When we do 1/4 mile passes our trucks shift somewhere between 3200 and 3500 rpm. At that rpm we are making close to our max hp but not our max tq. What would happen if you would tune the truck to shift at the peak tq rpm? Would it be quicker in the 1/4 mile?
TQ vs HP
- Thread starter TQMONSTR
- Start date
I know u can't compare big blocks to diesels but in most cases let's say a 454 makes 350hp but 450ftlbs or tq. Now put a cam, carb, heads on an it makes 475hp and 550-600ftlb. I feel that the hp increase makes the car/truck faster more then the increase in tq. Least it did on my 540. Pulled 803hp/860fttq. The 350hp increase was felt more then the 200fts over the 600 I had before.
Now u look at a cummins. They make way more tq then hp normally. And then a dmax with same tq as a cummin but most of the time makes more hp while doin same tq and 90% of the time a dmax wins a race. I think hp plays a huge roll. Imo I could be wrong.
Now u look at a cummins. They make way more tq then hp normally. And then a dmax with same tq as a cummin but most of the time makes more hp while doin same tq and 90% of the time a dmax wins a race. I think hp plays a huge roll. Imo I could be wrong.
Torque is analogous, or whatever that word is, to work, which is a force acting through a distance which is the distance of the drag strip. Now the torque can be manipulated through the transmission but remember that even though say a lower gear provides more torque therefore more force, it also gives up a proportional amount of distance.
The same idea applies to HP. Which is the work done divided by time, and if you do the same amount of work, but do it in a lesser time you can see you would make more HP. And you also want to do the dragstrip in a lesser time.
So in the ideal non real world it would be most beneficial to stay at Max HP when you want to go down the drag strip the fastest.
Feel free to correct me but that's how physics explains it torque may be a factor but torque has no time component so it is not important in a situation where you are timed, but what is important is the rpm range where you make the most torque but also where you make it the greatest amount of times.
Hope I don't confuse anyone.
The same idea applies to HP. Which is the work done divided by time, and if you do the same amount of work, but do it in a lesser time you can see you would make more HP. And you also want to do the dragstrip in a lesser time.
So in the ideal non real world it would be most beneficial to stay at Max HP when you want to go down the drag strip the fastest.
Feel free to correct me but that's how physics explains it torque may be a factor but torque has no time component so it is not important in a situation where you are timed, but what is important is the rpm range where you make the most torque but also where you make it the greatest amount of times.
Hope I don't confuse anyone.
Torque is not the same as work. Torque is a rotational force. Torque is measured in units like lb-ft. So 1 lb-ft would be a one pound force acting on a one foot lever to rotate a body. Work is like ft-lb, which is force applied over a distance. If you add the time element into work you get power.
Yeah sorry your right I don't mean to say torque and work were the same because you can have torque and no translational movement have have no work do e. Anyway I think the main point is that torque does not have a time component but HP does so when your racing and trying to get the shortest time you want HP not torque.
[QUOTE when your racing and trying to get the shortest time you want HP not torque.[/QUOTE]
X2. Exactly my thoughts.
X2. Exactly my thoughts.
Max area under the curve is your goal.
Like Dan said, it is normally a few hundred RPM past peak HP rpm if possible.
A stock LB7 charger is going want about 3200rpm
A stock LLY-LMM is going to want about 3400rpm.
A 66mm charger is going to want about 3600rpm
A 75mm about 4200
A 80mm about 4600
Like Dan said, it is normally a few hundred RPM past peak HP rpm if possible.
A stock LB7 charger is going want about 3200rpm
A stock LLY-LMM is going to want about 3400rpm.
A 66mm charger is going to want about 3600rpm
A 75mm about 4200
A 80mm about 4600
PS - Your peak torque with a stock charger is about 2200 rpm. If you shift there, you'd be going REALLY freaking slow.
Area under the curve is defined by an integral. We need to bust out calculus for shift points?? Lol
Good info!
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Naw, you don't need calculus. I got A's and B's in calc and didn't understand any of it. 
You just find the overlap/intersect point based on gear ratios and your dyno graph.
This is give you the biggest possible area (average HP) as you go through the gears.
You just find the overlap/intersect point based on gear ratios and your dyno graph.
This is give you the biggest possible area (average HP) as you go through the gears.
You are looking for the most avg HP like McRat was saying. I usually run about 500 RPM over on a Gasser but the diesels maybe that to a little less over. Looking at logs to see where you actually shift at will help you on gettting that set up.
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You can almost that torque is horsepower, horsepower is torque just modified by rpms. Your goal is to always make more torque, its just the higher the rpm you can make the torque, the more torque you made given a certain amount of time.
Another way to think about it is the more torque you make the more fuel you burned but the more rpms you go the more fuel you burn so if you have a lot of torque at a high rpm you will be burning a lot of fuel and if your burning a lot of fuel your going to be going faster and more acceleration.
Its hard to think why more torque dosemt necessarily equal more acceleration, it does, but in real life we can never ignore time.
Another way to think about it is the more torque you make the more fuel you burned but the more rpms you go the more fuel you burn so if you have a lot of torque at a high rpm you will be burning a lot of fuel and if your burning a lot of fuel your going to be going faster and more acceleration.
Its hard to think why more torque dosemt necessarily equal more acceleration, it does, but in real life we can never ignore time.
No torque does matter but the fact is the torque will be nearly double that of the HP and the HP will peak at different RPM's but the torque will peak near the same rpm's in any given engine. So running above peak hp will net more power under the curve.
Just had the truck on the dyno. My truck made 556hp and 1055 ft-lbs of torque. This is my daily driven tune and has been for the last 3 and half years. I'm happy with the tq as the motor is still stock. I may even want it a little lower. Here is what has me curious. If i add a few more parts (profab y bridge, up pipes and manifolds, batmowheel...) is it possible to tune it to make more hp (600ish) and less tq (950-1000)?