OT - horsepower vs. torque question?

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Model T Ford Forum: Forum 2013: OT - horsepower vs. torque question?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Thursday, June 13, 2013 - 08:16 am:

We had a dynometer test a few days ago, and one of the things the technician said was "the torque is really good" on our six cylinder engine (Model K).

I "googled" torque and horsepower, and am trying to get my mind around it. I always "assumed" torque was just a factor of horsepower. In other words, depending on gearing, torque would "react" to the amount of horsepower available.

However, are the two measurements quite different, and independent of each other? If so, is it better to have a more horsepower or more torque (if you must have more of one than the other).

Probably stupid questions, but I'll appreciate any answers or info,

Rob



Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, June 13, 2013 - 08:37 am:

I'm surprised nobody jumped on this in the original thread, Rob.

Off the top of my head, to be corrected by Royce :-)

HP = Torque times RPM


Top of pagePrevious messageNext messageBottom of page Link to this message  By Marshall V. Daut on Thursday, June 13, 2013 - 08:38 am:

There's an old adage that goes; "You build engines for horsepower, but you drive torque." In my old high performance big block Corvette days, the idea was to get as much horsepower into the engine as you could by putting in radical lumpy camshafts and cylinder heads with gigantic valves, open plenum intake manifolds, etc. But you know what? Those cars were a pain in the ass to drive on the street and were doggy, to boot. Until you got up into the 6500 RPM range, Volkswagens could be me on the street. I finally got smart (sort of) and realized that all the good stuff (torque) was found in the higher RPM range where the horsepower kicked in, not in the mid-range where you do most of the driving. For street driving, the higher torque was where the rubber met the road and made pleasurable and fun drivers. I started paying more attention to manufacturers' horsepower versus torque charts that were supplied with whatever speed goodie I bought. It's probably an oversimplification on my part, but I'll settle for more torque in the driving range (under 4500RPM on older performance engines) than high horsepower. It's the torque that works hand in hand with the horsepower that gives the car its driving personality. Other more data-minded folks can add to this "seat of the pants" feeling that I shoot for. High horsepower alone doesn't make a fun engine.
Marshall


Top of pagePrevious messageNext messageBottom of page Link to this message  By Marshall V. Daut on Thursday, June 13, 2013 - 08:39 am:

OOPS! "Volkswagens could BEAT me on the street."


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, June 13, 2013 - 08:53 am:

Unless you have a CVT, continuously variable transmission like a Metz or a new Nissan, the friendliness of an engine depends on the RPM range of its useful horsepower. With just a 2-speed tranny, 5 to 50 mph without shifting shows a wide range of power, and is a big deal.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Thursday, June 13, 2013 - 09:19 am:

I can't give a technical explanation as well as what you can find on the internet. However, my understanding and best explanation is like riding a bike. Let's say I have low torque but a ton of HP and you have a ton of Torque but low HP. Your torque will let you start the bike and accelerate from a stop whether you are in first gear or 17th gear. You have tremendous power to force the wheel to turn. On the other hand, I won't be able to start moving in 17th gear, but once I get there I'll be able to keep pedaling faster and faster while you're be stuck at a much lower maximum speed. To see this in person just pedal a mountain bike in first gear as fast as you can, you'll accelerate quickly and then top out because you can't spin the pedals any faster. You can feel it, you're pumping your legs really faster but it's not actually adding anything to your speed. HP lets you keep applying force at the top end.

Your large amount of torque means that your Model K will probably accelerate and comfortably run at 35 mph whether you are driving it by yourself or carrying 3 more large adults. It's not going to notice the weight difference very much. Your lower HP though means that you won't have as much top end speed. If you compared your car to a speedster T under a similar load with more HP you would see the difference in that the T won't be able to get moving as quickly, it will labor to get up to speed but it will have a much greater top speed.

As in Marshall's example - tremendous HP cars can run and run and run at top speed, they just accelerate poorly. The opposite of that equation is a Mack truck - it can haul thousands of pounds but it's top end is severely limited.

Which one is better? Somewhere in-between. It really depends on how you're going to drive. For your application more torque and lower HP is fine, you're not trying to drive 70, but you may carry some folks with you. I want to add HP to my speedster so that I can increase my top speed, but I'm not worried about carrying much of a load or accelerating really hard.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Thursday, June 13, 2013 - 09:54 am:

Thanks guys. Ralph and Seth, it appears we are where we need to be with the K (good torque). The "problem" with a big, two speed car (K at least) is you need good lugging power (torque?) to quickly transition from low to high. I like to shift to high quickly with all our Fords (Ts, N and K) for many reasons (mostly to save wear and tear on the planetary gears and bands, especially on the N and K with "exposed" transmissions).

Currently I'm able to shift at 5 - 7 mph on level pavement and pull comfortably up to cruising speed.

Ford advertised the Model K as being able to shift to high gear quickly and stay there (justifying their two speed vs. competitors three and four speed transmissions).


Top of pagePrevious messageNext messageBottom of page Link to this message  By Derek Kiefer - Mantorville, MN on Thursday, June 13, 2013 - 09:58 am:

HP = TQ x RPM / 5252


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Thursday, June 13, 2013 - 10:02 am:

Derek,
I saw this formula when I "googled" torque v. hp. However, wouldn't this just mean the torque (or horsepower) are just a factor of each other? In other words, wouldn't torque always be the same on any engine, just dependent on HP and RPM?

Another question, would a six cylinder have more "lugging" power (torque?) than the same cubic inch or horsepower four cylinder car? I thought the reason John Deere tractors were so popular compared with many competitors in the 40s through 50s (they were two cylinder, most competitors were four cylinder) was because they had better "lugging" or pulling power?

Or do number of cylinders have nothing to do with torque?

Thanks,

Rob


Top of pagePrevious messageNext messageBottom of page Link to this message  By Derek Kiefer - Mantorville, MN on Thursday, June 13, 2013 - 10:21 am:

Dynos measure torque. HP is just a calculation based on TQ and RPM. Any engine that will spin fast enough will show its HP and Torque curves cross each other at 5252rpm.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Thursday, June 13, 2013 - 10:25 am:

I believe cylinders and displacement play a big part in torque. Displacement and all else held equal, fewer cylinders will provide MORE torque, but more cylinders will allow higher RPM and provide more HP. With displacement being the same, you're getting a bigger, harder bang from the 2 cylinder John Deer, thus the lugging power, whereas the other tractors with 4 cylinders probably had way more speed or could turn a PTO faster.

My 4.2 L v6 F-150 actually has more torque than the 4.6 L v8 from the same year.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, June 13, 2013 - 11:01 am:

Doesn't stroke come into play, longer stroke = more lugging power, shorter stroke = higher RPM.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Thursday, June 13, 2013 - 11:18 am:

Mark, You are close. The longer the the longer the piston dwells. That means it stays higher in the cylinder than a short rod. The pressure pushing on the piston has something to push on longer. If the piston leaves the top of the stroke sooner the sooner you lose pushing power [torque]. Long rod motors wont rev as high as short rod motors and are for light cars [ sports cars]. Look at the jeep motor. Very long rod, good pulling power but wont rev to high. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Thursday, June 13, 2013 - 11:36 am:

Rob or anyone,
What is the horizontal scale to the image you posted? It shows 0 to 60, maybe seconds?

Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave DeYoung on Thursday, June 13, 2013 - 11:40 am:

Bob: Derek has your answer. Torque is what the dynos reads. HP is merely a function of what ever the torque is at a given RPM. Torque moves the load. Hp just tells you where in the rpm range you can sustain max speed. Just keep your eye on the torque.


When it comes to performance, I have found that people tend to gravitate to the highest number. Gas engines can be made to spin very fast resulting in a higher number for the HP versus torque. Diesels on the other hand tend to spin at a much lower rpm creating huge torque numbers, but don't have the rpms to boost the hp value.

The engines we tend to play with are in the low rpm family, so the hp number never looks that impressive.

As an example, the stock Model T produces 90 foot-pounds of torque @ 900 rpms. It produces 20 hp @ 1680 rpm. Using Derek's formula above, the actual torque at 1680 is 67 foot-pounds. That is enough to propel my T's at 40 mph all day long except on hills. Not enough torque.

Let's move to the Model A. It has a rating of 40 hp @ 2200 rpm. That filters down to 95 foot-pounds @ 2200. Most Model A guys that I know run their cars in the 45-50 mph range. The torque is up by 41% and the speed by only 13-25%. The difference is the A's ability to climb average hills without the loss of speed and not having to downshift. That is what torque does.

As for 6 vs 8 cylinders, the Ford 6 of the 40's actually made more torque that the v8, but could not match the hp number due the v8's ability to spin faster. The power of the 6 was made possible by its longer stroke.

What were you final hp and torque number at a given rpm?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Nathan Bright on Thursday, June 13, 2013 - 11:53 am:

Enzo Ferrari once said... "Horsepower sells cars, torque wins races." seeing as our old fords are far from ferraris it may not matter which ones better haha! but i prefer torque over HP due simply to this quote.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Thursday, June 13, 2013 - 12:46 pm:

Jim,

I don't know what the "horizontal scale" is? (in more ways than one :-()

I told Chad the operator to tell me when we hit 50 mph, and I shut it down then. I believe that's when he ended the test too.

Next week at the Speedster Reunion Chad will again run the dyno, and i think about 20 speedsters are scheduled to test. I hope I'm able to attend (Saturday morning) and learn more about the test.

The Model K six cylinder engine is 405 cubic inches, with a shorter stroke than bore of 4.25 in. stroke/4.5 in. bore. The Model K engine began life in late 1904 as an engine for Henry Ford's next racer. Initially it was rated at 40 hp, and by 1907 some Ford releases rated it at 120 hp (although a 105 hp car ran most of the competitions).

Judging by photos, It appears the crankcase was getting "deeper" and the jugs (cylinders) taller to create the additional HP ratings, but that's just a guess on my part.

Thanks for all the great info guys,

Rob

1905 Ford six cylinder racer engine:


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Thursday, June 13, 2013 - 02:08 pm:

Hey Rob, the horizontal scale he's asking about is the numbers across the bottom of the graph that go 0, 6, 12, 18, 24, and then 31.135 and yes I think it's graphed by the seconds of time for the test. What I'd really like to see is your HP and torque graphed by the RPM.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Thursday, June 13, 2013 - 02:21 pm:

Of all the things we can measure, horsepower isn't one of them. Horsepower is a theoretical number calculated using a formula and derived from torque, which we can measure. And the formula has changed over the years.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Peter Claverie on Thursday, June 13, 2013 - 02:39 pm:

This is a little bit off-topic, but not much.

I remember a friend who was in the railroad business telling me that the biggest operational difference between a Steam locomotive and a Diesel locomotive was that one "could start a train it couldn't pull" and the other "could pull a train it couldn't start."

I wish I could remember which was which, but the point was that the torque from any engine is dependent on the speed at which it is running.

Now that I think of it, I remember as a kid, watching steam locomotives working on the Public Belt in New Orleans, and seeing them spin their driving wheels while trying to start a train moving. I suppose that means the Steam engine has the low-speed torque, and the Diesel engine develops its torque at higher speeds. The Diesel locomotive, after all, is actually an electric engine, being driven by a generator attached to a Diesel motor.

What does this have to do with a Model K or Model T? Or any other automobile? I have no idea -- I just like walking down the old memory trail.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Thursday, June 13, 2013 - 02:54 pm:

Seth,

These are the pics Dean Yoder took during the test of the graph. I don't know if any of them tell us much or not........

Chad, the operator, said the horsepower rating of the machine was not very accurate with such a low hp engine (made me feel small :-)).

Thanks,

Rob











Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Thursday, June 13, 2013 - 05:40 pm:

I wouldn't consider HP to be theoretical. It's just not directly measurable. And like torque which is used to calculate it, it varies with rpm. One HP equals 550 ft-lbs per second. For any torque at any given rpm, the HP at that same rpm can be calculated.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Thursday, June 13, 2013 - 06:31 pm:

LOL... And where do you think they got the 550? They pulled it out of a hat (or some anatomical equivalent) after a few tests. That number has changed many times since the 1700's. It remains theoretical because it's a comparison of what work a "horse" can achieve to that of a machine. Why to you think it's called Horsepower?


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Thursday, June 13, 2013 - 06:51 pm:

The horizontal scale on the first shot is in seconds, your Max HP was 41 and if I did my math right, you achieved your highest HP at 1500 RPM. (the 31.135 second mark)

Were you to have been able to spin it 3000 RPM and still maintain torque your HP ~80HP.

As Nathan pointed out, and others have commented upon, and hate to pop ballons guys, guys love to banter HP. It's just a number and guys love numbers. My bro is one of these that insist on finding an additional 10-25 HP out of everything he owns with better breathing, fancier chips on his more modern stuff, etc. He's of the he with the more HP has bigger ones bunch :-)

As Ken could probably point out, take a half ton car, or a 3/4 ton car, crank up the ponies a bit, quite a bit, and in reality you may only shave parts of a second in tenths. Inertia (weight) is not your best friend because the math has funny superscript numbers by the time you get to what really happenes...but total HP has always led to bragging rights :-)

It's like when they went across the board to 6's maybe 20 or so years ago? The HP charts looked mighty good, great engine! Really, they just spun them at 3000 RPM for turnpike speed where those 8's would stoll along at 2400 or so and why 4's today really don't have tacho's :-) Old f**rts like us would wonder why these 4's dwelled at what we thought were red-lines back in the 60's but then we'd chalk it up to a CRS moment and figure they must know what they are doing and we forget :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Thursday, June 13, 2013 - 07:27 pm:

Just to be clear, I'm not saying horsepower can't be used for comparison. It is and has been for some time. The engineers got together and fixed (standardized) the formula so that torque values can be converted to horsepower for that comparison. The fact remains that the number is theoretical since the breed of horse is not defined. If we accept the theorem that all horses are equal then the formula works. Keep in mind that assumption is like saying all planets in our solar system are the same size because I measured earth and that's the standard. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Thursday, June 13, 2013 - 08:00 pm:

Oh yeah, and to be sure your comparing the same values be sure to use the same method. Brake horsepower (bhp) will be different than crankshaft horsepower (hp).


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chuck Hoffman - Gold Country of Calif. on Thursday, June 13, 2013 - 08:07 pm:

And then there is the advertised horsepower. How about a '59 Ford with a 300 horse 352. Then when insurers started getting snarky about muscle cars, suddenly the numbers dropped but performance didn't.
My wife's 140 hp maverick with a 302 would have blown those 300 ponies off the road. I don't put much stock in horsepower ratings.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Thursday, June 13, 2013 - 09:16 pm:

Granted, one could argue that the unit is not a fair comparison to an actual horse. Perhaps we should use gigawatts. Worked for Doc Brown.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Schrope - Upland, IN on Thursday, June 13, 2013 - 11:00 pm:

Peter - Steam will start a load it can't pull at speed. The diesel/electric will pull it if it can start it.
Steam has maximum torque a zero rpm. Not so for the electric.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Eric Dysart - SoCal on Friday, June 14, 2013 - 12:23 am:

In very layman's terms, it takes torque to accelerate, and it takes HP to maintain speed. More torque allows you to accelerate faster. More HP allows you to maintain a higher speed.

You can trade speed for acceleration though gearing and vice versa.

You can extrapolate all the permutations like climbing hills etc. from the statements above.

Eric


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Friday, June 14, 2013 - 12:37 am:

Hal - DIN horsepower is often presented in Watts. Look at any import engine specs and you'll see the power given in watts or kW. Under the DIN standard one hp equals 735.49875 W or 98.6% of one imperial mechanical horsepower. The DIN standard is based on a theoretical standard for gravity. There's that word again. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Friday, June 14, 2013 - 01:44 am:

Eric,
Torque is part of the horsepower calculation and really has nothing to due with acceleration. An engine's horsepower is measured at constant speed. If you think of a hit and miss engine that has high tongue and low rpm, but at the same time because of the large flywheel has really poor acceleration.

However you being up a good point, acceleration or the ability to change speed is an important thing to consider for some engines like an auto engine that require the speed change. Some engines run at a constant speed and the ability to change speed is of no concern.

Torque, speed and horsepower tell nothing about the ability of an engine to change speed. That is a whole other calculation involving the the rotational mass or moment of inertia or in simple terms, the weight of the flywheel compared to the horse power. The larger the flywheel/rotational mass is compared to the engine power, then the lower the acceleration and vice-versa.


Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Eric Dysart - SoCal on Friday, June 14, 2013 - 03:42 am:

Jim,
You make a good point. I was going to ask what does any of it have to do with Model T's, but then I noticed that this thread is labeled "OT". My comments were an oversimplification of the difference between torque and HP in cars like our T's. I guess my comment is the one that doesn't belong in this thread.

Carry on.
Eric


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Miller, Mostly in Dearborn on Friday, June 14, 2013 - 06:11 am:

I am seeing more and more German HP figures published in PS units and less in kW. PS is the abbreviation for Pferde Starke. And we all know what a pferde is if we saw the movie Der Pferdeflüsterer.

When it comes to engine design, under square and over square comes into the torque determination. Oversquare engines with large bores and short strokes are going to be capable of high revs and high horsepower but sacrifice torque to some degree. The undersquare engines have longer strokes with a longer lever arm on the crankshaft. The piston will take a little bit longer time wise to travel the long stroke so horsepower and revs will be lower. For towing, I'll take a low horsepower, high torque diesel any day. For driving, I'll take something a little more high revving and I'm willing to sacrifice a little torque.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money - Braidwood, IL on Friday, June 14, 2013 - 06:58 am:

From Wiki:

Mechanical horsepower[edit]Assuming the third CGPM (1901, CR 70) definition of standard gravity, gn=9.80665 m/s2, is used to define the pound-force as well as the kilogram force, and the international avoirdupois pound (1959), one mechanical horsepower is:

1 hp 《 33,000 lb-ftf/min by definition
= 550 ft,lbf/s since 1 min = 60 s
= 550〜0.3048〜0.453592376 m,kgf/s since 1 ft = 0.3048 m and
= 76.0402259128 kgf,m/s 1 lb = 0.453592376 kg
= 76.0402259128〜9.80665 kg,m2/s3 g = 9.80665 m/s2
= 745.699881448 W since 1 W 《 1 J/s = 1 N,m/s = 1 (kg,m/s2),(m/s)

Or given that 1 hp = 550 ft,lbf/s, 1 ft = 0.3048 m, 1 lbf 「 4.448 N, 1 J = 1 N,m, 1 W = 1 J/s: 1 hp = 746 W


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Friday, June 14, 2013 - 10:50 am:

Thanks for the great information. For some time I've wondered "why the six cylinder"? In other words, why did Henry Ford choose a six cylinder over a large four cylinder for the Model K? The Model B, predecessor to the K, had a large (for the period) four cylinder engine. Why not just increase the size? Was the six chosen for better "torque"? Or did he (Ford) believe that the "six" was the future in higher horsepower engines (see article below)?

Following is an excerpt (lengthy) from a journal article by Henry Ford, printed in 1906:

"The Horseless Age"
In reply to the charge frequently made by those who still advocate the four as against the more modern six cylinder type of motor car, Henry Ford has the following to say: "The six cylinder motor not only is not heavier than the four cylinder one of the same power, but, on the contrary, is even somewhat lighter. Without authentic power tests at hand, the only way to compare the powers is to compare the piston displacement of each. Compression and speed being equal, the difference between the two will be so slight it may be considered a negligible quantity. "The six cylinder Ford motor is rated at 40 horse power. The cylinder dimensions are 4 1/2 x 4 1/2 inches bore and stroke respectively. The total piston displacement in the six cylinders is therefore 360.5 cubic inches. Four cylinders having the same piston displacement would need to have a bore and stroke of 5 1/2 x 5 1/4 inches respectively. (Motors of these dimensions are ordinarily rated at 50 horse power.) A four cylinder motor of the above dimensions would ordinarily have a flywheel of 20 inches diameter and weighing not less than 140 pounds. The Ford six cylinder has a 16 inch flywheel, weighing 65 pounds.

By increasing this diameter to 20 inches the flywheel need weigh only 50 pounds, or 37 pounds if the diameter was 24 inches, the usual size in single cylinder motors. In short, the weight may be decreased to any desired amount by increasing the diameter. "Road clearance being an object a small flywheel is used. If the four cylinder maker wanted the same road clearance and so reduced his flywheel to the Ford
diameter16 incheshe would have to put 175 pounds of dead metal into it to get the same results as he gets with his 140 pound 20 inch wheel.

That the six cylinder motor of same total piston displacement is lighter than the four of same power is shown by the following: The two extra cylinders in the Ford weigh, with valves and all attachments, exactly 56 pounds. Two extra pistons and connecting rods complete, 17 pounds. The additional length of crank shaft and aluminum base is exactly compensated for by the necessarily larger diameter of parts in the four with its large bore and longer stroke. We then have 73 pounds of extra weight due to the addition of the two cylinders, which is, however, offset by 75 pounds reduction in the flywheel weight necessary for this type of motor. This leaves an advantage of 2 pounds for the six cylinder.

But the larger cylinders necessary to produce the same power in four that we get from six would weigh fully 25 percent more each than the smaller onesthey must not only be larger but the walls, water jacket spaces, pistons and other parts also must be larger. Consequently, the six cylinder motor is 25 to 30 pounds lighter than the four cylinder of same power. "An even more convincing demonstration would be to weigh a six cylinder motor on the same scale as a four cylinder of the same capacity."

Published as part of a discussion by E.R Thomas, Thomas Motor Company (against the six cylinder) and Henry Ford (for the six) in the "Horseless Age", 1906.

Complete article:

https://www.dropbox.com/s/aokar2fxwa2wd0m/Henry%20Ford%20on%20Six%20Cyl..pdf


Top of pagePrevious messageNext messageBottom of page Link to this message  By Eric Dysart - SoCal on Friday, June 14, 2013 - 12:17 pm:

I love you guys. A guy asks a simple question "If so, is it better to have a more horsepower or more torque (if you must have more of one than the other). " and what he gets is technical dissertations on the definition of torque and HP. We've gotten numerical tables cut and pasted from other websites as if we didn't have access to Google ourselves (the OP said that he had Googled the topic already).

I know that the thread is labeled OT, but that doesn't that you shouldn't try to stay on topic within the thread. Come on, we're all car guys. So in reference to driving a car (like a Model T or Model K), what is torque good for? What is HP good for? Or to get back to where we started "is it better to have a more horsepower or more torque (if you must have more of one than the other)?

Eric

If I ask what time it is, I probably don't need to hear about how the atomic clock in Colorado works.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Friday, June 14, 2013 - 01:24 pm:

Eric,
You may be correct, so getting back to the original question. The original question makes little sense and the obvious answer is more horsepower is much better then more torque. With more horsepower and proper gearing you can get higher torque but with higher torque and lower horsepower you will lose the the race in the end.

Rob answered the original question when he wrote, "I always "assumed" torque was just a factor of horsepower. In other words, depending on gearing, torque would "react" to the amount of horsepower available."

An analogous situation would be if a person owed you $100. Maybe you have a choice of ten $10 bills or five $20 bills to pay you the $100. Either way you get the $100 and if you don't like the denominations of bills you can convert it at the bank. Then, the person asks you, "would you rather have larger bills and or more money?". The obvious answer is more money. You can always convert it to the bill denominations you want.

Same idea when comparing horsepower to torque. If you have a choice between more horsepower or more torque, take more horsepower and just like going to the bank, you can covert the horsepower into whatever torque you want with gearing.

Now, if you have a gear system to match your engine to and a fixed horse power engine, then the correct question would be do you want more speed and less torque of more torque and less speed.

Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Miller, Mostly in Dearborn on Friday, June 14, 2013 - 02:00 pm:

If you're evaluating a powertrain on the original conditions for which it was designed, you want torque. Torque is what propelled you through the muck they called roads. Keeping in mind that all you had was one or two gears besides direct drive in your transmission, then torque is what you needed. In 1906, the only place you could drive fast for any distance was a frozen lake.

Modern engines rely on six speed (or more) transmissions to couple the engine to the wheels. You didn't have that luxury or the roads back then.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Derek Kiefer - Mantorville, MN on Friday, June 14, 2013 - 02:04 pm:

I only answered the part of the question that I felt qualified to answer. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Friday, June 14, 2013 - 02:14 pm:

Why would this six cylinder engine with a bigger bore than stroke have a better than normal hp to torque ratio (according to the dyno operator)?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Friday, June 14, 2013 - 02:21 pm:

Tom,

I agree with you about torque (if I understand it) being more important than hp. Especially with a two speed heavy car. I saw an article some time ago talking about the concept of a gearless car (from 1906/07) being possible if engine development kept improving. The Ford K was referenced. I'll try to find it again.

All things being equal, would the same hp and displacement four (or two) cylinder motor provide equal hp and torque?

Rob


Top of pagePrevious messageNext messageBottom of page Link to this message  By Andre Valkenaers on Friday, June 14, 2013 - 02:54 pm:

Rob,
The answer is in the definition of both.
Torque: Is the twisting force causing machinery to rotate. The more torque an engine has, the bigger the load it can pull in the SAME gear.

Horsepower: is a unit for measuring the power of an engine equal to the force needed to pull 550 pounds one foot per second. (Horizontal and without wheels)

Eric Dysart (SoCal) and Fred Schrope (Upland,IN)
give two fine images by telling that a steam engine has his max torque by 0 RPM and that you need torque to accelerate the engine and power to keep it at the same speed.
At our pre WWI cars speed was not very important but keep rolling over the bad roads was. There for the engines were big and had heavy flywheels for the inertia. The bigger bore means bigger piston surface this results in a higher force (Engine work pressure on the piston surface) to make the engine rotate.

Just my opinion.

Andre
Belgium


Top of pagePrevious messageNext messageBottom of page Link to this message  By Eric Dysart - SoCal on Friday, June 14, 2013 - 03:57 pm:

Hi Jim,

You said "You may be correct, so getting back to the original question. The original question makes little sense and the obvious answer is more horsepower is much better then more torque. With more horsepower and proper gearing you can get higher torque but with higher torque and lower horsepower you will lose the the race in the end. ". But that is only true if you have infinite RPM available. We see this all the time in drag races, you can gear the engine down for greater launching power, but you lose top speed.

What we want is enough HP to support the target top speed within the operating limits of the engine. Lets say I change the R&P to 4:1 in my T, better acceleration but lower top speed. Now change the R&P to 3:1, more top speed right? Not necessarily. I still need enough torque to accelerate to the higher speed as well as enough HP to sustain it. We all know that going to 3:1 can actually make you car less drivable with less acceleration and little increase in top speed.

So going back to "more horsepower is much better then more torque." If you could get a new cam that would increase your T's HP but lower the available torque, is it worth it? In a T probably not. Torque is more important most T drivers, since top speed isn't as critical. My '16 touring with a bone stock '26 engine (iron pistons and all) will run past 50mph on level ground, so 20 HP seems to be enough for most of us.

But there may be other considerations. I've got a V8 in my Porsche 914. I had the cam retarded to decease the max torque, and got higher max HP. Why less torque? The transmission is only good to about 300 ft/lbs, and even with reduced torque, it still accelerates fast enough (0-60 in less than 5 sec.). And in top gear, I would run out of HP before I run out of RPM, at least in theory, I've never run it past 140mph, and there was still throttle left. Right now I'm in the process of swapping the tranny to one that can handle 450 ft/lbs, and I am willing to trade back some of my HP for torque to increase my acceleration. The car should still be able break 160mph, but I may never verify that personally

Let's also consider a Z head. It provides more HP and more torque. Which makes the T more fun to drive? Again, the typical T driver will use the extra torque but run out of RPM before they can use the extra HP. When they are driving as fast as they are willing to go, there will still be throttle left. Of course, you could trade some of the new torque for more speed by changing the R&P to 3.25:1 or 3:1, giving you a higher top speed but returning your acceleration back to stock. What do most T owners do?

So theoretically HP is obviously better, but in practice it's more complicated.

Eric


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, June 14, 2013 - 04:31 pm:

Eric, I knew there was something else I had in common with you, back when we met at the HME.



I sold off my last 914 and all the spares back when I figured out a Model T was fast enough.



Screen shot from a video mounted to the seat.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Friday, June 14, 2013 - 09:09 pm:



Since horsepower is a conversion of torque, you can't get more horsepower without increasing torque and/or rpm. Take a look at the formula. Torque and rpm are the only variables. But increasing rpm alone will only increase horsepower for a short period since torque will start to fall off at a higher rpm. In other words, to increase hp you must increase torque at any given rpm (snapshot) or extend the torque range.

If we look at Ford's data for a stock engine in 1922, Peak torque of about 83lbs/ft occurs at 900rpm. This gives about 14.2hp. At Peak horsepower of about 20 and rpm at 1550, the torque has dropped to 67.77lbs/ft and continues to drop. If you extend the torque range (flatten the top of the bell), horsepower will increase as rpm increases.

So if you want more horsepower, increase torque! This makes increasing torque more important than horsepower at any given rpm.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Miller, Mostly in Dearborn on Friday, June 14, 2013 - 09:51 pm:

Rob,
Spending the better part of the last five hours in the back of a Model T tow truck gave me time to ponder your question. The answer is no. Designing engines that are identical in displacement with similar bore to stroke ratios will not guarantee the same performance. For instance, a one cylinder engine will prove a design concept. But if that single runner intake is replaced with a plenum and six or eight runners to more cylinders, the performance will not be six or eight times greater. I once saw two V8 heads cut into threes and grafted onto a similar displacement six. Horsepower and torque were improved but the engine was not equal to the V8 in performance.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, June 14, 2013 - 09:59 pm:

"If you extend the torque range (flatten the top of the bell), horsepower will increase as rpm increases."

For a car with limited number of forward speeds, fattening the torque curve gives you the widest power band, and most useful power.

How do you fatten the torque curve?

Use tuned intake and exhaust?

Optimize AFR with improved carburetion or EFI. (Rob, your K is running too rich, and 12:1 or richer actually cools the combustion. That robs power. Light aircraft carbs have an enrichment circuit at WOT to aid cooling.)

Optimize spark timing across the power band.

Yeh, easier said than done.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Friday, June 14, 2013 - 10:25 pm:

For sure. :-)
Flattening was probably the wrong term to use. Torque will "peak" no matter what is done but there are ways to broaden and move the torque band to gain horsepower at higher rpms. A simple cam change can do that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Friday, June 14, 2013 - 11:40 pm:

So carburation may be my best (and most simple) way to improve performance (and it is getting pretty good)?

I really appreciate all the effort and information provided.

Thanks,

Rob


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Saturday, June 15, 2013 - 12:57 am:

This has been entertaining. Actually while some say it bounces a bit, there isn't even a slightly wrong comment in anything above! It all depends on your point of view! :-) You can look at it from a Torque view...or you can look at it from the HP point of view. Once an answer is defined on the one basis it can always get calculated into the other.

Now as to Robs question...and looking at it from the torque side...

1- Put a turbo on the air intake! Seriously, all of these era carbureators breath horrible with a conversion efficiency down in the 20%.

2- Increase stroke! Ain't gonna happen is it :-)

3- Find a set of rings that are 'kissers', special ground edges, more controlled spring constant in the material, all to make piston friction less.

4- Open up ALL of the exhaust porting save the valve seat itself since you don't want to go and change them.

5- Convince Mike to make you an e-timer! Not a har-de-har...seriously...fact....optimized spark control point gives you a big bang for the buck.

6- Not knowing the K, do whatever to keep the crank from taking on that 's' snake like shape in a T due to the overhang. Less lost motion at the conn rod cap, smoother less friction on the aligned bearings.

The first gives you the biggest bang for the buck with what you can do...I don't have a clue what can be done to that carb to make it breath best, maybe Stan does, or Stan knows of a carb that will. The others are piddly things and not so piddling things.

ANYTHING you can do to reduce friction will increase net torque as friction just robs torque, won't probably find it in drive around's, but dyno would pick up all the smaller improvements in aggregate.

ANYTHING you can do to scavage exhaust gases out will help burn efficiency.

ANYTHING you can do to increase burn efficiency will improve net torque, and breathing improvement is by far the best and easiest.

The bore and stroke? Stuck with!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jon Crane on Saturday, June 15, 2013 - 04:03 am:

Now supercharging does it!

Saw an interesting article recently about a supercharged old corvette and impressive performance increases. The guy hooked an echo lawn blower to the carburetor and added 15mph to his top end in the 1/4 mile.
So if you see a Model K running around with a weed wacker under the hood you will know what is happening.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Saturday, June 15, 2013 - 07:13 am:

Rob,

I left one out.

7-investigate cam profile change. I have't a clue how to do that on a K either, but it's a fairly safe guess that it isn't optimized in the first place!

A cam lobe design change without a lot to go on would shift the torque curve with respect to RPM. So you might wind up losing at one place on RPM curve to pick it up on another.

Best bet is still getting it more air to the fuel mix


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Saturday, June 15, 2013 - 08:41 am:

Increasing compression ratio is typically the easiest way to increase both torque and horsepower, within the capabilities of the octane tolerance of the combustion chamber design and available fuel.

With the Model K this would mean a set of custom machined pistons. I would not do this because frankly a Model K has plenty of power just the way it is. Any time you modify anything there are unintended consequences that can be surprising.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Saturday, June 15, 2013 - 08:54 am:

Thanks guys. i suspect the best thing would be a better carb. The Schebler Model R (I believe they are early teen vintage) doesn't have a lot of intake room. In addition, it has an "automatic" air valve, so lots of restrictions and very few carb settings are available. I would think just improper spring size (tension) on the automatic air valve could cause problems, along with a number of other issues.

Stan Howe has rebuilt the original Buffalo carb, and I know of another K owner who says their K runs great with the original, so I'll try that later this summer.

Another friend, who posts on this forum, runs a Holley Model K carb, (on his Model K) and I know firsthand his car runs great with good starting and pulling capability but I've not been able to find one the same size.


Thanks again,

Rob


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Saturday, June 15, 2013 - 09:32 am:

That sounds like the best thing to do Rob. In general the closer you make your K to the way Ford built it the better it will run and the reliability will also be at its best. Plus the value of a modified Model K will be less than the value of an unmodified one.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Saturday, June 15, 2013 - 12:24 pm:

Related off topic - here's a friend of mine doing a dyno test that went horribly wrong in the end. It pays to double check the tie downs! Look here:
http://www.youtube.com/watch?v=nyWtoY7hW2k


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chuck Hoffman - Gold Country of Calif. on Saturday, June 15, 2013 - 03:50 pm:

Wow!! That was scary!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Saturday, June 15, 2013 - 04:45 pm:


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Saturday, June 15, 2013 - 07:28 pm:

I have a Master carb that must be sized about right for the K, Rob. It appears to be in good condition, but I have never tried it. Its principle is identical to the Harry Miller racing carbs.



If you're interested in trying it, without obligation, I'll measure its flange.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Saturday, June 15, 2013 - 08:58 pm:

Ralph,

If you measure yours, I'll measure mine :-)

Thank you,

Rob


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Saturday, June 15, 2013 - 09:13 pm:

Hey Ralph,.....Dyke's doesn't do much better at trying to spell distributor than you do! Sorry Ralph,....couldn't resist!


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