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Re: 327 torque monster [Re: panic] #622808 Tue Feb 23 2010 06:19 PM
Joined: Jun 2009
Posts: 2,269
FriedGreenTmater Offline
Shop Shark
It's like something going around in a circle at 1rpm. If the circle is 1 foot in diameter it is traveling at 3.14 feet per minute. If the circle is 10 feet in diameter it is traveling at 31.4 feet per minute. The bigger the circle (stroke) the faster the something (piston) travels. Did I get that right Builder?

Last edited by FriedGreenTmater; Tue Feb 23 2010 06:47 PM. Reason: feet per minute - not second

Fried Green T'mater (Vern)
1953 Chevrolet 3600
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Man who runs in front of car gets tired, man who runs behind car gets exhausted.
Re: 327 torque monster [Re: Builder] #622874 Tue Feb 23 2010 10:40 PM
Joined: Feb 2004
Posts: 19,021
Hotrod Lincoln Online
Which one will pull 80,000 pounds up a hill better, a Corvette or a Cummins- - - - -both with 350 HP engines?

Here's the Cummins numbers:

NTC-350: 350 HP @ 2100 RPM,
1120 lb-ft torque @ 1300 RPM

I guess Cummins got it wrong, too? last I heard, those 855 cubic inch engines had LOOOOOONNNNNNGGGGG strokes!

Last edited by Hotrod Lincoln; Tue Feb 23 2010 10:41 PM.

The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: 327 torque monster [Re: Hotrod Lincoln] #622898 Wed Feb 24 2010 12:55 AM
Joined: Oct 2003
Posts: 5,161
OldSub Offline
Cruising in the Passing Lane
Jerry, did you know there is a Cummins powered Corvette out there. I think the guy is on one of the 4x4 or Diesel boards. He has swapped a Cummins (6BT?) into a Corvette. I was too shocked to retain any details of how he did it.

I doubt it will pull 80,000 up a hill, but it will probably come a lot closer than my 350 powered Corvette...

And the reason is torque. The Cummins 6BT makes a better comparison to the Chevy 350, being closer to the same size. The Cummins has a four inch (4.02) bore like the Chevy (4.00), but where the eight cylinder Chevy has a 3-1/2 (3.48) inch stroke the six cylinder Cummins has a 4-3/4 (4.72) inch stroke.

Very similar size motors. Very different strokes. And very different in purpose.

While a new Diesel pickup and a new Corvette may be very similar in price, you probably don't compare them when shopping vehicles. You're looking for the features of one or the other. The engineers designing the motors used in each know that and make choices about bore and stroke and cam profile and a million other little things trying to create what you want to buy.

Much as I like my small block Chevy motors I just can't accept anyone calling one of them a torque monster.

Its true, I really don't do anything but browse the Internet looking for trouble... . . .
'55 1st GMC Suburban . '54 GMC 250 trailer puller project. '54 GMC 250 Hydra-Matic . '54 Chevy 3100 . '47 Chevy COE . and more...
Re: 327 torque monster [Re: panic] #622969 Wed Feb 24 2010 04:02 AM
Joined: Sep 2006
Posts: 841
hoggyrubber Offline
Shop Shark
it must be rough having set everyone straight. i still think a little more latin will help.

Re: 327 torque monster [Re: hoggyrubber] #622974 Wed Feb 24 2010 04:12 AM
Joined: Apr 2005
Posts: 1,944
Builder Offline
Shop Shark
I'm not sure I want another stab at a simplified response. I might complicate things more. computer_punch

Maybe a wheel barrow is too complicated for some.

Keep thinking. Maybe you will get it one day.

I wonder why panic has the handle "panic"?? I edited that line for you panic. It now reads "The ability of the piston in an engine to go faster in its bore (the track), requires a longer stroke."

I choose the Cummins Jerry....and I believe in gravity.

Re: 327 torque monster [Re: Builder] #622995 Wed Feb 24 2010 05:13 AM
Joined: Oct 2004
Posts: 129
john1 Offline
Shop Shark
Yes I believe in gravity, I also belive in Newtons first law, the law of inertia. The wheelbarrow example was an excellent analogy of the law of inertia, but it has nothing to do with the production of torque. Somebody else stated a heavy crankshaft increases torque, sorry same thing, gives the crankshaft greater inertia but does nothing to increase torque. If it were that easy, all I'd have to do is bolt on the biggest flywheel I could find and I'd have a torque monster. The only thing close to an apples to apples comparison was the comparison of the 292 to the 283. Both engines share the same bore size, but the 292 has a 37.5% longer stroke! Based on the calculations posted previously, when you correct for the difference in displacement, the 3" stroke 283 slightly out torques the 292 with a 4 1/8" stroke. When you don't correct for displacement the 292 wins by 5 lbft, produced from 9 more cubic inches. By the way, the 283/292 numbers were not provided by me, but by someone trying to illustrate just how much more torque the 292 produced. Now the argument was made that the 292 produced torque at a lower RPM and it was because of the longer stroke. A simple cam swap and you could reverse the results between the 2 engines. Peak torque is developed at the point where the engine fills it cylinders the best. This is largely affected by camshaft, head, intake, and exhaust design. The arguments been made a longer stroke accelerates the piston quicker therefore drawing in more air. In reality, swept volume is swept volume. If the engines have the same cubic inches they will displace the same amount of air per intake stroke given consistent cam, head, intake, and exhaust design. Some german mathametician figured all this out in the 1800's but his theories weren't proven true until the last 20 years or so when they could actually be tested with modern sensors and computers, on real engines. Sorry, forgot his name, when I remember it I will post it. So my question is, if stroke is King when it comes to torque production, why does it fail so miserably in the beloved 292 torque monster. A whopping 37.5% increase in stroke for a slight net loss in torque compared to the 283. And please no more wheelbarrow analogies, just some good sound physics this time. And I'm guessing the Cummins is turbocharged. If it can't make 1200 lbft. of torque out of 800 + cubic inches regardless of bore size or stroke length, then it's one weaksuck motor.


Re: 327 torque monster [Re: john1] #623001 Wed Feb 24 2010 05:54 AM
Joined: Sep 2006
Posts: 841
hoggyrubber Offline
Shop Shark
john, again i am not trying to argue with you. i have a 292 with a mild 264 grind cam and it NOT the same as a stock 283. this i can tell you for sure. while upper rpm torque and power are def increased, it still has way more guts at the lower end than a stock 283.
if you really want apples to apples bore the 283 out .060 over like you said and turn them both at 1600 and see what happens. and let me say i am not trying to drag a dead horse or annoy you.

Re: 327 torque monster [Re: hoggyrubber] #623004 Wed Feb 24 2010 06:02 AM
Joined: Sep 2006
Posts: 841
hoggyrubber Offline
Shop Shark
sorry i forgot to add. i think the weight of the spinning assembly has some effect on torque curve, response, and horspower. not as large as displacement of course. why else chop the flywheel or lighten the crank in the old days. it made the whole assembly lighter and more responsive, but had a slightly neg effect on low end torque. now i am not going to produce any paper that says so. if i'm wrong that's ok, i have been wrong before.

Re: 327 torque monster [Re: hoggyrubber] #623012 Wed Feb 24 2010 07:02 AM
Joined: Oct 2004
Posts: 129
john1 Offline
Shop Shark
You know,I'm not trying to argue either. Just trying to provide some current information on the production of torque from an internal combustion engine. But some of the responses recieved were long on opinion and light on fact. I do believe there is a misunderstanding between inertia and torque.

A light flywheel and crankshaft reduce the rotating mass. With less rotating mass less horsepower is required to accelerate the crank and flywheel, this frees up engine power to accelerate the vehicle. A light flywheel reduces inertia of the rotating assembly, it has no impact on torque production. With that said, an engine with a heavy flywheel will start from a dead stop easier and with less throttle applied than one with a light flywheel. Not because of an increase or change in torque, but because of the greater energy stored in the heavier flywheel, ie greater inertia.

I've been doing the car thing everday as a living a passion and a hobby for over 30 years. In college I learned long strokes make torque, exhaust flow follows the kadency theory, (basically it expands and contracts as a spring), and several other theories that have since been proven wrong. For the last 21 plus years I've worked for a major auto manufacturer in a technical position, and I have had to relearn a lot of stuff that was taught wrong 30 yrs ago. I study everyday, whether it be internal engineering memos, SAE documents, other manufacturers technical publications, or coming here or over to the HAMB. I usually just read and learn and rarely respond. When I do respond it is to correct what I feel is misinformation.
I knew the torque subject was touchy, and I probably should have just left it after my original post way back toward the beginning of this thread was dismissed. Maybe it was dismissed because in the eyes of the Stovebolt I'm still just a wrenchfetcher, or maybe I haven't posted here enough to earn any respect. Doesn't matter, I'll keep hanging around, I'll keep learning, and I'll keep posting whenever I feel my input is needed. No hard feelings, just give me some facts.


Re: 327 torque monster [Re: john1] #623053 Wed Feb 24 2010 02:53 PM
Joined: Apr 2005
Posts: 1,944
Builder Offline
Shop Shark
What??? John1 didn't like the wheel barrow analogy?? I'm crushed!!! I'm glad you didn't beat me up for the race track analogy.

So, this wheel barrow rolls into a bar and says to the bartender...

Knock, knock!
Who's there?
Wheel barrow.
Wheel barrow who?
Wheel barrow me an analogy on Torque. HAHAHAHAHA!!!
That's not funny.
Fine. I'll just wheel into a bar that doesn't take so much work to get appreciated.
You must be a short stroke, high RPM wheel barrow trying to be a low rpm, long stroke dump truck.

Oh yeah! And doesn't the change in stroke also change inertia?

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