Crank lightening

should work just fine...

and if it dont...just use someones super secret suuper dooper highlift camshaft....as a counter ballancer
 
There was a thing on TV this last weekend on Kenworths new truck, being the most fuel efficient ever built.In line 6 no counter weights compacted graphite block.I didn't see it but the others in the shop did. Interesting.
 
Did it blow up ? Not saying it will I just want to watch :Cheer:
 
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Here's the latest. Rough grinding has been done, now all it needs is to debur sharp edges and ones more, grind it throughout with finer paper to get smooth surface.

Timo
 

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Keep up the good work!!! I'm interested to see how it comes out!!
 
Very Cool. Nice to see someone trying something totally different just to see if it will work.

Just a though to throw out there for learning sake, to those that say it won't balance out, particularly Disturbed as judging by your avatar you do sled pulling. In high end sled pulling its fairly common to add weight to the crank correct? In that situation, besides building up the counter weights, are there any balancing issues there? Do you add a proportional amount of weight elsewhere or the same amount?

Not trying to call anyone out or be a jerk, just a question to see this particular build from another angle........
 
I would have to agree with a few people on here. Give the guy a break, it is his money, his time, his effort, his failure, his fortune. Do all you keyboard jockeys really think your input is helping the process. Henry Ford was called an idiot many times, his rich grandson is still smiling!
 
looking good

pics are looking good! put that sucka in something and torture it already. it doesent have to be a mirror:hehe:
 
Im very limited in knowledge on this subject, but Im watching it closely. It will be interesting to see what happens. I hope it works great. Best of luck man.
 
I would have to think that this is going to throw the oscillations created by the 3rd order harmonic at 5 grand through the roof. That being said - I think this could work - now I am going to ask the questions all the naysayers should have: What is the intended use and RPM range for the motor? What are your plans for the flywheel/flexplate? What is your plans for the harmonic damper? (the thing that might make this thing live - LOL) I think with the right damper and either keeping the RPMs below 5 grand or blowing right past 5 grand - you might be OK.

I'm interested to see the outcome of this experiment - but even if it fails - knowing some specifics on the damper and RPM range can shed an awful lot of light onto why and how.
 
IIRC, the 3rd order of torsional deflection harmonic on that length crank should occur ~1400rpm... maybe you're thinking of the 9th order? (~4200)
 
XLR8R said:
IIRC, the 3rd order of torsional deflection harmonic on that length crank should occur ~1400rpm... maybe you're thinking of the 9th order? (~4200)
Click to expand...

I'm going off of memory since its been a long time since I looked at it - I seem to recall a harmonic right at 5,000 RPMs and thought it was the 3rd order that was inherent in all inline 6 cylinder engines. There is so much misinformation out there though that now your statement is making me want to go bust out my vibrations book and run the numbers myself, because my memory isn't perfect and the inline 6 engine I was running the numbers on is quite a bit smaller (pushing the harmonics up the RPM range compared to the 5.9). Maybe I will be doing vibrations "homework" while I eat dinner tonight. LOL
 
Crank Failure

What is the crank failure rate of a stock Cummins crank (both in OEM and extreme builds)?

I know Duramax cranks have their issues, but have not heard much about Cummins' crank failures (that weren't caused by a broken rod bolt or other mechanical malfunction).

If the cranks are strong enough, I feel he may be on to something. Will it balance...absolutely. Will it be able to absorb harmonics without overcoming the torsional strength....

I would think tuning would become very important and with the advent of stand alone controllers, this technique (or a varient of it) might be seeing it's way into high end competition builds (if not already).

I know I've seen lightened and knife-edged cranks in many high performance V-8's but nothing this drastic. I can say I am definitely looking forward to the results.
 
OK HotRod - I checked my notes... mistakenly remembered the harmonic orders by dyslectic magnitudes - should be 9th, 6th & 3rd for 1400, 2100 & 4200 (torsional deflection order @ RPM respectively).

When you find your vibe book can you calculate a CTD crank & post it?
 
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