Hemi to be replaced by inline six?

Turtle n Peeps wrote:

mkirsch wrote:

Turtle n Peeps wrote:
A lot of misinformation and misunderstanding in this thread. And I do mean a LOT. :B

Long strokes do NOT make more torque. That is a myth.

Because some dumpy old guy who makes a youtube video sez so?

No. Because engineers say so that's why.

If anybody want's to learn why, this is a great video to learn from. If you just want to know about torque, start at the 3 minute mark and learn about long and short stroke and what it "doesn't do to engines."

Don't like videos? Fine. Lets talk about actual diesel engines.

Engine #1. 2006 LBZ 6.6 Duramax. (Why this engine?) Because I own it and know about it.

Engine #2. 2006 Ram Cummins 5.9.

Engine #1 according to the internet the Durmax has a bore of 4.055 and a stroke of 3.90. (almost a square engine)

Engine #2 according to the internet the Cummins has a bore of 4.02 and a stroke of 4.72.

According to a lot of people on here the Cummins should kill my engine in torque because of the long rod.

Here are the dyno numbers:

2006 Duramax puts out 650 ft/lbs of torque.
2006 Cummins puts out 610 ft/lbs of torque.
So much for the long stroke putting out more torque.

I can hear the fan bois all ready saying that's not fair!! Your Dirty Max is a waaaaaay bigger engine!!! Fine, more facts:

2008 Duramax 6.6 L vs 2008 6.7 Cummins:

2008 Duramax 6.6 L = 650 ft/lbs of torque.
2008 Cummins 6.7 L = 650 ft/lbs of torque.

Well would you look at that? Same exact torque even though the Cummins has a waaaay longer stroke. :B

Engine Masters did a TV show a few months back about rod length. Everybody on the show (me too) thought the long rod engine was going to put out more torque. WRONG!! They were the same within dyno measurements. Link to Engine Masters rod article.

Your numbers are meaningly, because it is unknow how much power the manufacture of any given engine had tuned for! Cummins has traditionally tuned for longevity. Think million mile motors. How many Duramax's or Powerstrokes go a million miles?

Turtle n Peeps wrote:

Here are the dyno numbers:

2006 Duramax puts out 650 ft/lbs of torque.
2006 Cummins puts out 610 ft/lbs of torque.
So much for the long stroke putting out more torque.

I can hear the fan bois all ready saying that's not fair!! Your Dirty Max is a waaaaaay bigger engine!!! Fine, more facts:

2008 Duramax 6.6 L vs 2008 6.7 Cummins:

2008 Duramax 6.6 L = 650 ft/lbs of torque.
2008 Cummins 6.7 L = 650 ft/lbs of torque.

Well would you look at that? Same exact torque even though the Cummins has a waaaay longer stroke. :B

As somebody that has used a lot of torque out many engines I can see a major problem with the numbers you post; You only list peak, and don't relate it to RPM. This would matter if the engine worked at that RPM. But most useful would to compare the graph of torque output over the RPM range.

mkirsch wrote:

Turtle n Peeps wrote:
A lot of misinformation and misunderstanding in this thread. And I do mean a LOT. :B

Long strokes do NOT make more torque. That is a myth.

Because some dumpy old guy who makes a youtube video sez so?

No. Because engineers say so that's why.

If anybody want's to learn why, this is a great video to learn from. If you just want to know about torque, start at the 3 minute mark and learn about long and short stroke and what it "doesn't do to engines."

Don't like videos? Fine. Lets talk about actual diesel engines.

Engine #1. 2006 LBZ 6.6 Duramax. (Why this engine?) Because I own it and know about it.

Engine #2. 2006 Ram Cummins 5.9.

Engine #1 according to the internet the Durmax has a bore of 4.055 and a stroke of 3.90. (almost a square engine)

Engine #2 according to the internet the Cummins has a bore of 4.02 and a stroke of 4.72.

According to a lot of people on here the Cummins should kill my engine in torque because of the long rod.

Here are the dyno numbers:

2006 Duramax puts out 650 ft/lbs of torque.
2006 Cummins puts out 610 ft/lbs of torque.
So much for the long stroke putting out more torque.

I can hear the fan bois all ready saying that's not fair!! Your Dirty Max is a waaaaaay bigger engine!!! Fine, more facts:

2008 Duramax 6.6 L vs 2008 6.7 Cummins:

2008 Duramax 6.6 L = 650 ft/lbs of torque.
2008 Cummins 6.7 L = 650 ft/lbs of torque.

Well would you look at that? Same exact torque even though the Cummins has a waaaay longer stroke. :B

Engine Masters did a TV show a few months back about rod length. Everybody on the show (me too) thought the long rod engine was going to put out more torque. WRONG!! They were the same within dyno measurements. Link to Engine Masters rod article.

Me Again wrote:

JRscooby wrote:


Back in early '70s I leased on to a company that half the company trucks where inline 6I71 2-stroke. The others, 6V71. The worst of the I6s could out pull the best of V6s. Most of the owner operators had 8V71s Some of them could be passed by the best of the I6.

The 350 Detroit 8V71 with 13 speed in the truck was more or less a dog. Any 350 Cummins I6 would walk all over it. And it was a fuel and engine oil hog.

For a long time 8V71 was the engine of choice in a lot of applications. Until Cummins started putting turbos on their 855 CID I-6, the lighter 568 inch could do a good job with a less skilled driver. If yours was 350 HP that means it had a turbo. Detroit did that because a average 290 Cummins was so much better than a 318 when pulling a van

Thanks Turtle

It is PSI x surface area of the piston top and the amount of time that high PSI is in effect on the piston top

Turtle n Peeps wrote:
A lot of misinformation and misunderstanding in this thread. And I do mean a LOT. :B

Long strokes do NOT make more torque. That is a myth.

I had a 1963 Suburban with a 292 I-6 engine and it would pull a house over. We towed a E racing runabout all over the NW to races. I removed the 292 and install a 283 V-8. Pull a house over was not going to happen any more. However it cruised on the freeway much better enjoying the RPMs.

JRscooby wrote:


Back in early '70s I leased on to a company that half the company trucks where inline 6I71 2-stroke. The others, 6V71. The worst of the I6s could out pull the best of V6s. Most of the owner operators had 8V71s Some of them could be passed by the best of the I6.

The 350 Detroit 8V71 with 13 speed in the truck was more or less a dog. Any 350 Cummins I6 would walk all over it. And it was a fuel and engine oil hog.

Turtle n Peeps wrote:
A lot of misinformation and misunderstanding in this thread. And I do mean a LOT. :B

Long strokes do NOT make more torque. That is a myth.

Because some dumpy old guy who makes a youtube video sez so?

First question I have for OP; The article suggest plans to build new design in 1 plant instead of hemi. Is that the only place hemi is built? I can't see where the idea is replace for end user.

Me Again wrote:

FishOnOne wrote:

theoldwizard1 wrote:

BenK wrote:

In-line is smoother and of higher torque, generally speaking, than V's

I6 will always have more low end torque.

Why?

Longer stroke in most cases. Or under square. V engines tend to be square or over square.

Under square = bore less than stroke
Square = Bore and stroke the same
Over square = bore more than stroke

Short stroke engines make RPM's and HP
Long stroke engines make torque.

That is why OTR trucks are mostly I-6, and Cat and other V-8s have gone by by!

Sorry, but the most Cats used OTR where I6. Most Cat V8s where used in light duty or short haul. The bigger V8s where too heavy for most buyers.

valhalla360 wrote:

theoldwizard1 wrote:

BenK wrote:

In-line is smoother and of higher torque, generally speaking, than V's

I6 will always have more low end torque.

Only if "all else is equal"...which of course, it never is.

Back in early '70s I leased on to a company that half the company trucks where inline 6I71 2-stroke. The others, 6V71. The worst of the I6s could out pull the best of V6s. Most of the owner operators had 8V71s Some of them could be passed by the best of the I6.

A lot of misinformation and misunderstanding in this thread. And I do mean a LOT. :B

Long strokes do NOT make more torque. That is a myth.