Hemi to be replaced by inline six?

Turtle n Peeps wrote:


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.

A few things...your example engines are all turbocharged. That throws everything out the window since the boost levels and other tuning parameters can easily change the power levels.

And longer rods to not always mean longer stroke, as in that engine masters comparison.

However, I do believe that in naturally aspirated engines, displacement is what increases torque in an apples to apples comparison. It just so happens that usually the easiest way for a manufacture to add displacement is to increase the stroke.

If you have two engines that are an I6 and a v8, with the same displacement, the I6 will not inherently make more torque or be a "stump puller" just due to its inline architecture.

Engines are air pumps. The only ways to pump more air is to increase flow efficiency, increase size, or increase air density (boost or elevation changes for example).