Oh great tech gurus,

I'd like some suggestions for a good reputable shop to knife edge my Lunati crank. One on the E Coast would be aces, so I don't have to ship halfway to Timbuk 3.
And any discussion about knife edging is OK, too. Can't get enough tech.

So which project is this for, Unstablous Maximus?

Originally posted by kmook

So which project is this for, Unstablous Maximus?

unstable bob sez:

There is only one project for me, Mookie baby. Starts with "D," ends with "N," and has "OMINIO" in da middle.

Yeah, what's the poop? Dominion head engine?

Tests I read about showed 4 hp gain at 7500 on a Chrysler engine. Knife edging the leading edge toward the main bearing caps may aerate the oil less than angling it the other way. A full radius on the leading edge seems to do about the same thing as knife edging. Leaving the trailing edge flat or square seems to shed oil easier.

How about buying one already done? You are going to rebalance anyway, and probably need some(?) heavy metal. Lunati Pro series seem to already have knife-edging angled the "right" way.

Perhaps just radiusing the front and coating the crank with an oil-shedding coating would be the plan. Less heavy metal.

No comment on not using Left Coast shops. Lunati is in Memphis, right?

Is not "Wastelands of NJ" redundant?
Sorry, some of my best friends live in NJ...but I wouldn't want my daughter to...etc.

I once knife edged a crank. Took the better part of a couple of days with a grinder and then it needed to be rebalanced! I have no idea how much hp (if any) it's worth. I probably did it the wrong way anyway, I had no idea of exactly what I was doing, it just seemed like a "cool' idea. I also messed with the trailing edge, which from what the Old Stroker says was a bad idea.

Rich Krause

I have a different view of Knife edging. I think it should just be referred to as streamlining. The common misconception is that you want the knife edging on the leading edge of the crank. This is not the way it should be done. Look at an airplane wing sometime. It resembles a teardrop shape but the leading edge is a large radius terminating in a sharp edge on the trailing end. If your going to try some windage reduction with your crank then this is the way you should do it. You can even do it your self and then just have it balanced. Since the labor can be done on your own time and you usually need to have your crank balanced when building an engine then you really arent loosing anything but your labor time. Use a grinder and take your time and be conservative. Mask off all the journals and slowly work back and forth on the counterweights until you have a nice radius on the leading edge and the the trailing edge is more knife edged. Just dont get carried away.

Originally posted by OldSStroker

Yeah, what's the poop? Dominion head engine?

Yessir, I have most of the parts to build/rebuild a 396 LT1/Dominion combo. I was hot stuff around here a few years back when I bough the stuff.

Tests I read about showed 4 hp gain at 7500 on a Chrysler engine. Knife edging the leading edge toward the main bearing caps may aerate the oil less than angling it the other way. A full radius on the leading edge seems to do about the same thing as knife edging. Leaving the trailing edge flat or square seems to shed oil easier.

How about buying one already done? You are going to rebalance anyway, and probably need some(?) heavy metal. Lunati Pro series seem to already have knife-edging angled the "right" way.

I'd really rather use what I have, as getting the crank done/balanced will be cheaper than getting pennies on the $ selling my old crank and starting over.

Perhaps just radiusing the front and coating the crank with an oil-shedding coating would be the plan. Less heavy metal.

No comment on not using Left Coast shops. Lunati is in Memphis, right?

I'm not against using shops out West, I just like options closer to home. If you have any suggestions about West Coast shops I am def. all ears.

Is not "Wastelands of NJ" redundant?
Sorry, some of my best friends live in NJ...but I wouldn't want my daughter to...etc.

Old Man,
Out of respect for your advanced age, and engine building skills, I will look the other way about your cracking wise about my home state. Do not fear if a late model Caddy with NJ plates pulls up in front of your shop real soon. It will just be a few of my associates looking to "pick your brain" about engine tech.
And if the truth must be known, I deal with so many NY and Pa scabs coming over here stealing jobs from NJ residents that I sometimes forget I'm in Jersey. Nothing like being surrounded by a bunch of NY and Pa goons when I'm trying to get somewhere.

And gentlemen, thank you for the good theory/ideas. And to the gentleman whom suggested that I attempt to streamline my crank myself, I am both honored and humbled that you have that much faith in my abilities. But I would liken any attempts by myself to perform such a procedure to the old cartoon gag where one whole tree is fed into a machine, and then whittled down into one toothpick...

Unstable one, you might consider picking up an old crank to practice on before getting that Lunati crnak anywhere near a grinder

Well im glad to see that your moving foward with the Doms, at whatever pace it may be.

Oh and Jon, you may want to look into some help, maybe the services of Vito... since UB's boys might be stopping by

Originally posted by AdioSS

Unstable one, you might consider picking up an old crank to practice on before getting that Lunati crnak anywhere near a grinder

unstable bob sez:

Yessir, that is a good idea. Especially since the u b motto is:

"Measure 30 times, cut it once, and still screw it up. Get pizzed, smash stuff, throw stuff in garbage, and abort project."

Originally posted by kmook

Well im glad to see that your moving foward with the Doms, at whatever pace it may be.

Oh and Jon, you may want to look into some help, maybe the services of Vito... since UB's boys might be stopping by

ub sez:

Yeah, Mookie. Spend a dolla here, a dolla, there. Maybe even spend a dolla on some new underwear.

And Mr B has nothing to fear from me and my boys. As I stated above, it would only be a social call. But then again, Mr B and his equally impressive engine building son have an engine entered in the Engine Masters program. And it turns out that a couple of my associates have an Oldsmobile engine entered in the same program. Hmmmm, and there can only be one winner, right?
Ma-doan! Life can be so complicated at times...and UGLY, too.

If you get mad enough, throw lots of newspaper and cardboard in the trash, then lightly place the Dominions in there and give me a call so I can pick your trash up for ya

interesting....
Just dont do a good enough job that you turn it into an actual air foil. I have a feeling your thrust bearing wouln't like that.

Some different thoughts on this, Dan:

The air/oil mixture in the crankcase isn't a homogeneous mix like a fog, but rather more like a couple handfulls of wet spaghetti, which is the oil, flailing around and wrapping itself around everything. We're really not driving the crank thru air like an airplane wing. My guess is that the high surface tension of oil promotes this behavior.

We're not talking very high airspeeds here: The outside edge of a counterweight at 7500 rpm is going about 150 mph. The squared off trailing edge, like the rear of a C5 Vette is very similar in drag to a very long taper trailing edge. We're not trying to create lift, we're trying to get the crank thru the air/oil mix with the minimum amount of drag and (perhaps more importantly) shed oil.

Not saying a trailing edge taper won't work, but to keep the drag down below a flat or "Kamm-back" trailing edge, the taper might have to be gradual, like an airfoil section.

Crank scrapers can strip a great deal of the oil off the counterweights, especially if most of them are the same thickness after you get past the leading edge. IMO, the tapered trailing edge would promote more laminar flow making the oil cling, and because of the taper, the scraper wouldn't get the oil off.

Hey, if we're talking only a few hp, spending the money on scrapers, windage trays and lots of vacuum, if allowed, is probably more bang for the buck/hours. I do like the full radius leading edge as you mentioned.

My highly-opinionated $.02.