Hey people Im getting things ready for a nice hi reving L 16 motor and Im looking for some advice on knife edging the crank. So do I or dont I and what are the pros and cons? Thanx guys

DO IT! I think its only of use in a motor that is to maintain highe revs, and to 'cut' through the oil in the sump

Thanx man then its a go for that seems like it may end up a nasty little motor after all

If you do do it, there's two schools of thought, some knife edge it front and back, others round off the leading edge and knife the tail section - sort of like a plane wing, in the direction of rotation, the idea being it cuts through the air better. On the other hand there's fluid involved (i.e. the oil dripping down and frothing about) not just air. You also have to be careful - as you can get to the point where you don't leave enough counterweight weight to adequately balance things out.

As much of a diy fan as I am, I think this is an option best professionally handled.

The question is - how much will it improve things - in all likelihood bugger all. It won't have a 'drawback' and the throttle response and first gear response will be improved, but by the time you are in higher gears, the weight of the crank is practically meaningless as far as acceleration goes. It can assist in oil control, and indeed help a borderline crank hold together at a higher rpm safely, but I'd add in that the datsun engines are (imho) very solid and don't need a hell of a lot of work to hold together at high rpms.

Last tid bit - this is purely my own idiosynchrasies, but if I was going this route, and modding the crank like that, I'd look into a fluid damper for the front pulley. I have no idea if there is any commercially made option, but what has been done on other engines is to get a custom front solid hub machined up, and bolting on a fluid dampener off something else (either a race made piece, or possibly one off certain trucks, but you have to be careful as whilt they 'work' at all rpms being a fluid medium, they might not be suited (as in they might come apart) to sustained high rpm, if coming off a lower revving engine.

This sort of thing has been done, for example, on hemi 6 cylinders locally, which have a harmonic issue with teh crank at around 6100rpm, and have to be kept either side of it (or at least not held near it) for max longevity. I can probably find pics of the hubs/adapter and finished pieces for them.

The fluid dampener might not improve power or throttle response, but it _will_ help keep a lightened crank together at higher rpm.

Repeat: If you knife edge the crank, it will require rebalancing. All Datsun cranks are balanced at the factory.

Wow thanx for that input. As for your concerns it will be done by a pro in this field after my 1st post regarding this topic I got hold af a guy that has around 30 years experiance in doing knife edging for race motors. As for balancing to me thats standard practice if the motor is modified or not. In all aspects they just tend to rev up a bit better and most important last longer! As for the fluid damper we had one made up for a 450 hp chevy powerd ac cobra me and my old man built a few years ago. I forgot about that so jmac thanx for the reminder. Ill keep you posted as I start with everything. Thanx again

So where does a crank scraper and windage tray fit into all this- and what difference if any would that make and should they go hand in hand with a knife edged crank?
Cheers
Dave

Good question Dave, here is SA I dont even know of any place that sell those crank scrapers. So I would also like to know.

B110sss, a winged sump is puerly for a larger copacity of oil witch has multipul benifits.

and scrapers are for runing a dry sump set up and coach the oil taward the pick up.

Hi Conner,
I think that you have misunderstood my question.
I'm sure that crank scraper technology is used on non dry sumped engines and the windage tray helps to keep the oil that is agitated up by the revolving mass of the crank down in the sump but what I am trying to ascertain is what, if any benefits are gained by running these?
I have I link that I have sitting on my computer at work of a business in the States that makes these and they are not too dear ( $150 odd USD )but do they work and make an appreciable difference and would you really need to combine with a knife edged crank to gain the most benefit or are they a much cheaper option of effectively doing a similar job? - JMAC can you throw some light on this??
Cheers
Dave