mythical numbers to avoid

[bgd73]

I only came up with a few things to avoid, of course epa fuel mileage is one..as most of us under our own hoods knows.

Horspeower in general is another bad think to rely on..
I recently saw mention of "horsepower to weight" as a reminder how silly that number is: "horsepower"

I also wanted to share how I decipher a car...
ecomodder:
horsepower is often less than the torque.
mid range >4cyl:
horsepower is often squared up with torque.
race car:
horsepower exceeds the torque.

To give an idea how silly the hp number is...
my 90hp subaru at 2800 pounds can do a quarter in 15seconds as a 4x4...33.1 pounds of weight per horsepower..
the brand new 412hp mustang with just 8.8 pounds of weight per horsepwer is getting there just 2 seconds earlier...
something is way offset here...

and lastly, a figure from my dads rig..
500hp for 79,000 pounds is..158 pounds of weight per horsepower..and it will do 85mph+ loaded. I don't think a 500hp mustang could do that..

if you cannot decipher numbers for power on any given car, find out the engine and figure bore and stroke...
an inline needs a deep one in the same car weight as a boxer, in the four cyl category, the 6 and 8 can be little strokes and big bores, and vice versa, it does'nt matter..this is where weight of car comes into play...all while ignoring the hp, go by liters and weight, derive your own conclusion, with engine design, like diesel or gas etc...

that hp number is like a fantasy derived from drug addiction.

[SentraSE-R]

Um, 15 second quarter miles with a 90 hp 4X4 at 33 lb./hp? I don't think so. The only quarter mile time I could find for your '87 wagon was 3 seconds slower at 18.7. That's a lot more realistic for a 33 lb./hp vehicle. You need a 15 lb./hp weight to hp ratio to turn mid 15s. It's simple physics, and the numbers do not lie.

And the 2011 Mustang GT will be in the high 12s, or very low 13s.

[MadisonMPG]

1/4 time improvements are not linear.

i.e. 8000hp = 4 second quarter, whereas it requires much less than 2000hp to run a 16 second time.

*not the best explanation, but the best I could do with my current brain power.

[stevet47]

Originally Posted by MadisonMPG

1/4 time improvements are not linear.

i.e. 8000hp = 4 second quarter, whereas it requires much less than 2000hp to run a 16 second time.

*not the best explanation, but the best I could do with my current brain power.

Actually that is a very good explanation. I ran high 16's in my stock ford taurus... I think that was 130hp or so.

[Patrick]

Originally Posted by bgd73

and lastly, a figure from my dads rig..
500hp for 79,000 pounds is..158 pounds of weight per horsepower..and it will do 85mph+ loaded. I don't think a 500hp mustang could do that..

And your Dad's rig has what, 1400 ft-lbs of torque?

[AeroModder]

I think he means an eigth of a mile in 15 seconds...

I actually got to watch a jet-engined dragster make a run. 5.6 seconds for the quarter at 300 MPH. Loud as heck.

[comptiger5000]

Horsepower allows you to sustain high speeds, torque gets you moving. That's why I love my V8. 245 hp in a brick doesn't make it fly (15.2 1/4 mile), but the 345 ft lb of torque kicks it off the line pretty hard.

I can get almost the same mpg as a the same vehicle with the much smaller 4.0 I6 (22-23 @ 60mph vs 20-21 @ 60mph, both around 12 - 14 city), but I can haul it from 0-60 in 6.8 seconds if I need to. Plus, the V8 never downshifts on the highway (will happily turn 1800 in OD with the TC locked doing 60 up some BIG hills), and can get into the high gears faster around town. In areas with lots of big hills, the V8s sometimes get better mileage than the 6.

Having good power AND FE is all about a good, usable, low powerband and matching the engine to the vehicle.

[IsaacCarlson]

YEE HAAWWW!!!! I don't even bother looking at HP. If someone starts telling me how much HP something has I like to ask them how much torque it has and then they admit they don't know and it doesn't matter. I like having torque on tap. My truck does not care if it is empty or has 6,000 lbs in it...it still goes....it just takes a little more pedal to stop.

[Christ]

HP does not allow you to maintain high speeds.

HP, technically, is an imaginary number, created by an algebraic equation which factors torque over time.

While it does give you an easier to understand indication of the correlation between torque and engine speed, it does not "allow" for anything.

Torque at 2,000 is the same as torque at 5,000, plain and simple as it gets. But if you only had Torque figures to rely on, you'd think that engine was puny at 5,000, because it makes so much less torque (in some cases, like my 300 I6 Ford) than it does at 2,000 RPM.

The figures are simple, when you actually know what they're for.

Torque = work performed (able to be performed)

HP = Work able to be performed in a certain span of time.

They mean nothing more than that.

And NO, a 90HP Subie WILL NOT make a 1/4 pass in 15 seconds. My 92 HP Civic could barely keep 16-17second runs, and it was nearly 1,000lbs lighter.

[Christ]

Originally Posted by IsaacCarlson

YEE HAAWWW!!!! I don't even bother looking at HP. If someone starts telling me how much HP something has I like to ask them how much torque it has and then they admit they don't know and it doesn't matter. I like having torque on tap. My truck does not care if it is empty or has 6,000 lbs in it...it still goes....it just takes a little more pedal to stop.

Yeah, around 260ft lbs just off-idle will do that for ya.

I've been running around on 5 cylinders with a really bad misfire for quite awhile, and I can still hold 60-65 MPH with no problems, and tow a trailer doing it.