Knife edgeing crank?

[yogurtslinger]

Hey gents, I am about to rebuild my bottom end and have to decided to go with a 2.2 crank cause it seems to rev a bit quicker than my 2.5. Now, I've *heard* that some of the rice boys out there are "knife edgeing" their cranks to make em quicker revving. Has anyone done this to a TD or is this even possible or worth the effort..
Thanks
Bryan

[glhsken]

Minimal gains.. better off to get a crank scraper... I did...

[BuRn__]

what is knife edging n e ways?

[Mike Radowski]

it is the reshaping of a crankshaft's leading edges to eliminate aeration of the engine oil

[glhsken]

The motor loses HP due to oil "hanging" in the path the crank has to turn. The crank has to fight its way through the oil. Knife edging reduces the turbulance which causes the aeration. Reducing the amount of oil the crank has to "puch" out of the way.

A crank scraper does just that... The oil that is TRYING to fly up hits the scraper and is directionally sent back to the pan. Again, reducing the oil the motor must fight through.

Hope this helps understand the process.

I did a LOT of work to the crank in my 2.5 a couple years back. Mainly because I was working at a machine shop and had access to the equipment, wanted to see what it would do. Honestly, I'd go with the crank scraper for a results vs. investment comparison. Knife edging gets expensive in a hurry... since you have to balance the crank afterwards, it's nice having a well balanced crank!
Oh yeah, 2.5's can rev rather quickly with the bottom end lightened...

Andy

[glhs636]

Andy,
How about gun drilling the crank?
Alot of people claim the forged cranks are overkill for our engines
I was wondering if a forged crank was strong enough to gun drill to reduce the weight a little a still retain a beefy crank?

If so was the center of crank drilled and/or the rod journals?

[glhsken]

You're gonna need all the help you can get "Top Fuel" BWAHAHAHAHA


Ve Hav Planz.....

[glhs636]

Quote:

Originally posted by glhsken You're gonna need all the help you can get "Top Fuel" BWAHAHAHAHA Ve Hav Planz.....

JUST YOU WAIT
You guys keep forgetting I haven't really used 2nd gear yet because of TRACTION issues and that I had to turn the boost down to 19-20 PSI

What are going to do when I start turning the boost back up

I do envy your mostly stock GLHS
to look that nice and put down those numbers in streetable trim (minus slicks) is outright awesome "thumbs up

[glhsken]

AWWW schucks.... You make it tough to give you crap ... Thanks for the kind words...

I didn't play much with gun drilling (saw it done on a couple of SB Chevy 350->383 stoker conversions though) so I really can't offer much advice there. What I did do whas grind almost 5lbs out of the 2.5 crank, then go back and knife edge each counterweight. Add that to the 8.3# aluminum flywheel I used and you talk about one FAST revving 2.5! I also balanced the bottom end well enough that it sang all the way to 8500rpm easily (twice, both times it was due to my 555 2nd gear woes). VERY smooth, I spent weeks doing bottom end balance work.....

Andy

[cj011]

alabama man, where was your power band and how much boost were you running? i have a 2.2 but i am really trying to decide to go with the 2.2 with longer rods swinging 2.5 pistons, or to just drop in a 2.5 crank, rods, pistons. i am afraid that the 2.5 will only destroy the tires and will have no pull above 100.