Crankshafts - 3 different weights

[W. Tripp]

I thought some of you might be interested in this photo of three different crankshafts.
Left - stock crank with oil shedding coating
Center - Diamond Marine Ultralight - 5 pounds lighter than stock & Balanced.
Right - Diamond Marine Sportsman crank - 2.5 pounds ligher than stock & balanced

[1BadAction]

How close are the factory HP cranks balanced in the 280s?

[W. Tripp]

Let's just say that an engine with a balanced rotating assembly runs MUCH smoother. Even at idle the difference is very noticeable.

The stock cranks need weight added to balance if you cannot lighten them to match the reciprocating and rotating weights of lightened rods, pistons, and wrist pins.

Balancing the reciprocating and rotating weights of just the rod/piston assembly makes a noticeable difference in a 260, 280, or Drag. My latest lake ported 280 is done like this.

[Chummy]

What does it cost to have a crankshaft balanced for a 280?

[1BadAction]

Its pretty big $$... 2k+ for the sportsman IIRC...

[RBT]

yes 2k....... but they are SO PRETTY. At the bare minimum you have to admire the bling factor, let alone the gains.

RT

[1BadAction]

well, when ya get stuff from Diamond its top notch, and those guys arent going to steer ya wrong on what to do with your equipment.

[RBT]

almost to pretty to put in a motor!.

RT

[G Rowe]

5 pounds lighter! Thats alot of meat to cut away, any loss in strength?
Very nice

[RichS]

What ya lose in static strength ya gain in longevity because of the lower harmonics in the balanced assembly

[W. Tripp]

I have had 5 lightened cranks by Diamond Marine, and never had an issue with any of them. I can't say the same for stock cranks.

If you look at the photo, the places where material is removed is the least stressed part of the crank. And The Signorelli brothers at Diamond Marine do NOT put their name on anything that is not well designed.

Lightening the crankshaft accomplishes several things:
1.) Reduced rotating mass.
2.) Increased crankcase volume.
3.) Balanced rotating assembly.
4.) Reduced engine harmonics - this is a BIG issue at Drag racing rpm.
In my experience, this all results in an increase in life and durability for race parts and engines.

A broken crank can be devistating to a race engine with many hours of work and many other expensive parts.

Then again, I know a LOT of very fast racers who use stock cranks.
______________

I placed this photo here to give a lot of the members a chance to see what these parts actually look like, whether they would ever want or need one or not. There are not a lot of them out there and getting a chance to see the differences is pretty cool...at least to my line of thinking.

Just trying to share information, NOT start issues. The lack of good information about these engines is overwhelmed by bad info and old wives tales. If more knowledge is shared, everyone wins.

-Wayne

[THE FAST ONE]

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[G Rowe]

Cheers W.Tripp, what kind of price to get just the coating done?

[stoker2001]

Looks to me that the ultra light one looses some of the sealing rings?less friction is good,but what about cons?please tell

[hydroholic]

OK so the weight factor is a plus.But the so called "BLING" factor ain't worth 2k.It's on the inside of the mota.As long as it's on the inside of the motor and it performs the way it is intended,who cares what it looks like.