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Discussion Starter #3
Thanks, Mark, I will look for a 1.6 for a crankshaft.

Plans are to build a high rpm 2.0 and this crankshaft is best to use it is said.
 

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There was also a 1.6N that had a 4 weight crank. I think the S is a rare item, if you find two of them let me know.:)
 

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Pedal Smasher
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If you found an 8 counterweight crank in Germany, it's probably for a 2.4. Finding a 1.6S crank is probably impossible. Have you considered commissioning a company like Crower to create a custom crank shaft? That's about the only way you'll get an 8 counterweight crank with a 69.8mm stroke. I could see there being some interest in such a crank, brand new.
 

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Pedal Smasher
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I stand corrected, there is one. But, the seller will only do a local pick up. And finding out they are cast steel, not the kind of crank you want in a high RPM motor.

Sure, it could be just fine in a high RPM motor and not give you any trouble. But is it worth risking the engine over it? Obviously Opel learned something about the CIH engine and changed to a forged crank, or else they wouldn't have done it. It's considerably more expensive to go with a forged crank, and Opel is an economy car brand. I wouldn't be surprised if there was an important meeting that decided to go forged on their main engine family at the time, requiring new tooling and a higher cost per part. I could be wrong of course. But everything I've learned about business says an economy based company will not splurge on a part that doesn't require it. This isn't a part or option that would generate more sales.
 

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Discussion Starter #9
The crankshaft I bought was from a late 80's model Opel Rekord 2.0, so I am guessing that the quality should be better than the older 1.6S versions. We will find out soon as the engine is nearing completion. (it took some time.. ;-)...)
 

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The 8 counterweight cranks were mostly used in 16N, 19N and 20N engines according to what I have read on some German Opel forums. I have personally only seen one such crank, but I didn't check if it was forged or not. If a cast crank is so much worse than a forged is difficult to say, at least considering that all OHC engines had cast Nodular iron cranks. And usually had a RPM cut off limit at 6500RPM.
 

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Opel Rallier since 1977
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I agree with Commodaren.... it is all in the details of the crank. While cast is generally has less of what is technically called 'toughness', there are plenty of cast cranks around that can be very safely run up to the level of 1.3-1.5 HP per cubic inch.

As for some thoughts on the 8 weight crank....It seems like that is only of help in further reducing the localized twisting and bending within the crank, as opposed to a 4 weight crank. But if that is of such importance, then I would think it is even more important to either keep the stock piston/rod weights, or modify the counterweights if the piston-rod weights are reduced. The counterweights in an inline engine are sized for balancing against the weights of the crank throws, pistons, and rods, to minimize crank twisting/bending; that is different than for a V engine where the counterweights also serve the primary engine balance function.
 

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Discussion Starter #12
The crankshaft itself is ballanced on its own, and the 8 counterweights should be more stable. That is the thought behind it. We are using lighter H beam conrods and pistons. This is al based on engines which were used in the 90's for Opel Asona B racing class.
 

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Opel Rallier since 1977
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If it worked fine before that is a good sign that you are fine now. And yes the 8 weights make for less internal crank flexing than with 4.

Just be aware that the crank is not only 'balanced on it's own'. It is done that way as a factory-finish and field operation, but you can double or halve the counterwight gram values and the crank will still be balanced on its own. The actual setting of the counterweight gram values is based on minimizing crank flex, and that involves the piston/rod and journal weights.

Not saying you ought to back up and change anything... more just making folks aware. If I was reeeeeally, seriously leaning hard on an inline engine and made the pistons/rods lighter, I would also be thinking of making the counterweights lighter to compenstate.
 

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Discussion Starter #14
Of course, we make sure the rod and piston combinations will be of the same weight. As well as the CR per cilinder. It is new for us, we always used the 4 weights crankshaft before. We want to take this new build a step further with this crank and using the Catcams rocker kit and matching cam to get a higher reving 2.0
 
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