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Old 14th April 2015, 06:32   #31
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What amazed me most is the cutaway of the Isuzu Dmax inline 4 engine. It is a parallel tandem- in this day and age !!! meaning piston 2 and 3 are at TDC and piston 1 and 4 are at BDC. Is this common to most I4 diesels available in India? Are all the cranks tandem cranks - 180 degree from each other or are there diesel engines in India with 90 degree crank seperation. Tandem cranks vibrate more and they have a power stroke every 180 degrees limiting their rpm
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Old 14th April 2015, 12:28   #32
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Originally Posted by drsamuelk View Post
Tandem cranks... have a power stroke every 180 degrees limiting their rpm
Take a look at how 4 stroke Otto cycle engines work. Nothing exceptional in what you see in the cutaway view in question.
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Old 15th April 2015, 19:35   #33
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Originally Posted by drsamuelk View Post
and they have a power stroke every 180 degrees limiting their rpm
4 stroke = 2 revolutions = 720 deg.
720/4 = 180.

And primary forces are balanced.

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Old 16th April 2015, 02:31   #34
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I got it, most diesels have a tandem crank a.k.a 'flat plane' crank. Its not what I had written earlier but this.....

Of the 2 pistons at TDC one is in exhaust and one is end of compression stroke. Of the two in BDC one is in end intake stroke and the other end power stroke.
This means, there is only one power stroke every 360 turn of crank !!!
The engine behaves like a single cylinder engine !!!
Ideally inline 4's need 2 balancer shafts one fore and one aft, geared to the crank.
With the lack of balancer shafts, the safest option is to have one power stroke every 360, that way the vibration is less, engine lasts long and can be serviced after long intervals.
Flip side, these engines don't rev much and have less bhp.
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Old 16th April 2015, 07:17   #35
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Default Re: Technology @ Auto Expo 2014

Quote:
Of the 2 pistons at TDC one is in exhaust and one is end of compression stroke. Of the two in BDC one is in end intake stroke and the other end power stroke.
This means, there is only one power stroke every 360 turn of crank !!!
The engine behaves like a single cylinder engine !!!
The other two cylinders, the pistons of which are at TDC ans BDC in tandem, would be at two different cycle strokes. This would mean that there is one power stroke every 180.
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Old 16th April 2015, 07:40   #36
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Oh yeah, thanks for pointing that out, I completely missed that and was sulking at the poor design. I'm drifting more to an inline 6 for a jeep project. I'm in search of something <350 kgs......and the search continues.
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Old 16th April 2015, 19:49   #37
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Originally Posted by drsamuelk View Post
Flip side, these engines don't rev much and have less bhp.
What rpm ballpark values are we talking about?

Must say your post left me totally and thoroughly confused.

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Old 19th April 2015, 20:01   #38
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Sorry for the heartache.
I was of the opinion that flat plane crank was a thing of the past and ended with the Mahindra B275 international engine. I was shocked to see the pics of new Isuzu engine cutaway, have the same flat plane crack. A frantic search of other engines made in India, enlightened me that all of them are flat plane cranks.
I'm not against flat plane crank, they're good in terms of longevity and fuel economy but suffer on the performance front even after turbocharging.
Most flat plane cranks diesels engines available rev to around 3000 rpm max. There aren't many that can reach 4000 rpm.
Inline 6 on the other hand is a multi plane crank with crank throws every 120 . They have 2 cylinders firing every 120, they're well balanced.
Can anyone list inline 6 engines for LCV's, made in India and include their weight if possible?
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Old 19th April 2015, 20:50   #39
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Originally Posted by drsamuelk View Post
Sorry for the heartache.
I was of the opinion that flat plane crank was a thing of the past and ended with the Mahindra B275 international engine. I was shocked to see the pics of new Isuzu engine cutaway, have the same flat plane crack. A frantic search of other engines made in India, enlightened me that all of them are flat plane cranks.
I'm not against flat plane crank, they're good in terms of longevity and fuel economy but suffer on the performance front even after turbocharging.
Most flat plane cranks diesels engines available rev to around 3000 rpm max. There aren't many that can reach 4000 rpm.
Hi,
Could you give us a couple of examples of I4 diesels with a non flat plane crank, and its rpm limits.

If the crank is the limiting factor for rpm in I4s, what about petrols?

Quote:
Inline 6 on the other hand is a multi plane crank with crank throws every 120 . They have 2 cylinders firing every 120,
Not 1?

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they're well balanced.
Here I'll agree.

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