HP vs Torque

[Tom Kirkham]

Here is a pretty good article on the differance between HP and torque.

http://articles.domestictunerz.com/article.php?ID=167

[Tom Wells]

Hello Tom,

What a neat article

It explains what the Japanese figured out decades ago starting with motorcycles and then with cars: if you have enough rpms and enough gears in your gearbox you can whup anything that comes along.

Probably the ultimate example of this would be 1500 model airplane engines on a common crankshaft running at 150,000 rpm on nitromethane and hooked to a 500 speed gearbox. It would sound worse than a dentist's drill and go faster than most humans could tolerate

While I admire this performance, I prefer the sound, no - MUSIC, of a big block

Neat stuff,

Tom

[Bob In Ct]

It's all about HP. Some guys want it at low RPM and some want it at high RPM, but it's all about power. I can generate 500 FT-LBS of torque on my bicycle, but it's at 20 RPM!

Bob

[grumpy]

Bob,
Hate to differ, 75% of the rides offered in a COBRA to a passenger, and asked of their opinion, will result in the COBRA with the most torque will always win hands down.
Tire shredding torque, not some peaky HP curve that is never just right for that 0-100 MPH blast is what most are looking for.
This subject remind me of the YZ Yamahas of the 70's versus the Husquvarna, again HANDS down, torque, more fun and controllability in the Husky, but maybe there were a few that like the outta control feel of the YZ. A very similar comparison.
grumpy

[bmalone]

From that time period, I'd use a Maico or CZ in the comparison. Sorry, partial to Maico's from the late seventies up to and including '81 490.

Interestingly enough, a lot of guys switched back to the Japanese bikes starting in '82. Why? Still very peaky compared to the European bikes, but ala Bob Hannah and others, all the top American rides started incorporating a new riding style. That is, exit the corners one gear higher than normal and brutalize the clutch. Kind of mitigated the narrow powerband.

Tom, thanks for the link--that was interesting.

[Bob In Ct]

Hey Grumpy:
Cars with more low end torque have more low end power! Power is nothing more than torque X RPM. Engines with more HP through the whole RPM range will outperform with less HP through the same range.

Do you really think that 500 FT-LBS of torque at 2000 RPM will out perform 350 FT-LBS at 5500? I think not!

Bob

[Excaliber]

Ah the classic H.P. vs Torque debate!

Me? I'm a horse power kind of guy. I guess with the new ERA I got I will now explore the wonderful world or torque. It's all good!

Ernie

[SnakeBitt]

Torque is what launches you off the line while HP is what gets you down the track. If you have tires that can handle it (and it's hard to find that in 15 inch tires), then go for all the low end TQ you can get. On the other hand, if you're a little too anxious on the "go pedal" and all you have on the back are 15" BFG's (or the other popular H rated meats out there), then all you'll do with gobs of low end TQ is go up in smoke, while the guy next to you in his Honda S2000 (about 190lbs / tq) will leave you in his dust. With lots of HP to get you down the road, by the time you're getting through 2nd gear, you'll be laughing at the guy in the Honda and pulling away with a big grin on your face.

Would I be starting something if I said that this "formula" holds true in the case of a Big Block vs. Small Block, as well?

[jeff harvey]

torque is quick (e.t.)
horsepower is speed (mph)

[cobrashoch]

Tom - The site you listed is indeed a rehash of the classic engineering thinking of torque vs horsepower. Unfortunatly such thinking is incomplete. What is not mentioned is the ability of a engine to "rev". Ever notice how slow a diesel winds up? For example a diesel engine may have identical horsepower and torque numbers with a gas engine. In a drag race which one would you take? It's about reciprocating weights, elimination of internal friction, head design and soooooooooo much more, such as in a formula engine. Way, way to simple such thinking is, as shown in the site above. I personally also disagree with the gearing premise for cars stated in the text. The word "compromise" comes to mind on such matters, even for race cars. The site you listed is however a good place to begin with, ibet a bit simplistic though.
cobrashock

[DAVID GAGNARD]

I guess it was four or five years ago at a World of Outlaws race in Mississippi,talking with Mark Kinser and his dad/car owner/crew chief Karl Kinser,as they had just switched to running Mopar engines..... I asked why??? They said "torque" that's all.... I said,what kind of hp do these enignes make,he said enough....Mark said torque wins races and hp and dyno numbers sell engines.....They do look at hp numbers,but concentrate on a big flat torque band....Torque gets the car moving from point A to point B,hp keeps it moving once you get to your desired speed.....

Most people that ride in my Mustang cannot believe how much low end torque my motor makes,yet it only makes 350 hp....The cam in it is designed for RV's and tow type trucks,lot of low end torque,but still pulls hard thru 5500 rpms.....I have it geared to take advantage of it's power band,no need to try to make it scream to 7000 rpms,it will do it,but it ain't making much power.....

Regardless of your engine/hp/torque combo,you have to gear your trans and rear end to take advantage of what your engine produces and at what rpm range it produces it's power....

I'll like motors that have a broad flat torque curve and top out around 6000 rpms,but that's just my preference....

David

[Excaliber]

Torque!!! Thats how those 500 hp turbo charged Hondas do their 9 second 1/4 mile?

......I don't think so!!

Ernie

[BANDIT 1]

Mr. Excalibur:

Congratulations on stepping up to a big block powered Cobra.

The reason a "rice burner" with 500 turbocharged horsepower can run so fast is easily explained.

1. power to weight ratio

2. power to the ground (since these car can't run huge slicks, they use low torque to get off the line and then were traction is no longer a issue the horsepower and aerodynamics of the car come into play).

3. Aerodynamics

While these are just a few examples, this is no different than when I ran against a 800+ horsepower Supra with My big block Cobra. I made sure the race started at 35 - 45 mph (were putting down my 699 ft. lbs. torque wasn't a issue) and leaped ahead off the "go" and only lost a little ground at around 150 mph were the race ended. From a 0 mph launch I would have lost due to traction issues, were my heavier 69 Mach 1 Pro Street car (with about the same horsepower as the Cobra) would have easily beat the Supra due to the huge Mickey Thompson slicks.

As far is which is better, depends on your use of your Cobra. It is not the added weight of the big block that makes it harder on a road course, but the extra torque. It boils down to putting the power to the ground. A 500 ft. lbs. torque small block Cobra can go into the turn with the throttle gunned and have the car not go around as easily as a 600 - 700 ft. lbs. torque big block powered Cobra.

[Excaliber]

Power to weight ratio has always been the key to a winning race car. THATS what the Cobra was all about. The heavier the car the more torque you need. 18 wheelers are all about torque. I'll take light weight high horse power if I want to get things done "quickly".

It will be interesting to see how the BB ERA will perform on our narrow very twisty SCCA cone course we have here. Sometimes, depending on how the track was set up that day, I couldn't even use all the power the little 5.0 in the Excalibur had! Other times I had "just enough" and could do really well.

I suspect the BB ERA will have a lot of "push" in the corners issues I'll have to sort out. Certainly will call for a "light touch" on the throttle getting around the cones!

Ernie

[grumpy]

Snakebitt,
You just solved the question, TORQUE is what gets you off the line, and since these are street cars, you don't need the high horspower band since we are not a ROAD ATLANTA for the finals.
THe old FE with a averge cam/head job and a good 750 4bbl that will hook up will pull away from the majority of the overstroked small blocks and still be ahead at the century mark, high enough speed for the street!
This has never really been a debate, just simple fact/logic.
bMalone,
Rode several brands, just never liked being broke at the track, so HUSKY it WAS!
grumpy

[Bob In Ct]

I'll say it again, engines with tons of low end torque also have more low end power. You can always make more torque, just lower your gear ratios. Nothing has more torque to the rear wheels than a tractor. I'll bet not too many tractors are are winning drag races!

My engine has a dual plane manifold. I have it this way because it gives me better mid range torque numbers, which translates to better mid range HP. Like lots of other owners, I give up high end HP for mid range HP.

Bob

[Mr.Fixit]

same gearing, traction, and redline : more torque wins

Run more gearing and move up the redline : HP can win

since our V-8's can't have an unlimited redline, and gearing is pretty limited, torque is what you want, you just don't want it to quit spinning at 4500 RPM. Maximise torque at your shift recovery point, which for most of us is still considered midrange.

[Daniel Jones]

It's torque at the rear wheels, not torque at the crankshaft, that determines acceleration and it's horsepower that determines how much RPM you can trade for wheel torque. The more horsepower you have, the more RPM you can trade for torque at the rear wheels via gearing. I derived the relationship from fundamental concepts and did a write-up several years ago:

http://www.mustangsandmore.com/ubb/D...orqueVsHP.html

Dan Jones

[Tom Kirkham]

Dan,
Thank you. I think your answer should be put into the CC FAQ.

[flipper35]

Explain this to me.

2003 Neon SRT-4 2970lbs. 215hp/245tq 14.1 quarter mile.
2004 S2000 2835lbs. 240hp/163tq 14.19 quarter mile.

The 2004 Neon is quicker, but it is 230hp. This shows two approaches to the same end, though the SRt is quicker by 2 10ths to 60mph.