zstroken
For $$$ your name here
- Joined
- Sep 27, 2006
- Messages
- 23,151
Wheel Speed
- Thread starter 1997-12
- Start date
smokingoat04
Not real sure
- Joined
- Dec 8, 2007
- Messages
- 948
I thought Ron was tearing rearends up, and had transmission/computer issues
smokingoat04
Not real sure
- Joined
- Dec 8, 2007
- Messages
- 948
When it runs it runs hard though
This thread seems like a bunch of tail chasing to me.
What we have are a bunch of guys talking about a few basic things, hooking up to the track, normally successful final drive ratios, and tire speed achieved during a run.
And with those three things you've got all the ingredients to a pull. Proper final gearing to produce the needed torque at the ground, the ability transfer that torque to the ground with good traction, and the ability to do it all fast enough to make use of momentum.
Here's the thing though. Looking at that video posted I don't see an engine that could make use of less final drive. I see an engine that if given less final drive would get crushed. It doesn't come out of the hole like an animal and then flatline. It comes out so-so at best, then kind of roooooooooooolls up on the gov springs and then gets pulled back down hard at the end.
Less gear would only suck the engine down quicker.
Which brings me to the main point. Assuming you get the chassis to hook, then the two things that everybody keeps talking about in this thread are final drive ratios (determines vehicle output torque), the speed that it's happening at (tire speed). So you've got a force applied to the ground from the turning tires over the distance you pull the sled. Well, that's easy, force times distance is work. If you can put more momentum into the sled it's because you produced the torque at a higher rate, giving you more distance meaning more work getting done, and in less time usually.
Well since work per time is the definition of power, I'd say the OP just found his problem. He doesn't have the power.
Now some trucks might have the power, but are running too much final drive and because of this they end up running down the track at an rpm where the engine power output is well below peak. Then they just get a taste of the power as the weight hits and the engine gets sucked back through peak. In a situation like that, then yes, reducing the final drive would work well. The average power down the track would increase because the engine isn't being run at an rpm above where it makes power.
I don't think that's the case for the OP. I think his pull isn't limited by his ability to effectively use the engine's power, but instead, I think it's limited by the fact that the engine isn't making enough in the first place.
"Wheelspeed" is effecting the rate at which you apply the force. And to apply any force at an increased rate requires more power. In the example I gave above the additional power came from an engine bouncing off the gov-springs that was allowed to drop back down to an rpm where it made more power. The power applied went up.
But my point is that you can't just change gears and get more wheel speed unless you reduce traction, or unhook from the sled because without the power to support it, you'll never realize that speed as the engine won't have the ass to ever see it.
Or does everyone think the truck in the video would have pulled a higher gear and not fallen on it's face?
It's not like it blew the tires off in a split second and then sang out on the back end on the gov springs once the weight hit. It dogged in both cases. Meaning it was taxed out.
Less final drive and that thing's not going to like it IMO.
What we have are a bunch of guys talking about a few basic things, hooking up to the track, normally successful final drive ratios, and tire speed achieved during a run.
And with those three things you've got all the ingredients to a pull. Proper final gearing to produce the needed torque at the ground, the ability transfer that torque to the ground with good traction, and the ability to do it all fast enough to make use of momentum.
Here's the thing though. Looking at that video posted I don't see an engine that could make use of less final drive. I see an engine that if given less final drive would get crushed. It doesn't come out of the hole like an animal and then flatline. It comes out so-so at best, then kind of roooooooooooolls up on the gov springs and then gets pulled back down hard at the end.
Less gear would only suck the engine down quicker.
Which brings me to the main point. Assuming you get the chassis to hook, then the two things that everybody keeps talking about in this thread are final drive ratios (determines vehicle output torque), the speed that it's happening at (tire speed). So you've got a force applied to the ground from the turning tires over the distance you pull the sled. Well, that's easy, force times distance is work. If you can put more momentum into the sled it's because you produced the torque at a higher rate, giving you more distance meaning more work getting done, and in less time usually.
Well since work per time is the definition of power, I'd say the OP just found his problem. He doesn't have the power.
Now some trucks might have the power, but are running too much final drive and because of this they end up running down the track at an rpm where the engine power output is well below peak. Then they just get a taste of the power as the weight hits and the engine gets sucked back through peak. In a situation like that, then yes, reducing the final drive would work well. The average power down the track would increase because the engine isn't being run at an rpm above where it makes power.
I don't think that's the case for the OP. I think his pull isn't limited by his ability to effectively use the engine's power, but instead, I think it's limited by the fact that the engine isn't making enough in the first place.
"Wheelspeed" is effecting the rate at which you apply the force. And to apply any force at an increased rate requires more power. In the example I gave above the additional power came from an engine bouncing off the gov-springs that was allowed to drop back down to an rpm where it made more power. The power applied went up.
But my point is that you can't just change gears and get more wheel speed unless you reduce traction, or unhook from the sled because without the power to support it, you'll never realize that speed as the engine won't have the ass to ever see it.
Or does everyone think the truck in the video would have pulled a higher gear and not fallen on it's face?
It's not like it blew the tires off in a split second and then sang out on the back end on the gov springs once the weight hit. It dogged in both cases. Meaning it was taxed out.
Less final drive and that thing's not going to like it IMO.
1997-12
Rookie to this game
- Joined
- Jan 20, 2009
- Messages
- 168
Your probably right a higher gear with the way it ran in the video it would have fallen on its face at about 150 ft mark. That was a fueling, and a rpm issuse. It was running a little less than 3/4 throttle with the way it was set up. Both issues have been taken care of.
full pull
Sales&Support Valair Inc
- Joined
- Jan 12, 2009
- Messages
- 1,683
One way or the other the objective is to get the right gearing for the power that a truck makes.
A 800hp truck would need a differant final gear than a 600hp truck. You can change gearing or raise the HP. one might be easier than the other.
A 800hp truck would need a differant final gear than a 600hp truck. You can change gearing or raise the HP. one might be easier than the other.
And changing gears all the live long day on a 600hp truck isn't ever going to make it capable of doing what an 800hp truck can either.
:hehe:
If easier were the name of the game then a case of beer and a couch would be a lot easier than anything.
Last edited: