Other Engine Conversions - non V-8 Discussion of non-rotary engines, exc V-8's, in a car originally powered by a Rotary Engine.

torque misconceptions

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Old Oct 7, 2006 | 09:44 PM
  #51  
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Originally Posted by wingsfan
I don't see anyone doing that. Or you'd see people touting the virtue of their Cummins swaps.
Lol!!
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Old Oct 7, 2006 | 10:25 PM
  #52  
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Originally Posted by GtoRx7
Thanks for pointing out the obvious.....
then what the hell is the point of this thread? to try to bash (horribly at that) the v8 swaps? or did one of you get a new drifting magazine and see an article in there and copy and pasted?
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Old Oct 7, 2006 | 10:41 PM
  #53  
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Originally Posted by razorback
then what the hell is the point of this thread? to try to bash (horribly at that) the v8 swaps? or did one of you get a new drifting magazine and see an article in there and copy and pasted?
I have no idea what the point of the thread is. I dont think anyone was trying to bash V8's ( I know for sure I wasnt). I think he was trying to simply state that people are wrong going around saying "I have 200ft-lbs of torque, and you have 100ft-lbs, so I will out accelerate you, since we weigh the same." Because that can be a false ( or true) statement.

Last edited by GtoRx7; Oct 7, 2006 at 10:43 PM.
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Old Oct 7, 2006 | 10:51 PM
  #54  
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I like cheese.
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Old Oct 7, 2006 | 10:53 PM
  #55  
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Originally Posted by 13B-RX3
I like cheese.
Cheese is alright..
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Old Oct 8, 2006 | 12:31 AM
  #56  
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From: And the horse he rode in on...
Originally Posted by ericgrau

Razorback: Ya, you can make a 100HP, 4000lb. car with a 0-60 of 5s if you just engineer those, um, other factors.... a lot. And hard. Better work overtime.
No one is going to call weak bullshit on this statement????
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Old Oct 8, 2006 | 12:36 AM
  #57  
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they see me rollin.....they hatin.....
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Old Oct 8, 2006 | 02:37 AM
  #58  
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Originally Posted by ericgrau

Razorback: Ya, you can make a 100HP, 4000lb. car with a 0-60 of 5s if you just engineer those, um, other factors.... a lot. And hard. Better work overtime.

No one is going to call weak bullshit on this statement????
Weak bullshit, this would not be possible on strait and level ground.

Last edited by slo; Oct 8, 2006 at 02:40 AM.
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Old Oct 8, 2006 | 08:17 AM
  #59  
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Originally Posted by RaPtOr-T
they see me rollin.....they hatin.....
You're so gangsta.

In your case it's more like this.

http://www.youtube.com/watch?v=-xEzGIuY7kw
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Old Oct 8, 2006 | 11:34 AM
  #60  
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Originally Posted by RaPtOr-T
they see me rollin.....they hatin.....
What the hell??
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Old Oct 8, 2006 | 12:41 PM
  #61  
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This guy has it right on the ball. I had this conversation with an 85 year old engineer who now teaches at Kettering University (formerly General Motors Institute). Torque can move things, horsepower moves it with respect to time.

Does anyone see a unit that relates to time in torque? No. Ft.*Lbs.

Does anyone see a unit that relates to time in horsepower? YES! FT.*Lbs.*Revolutions/Minute

Acceleration's units are Feet/second^2

Velocity's units are Feet/second

Horsepower is what determines acceleration, not torque. Torque can be produced via gearing, trading RPMS.

Now this gets into real life applications. A motor that tends to produce less torque and produces horsepower by RPMS (say a rotary) is usually lighter than an engine that produces lots of torque at lower RPMS (say a v8). This is usually because the high rpm engine has much less displacement, and therefore much less mass and volume.

Torque does break things. Torque is what causes driveshafts to break, transmission cases to crack, gears to shear teath off, and bodies to twist. So, what do we do to remedy this problem? Put a heavier duty (thus heavier weight) transmission in it! Put a larger diameter driveshaft in it! Put more steel in it to brace the unibody! All of this adds up to more weight.
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Old Oct 8, 2006 | 12:54 PM
  #62  
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Originally Posted by shm21284

Horsepower is what determines acceleration, not torque. Torque can be produced via gearing, trading RPMS.

.
but without torque, there is no horsepower.. and torque is what moves cars/trucks...

you guys are horrible at bashing v8s

why do i feel like im on a honda forum?

"My 500hp 120 ftlbs of torque is better than your 500 ft lbs of torque and 400 hp"
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Old Oct 8, 2006 | 12:55 PM
  #63  
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You are missing the point. And I'm not trying to bash v8's. I love them. I'm trying to show the reality of torque vs Hp.
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Old Oct 8, 2006 | 12:56 PM
  #64  
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Torque is what applies the force. Hp is what applies the force over time, thus, acceleration.
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Old Oct 8, 2006 | 12:57 PM
  #65  
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but without torque there is no horsepower... the way you (well some of you act) is that torque does not matter one bit, its a mute point.. which is not the case..
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Old Oct 8, 2006 | 01:02 PM
  #66  
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Horsepower is what matters when it concerns acceleration. Period. How you get that horsepower is up to you: whether you want gobs of torque or gobs of RPMs.
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Old Oct 8, 2006 | 02:56 PM
  #67  
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Wow, another classic smack fest centered on what wins races. I've always liked to visualize the entity that moves the car as the area under the torque * RPM curve, AKA integral of the torque function with respect to time.

No worrries. Real evidence (ie. empirical race data such as 1/4 mile trap speed, ET, vehicle weight, or a dyno graph) doesn't lie. Can't we all just get real numbers?
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Old Oct 8, 2006 | 04:22 PM
  #68  
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Originally Posted by shm21284
Horsepower is what matters when it concerns acceleration. Period.
Do you know how to calculate acceleration?

"While the horsepower number is the most frequently quoted figure for an engine's performance, I really consider the torque curve to be the most important graph to indicate the performance of a car .... engine torque is multiplied by the driveline gear ratios and then acts through the distance of the rear tire radius to produce thrust at the contact patch of the tire. That's what makes you go."

The amount of torque you can apply to the drivetrain at any rpm is what determines the acceleration potential of the car. Maximizing torque at the axles (and therefore thrust at the tire's contact patch) is what makes a car fast... not quoting peak horsepower numbers.

Time will take care of itself. An engine's output shaft rotates continuously while the engine is running. It's not a ******* torque wrench, and it's not "like applying x lb-ft. of torque y times a minute". It is a continuous force and we are not tightening bolts with it, we're turning tires.
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Old Oct 8, 2006 | 04:28 PM
  #69  
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A motor that tends to produce less torque and produces horsepower by RPMS (say a rotary) is usually lighter than an engine that produces lots of torque at lower RPMS (say a v8). This is usually because the high rpm engine has much less displacement, and therefore much less mass and volume.
some cases thats true, but the aluminum Ls1 is 346cubes and weighs close to the same of the twin turbo fd. and if the motor is built right, then it can rev. my buddy has a 496 inch (well now its a 498) big block... revs to 7000rpms


jim is right tho.... torque is applied to the tires to rotate them which leads to movement. a lower torque car wont get off the line as fast as a higher torque one. cuz the thrust force is less on the tires. thats why my 230ish whp (i'm guestimating) L98 350 with 3.27 gears gets off the line as fast as my buddies 365whp ls1 ss with 4.30's. i got a ton more torque at launch rpms...i launch 2800 with my converter which also amplifies torque, to his 6speed clutch slip/drop at 3000rpms. therefore my thrust is harder and i accelerate abit faster. but as rpms go up, horsepower takes over...and its easy to see how his car rapes mine after the launch...he's applying more power to the tire in the form of hp and torque than my car

Last edited by Orr89rocz; Oct 8, 2006 at 04:33 PM.
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Old Oct 8, 2006 | 04:39 PM
  #70  
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"torquey" motors have big powerbands.

Bigger powerbands are better than small ones, as bigger = better.

Therefor STFU AND STOP BEATING THE DEAD HORSE.

What people dont realize is we dont all have CVTs or stalled torque converters at peak power all day, in NORMAL cars, and the time spent as you sweep over the rev range in each gear matters! If youre at the power plateau of a v8 (aka torquey motors) throughout each gear sweep you're getting that power to the wheels at all time and thus getting the maximum acceleration with that power.

If youre in a peaky car youre not actually making the power rated except at the rpms in which you are.

THAT is what everyone is trying to say but oh well nobody understands the concept of 'rate' if they're rotarded, right?

Quick, someone start talking about ignition events or combustion chambers being related to displacement!
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Old Oct 8, 2006 | 05:30 PM
  #71  
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Originally Posted by shm21284

Torque does break things. Torque is what causes driveshafts to break, transmission cases to crack, gears to shear teath off, and bodies to twist. So, what do we do to remedy this problem? Put a heavier duty (thus heavier weight) transmission in it! Put a larger diameter driveshaft in it! Put more steel in it to brace the unibody! All of this adds up to more weight.
huh... yet you seem to disregard that fatigue strength is a function of the number of stress cycles (think rpm), and an engineer must design w/a higher safety factor which usually translates on beefing up both tranny gears and engine components. I mean, the fc tranny seems way big for 190 lb-ft of torque.
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Old Oct 8, 2006 | 05:44 PM
  #72  
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usually everything is over engineered to account for fatigue and abuse. safety factors as you said. it just depends on how much safety was factored in.
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Old Oct 8, 2006 | 05:55 PM
  #73  
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Originally Posted by Orr89rocz
usually everything is over engineered to account for fatigue and abuse. safety factors as you said. it just depends on how much safety was factored in.
Usually to reach an "ideal" infinite life. That was not the point however. The point is that just as a transmission may be bulky and heavy to sustain the torque, a tranny may be bulky and heavy to sustain high rpms.

It's like the new excuse is... the rx7 is built for rpm's and not torque... but at the end of the day, either factor can break a driveshaft just the same.
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Old Oct 8, 2006 | 05:58 PM
  #74  
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The cycles / stress graph for aluminum does not reach a flat line like ferrous alloys, no matter how small the load is. In other words, you can't design typical aluminum parts to last forever (ie. aluminum heads, blocks, airplanes, etc.).

[/ME383]
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Old Oct 8, 2006 | 10:02 PM
  #75  
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Originally Posted by jimlab

"While the horsepower number is the most frequently quoted figure for an engine's performance, I really consider the torque curve to be the most important graph to indicate the performance of a car ....
HUH, i always thought the best indication of the performance of a "CAR" was it's performance??? We can argue about theoretical figures and specs till the end of time but the only true indication of how fast a car is are time slips, lap times, skid pad #s, 0-60s that's it!!! Remember we are building cars not engines.
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