Dan87IROC-Z

I am quite confused about horsepower and torque. I know that horsepower is like how much power it takes to raise 33k lbs 1 foot or somthing crazy like that, and I know that torque is rotational force. But how does it all come together in an automotive sence? I once read a motor trend article on high torque motors in cars, and said basicly horsepower isn't good for anyhting, torque is what you need lots of to go fast. So, if thats true, would be car be faster if I had like 70hp but like 550 ft lbs of torque or WHAT? I am just confused......

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 Hot Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

7.5" 10 Bolt with 3.42s soon to come!

AlkyIROC

go here.
http://www.calgarydragracing.ab.ca/hpandtorque.html

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z Pro ET Bracket Race Car
383 stroker (carbed) with double hump cast iron heads and pump gas
461 Big Block installed and ready for the 2001 racing season

Best results before the 383 blew up
Best ET on a time slip: 11.857 altitude corrected to 11.163
Best MPH on a time slip: 117.87 altitude corrected to 126.10
Altitude corrected rear wheel HP based on power to weight ratio: 476.5
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

Paul Riccioli Jr

iTrader: (1)

Here's a little saying I heard a few years back. "Torque is how hard you hit the wall, and horsepower is how fast." Basically this is my understanding. Torque is what's utilized to build acceleration. Horsepower is basically your top speed potential at each RPM level. Anyone correct me if I'm wrong.

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Riccioli Performance Motorworks

--RPM Racing--

-Currently building first ever engine. 383 with Super Ram plenum and runners, Edelbrock lower intake, Bosch 24# injectors, either AFR or Trick Flow heads, MSD ignition.
-Will be installing Baer Brakes
-Will be installing full Spohn suspension in rear
-Art Carr 700R4 trans??


***** Flyby: (n) When you let off the throttle after beating a ***** Racer by a few car lengths and he then blows by you in an attempt to convince you he really won the race.

I ROCK

hp = rpm * tq/5858 (think that's right). Basically how much cylinder fill you have (by displacement or forced induction or both) and how efficiently you fill it makes torque, the force that snaps your neck forward and may snap a 10-bolt in a thirdgen. You need rpms to make more horsepower for a given level of torque. Horsepower is sustained torque up through more rpms. Needless to say, the more horsepower you have at lower rpms, the more torque you have at the same rpm. But basically the most important thing is to have a high, flat torque curve from as low an rpm as you can to as high an rpm as possible.

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Base: 89 Iroc-Z LB9 auto 2.73 posi
Exh: 3" Dynomax muffler, 3" Pipe in place of cat
Ign: GMPP 8MM wires, Accel cap&rotor, AC Plugs
Fuel: Cleaned and flow-matched injectors, afpr, !air pump&diverter valve
Sound: Clarion deck, Kicker speakers and amps
Suspension: KYB Shocks, BMR Strut Tower Brace
Misc: TB Bypass, Synthetic Oil, Flexlite Transmission cooler,
free mods, flow tech headers on the way,
engine swap and 4th gen seats in the works...

[This message has been edited by I ROCK (edited February 05, 2001).]

83CAMAROMAN

I have always heard that torque is like a slingshot to get your cars heavy *** off the line and hp keeps it going. i dont know if that helps but thats what ive been told..




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1983 CHEVROLET CAMARO
305 C.I.D.V8 BORED .30 OVER
HIGH VOLUME OIL PUMP
FLAT-TOP PISTONS
MILD CAM
3" CAT BACK EXHAUST W/ FLOWMASTER MUFFFLER
KEYSTONE CLASSIC WHEELS.
B&M RATCHET SHIFTER
STAGE THREE SHIFT KIT

MUSTANGS SUCK

R.O.B.

Horsepower is a mathmatical diritive of torque. So with that said, torque is strength, horsepower is speed. You must build an engine around torque, because like I said, the horsepower is just an equation from torque.

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Rob
'86 TA 305 TPI
Gutted MAF
Ported Plenum
TB Bypass

Mkos1980

iTrader: (8)

I remember something on speed vision where the indy cars have like 200FTLBS and like 880 Horsepower

The ODB

Dan and Paul,
You're a little bit off.
Torque is THE only direct measure of power (turning force) that you can get from your engine.
Horsepower is based on time, and is only the mathematical product of an equation that uses TORQUE as the power variable, and RPMs as the time factor.
One horsepower is roughly the amount of energy it takes to move 550 lbs 1-foot in 1-second. Don't forget the time factor. So naturally if you make torque at very high RPM's then you will come up with high horsepower numbers.
Horsepower numbers are only good to use as input in other time-based equations. Torque in your useable RPM range is the only thing you should worry about building for. The indy guys also build for torque. Their RPM range just happens to be very high resulting in big horsepower numbers.

hope this helps


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*I do custom performance mods on Edlebrock Performer carburetors (dualplane intake mods in the works),
White 1986 Irocz, 305/383 with Edlebrock Performer-RPM intake and Performer #1407 carburetor, +110hp shot of crack, 700R-4 tranny, 3.25:1 rear, Mcreary Road-Stars, SLP-stainless 1.75" shortie headers & Y-pipe, single 3" Borla exhaust, Linginfelter-TPI camshaft part number 74216 pulls 17" vacuum solid. Cam specs 213/219 @.050 114-LSA, .462/.470 lift @1.5:1 ratio. MSD-6AL, billet distributor, multi-retard, blaster-3 coil, and RPM switch.
N/A runs 10.9 @124,
Crack-runs 10.3 @135
haven't run at track since Oct-99

TonyC

iTrader: (1)

Good article!!! ***** Flyby!!! HAHAHA!!! That has to be the funniest thing I've heard for a while, but only because it's so true!

RB83L69

ODB has it exactly right. Torque is the real stuff consisting of the work the engine is doing, horsepower doesn't exist by itself, it is merely the time rate at which the work is done. So, if you can do a moderate amount of work at very high speed, you can still put up impressive HP numbers. Or conversely, you can move a mountain slowly, which would correspnd to huge torque and low horesepower.

There really should be a FAQ about this... it is something alot of people don't understand, since it's not really taught in regular science classes in school or anything. If you're not a physics major (I was, along with math) then you never get exposed to it. There's a whole lot of confusion about it among car people who you'd think would be those who would know.

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"So many Mustangs, so little time..."
ICON Motorsports

mtx28

yea, im one for the crowd who cant explain the difference.. so they both basically do the same thing(i always hear people say 'torque is what gets you moving, but horsepower will get you down the track in the high rpm's'), but horsepower is more of a representation of how quickly things happen?

mtx28

well, i must confess, i was lazy and didnt read the related article first, but now(after i've responded) i read it and more fully understand the subject thanks

merf23

Since horsepower is a mathematical derivation of torque, HP=RPM*torque/5252, HP will always equal torque at 5252 RPMs. But, HP and torque numbers can be deceiving since they dont measure engine acceleration under a given load. Light weight drivetrain components are a lot more impressive on the track than on the dyno because even though they dont change the combustion in the cylinders, they reduce the resistance on the engine. This is why many professional engine builders measure the time it takes an engine to accelerate a given load (which represents the drag from the car) through a given RPM range. In circle track racing for example, this would simulate the car coming out of turn 2 onto the back straight. This is much more important than HP/torque numbers since it gives an actual time and in all forms of racing its the time (or lack there-of) that counts.
But,IMHO, HP is a useful tool for comparing similar engines for similar cars. An example - a 200 HP honda engine in a thirdgen would be a h+ll of a lot slower than a 200 HP SBC in a Honda. I am neither an engineer nor a physicist, but i read a lot and spend a lot of time at the track. I am sure many others on this board could get more specific and detailed. A FAQ would be nice; RB? Vader? Engineboy?...

87kevroc

mtx,

Glad you understand it now. Explain it to me, then we'll both know. Just kidding.

When people ask me about the distinction between hp and torque, I use this illustration. In days gone by, I rode motorcycles. One of the first I had was a Kawasaki 3 cylinder two stroke 500cc, called the Z1 (it later became a 900cc 4cyl 4stroke). It was fast. Mfr. claimed 0-60 in 4sec flat, 1/4mi 12.5sec. Stock. But to really get it going, you had to rev it real high. Later I got a Harley Sportster V-Twin (of course) 1000cc. The Harley was a completely different experience. It was a 4speed, and you could take it from 15mph to 115mph without changing gears. Instant throttle response in any gear, with or without a passenger. Not the raw speed and accelleration of the Kawasaki, but with the Kaw, if you wanted to speed up, you better be downshifting. To me the Kawasaki represents horsepower, the Harley torque.

AlkyIROC

Ohhh. Good examples with the bikes. Needing to build rpm to get the HP also decreases the life of an engine. That 900 would be worn out at 100,000 miles but the Harley, being a low reving engine, be still have many miles left before needing a rebuild. Take a look at big rigs. They have 14 liter engines, produce in excess of 1200 pounds of torque with about 350-400hp and don't go over 2200 rpm. Those engines last close to a million miles before needing a rebuild.

As a comparison example. Torque is what you feel on your back when you accellerate from a stoplight. HP is what you feel when you quickly pass someone on the highway who is going 70 mph. You feel other stuff also if it was a blue oval vehicle you passed but that's getting off the subject.


[This message has been edited by Stephen 87 IROC (edited February 05, 2001).]

mark406

hey i know the more you got the faster you go.do i win a prize???/ lmfao sorry couldnt resist

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89 pontiac firebird{looks like a trans am }
406 pontiac {carbed}
12 boly posi rear end
17 inch zr1 silver wheels
11 inch wide in back
bfg g force ta tires
maui blue hardtop
4th gen rear wing
fast as hell

87RS402

One of the semi's I drove for awhile had a 600 hp cummins engine. That's actually 605 hp @ 1800 rpm and 2050 ft-lbs @ 1200 rpm. (rebuilds are at around 600 to 700k miles) That's what you need to get down the road at 80,000 lbs, torque, it's what moves you. Horsepower, that's how fast it moves you. Hopefully this will help you understand whats lots of torque and only a 4th of the hp accomplish.