4.0 HO vs 401 - Fight!

[Ristow]

You're not even talking about a internal combustion engine now.

All things being equal? You guys have been arguing about power output between a 242ci I6 and a 401 ci V8 and now you bring the " all things being equal" stipulation?

That was the whole point. They're not equal. A 350 horse small block and a 350 horse 3406 cat and a 350 horse snowmobile engine aren't equal.


This whole thread is kinda silly.

[SJTD]

All things being equal and with similarly efficient drivetrains, a truck with 501 HP will beat one with 500HP in a race every day of the week.

What kind of race? For top speed it will but the rest of that power curve you were talking about will determine the winner on a track.

What people mean when they say "torque" is low RPM power. As you described, lotsa torque at low speed means lotsa power at that speed.

I've tried baiting people telling them I've got an engine that makes 600 ft-lb. The first thing they ask is about the RPM. I reply oh, now your asking about power.

[Cecil14]

I've tried baiting people telling them I've got an engine that makes 600 ft-lb. The first thing they ask is about the RPM. I reply oh, now your asking about power.

Not necessarily; torque is measured at a given RPM, power (horsepower) is a normalized figured at a given RPM. They are not the same thing. I may well want to know how much torque you have what RPM. I could, if I chose to, then calculate horsepower from that figure, but I don't have to. Both figures give you information, power is simply used to compare (poorly) between one engine and another.


aa

[SJTD]

I didn't say torque and power are the same thing.

I said when you specify torque at an RPM you are defining power whether it's kW, hp or ft-lb/min.

[Cecil14]

I didn't say torque and power are the same thing.

I said when you specify torque at an RPM you are defining power whether it's kW, hp or ft-lb/min.

But again, you're not. Power is not *just* torque @ RPM. Power has to involve time, that's the point. That's why you divide by 5252 (good derivation here), to account for time.

Many people, most probably even, will mean horsepower when they think they're talking about torque, but your "bait" is incorrect. If I ask you what the torque output of your engine is at a specific RPM, then that is exactly what I want to know. If I want to know power, then I will ask for that.


aa

[Der Kaiser Jeep]

I have been told you read about horsepower but you drive torque.

[yossarian19]

If I ask you what the torque output of your engine is at a specific RPM, then that is exactly what I want to know. If I want to know power, then I will ask for that.


aa

Torque @ RPM is only a bit of division away from a horsepower number; it's just a unit conversion. The "Time" component is the M in RPM.

And really - whether it's from a Honda 2 liter on boost or a Cat Diesel - 350 horsepower is 350 horsepower // the same amount of work is being done, it's just the impracticality of redlining the honda before you let out the clutch every gear.

[FSJunkie]

Torque = Force

Work = Force * Displacement

Power = Force * Displacement / Time = Work * Displacement / Time = Force * Velocity

Horesepower is a measurement of power because the equation for horsepower is Torque * RPM / 5252. RPM is already Displacement/Time, and the 5252 is just a constant to reduce the answer to what James Watt said one horsepower is, otherwise it would just be a number without units.

Force and velocity together produce power. Either one by itself does nothing. Some engines make a lot of force and not a lot of velocity and others make a lot of velocity and not a lot of force. Which one doesn't matter if the drivetrain is geared to take advantage of that particular engine's characteristics because force and velocity can be interchanged by the use of ratios.

Power is what really matters in an engine. Torque and RPM are just factors that produce power. Lots of torque at low RPM will make the same power as little torque at high RPM and will both move the car equally quickly if the drivetrain is geared to use the engines in their power curves.

Which is why I developed my method of integrating the power curve of engines with respect to velocity and comparing them to the integrated power curve of other engines. This calculation shows you the total power produced by that particular engine through that particular RPM range for purposes of comparing it to another engine of a dissimilar power curve.

[ZackN920]

Now y'all are getting into the science of it... It's interesting but i'd rather go with what I can feel

[yossarian19]

Well if we are going by feel then big cubes & high compression are always the right answer. Throttle response is, for me, where it's at. My Subaru makes more horsepower than my old Jeep I6 - but that Jeep would move out when you goosed it. More cubes, more better.

[Ristow]

Torque @ RPM is only a bit of division away from a horsepower number; it's just a unit conversion. The "Time" component is the M in RPM.

And really - whether it's from a Honda 2 liter on boost or a Cat Diesel - 350 horsepower is 350 horsepower // the same amount of work is being done, it's just the impracticality of redlining the honda before you let out the clutch every gear.

really? so the FACT that the cat will be making over 1000 lbs of torque at it's rated 350 horse power,and the little honda will be making maybe 250lbs means nothing?

the impracticability of redlining the honda has nothing to do with it. the honda will NEVER be making the amount of torque the cat does. so it can not do the same amount of work.

horsepower is nothing more that a math equation. it can't even be explained to the layman in a relateable way, you'll get some stupid story about horses pulling weight up a certain distance in a certain time.engines make torque,and it is mathematically converted to horsepower.

torque is easy. wanna visualize 1000 lbs of torque? take a 12" breaker bar,put one end on a bolt and put 1000lbs on the other end. you have 1000 lbs torque. wanna see where the horsepower comes in? maintain that 1000lbs on the breaker bar,and rotate it 1800 times in a minute. theres your 350 hp rating.

lets do the honda now.

this time you'll only put 250lbs on the breaker bar. and for the 350 horsepower rating you;ll maintain that pressure for 7000 revolutions in a minute.


do you see how the two motors really don't compare power wise? this is why you don';t see honda 2L engines in peterbilts,even tho they might have the "same power" as a 3406 cat. the fact is,they don't have the same power. but they can attain the same number in a mathematical equation regarding torque and time,altho those numbers will be many thousands of rpms between them.


lets go back to this 401 vs 4.0 thing.

the 401 made about 340 lbs of torque. the 4.0 ho made about 225lbs.

so,as stated earlier in this thread.... put em both in the same car,same trans,same rear end and race em. anyone wanna guess which one wins?? even tho according to some they both make "the same power"?


see,it really is about torque. cecil understands this at the technical level. i think zack gets it at a practical level.

[FSJunkie]

I'll give a really practical answer for a change.

I have a 4.0L Grand Cherokee (190 HP) and I have a 360 2bbl Wagoneer (175 HP). Both stock, minus an exhaust system or carburetor change. Transmission gearing is almost identical, but the Grand Cheroke has an overdrive and a higher 3.55 axle over the Wagoneer's 3.31. Tire size is identical, vehicle weight is similar. I've driven both of them many miles.

The Wagoneer is a little quicker off the line but its worse aerodynamics level the playing field at high speed. Their performance is extremely similar under all conditions. They are too close to call without actually having a stopwatch.

The only major difference I notice is at high speed (75 MPH). The Wagoneer requires quite a bit of throttle to maintain this speed because of its aerodynamics, however it does not require much more throttle to maintain this speed up even a major hill. It also does not downshift since it is already at 3000 RPM. It pretty much just quietly chugs along with about the same amount of throttle no matter what you put in front of it.

The Grand Cherokee's aerodymanics help it cruise on a level road in overdrive with very little throttle, however any major hill causes it to gutlessly bog down until it downshifts and cranks its RPM up to 3500 or so. It then has about the same power as the Wagoneer.....only that 4.0L makes a very loud and irritating sound at that RPM and you cannot wait until you reach the top of the hill so you can upshift to overdrive and hear yourself think again.

And that is where the difference in power curves shows. Both engines make about the same power and performance at high RPM, but the 360 makes more at low RPM than the 4.0L, which enables it churn away at low RPM most of the time with no need or reason to spin any faster. The 4.0L meanwhile, has to downshift and increase its RPM quite often...which is noisy and annoying.

Based on my real-life experience with those two vehicles, a 401 (even a stock one) verses a 4.0L in the same vehicle with the same gearing is no contest. The 401 will be faster than the 4.0L and has a broader power curve that would mean less downshifting for hills. It would chug along and do anything you need it to in pretty much any gear...unlike the 4.0L. That makes it easier to drive. I like big, torquey, low RPM engines for that reason. They quietly do their job with little fuss.

[ZackN920]

Finally! A practical real world example! I pretty much agree with what FSJunkie has to say here with his comparisons. Its rouphly the same between my GW and my dad's 02' GC.
Different story though with my Cherokee, But, you gotta remember. A Cherokee weighs around 3300lbs, and it has the AW4 instead of Chryslers 42RE. My Cherokee also has 3.73 gears. It will hold 4th on any hill that i've been on at 55.
Though, I wouldn't say the 4.0 makes irritating sounds at high RPM's. Actually I think its one of the best sounding 6 bangers, at least with my exhaust. It's all open, with only a glasspack on it. Still not super loud though... It was only super loud when the exhaust fell apart behind the y-pipe after I got it. When that happened, well... It really sounded like a loud POS while any V8 just sounds great, fully uncorked.

i think zack gets it at a practical level.

Yup, I's aints got no coll-age edumucation over here. I's donts gets all that science mumbo junbo, but I's gets that butt feelin' when i's in ma car


Yea, in seriousness now, more so a practical level. I still need to learn more about the science side to really start grasping it better.

[babywag]

I have a car made in 1977 with a 232 CID I6 with a factory horsepower rating of 86 SAE Net. It has a 190 CFM 1 barrel carbruetor, 8.0:1 compression, EGR, AIR, TCS...just about every emission control you can think of except for a catalyst. Absolutely completely stock under the hood. I drive it at 7000 feet above sea level where whatever power the engine makes at sea level is reduced by 23%. That rated 86 horsepower at sea level would be 62 horsepower at this altitude. I also have an automatic transmission that the internet experts says wastes 25 horsepower. By that wealth of internet knowledge, I should have 37 horsepower at the wheels at 7000 feet. It is a 3300 pound sedan with a 2.73 axle ratio.

Guess what it's 0-60 time and top speed is at 7000 feet and guess what both are at sea level. Go ahead. I've timed it, I know what the numbers are. Lets see how well you think you know my engine based on what you think you know about smog-era engines.

Also, my friend has a 2014 Subaru Outback and I drove it with a stopwatch in my hand. Guess it's 0-60 time at 7000 feet and think about how it compares to my 1977 car I described above. Keep in mind that only one of these cars gets called a "slow emissions-choked piece of junk that cannot get out of its own smoggy way".

Also, my 1972 Wagoneer has a 360 that is totally stock except it has a 2150 carburetor from a 1984 360. Otherwise, stock smog 8.5 compression, stock smog timing.....smoggy smoggy smoggy slow slow slow slow as people tell me. You tell me what my 0-60 time and 1/4 mile time are at 1500 feet above sea level. Go ahead. I ran it at a drag strip, I know the time. I just want to see what people think it is.

This should be fun.

Why not just simply post the info?

My ‘88 from an app using accelerometer & GPS.
Bone stock internals, TBI, headers. 129k engine 1cyl little low on compression.
3.31 gears 30” tires ~4500lbs
9.516 0-60
17.546 @ 76.06
Just mashing go pedal from a dead stop.
It’d probably do better if I wound it up then launched?
Using calc from web(yes realize not 100%, app probably isn’t either. It’s ballpark though)
Your HP is 169.32 from your ET
Your HP is 159.30 from your MPH
Your HP Correction Factor is 1.03
Your Grains of water is 21.89
Your DA (Density Altitude) is 576 feet
Your DA (Density Altitude) is 175 meters

[rang-a-stang]

... from an app using accelerometer & GPS...

Which app? I'll use it, too. I have one of these but loaned it to a buddy in San Diego so it will take a few days for him to mail it back.
G-Tech performance meter