as per title what are peoples views on this
as per title what are peoples views on this
A lot of money for questionable / measurable returns. If you are turning large rpm in a wet sump engine with big budget.............buy a dry sump kit and vac. pump first!
Less rotating mass, if balanced right should revv up quicker, for most engines not worth the hassle I guess ?
I always like the idea of less mass, faster rotation, more power, quicker throttle response etc.. But if I take a Honda crank the next day I can only see they fitted a very heavy crankshaft in the S2000 (running 9K standard). They also fitted a much more heavy crankshaft in there "high power" version of the K24 engine compared to the standard (lower powered) K24 version. I once had the chance to open a Toyota (TTE) race engine. Build up with an endless budget and found again ....... a serious heavy, not sporty looking crankshaft.
It makes me wonder all this mass lowering processes do add more power? Maybe opposite is true??? Maybe it's better to have a nice and balanced crankshaft instead of a super light vibrating piece of steel ? Maybe it's better to leave it all alone?
I read of an engine tuner who welded weights onto cranks to make them heavier. Competitors always ridiculed his methods but he claimed that his engines were race winners and that his reason for making cranks heavier was that it helped with torque and throttle response in corners, much like a heavy flywheel.
I would have thought the greatest advantage would be windage as the crank cuts through the air/oil mist. not the weight removal as lighter flywheel would have the same effect ?
The crank needs to well balanced for high revving engines
It has little to do with weight when going for big revs
The weight in the crank will help it hold momentum
Like drag cars with there heavy fly wheels
It won't add power but aid it's delivery in certain circumstances
A lighter one will help revs be achieved quickly
But the revs will return back to idle faster to due to less momentum mass
Which is not the best if you car is heavy
A good jap bike has lighter this and lighter that
And revs very quick but a bikes weight is very little in relation to a car
Hence why they say a bike engine kit car ain't to great unless
It's mega light
Knife edging on its own is a bonus
Add strength by removing potential crack points
Cut the oil = less drag = lower oil temps = less air reation
= better oil return to pan = better oil pressure
As always it really depends on the use
I have lightened/balanced/knifed cranks in my pinto turbo
My cosworth and I even had one in my gsxr 750
Also they almost look to good to hind away inside a engine
all perfect and I add also that it depends on the number of cylinders.
The higher the number of cylinders, the lightest you can go
The closer the gearbox ratios...the stroke of the engine...there are many variables
I don't see really a must to have a knife edged crank.
If I'm right I remember that Dave Walker wrote that he had gain on a Pinto (or was a xflow?) keeping the oil level at minimun and he presumed it was due to less drag on the crank.
I would be very pleased I would own a dyno who can measure the difference in power when you crank is cutting the oil mist or not. I'm willing to understand it is better to "cut" through the oil mist to prevent it from splashing it to the pistons and sending the oil rings more work. But even here I would like to see the difference. More like zero to nothing. Maybe an oil winding plate ? The "cutting" by itself should be not possible to measure.
Anyway, I always try to put my energy and budget in the most "economic" way of making more power. This would not be my first option.
In my opinion it is best to have a crank build up as heavy as needed for best balance. Less stress in the crank and block. If you need less rotating mass, reduce the flywheel.
BUT, I can be totally wrong !!!! I have no prove at all.
Its probably more along the lines of 'it LOOKS like it should work, it does no harm so why not' rather than having empirical evidence to support the theory.
And shining parts sell 👍
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This isn't something I am planning on doing but just wondered what others thoughts were on the subject. I remember a thread where Jason rwd fords said he had tested back to back and crank scrapers, and had shown a increase so wondered if anyone had proof this worked
Thanks for replys
Despite I've never tested myself, I believe more in crank scrapers as knife edging crankshafts. Not because of the knife edge, more about the lost of balance weight. The crank scraper, if it does not help it will not harm. Not the same for the knife edging.
We have had Holbay, Farndon and an early 84mm Millington Diamond twin web cranks in EN40 in our NA Cosworth engines over the years and not one of them was knife edged.
We Rallied an Escort Cosworth GP A Turbo in the mid 2000s fitted with a Mountune spec engine which was fitted with a Std Cosworth crank which was knife edged.
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