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  #106 (permalink)  
Old 05-15-2010, 09:09 AM
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BTW, this type of comment will get you suspended.


Quote:
Its kind of a shame it took him 50+ years to learn what some guys pick up by their junior year isn't it? Imagine what more he could have done if he would have knew then what he knows now...



Your attitude in this thread is way over the line especially when many of us have attempted to illustrate the subject to you in a way you will understand. This isn't the first time you have adopted this behaviour...it has been discussed at length...I guarantee it will be the last.

BTW, the thread won't be locked, you will just be excluded from it, consider this the last warning.
If you are going to chastise ap, you had better be prepared to get after those who have called HIM names- except they've really called him names, not just some misunderstood comment.

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Last edited by cobalt327; 05-15-2010 at 10:16 AM.
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  #107 (permalink)  
Old 05-15-2010, 09:09 AM
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Originally Posted by 355Nova
IF HP WAS THE REAL REASON, WHY DON'T 18 WHEELERS AND DUMP TRUCKS, ETC HAVE HIGH HP 4 CYL & 6 CYL ENGINES?
If you look at the torque/hp curves of big Cat engines they make peak power at very low rpms, compared to our smaller passenger car engines. They make that power at low rpms by making a lot of torque down low. It does not change the fact that in order to move a heavy object you need energy, and in order to transfer energy from an engine to that heavy object, like a truck, you need power NOT torque.

I have done some dyno testing with a 4-cyl diesel tractor engine. We ran the engine for a good hour to determine volumetric efficiency, brake specific fuel consumption, etc. And we ran it at it's peak hp output, not peak torque. The reason? An internal combustion engine is most efficient when running at or near peak power output (peak efficiency may end up somewhere below peak power, like 80% or so, just depends on the engine design). Anywhere above this and the losses due to friction, airflow interaction with valves, etc. robs power quicker than the engine can build it.
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  #108 (permalink)  
Old 05-15-2010, 09:19 AM
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And here I always thought peak VE = ~torque peak.
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  #109 (permalink)  
Old 05-15-2010, 09:32 AM
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Originally Posted by cobalt327
And here I always thought peak VE = ~torque peak.
It believe it typically does. I stand corrective on my previous statement: "An internal combustion engine is most efficient when running at or near peak power output." You are correct, that should be peak VE/torque. I have been brushing up on this stuff lately and it apparently is not all there yet. Sorry for the confusion. I hope you guys will read my previous posts and see that I don't post on things of which I am not knowledgeable, and I am willing to admit where I am inexperienced or uneducated, or just plain wrong as in this case.

However, sometimes peak tq/efficiency and peak HP occur at the same place, it just depends on the engine design. On the dyno testing I did they just happened to be very close.

That doesn't mean that running your engine at peak efficiency or peak torque is going to win a race. If you really think about what makes a car move it is energy, NOT torque. To make a car get from point A to point B faster you need more energy delivered more quickly (aka more power) to the rear wheels.
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  #110 (permalink)  
Old 05-15-2010, 09:45 AM
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Here's something everybody can try.

Go download the Virtual Engine Calculator (http://www.hotrodders.com/kb/general-engine-tech). There is a function that calculates horsepower from vehicle weight and 1/4 or 1/8 mph. There is another function that calculates ET from power and weight. Nowhere will you find a calculator that takes engine torque and vehicle weight and spits out ET or MPH. That's because the calculator uses kinetic energy, KE=1/2 m V^2, where V is the velocity of the car at the end of the run. If you know the velocity of the car at the end of the run and assume constant acceleration, you can determine ET. Knowing any of two of these three values will allow you to determine the third. The only things that influence your ET & MPH are vehicle weight and average power transferred from the tires to the pavement.

Recall that I was totally with some of you on the whole "Torque is better than HP" thing, until I thought about what really makes a car move. It's not torque, it's power.

Last edited by PontiacPhil; 05-15-2010 at 09:50 AM.
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  #111 (permalink)  
Old 05-15-2010, 10:22 AM
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Originally Posted by 355Nova
Man this thread was a ride!!!!!!!!!!!!!!!!!!!
Ultamitely seems like the SMART EXPERIENCED guys KNOW THAT MORE HP TO WHEELS WINS RACES LOL. Then you got a guy who says HIGHEST HP wins races LMAO. Then the experienced guys say torque wins races. Then you got mathematical guys talking physics? LMAO!!

Well commen sense is NATURALLY your going to have more HP TO WHEELS FROM MORE TORQUE ENGINES.

IF HP WAS THE REAL REASON, WHY DON'T 18 WHEELERS AND DUMP TRUCKS, ETC HAVE HIGH HP 4 CYL & 6 CYL ENGINES?
Why don't double A dragsters use dunp truck engines?

Bogie
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  #112 (permalink)  
Old 05-15-2010, 10:49 AM
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Quote:
Originally Posted by oldbogie
Why don't double A dragsters use dunp truck engines?

Bogie
This article might clear up this whole thing.

http://www.allpar.com/eek/hp-vs-torque.html

Answer to oldbogie's question:

A dump truck engine in a drag car making 1000 ft-lbs at 3000rpm (which is 1000x3000/5252 = 571hp) would get smoked by the same car with an engine making 1000 ft-lbs at 6000rpm (which is 1142hp). The amount of power delivered through the transmission to the tires is greater, therefore it will go faster if installed in a vehicle with the same mass.
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  #113 (permalink)  
Old 05-15-2010, 10:52 AM
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Quote:
Originally Posted by oldbogie
Why don't double A dragsters use dunp truck engines?

Bogie
They do, they are. Look at the history of the hemi, many heavy applications and commercial use. Another useless point for another days discussion.
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  #114 (permalink)  
Old 05-15-2010, 10:58 AM
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Quote:
Originally Posted by cobalt327
If you are going to chastise ap, you had better be prepared to get after those who have called HIM names- except they've really called him names, not just some misunderstood comment.
Habitual abuse won't be tolerated, thats the issue here.
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  #115 (permalink)  
Old 05-15-2010, 12:24 PM
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Quote:
Originally Posted by oldbogie
Why don't double A dragsters use dunp truck engines?

Bogie
Hemi MOPAR's were the 'best' in a line of fuel engines that had their beginning as a low RPM, torqey engines used in large luxury passenger cars and trucks. The TD BBC is purely a truck engine AFA OEM goes- and it and the passenger car deck BBC are a staple in the gas and alky classes.

So, what I'm saying is, they DO use 'truck' engines, of a sort. The reason behind the success of the Hemi (besides the heads that will accept a load of nitro w/enough advance) is the beefy bottom end- just what you still find in trucks.

If the AA cars had to make 8000 HP and use diesel and a single turbo or were NA, they, too would be HUGE. Way bigger than any 18 wheeler's engine, that's for sure. lol

Last edited by cobalt327; 05-15-2010 at 12:36 PM.
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  #116 (permalink)  
Old 05-15-2010, 04:09 PM
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Blah blah blah blah

Vince
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  #117 (permalink)  
Old 05-15-2010, 04:13 PM
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Originally Posted by 302 Z28
Blah blah blah blah

Vince
You don't suppose this will reach so much torque the whole blog will fall over.

Bogie
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  #118 (permalink)  
Old 05-15-2010, 05:10 PM
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Originally Posted by oldbogie
You don't suppose this will reach so much torque the whole blog will fall over.

Bogie
A definite possibility

Vince
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  #119 (permalink)  
Old 05-15-2010, 10:01 PM
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I suppose if you get enough stubborn people in one room, especially me, this is what you end up with. A thread about torque that gets all bent out of shape...

Mr. Lansinger seemed to do a better job than me at explaining it anyway. Arguing with Newton is like arguing with a dead body.
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  #120 (permalink)  
Old 05-16-2010, 07:15 AM
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LOL,,,well it was me who caused this mess...

I tried two different ways to try to get AP to understand that it is TQ that determines rate of acceleration which then determines ET to win the race....

here's my last shot:

what really screws up most folks is the motor TQ notation "ft/lbs" is ambiguous and incomplete!!!
once you understand that it is meant to mean: energy "force" lbs (not mass lbs) per linear foot of travel it all starts to fall into place...

the extremely fast rising psi "energy force" in the chamber from the combustion btu's event moves/drives piston a "linear" distance down the bore on the power stroke...
CRS=a 10/1 CR motor is somewhere around 1200psi at peak combustion pressure at the TQ peak onto the face of the piston to act to accelerate it???

you are using rpms to determine the "frequency" of those linear power stroke combustion events over a 360* rotation movement...
CRS= a 6k there are 400 linear TQ power stroke events per second on a V8???

the TQ climbs from idle up to the peak value rpms due to both better A/F fill with more piston speed=more Hg force to then raise cylinder peak combustion pressure results "and" there are more frequent power strokes events per minute as rpms go up to build TQ rotational inertia into the crank....

the HP peak rpms is the point where increasing power stroke frequency with more rpms won't help because the peak psi pressure force in the chamber acting on the piston to make TQ has fallen to critical due to lack of A/F fill time....

I gota' go for now but those linear TQ power strokes are converted from rotary back to the car linear travel at the tires contact patch...

the raw formula to determine acceleration rate is:
acceleration = motor TQ x twice pi x rpms/(mass x velocity)=Newton's 2nd law for linear acceleration converted to rotary)

and with that math you can directly input the tranny, rear gears ratio's and tires circumference/ratio =TQ on the tires versus mass weight....

Last edited by red65mustang; 05-16-2010 at 10:53 AM.
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