Horsepower sells cars, torque wins races.

[Dave-O]

Correct me if I'm wrong here, but ...

 

... if an engine is doing half the work twice as fast, won't it be doing the exact same amount of work as an engine doing twice the work half as fast? Given a specific TIME constraint, I'm inclined to say yes. In theory, that is. Real-world application has too many variables to answer my question.

 

Continue on, this is an entertaining read.

[lmwii]

Correct me if I'm wrong here, but ...

 

... if an engine is doing half the work twice as fast, won't it be doing the exact same amount of work as an engine doing twice the work half as fast? Given a specific TIME constraint, I'm inclined to say yes. In theory, that is. Real-world application has too many variables to answer my question.

 

Continue on, this is an entertaining read.

if you change that to say "if an engine twists half as hard twice as fast won't it be doing the exact same amount of work as an engine twisting twice as hard half as fast?" then yes. and that's why we use HP to measure power, not TQ.

[Chad]

Yah, thats the reason we have transmissions, the motor has a set power curve, but we need access to a varriable amount of torque and axle speeds, so we sacrifice axle torque for axle speed every time we upshift, and the reverse is true when we down shift. No matter what gear it's in, the same power is applied to the wheels, it's just at a different torque and different speed. If you change motors to one with a higher RPM range but the same net power, you just need to change the gears accordigly and the net result is the same. When you have 2 motors with equal power but different torque, you can make them behave identially in the torque realm with a simple gear change.

 

It's like bailing out a sinking ship, you can use a big bucket or a small cup. If you bail it out at the same water flow rate (power), the small cup move less water per cycle, but cycles much faster, the net result is the same. Only difference is the guy with the big bucket gets to brag about his bucket size (torque) the ship will still get bailed out just as fast either way.

 

Arguing bucket size is silly if the small cup guy can bail 20-times faster than the guy with the 10-times larger bucket. the 20-times faster at 1/10th the size will bail the ship out twice as fast.

[Shelby]

one of the easiest ways to understand the diff in hp and tourge is to do a test with a couple boats

 

lets same you have two identical boats both weight exactly 2700 lbs , both have 120 hp engines ,the diff is one has a 17 degree prop and the other a 23 degree prop ,,what the degree means is the prop moves thru the water that number of inches per revolution

which boat will be faster , the 17 degree prop moves 17" per rev, the 23 degree prop moves 23" per rev ,

now you tell me which boat will be faster in the water

[ucw458]

one of the easiest ways to understand the diff in hp and tourge is to do a test with a couple boats

 

lets same you have two identical boats both weight exactly 2700 lbs , both have 120 hp engines ,the diff is one has a 17 degree prop and the other a 23 degree prop ,,what the degree means is the prop moves thru the water that number of inches per revolution

which boat will be faster , the 17 degree prop moves 17" per rev, the 23 degree prop moves 23" per rev ,

now you tell me which boat will be faster in the water

 

 

The 17 pitch prop will be alot faster out of the hole. Especially if it's a 4 blade prop. But top speed the 23 pitch might beat it if the engine has enough torque.

 

Too many variables to the boat scenario. My old boat with a 40HP engine could do 23mph with the 4 blade 11 pitch prop. When I put on a 14 pitch 3 blade it bogged out of the hole and would only do 21mph. Boat motors see more load than car motors. Only way I know to compare them is picture a car going up a 30 deg road that never ends.

[Technology]

My car makes pretty close to 500hp at the engine. It's for sale for 10,000 dollars. How much more power will I need before that price becomes very attractive to people here? 200 more? 300 more?

 

My goal used to be 500, then it was 600, but now I believe that it's 800. 800whp for all you suckas, and I will get it restored and drive it like a regular car. w00t!

[Shelby]

The 17 pitch prop will be alot faster out of the hole. Especially if it's a 4 blade prop. http://www.starquestclub.com/forum/public/style_emoticons/default/tongue.gif But top speed the 23 pitch might beat it if the engine has enough torque.

 

Too many variables to the boat scenario. My old boat with a 40HP engine could do 23mph with the 4 blade 11 pitch prop. When I put on a 14 pitch 3 blade it bogged out of the hole and would only do 21mph. Boat motors see more load than car motors. Only way I know to compare them is picture a car going up a 30 deg road that never ends.

 

 

ok your on the right track but explain why they act diff

[Chad]

The boat analogy only demonstrates the effect of gearing. Just like if you did a race in two equal cars from a dead stop, one in 2nd gear and one in 4th. The one in 2nd will get going quicker, but eventualy the one in 4th will pass it. The different angles of different props is just like the different gears in a transmission. Imagine if you had a variable pitch prop...

[Shelby]

sorry Chad but it also demonstrates the aplication of tourqe and hp

and your wrong to say the car with the taller gear will reach the same mph as a lower gear'd car that is not always true

 

pushing a boat thru water is a perfict example of a car at top mph , now i want you educate'd guys to tell me why and what can effect the out come of whitch of my boats will be the faster with what prop and why

and don't say you have already answer'd the question cause you haven't

[Chad]

sorry Chad but it also demonstrates the aplication of tourqe and hp

and your wrong to say the car with the taller gear will reach the same mph as a lower gear'd car that is not always true

 

pushing a boat thru water is a perfEct example of a car at top mph , now i want you educate'd guys to tell me why and what can effect the out come of whitch of my boats will be the faster with what prop and why

and don't say you have already answer'd the question cause you haven't

 

 

A car in different gears also demonstrates HP and TQ beign put to use, my annology with the 2nd and 4th gear race is just the same as your 2 props, they bogh have the same HP applied. Your different props represent a car wtih different rear differentials, one is better for high speed travel, the other ideal for low speed acceleration.

 

If you raced 2 equal cars, one in 2nd and one in 4th, they will both reach 35 MPH, and the one in 2nd gear will reach it much more quickly. If the race continues past 35, eventualy the one in 4th will pass the one in 2nd due to gearing. in the case of most cars, that will probalby happen around 65 MPH, at which point the one in 2nd has no chance ot catch up, or even keep up. Same will be true of the two boats with diffrent props, there will be a point where the slower one passes the quicker one, and then the rece is over cause the slower one is able to reach and maintain higher speeds.

 

Your annolgy does nothing to demonstrate the merits of torque vs. horsepower, it demonstrates the need for optimization of the power source to the load through gearing (in the case of cars) or prop angle (in the case of boats).

[Shelby]

c-p Chad>

Your annolgy does nothing to demonstrate the merits of torque vs. horsepower, it demonstrates the need for optimization of the power source to the load through gearing (in the case of cars) or prop angle (in the case of boats).

 

 

tourqe and hp are the same for both boats , and the example of them reaching top speed is exactly the same for a boat and a car , once you reach the point the amount of apply'd tourqe is exacly the same as require'd to increase speed , you will cease to increase speed , now in my example the 17" prop will be faster even at high rpm because there is less strain on the prop per revolution then the boat with the 23" PROP

here is a partial list of diff gearing,

2:71, 2:91, 3:23, 3: 33, 3:54, 3:90, 4:11, 4:22 , 4:56, 4:62

 

now i know you have a lot of real world experiance so tell me which of these gears will give you max top end with a max rpm range of 6500 rpms and

an 8.571 hp to weight ratio

[Chad]

The difference between a 17" prop vs a 23" is the same as the difference between a 32" tire and a 44" tire. They both can drive at 55 MPH, the only difference is the axle speed and the torque required to maintain. the 44 needs more torque, but it also needs less RPM, if you change the rear diff gearing correclty,they balance out.

 

You are speaking of optimizing the load to the source, it has nothing to do with the torque vs horsepower because all you need to do is change gearing to optimize. You want the 23" prop to mimic the 17's performance? run 0.73:1 gear reduction, the same amount of power applied to the water. The 23" will turn slower, but will have more force on it than the 17", the same net result of forward motion will be acchieved. You don't throw a 23" prop on a boat that had a 17 and expect it to go faster, just like you don't throw a 44" tire on a a truck that had 32's for the same reason. You gotta change diff gears to get the optimization corrected. It has nothing to do with the torque vs. HP arguemnt.

[ucw458]

ok your on the right track but explain why they act diff

 

 

The boat analogy only demonstrates the effect of gearing. Just like if you did a race in two equal cars from a dead stop, one in 2nd gear and one in 4th. The one in 2nd will get going quicker, but eventualy the one in 4th will pass it. The different angles of different props is just like the different gears in a transmission. Imagine if you had a variable pitch prop...

 

 

sorry Chad but it also demonstrates the aplication of tourqe and hp

and your wrong to say the car with the taller gear will reach the same mph as a lower gear'd car that is not always true

 

pushing a boat thru water is a perfict example of a car at top mph , now i want you educate'd guys to tell me why and what can effect the out come of whitch of my boats will be the faster with what prop and why

and don't say you have already answer'd the question cause you haven't

 

 

The car gearing compared to boats isn't exactly correct. I'll try to explain to the best of my knowlege.

 

First boats see MUCH more load than cars. In fact the only way to truly replicate the same load on a car is to run it on a dyno that can hold the engine at X rpm no matter how far the accelerator is pressed.

 

 

Boat size, weight, hull design and engine power are all factors in determining what prop to use. Most boats do not have a transmission they only have forward and reverse making prop selection even more critical. The best prop for a give boat is one that maxes the engine's power output. Meaning it's small enough to let the engine get to redline but large enough to not let the engine rev past redline at full throttle. Most boat drives have NO gearing changes that can be made so prop selection is crucial.

 

 

Blade design can have a bigger impact on performance than pitch. You have pitch, diameter, # of blades and shape of blades to consider. A 10"diameter 14 pitch 4 blade prop will be slower than the same prop with only 3 blades. The 4th blade imparts extra force on the water. Typically when switching from a 3 blade to 4 blade prop you reduce the pitch by 2. This gives you the same top speed but gets you out of the hole faster.

 

 

In Shelby's example the 23 pitch may be too big and not allow the engine to reach redline. In that case the 23 will be slower than the 17. If the 23 is a 4 blade it will be considerably slower than the 17. From my experience a normal 17-18 foot boat with a 120HP engine doesn't have the power to drive a 23 pitch prop sucsessfully. A 16-18 pitch 3 or 4 blade will work better. The smaller prop will allow the boat to get on plane and reach top speed where the larger prop will make it struggle to get on plane and may never reach top speed.

 

 

 

I'm not a boat expert. These are just observations I've made during my time working at a boat shop and playing with my boat. My boat was only a 16 footer with a 40HP engine but it came with different props so I got to experiment. I had 10, 12 and 14 pitch 3 blade and the 11 pitch 4 blade. The 4 blade prop was the best all around prop for that boat. The 4 blade got up on plane the fastest and reached the highest top speed.

[Shelby]

The car gearing compared to boats isn't exactly correct. I'll try to explain to the best of my knowlege.

 

First boats see MUCH more load than cars. In fact the only way to truly replicate the same load on a car is to run it on a dyno that can hold the engine at X rpm no matter how far the accelerator is pressed.

 

 

Boat size, weight, hull design and engine power are all factors in determining what prop to use. Most boats do not have a transmission they only have forward and reverse making prop selection even more critical. The best prop for a give boat is one that maxes the engine's power output. Meaning it's small enough to let the engine get to redline but large enough to not let the engine rev past redline at full throttle. Most boat drives have NO gearing changes that can be made so prop selection is crucial.

 

 

Blade design can have a bigger impact on performance than pitch. You have pitch, diameter, # of blades and shape of blades to consider. A 10"diameter 14 pitch 4 blade prop will be slower than the same prop with only 3 blades. The 4th blade imparts extra force on the water. Typically when switching from a 3 blade to 4 blade prop you reduce the pitch by 2. This gives you the same top speed but gets you out of the hole faster.

 

 

In Shelby's example the 23 pitch may be too big and not allow the engine to reach redline. In that case the 23 will be slower than the 17. If the 23 is a 4 blade it will be considerably slower than the 17. From my experience a normal 17-18 foot boat with a 120HP engine doesn't have the power to drive a 23 pitch prop sucsessfully. A 16-18 pitch 3 or 4 blade will work better. The smaller prop will allow the boat to get on plane and reach top speed where the larger prop will make it struggle to get on plane and may never reach top speed.

 

 

 

I'm not a boat expert. These are just observations I've made during my time working at a boat shop and playing with my boat. My boat was only a 16 footer with a 40HP engine but it came with different props so I got to experiment. I had 10, 12 and 14 pitch 3 blade and the 11 pitch 4 blade. The 4 blade prop was the best all around prop for that boat. The 4 blade got up on plane the fastest and reached the highest top speed.

 

 

your very much right on the money,, as to comparison to car at top speed

the two do relate because realy at top max'd out speed is the only time the cars engine will be under full load 100% of the time , and the force reverts back to tourqe available not hp , but hp is words we use to put meaning to a force create'd by useing tourqe to perform work

 

none of this is 100% acurate when figureing 1/4 mile or 1/8 mile track gearing and tire size , why because you do not want to maximize your rpm

nor your hp and tourqe curve but stay in the upper level of the max g-force

curve , and the area of max excelleration may not be at eather end , lower or top of your engines power range

 

top end speeds i have always saw have been with the use of gears from 3:23 to 3:55 . lower gears like 2:76 may show on paper to give higher mph but in the real world don't have the tourqe need'd to attain it , refer back to the boat with too big of a prop

 

gearing for the 1/4 depends largely on the engines rpm ,hp , tourqe range

[ucw458]

top end speeds i have always saw have been with the use of gears from 3:23 to 3:55 . lower gears like 2:76 may show on paper to give higher mph but in the real world don't have the tourqe need'd to attain it , refer back to the boat with too big of a prop

 

 

That's true, my wife's escort for example has a fairly high axle ratio and can only do 97 mph. It doesn't run out of gear it runs out of torque. If I put a numerically lower ratio in I would reduce it's top speed.

 

Conversly my galaxie has an abundance of torque. That car with 2.70 gears hit 135 mph before I backed off. (power steering pump started cavitating and I lost power steering at 135mph) When I put 3.50 gears in I ended up running out of gear at 105mph buuut it gets there a whole lot quicker.

 

But these are vastly different cars. The escort is rated at 88HP 108TQ where as the galaxie is rated at 305HP 425TQ.(stock ratings) The galaxie weighs 1,000 lbs more but has 4x the torque.

[Chad]

The top speed in the viper is acchieved in 5th gear cause 6th is too steep. Doesn't mean the viper needs more torque, it means the gearing for 6th isn't suited to the task. If it were all about the torque, don't you think we see cummins swaps into vipers and vettes?

 

Don't modify your motor make more torque just to cover up a gearing problem, or in the case of a boat, a poor choise of props. Don't blame the motor if you use the wrong delievery system, weather it be prop angle, prop diameter, tire diameter, transmission gearng or differential gears.

 

Just as Jinx said, you can screw up any cars performance with impropper gearing, and I agree. I don't however feel that the best fix is to throw more torque at the problem when you can also throw more RPMs at it instead. Better yet, do both. Either way, you will make more horsepower.

 

And to say that a car never sees load like a boat, when the boat is on plain, it has a lot less drag, and the power transfer is much like a very mushy autotrans untill it reaches very high prope speeds, you are pushing against a liquid, not rubber on pavement. Also, wind drag on a car increases at a square rate, double your speed and you quadrouple your wind resistance. That is the sole reason why the viper can't run 240 MPH in 6th, it doesn't have enough HP to push through the wind. And youp can't say it's all about torque, F-1 cars will do over 240 MPH easily, with a mere 275-300 ft/lb, but over 900 HP.

 

From a top speed perspective, assuming gearing is dialed in correclty, it's all about horsepower, not torque. It takes about 500 HP to break 200 MPH, regardless of your torque (assuming a normal wind CD of .32-.36).

[jinx]

whoa.... Chad. You're fulla crap. You deliberately skipped over the real world examples, like you always do. Try again.

Don't you like analysis ?

see if ya can follow this logic. A 12 year old could

duramax stang lose 1000 pounds and let it play in our 2750 pound sandbox.

What ET do ya reckon.... 9.2ish ? ....still at 600hp

Pound for pound, that li'l nissan 1.8 will pee on any street honda 1.6. At 600hp, the 1.8 ain't in the same stratasphere as the 600hp stang

What's worse, you (and your crew) think, that in a 7000 pound truck, the landscape changes miraculously (simply by gearing).... when in fact, the butt-whoppin will be even more severe

"the honda wins".... I'm still laughin' man - lol

You can't produce a single 2750# 420hp 1.6 that will touch a 10.8. Non existent.

Nor a 2750#, less than 474hp, 1.6 that will et a 10.4, as the blue eip. I dare you.

That 600hp stang would flirt with low 9s/hi 8s on said diet. You claim a 600hp 1.6L will match that, same weight. Why .....because YOU understand gearing & HE doesn't ?

Impossible a 1.6 can't ET close at almost one third the weight, but it will at 7000 pounds ?

 

Put your money where your mouth is, lets see these examples. Very ez to produce

 

Oh, and GNX's are slow piles of junk!

hehhe.... yep, that's why he made that duramax edition

[Starwolf]

LOL ^^^ wow...

 

So basically what the point is.....would you trade having 50 less horsepower for 50 more torque if everything else on the vehicle stays the same jinx?

 

If so lets find that example and ill put $100000000 on the higher horsepower car.

[Shelby]

personaly i don't understand the talk about 14k lb tractors and 1.6 honda's,

if any of this on paper talk is intend'd to be of any use to guys with a 2.6 Conquest why not use those weight figures and come up with a gear combination and engine rpm range that can be put to real world useage, eather on the street or for 1/4 runers and or 1/8th mile tracks and of course the usually street machines ,

 

the simple truth is to make use of high hp you need to increase your power range to almost 7 k rpms and have a useful long power curve throu out the rpm range from 4k to 7k , heck even a 6500 rpm max will do a very good job if properly set up

gear , cam and hp set up for each are very different and no one set up will be optimum for all conditions

cam and fuel tuneing can be many diff ways and many diff combinations each for a single useage , a super quick 1/8 mile track car will be useless for a daily driver and not much fun as a daily driver , for street driveing a 300 hp car with stock gearing can be a blast to drive on the street but the same car with 4:22 gears while a bear in a an 1/8 mile run will be useless trying to have fun arround town cause it'l only have one point where it'l be fun and thats at wot , by the same token a car set up for an 1/8 mile track is run out befor it gets to the 1/4 mile end , another thing is shifting , the more power you have the harder it is puting that power to the pavement an the fact is with out traction that 10 sec run will never happen , it's like this every change you make to the power curve means you have to change other things like tires

shift points and of course find a clutch that will hold it,, and loss time makeing those shifts ,thats one huge reason guys end up with an auto trans , no time lost makeing a shift but other things come into play with an auto like convertor stall rpms and tires , that and the impact on the drive line every time you do make a shift with the 5 spd , that impac is gona sooner or later break something

 

what you need to do is decide what it is you want your car to do then tune it

to do what you want ,and by tuneing i mean tune the entire car not just the engine , but be sure what you want is realy what you want then go for it,, just remember any thing is changeable back to what it was http://www.starquestclub.com/forum/public/style_emoticons/default/wink.gif , and trying to make 400 hp on TBI is a lost cause even if you do manage to do it , way too much stresss on all the drive line

Edited March 21, 2011 by Shelby

[lmwii]

jinx, this is not about what is practical or financially realistic. it is about what is POSSIBLE in a perfect setting. the real world is about compromises and uncertainties, and all real world cars are compromises. with no rulebook, and no limit on resources, any 600hp engine would beat any 500hp engine. it might take a 10 speed transmission, or some other fantasy piece of drivetrain, but that is the whole point. with perfect gearing, and all else being equal, the higher hp engine wins. your examples are fine; but they represent real-world cars with off the shelf parts and other hardware that required the builders to make compromises. you refuse to accept that our premise is about the possible.

 

we talked about a water wheel in an earlier post. another example that is similar is an electric motor. electric motors generate maximum torque at 0rpm - do you think that torque will move anything at 0rpm? the faster it spins, the more hp it makes, but the less torque. the rpm is what does the work; torque with no spin isn't doing anything.

[Shelby]

old Vietnamize saying "over 300 ways to skin cat" ,, but only thing matters is it's in the pot

[Technology]

Anyone making 460wtq and less than 450whp with the g54b motor? If so, lets race. It could put this issue to bed. You have to wait a year probably, but when the time comes, it will be great!