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Discussion Starter #1
I'm about to do an engine build and was wondering about doing a knife edged crank on the VQ. I've seen DSM guys doing it, but with a motor as big as ours, is it a good idea to have done?
 

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It's been done. I personally see no reason to do it on a street build. Or a build that is going to function within the factory rev range.

Ronin Z
 

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OK well here's some background: The engine will be an N/A application and a nitrous application. So it would be beneficial for a high rev range in N/A form right? I'll have two different rev limiters set (because of the different maps for N/A and nitrous). Would it help at all?
 

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The main idea behind knife-edging is to reduce your windage losses associated with crankcase oil slinging. The loss in HP associated with windage losses tends to be felt more on smaller displacement engines.

To a lesser degree you are also lightening the rotating assembly which allows for a marginally higher RPM threshold. This, of course, assumes that you are using lighter rods and pistons as well.

My biggest beef with knife-edging is that it gives you minimal gains for a host of potential problems (poor mechanical balance, poor harmonic balance, reduced strength). In the vast majority of cases windage trays and/or crank scrapers do the job better and cheaper.

Ronin Z
 

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What is funny to me is every company that provides knife edging services uses the same copy writer apparently. Practically every site uses the same copy....
"In any engine, oil is always draining down into the pan from the top and being sloshed back up from the bottom. When the counterweights on your crank hit the oil, you get loss of power. In addition, you also get loss of power just from spinning the heavy crankshaft around. Knife-edging will reduce power lost from hitting the oil and also takes off several pounds of weight from the crank. You get higher RPM and better reliability."
It seems to be the next "boutique" mod. If your gonna have it done, have a reputable shop do it.
 

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OK thanks for clearing that up for me. What are windage trays and crank scrapers?
My personal advice is to speak with your engine builder about your intended usage and power levels. You should be building an engine that your builder is comfortable with. If he has worked with knife-edged cranks on the VQ, and recommends it for your application , then go for it.

The internet (and forums) have produced a slew of engines that are being built with mods that are unnecessary for their particular power level or usage. Like all the Honda guys who were running around with titanium valve retainers running the stock redline. Guys read up on what race teams and ultra high end tuners are doing and go "I want that too" With little regard for the actual reasoning behind it.

Ronin Z
 
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