps in the torque offset at the bottom of the rpm range and it extends the RPM range needed from the engine for the same speed.
Simple math works to this, 400 x 3 x 4.1 = 4920lbft
3.73 = 4476 lbft
Reason you need deeper gears with a larger cam is they need help down low and they can usually run upstairs better than a smaller cam. So, the gearing helps in the torque offset at the bottom of the rpm range and it extends the RPM range needed from the engine for the same speed.
speed and rotating weight play the biggest factor. if your engine makes the same TQ and HP you could put in a lighter flywheel and boom you HP is more. this is cause TQ is how much work can be done and HP is how fast you can do that work. a big block or big displacement motor makes lots of TQ cause they can do alot of work, just like a Diesel they make like 600 ft lbs and 300 HP thats cause they do tons work with there discplacemnt and heavy rotating assem. but not as muxh HP casue they cant rev that fast.
its all about how fast you can rev and how much work can be done!
its all about how fast you can rev and how much work can be done!
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On The Tree
Joined: Aug 2005
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Originally Posted by camarokid94
speed and rotating weight play the biggest factor. if your engine makes the same TQ and HP you could put in a lighter flywheel and boom you HP is more. this is cause TQ is how much work can be done and HP is how fast you can do that work. a big block or big displacement motor makes lots of TQ cause they can do alot of work, just like a Diesel they make like 600 ft lbs and 300 HP thats cause they do tons work with there discplacemnt and heavy rotating assem. but not as muxh HP casue they cant rev that fast.
its all about how fast you can rev and how much work can be done!
its all about how fast you can rev and how much work can be done!
A diesel makes all its torque at low rpm due to its large stroke. If you compared two identical diesels, one with a light rotating assembly and one with a heavy assembly, The light one world produce more torque at the flywheel because less energy is needed to move the mass of its rotating assembly.
Most diesels are built with relatively heavy rotating assembles because they must run in the constant stage of “knock” that is compression ignition without flying apart.
On The Tree
Joined: Aug 2005
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Originally Posted by leftme4dead
so each engine has a peak torque ? like an engine has a max torque? i guess what im getting at is why, like what decides the max torque the engine can reach? and i noticed like when it comes to cams ill see hp #'s higher than torque #'s, and when I start looking at like FI Ill normally see torque higher if it was originally higher to start out with. Lik ex: if my engine stock had 300hp and 325tq after a cam ill notice higher hp like 375hp and 360tq, but with FI maybe I would see 360hp and 375 tq
For the most part a cam just decides were the engine makes its torque. Most stock cams are designed to provide plenty of low / mid range torque because a street car spends most of its time at lower rpms.
After market cams simply shift where an engine produces torque to higher rpms thus making more hp. This does not always mean that the motor will produce more torque. Refer to the equation of hp/tq above in this post.
Example: Say you can carry 2 kegs of beer (lets say 2 keg*lbs is your torque rating) at a walking pace. Your stronger buddy can carry two kegs of beer at a full sprint. You both are carrying the same weight but your buddy is a lot more powerfull because he can carry it at a faster speed than you. That’s why engines output is defined using both tq (“how much you can move”) and hp (how fast you can move it).
Ok i was trying to say that the heavy rotating assm would limit the HP they could produce not that the it helps to make TQ and produce that big TQ to HP ratio.
and they have heavy rotating assms cause they run like a 20:1 CR and need strength.
and they have heavy rotating assms cause they run like a 20:1 CR and need strength.
