The big horsepower question?
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Joined: Jan 2006
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From: Sweden
The big horsepower question?
I've looked around and gotten some answers - but not all of them. So I would like all advanced tuners/deep interested users to say there experience in the matter.
First off - straight facts.
We know that an engine don't produce horsepowers - it produces torque, which we can put into a formula and calculate a value.
Formula:
Horsepower = Torque * RPM / 5252
Which means that basicly 400hp can be a higher output than 600hp i terms of power. If we try setting up "engine 1" with X lb/ft @ 4000 rpm. Let's say that by that RPM that engine gives 400 hp with X amount of lb/ft at that engine speed.
Give next engine the same amount of lb/fts (as made 400hp at engine 1) but at 8000rpm. Which would give engine 2, 800hp. Even so it doesn't make any more power at what we call it's highest hp.
Which means - in some cases by getting a bigger turbo and gain maybe 50 hp, if that gain is in a lot higher RPM you might have lost power but think you gained cause of the higher amount of horsepower. I guess this is where a good setup with cams/turbo/headflow comes in
Why? Cause that formula is dependent on how high revs you have your torque.
So far I understand everything, reasons for a 700 hp Cummins being able to make a truck go fast is cause 700 hp @ 3500 rpm = 1400 hp @ 7000 rpm. That is in pure engine output. Same amount of torque at that specific amount of revs.
But here it comes, why do we want a lot of horsepower?
Having torque on high revs saves lowers the load - bottom end torque kills rods. Most ppl know this, but what I came to think of yesterday. Having higher gear ratio - will that lower transmission losses?
Of course it's faster (disregard from the loss in shift) by having close ratio gearing. But is it more adventageous to have a closer gear ratio in terms of having less transmission loss?
It's just the losses I'm thinking about, in terms of matching the powerband to the gear ratio and the want for a wide powerband I'm pretty clear!
First off - straight facts.
We know that an engine don't produce horsepowers - it produces torque, which we can put into a formula and calculate a value.
Formula:
Horsepower = Torque * RPM / 5252
Which means that basicly 400hp can be a higher output than 600hp i terms of power. If we try setting up "engine 1" with X lb/ft @ 4000 rpm. Let's say that by that RPM that engine gives 400 hp with X amount of lb/ft at that engine speed.
Give next engine the same amount of lb/fts (as made 400hp at engine 1) but at 8000rpm. Which would give engine 2, 800hp. Even so it doesn't make any more power at what we call it's highest hp.
Which means - in some cases by getting a bigger turbo and gain maybe 50 hp, if that gain is in a lot higher RPM you might have lost power but think you gained cause of the higher amount of horsepower. I guess this is where a good setup with cams/turbo/headflow comes in
Why? Cause that formula is dependent on how high revs you have your torque.
So far I understand everything, reasons for a 700 hp Cummins being able to make a truck go fast is cause 700 hp @ 3500 rpm = 1400 hp @ 7000 rpm. That is in pure engine output. Same amount of torque at that specific amount of revs.
But here it comes, why do we want a lot of horsepower?
Having torque on high revs saves lowers the load - bottom end torque kills rods. Most ppl know this, but what I came to think of yesterday. Having higher gear ratio - will that lower transmission losses?
Of course it's faster (disregard from the loss in shift) by having close ratio gearing. But is it more adventageous to have a closer gear ratio in terms of having less transmission loss?
It's just the losses I'm thinking about, in terms of matching the powerband to the gear ratio and the want for a wide powerband I'm pretty clear!
Thread Starter
Newbie
Joined: Jan 2006
Posts: 42
Likes: 0
From: Sweden
Which means having 2 cars. Both run in there powerband. 3-6000 rpm curve with low amount of hp - but high torque all the way might be faster then car 2 with a 5-8000 even if car 2 has a lot more "horsepower"? This is based on 2 identical cars with same weight but a matching gear ratio for them both.
I just wanna know how "off" I am from the truth 
Which means having 2 cars. Both run in there powerband. 3-6000 rpm curve with low amount of hp - but high torque all the way might be faster then car 2 with a 5-8000 even if car 2 has a lot more "horsepower"? This is based on 2 identical cars with same weight but a matching gear ratio for them both.
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Which means having 2 cars. Both run in there powerband. 3-6000 rpm curve with low amount of hp - but high torque all the way might be faster then car 2 with a 5-8000 even if car 2 has a lot more "horsepower"? This is based on 2 identical cars with same weight but a matching gear ratio for them both.
Scorke
What you've just said is one of the most insanely idiotic things I have ever heard. At no point in your rambling, incoherent response were you even close to anything that could be considered a rational thought. Everyone in this room is now dumber for having listened to it. I award you no points, and may God have mercy on your soul.
Scorke
Scorke
Thread Starter
Newbie
Joined: Jan 2006
Posts: 42
Likes: 0
From: Sweden
I found my answer - even though having lower torque i.e power. It's better to have the torque up high cause then we can get an advantage of gearing. Which means that, answer to the question was that yes - it does make a change cause we will be having more torque to the ground when having it further up in the rpm
THE ONLY THING YOU REALLY NEED TO KNOW
"It's better to make torque at high rpm than at low rpm, because you can take advantage of gearing."
Read this
http://www.to4r.com/techarticle.php?id=8
"It's better to make torque at high rpm than at low rpm, because you can take advantage of gearing."
Read this
http://www.to4r.com/techarticle.php?id=8
What you've just said is one of the most insanely idiotic things I have ever heard. At no point in your rambling, incoherent response were you even close to anything that could be considered a rational thought. Everyone in this room is now dumber for having listened to it. I award you no points, and may God have mercy on your soul.
Scorke
Scorke
