Crank scraper

[Don W.]

Anybody ever use a crank scraper on our engines? I know Renz mentioned it awhile back, little seemed to come of it.

Thoughts?

 

[MikeRenz]

Re: Crank scraper

chris keith had purchased one and I took a look at it - i forget where he bought it from but it was well worth the $120ish that i think he paid for it.

I don't have any intention on making these anytime soon (little market...and there is an affordable out there already)

 

[bezerk]

Re: Crank scraper

so what does it do for $120?

 

[Chest Rockwell]

Re: Crank scraper

Scraped excess oil off the crank as it spins. Less reciprocating weight=more power.

 

[Z SKI]

Re: Crank scraper

I think it's oil control and windage. Especially windage. Not spinning the crank through the oil mist is what makes the power.

Engines that utilize these usually have perfectly smooth crankshaft surfaces, Helps with the windage deal. Smooth surfaces don't carry a 'boundary layer' of air with them. The rougher the surface, the thicker the boundary layer of air thats moving along with the crank. The scraper will encounter this boundary layer, and cause drag, as well as pulling the oil off the crank causes drag. Both power losses.

I think if gains are to be had, they're in an engine that revs very high, and the windage losses are great, has a dry sump oil system with restricted oil galleries to keep oil from raining on the crank, and has a shallow-sump (road racing). It will also have a crankshaft with perfectly smooth counterweight surfaces. None of these are SyTy attributes. I can see where a scraper in a SyTy engine could actually be detrimental, until a certain RPM is achieved, and the 'gain' (less windage) finally off-sets the 'loss' (parasitic drag). That "certain RPM" is probably pretty high.

:2cents:
Dave

Damn Dave your a smart dude :tup: Speaking of that I need to give you a call. Now im being Polish as I type out what I am thinking:rotf:
See ya,

 

[It's just a six]

Re: Crank scraper

Here is a Co. that makes scrapers with teflon rub strips that self clearance for maximum scrapage.

http://www.crank-scrapers.com/products.html

I had them make me one for my inline Chevy 250 6,very nice work!

 

[Don W.]

Re: Crank scraper

Here is a Co. that makes scrapers with teflon rub strips that self clearance for maximum scrapage.

http://www.crank-scrapers.com/products.html

I had them make me one for my inline Chevy 250 6,very nice work!

Yup, that's the guy. Mine is coming. It will become part of my build pics when everything starts going together.

 

[Mtn Z]

Re: Crank scraper

Damn Dave your a smart dude :tup: Speaking of that I need to give you a call. Now im being Polish as I type out what I am thinking:rotf:
See ya,

That was awfully Polish of you wasn't it? As soon as you call me back, you'll be all set.