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Discussion Starter · #1 ·
Heres an image from the Furdcummins website;

http://www.fordcummins.com/images/rodcomparison.jpg

You'll note the massive size of the Cummins rods. You'll also note the offset cap. This is done to lessen the load on the bolts.

It's no wonder the Furd boys want a Cummins instead of their own crappy Intertrashinal Power(less)stroke.

Ed
 
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Ya- this has been around the net Diesel sites for some time- but Advanced Adapters is making quite a living selling kits to switch the Ferd to a cummins LOL- though I have to admit- I like the ford four door cab for seating and kid friendly loading.
 

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...and the fact that the straight design is better for torque then the "V". Doesn't hurt that they're in a Dodge too!
 

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Discussion Starter · #5 ·
kyot said:
...and the fact that the straight design is better for torque then the "V". Doesn't hurt that they're in a Dodge too!
There is no proof that an Inline engine is better for torque than a "V" engine or any other configuration. In fact one could argue that a V8 vs an I-6 would have more cylinders turning the crank (Every 90 degrees for the V8, vs. every 120 degrees for the I-6)

What an inline does have as an advantage is a simplier, easier to maintain design. Less moving parts to fail, greater bottom end strength (A typical I-6 has seven main bearings, compared to a V8s five.) and much more room for external components.

Ed
 

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If there is no proof then how is it that Cummins matches the others for output with a smaller cubic inch?
 

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Discussion Starter · #7 ·
kyot said:
If there is no proof then how is it that Cummins matches the others for output with a smaller cubic inch?
I didn't say anything about displacement. I was talking about engine configuration. There is no evidence or support that an inline engine makes more torque than a "V" engine. It's a myth. I'm not trying to suggest that a "V" engine is superior to an inline, but the Cummins matches and exceeds the competition thru robust design and a more efficent layout.

Ed
 

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Before I go further....I'm not argueing.......just want to make that clear. So far...this seems to be the only board that doesn't have pissing matches.

So.....doesn't your last statement also support what I'm saying? The straight is making the same power with less cubic inch , being that it is more efficient. So then the straight does make more power then a comparable V design of the same cubic inch.
 

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Discussion Starter · #9 ·
kyot said:
Before I go further....I'm not argueing.......just want to make that clear. So far...this seems to be the only board that doesn't have pissing matches.

So.....doesn't your last statement also support what I'm saying? The straight is making the same power with less cubic inch , being that it is more efficient. So then the straight does make more power then a comparable V design of the same cubic inch.
I never get into pissing matches.. ;D

Torque is the rotational force applied to the crank. Alot of things can affect how much torque an engine makes from induction, cylinder head design, piston size and stroke, engine efficency, exaust, etc. How you line up your pistons has little to do with torque other than the torque overlap you have depending on the number of cylinders you have working. Modern V6s are making more torque and horsepower than similar (or larger) displacement I-6 engines of a few years ago. I wouldn't conclude that the "V" configuration is the reason. A modern V6 has fuel injection, better breathing, better exaust, and greater efficency. The old I-6s don't, but use the same types of tech, and you'll increase the torque of those old inlines.

Yes the Cummins has less displacement then it's V8 competitors. The closest V8 diesel displacement is the new Ford / International 6.0 Powerstroke. When the 6.0 was introduced a couple of years ago, the Powerstroke had more torque than the then current H.O. Cummins. It had nothing to do with being a "V" configuration. Now the Cummins has the most torque.

What the inline Cummins diesel has in an advantage over the V8s is the Cummins is a much more robust design. With some improvements such as O ringing the block, the Cummins can push 600+ hp and 1200lb-ft of torque, because it has the biggest and strongest internal parts. Neither V8 offered has that much strength to support that much torque.

Ed
 

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I think so
 

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Discussion Starter · #12 ·
RCC_SaMiaM said:
So are you saying the cummins has a longer stroke then the V-8's
Nope I didn't say that. The Cummins does have a longer stroke than the V8 diesels, but stroke alone will not nessarily increase torque. What gives big torque gains is how much crank throw there is. Look at a bicycle. Your legs push the pedals in a circle, the larger this circle is, (or longer the crank throw is) the more leverage your legs have to push the pedals. The crank in your engine works the same way. Any short stroke engine can have a crank with alot of throw, but you run into another problem. The con-rods will have a much greater angle to work thru as it converts the piston's up & down movement into the crank's rotational movement, much of it's push efficency is lost at a high angle relative to the piston travel. For the piston to push the crank efficently, you need to keep the con-rods as parallel to the movement of the pistons as possible, often this is accomplished with longer rods. This doesn't nessarily mean the engine will have a long stroke, just that the con-rods max out at less angle in relation to the crank at 90 degrees to the piston bore. (Usually this means that the piston will be further away from the crank centerline at BDC)

.....since the crank has to rotate more per cylinder? Does longer stroke have anything to do with torque?
No the crank does not have to rotate more per cylinder. Your typical 4 stroke engine, no matter how many cylinders, turns the crank thru 720 degrees of rotation to complete all the strokes in any given cylinder. (320 degrees x2) Power is made for only 180 degrees of crank rotation in any given cylinder. (TDC to BDC during the powerstroke)

If you had a single cylinder engine, all of it's torque is made during that 180 degrees of crank rotation. For the remaining 540 degrees of crank rotation, the crank is simply turning by inertia.

In an inline four cylinder engine you'll note that two pistions are moving up and two are moving down when you turn the crank. Each is on it's own stroke. The two going up will have one on it's compression stroke, and the other on it's exaust stroke, while the two pistons going down will have one on it's intake stroke, and the other on it's power stroke. In a four cylinder this means that for every 180 degrees of crank rotation, a cylinder is firing and the crank is made to turn.

In an Inline 6, the pistons are now seperated by 120 degrees of crank rotation, since power is made thru 180 degrees of rotation we now have an overlap of power from one cylinder completeing it's power stroke, to the next cylinder thats beginning it's power stroke. In the inline six, this overlap is 60 degrees long.

In a V8 the cylinders are now firing 90 degrees apart, and likewise, the overlap in power is now greater, being at 90 degrees apart. You'll also notice that all modern V8s have their two cylinder banks spaced at 90 degrees apart from each other, this directly coincides with the 90 degree power overlap.

I won't get into discussing the relationship of the "V" angle to the crank in a V6, but I will say that as you increase the overlap in power, you technecally produce more consistant torque from one cylinder to the next.

Ed
 

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RXT said:
RCC_SaMiaM said:
So are you saying the cummins has a longer stroke then the V-8's
Nope I didn't say that. The Cummins does have a longer stroke than the V8 diesels, but stroke alone will not nessarily increase torque. What gives big torque gains is how much crank throw there is. Look at a bicycle. Your legs push the pedals in a circle, the larger this circle is, (or longer the crank throw is) the more leverage your legs have to push the pedals. The crank in your engine works the same way. Any short stroke engine can have a crank with alot of throw, but you run into another problem. The con-rods will have a much greater angle to work thru as it converts the piston's up & down movement into the crank's rotational movement, much of it's push efficency is lost at a high angle relative to the piston travel. For the piston to push the crank efficently, you need to keep the con-rods as parallel to the movement of the pistons as possible, often this is accomplished with longer rods. This doesn't nessarily mean the engine will have a long stroke, just that the con-rods max out at less angle in relation to the crank at 90 degrees to the piston bore. (Usually this means that the piston will be further away from the crank centerline at BDC)
can you elaborate on that a little bit? how can an engine have a short stroke but a long throw? If the crank throw is 3 inches, then the stroke is 6 inches, no matter how long or short the connecting rods are. I agree with you on the fact that longer con rods equate to lesser angles when the crank is 90 degrees atdc and 90btdc, but then you can run into problems of the connecting rod hitting the bottom of the cylinder wall, or pushing the piston up too high, and hitting the head.
 

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Discussion Starter · #14 ·
CJ's84RC said:
can you elaborate on that a little bit? how can an engine have a short stroke but a long throw? If the crank throw is 3 inches, then the stroke is 6 inches, no matter how long or short the connecting rods are. I agree with you on the fact that longer con rods equate to lesser angles when the crank is 90 degrees atdc and 90btdc, but then you can run into problems of the connecting rod hitting the bottom of the cylinder wall, or pushing the piston up too high, and hitting the head.
I wasn't trying to make an arguement for stroke. I was trying to 'splain crank throw in relation to torque. On second thought you are right, no matter how long the con-rods are, the crank throw will dictate the stroke. The point I was trying to make was in how much angle the con-rods must tilt out if they are short.

Ed
 

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I say the V motors make more power, i guess you guy's never had the opportunity to drive the older V motored diesels, lol make the new inline motors look like junk, to bad there gone now
 

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Also piston speed/weight greatly affects why a rod needs to be so big and have a certain degree of strength, the cummins with a piston that is by far far far heavier than a p stroke or gm it had better have a big heavy rod in it, it needs all that rod to keep the piston attached, this is why i wonder why there has been no experiments with _________ pistons.

(that's right im not F'ing myself again and losing out on a multi million dollar money maker by saying it out loud again and watching someone else get rich again)
 

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Discussion Starter · #17 ·
Evildriver-3 said:
Also piston speed/weight greatly affects why a rod needs to be so big and have a certain degree of strength, the cummins with a piston that is by far far far heavier than a p stroke or gm it had better have a big heavy rod in it, it needs all that rod to keep the piston attached, this is why i wonder why there has been no experiments with _________ pistons.
Yes piston speed and weight are big factors. Unlike gas engines that can run upwards to 10,000 rpm in full race trim, a typical turbodiesel has a relatively low rpm range of operation, therefore there is another reason you didn't mention, and it's simply added strength for heavy engine loads such as the type seeen in work engines.

Ed
 

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Marty, I read an article in wards auto world or the like a few years ago, a couple of guys were working on berylium or berylium alloy pistons but have never heard anything else on the subject. I've read a couple articles on ceramic pistons but that doesn't seem to be going anywhere either. titanium would be too heavy by itself but who knows what all it could be alloyed with. Titanium is tricky, the crystal structure is enlongated, if the crystals aren't all laying parallel you get weak spots.
 

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I have an idea with a piston to work in a diesel to deal with the heat, my buddy who is a machinist thinks it could work but gotta make 1 1st and then beat it to death (my job) see how it holds up, but the thing is making 1
 
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