knife edged crank for daily driving

[word]

hey,
i know its been said that its untrue that light weight flywheels will lower torque figures, though it does require more careful driving due to the loss inertia.

since it IS untrue, why is there so much negativity against crank lightening via knife edging?

there are various benefits to lightening the crank, such as less rotating mass, less oil foaming in the oil pan, less resistance from the journals/counter weights going through the thick engine oil.

assuming the crank can be properly balanced after the knife edging, shouldn't it be great for daily driving?

thanks
chris

 

[E_SolSi]

i know a few people that have had it done on various cars .... none have had any problems as of yet

 

[word]

another quick question.....does it affect the integrity of the crank?

doesn't make sense in my head that it would because its not shaving off the stress points, just want to make sure.

 

[E_SolSi]

i dont see how it would

 

[MikeBergy]

Originally posted by word@Jun 10 2004, 09:38 PM
hey,
i know its been said that its untrue that light weight flywheels will lower torque figures, though it does require more careful driving due to the loss inertia.

since it IS untrue, why is there so much negativity against crank lightening via knife edging?

there are various benefits to lightening the crank, such as less rotating mass, less oil foaming in the oil pan, less resistance from the journals/counter weights going through the thick engine oil.

assuming the crank can be properly balanced after the knife edging, shouldn't it be great for daily driving?

thanks
chris

Didn't you ask this question before? Why didn't you just bump the thread you already started? You didn't believe me about the knife-edging thing? Oh well, good luck with your knife-edging. I am only telling you this because I asked my machine shop about doing this for me with my b16a, and they told me knife edging really messes with the internal balance of a motor, and they didn't recommend it for a street driven daily driver. I don't know if they were just referring to four bangers, or if they were talking about all engines in general. V engines are typically smoother motors because of their firing order and geometry, so knife edging might have a little less of an effect, but nevertheless, removing material from the rotating mass of the motor will just accentuate all the vibrations that were previously damped out by the counterweights. But if you want a good solid answer, email RS machines, or endyn, or RLZ, or any good automotive machine or engine builder. They will definitely give you a straight answer. The guys on this forum aren't engine builders, they are guys that know hondas, and have hands on experience dealing with hondaswapping, or aspire to have experience one day. If you want to go to find more advanced tech topics, like the one you are inquiring, go to Rocket Motorsports and read up on some of their work. Lots of engine BUILDERS that will give you more information than you probably need. Sorry for the long reply.
Mike

 

[StyleTEG]

Yeah, knife edging really isn't a good idea unless you are building a full race motor.

You really would need to do it while rebalancing the whole motor, and no matter how you do it there is no way to shave off material with out creating stress points. Which through the vibration of combustion can cause serious problems.

Not to mention stock hondas have a windage tray. The trick was designed for big V8's that had the crank sitting in the oil. Hondas have an oil cloud, but its nothing compaired to the big blocks out there.

If you want to cut down on windage or rotational mass, do it the safe way through the flywheel and using a dry sump system or a crank scraper.

 

[phunky.buddha]

Scraper, not scrapper. I thought you were talking about junking the crank or something there for a second.


I've seen a bunch of people online say that they've knife edged their cranks and been ok on the street, but I personally wouldn't do it for a street car. I've done everything I can to reduce rotating mass in my engine, but I won't knife edge the crank or replace the stock crankshaft pulley / balancer. I don't think it's worth it. I'd rather be a little bit on the safe side with respect to knife edging.

 

[StyleTEG]

Speaking of the pulse dampener,

fluidyne is now selling street dampeners (along with the race ones, only the alternator pulley). Not that much lighter than stock, but it actually dampens the pulses better than the stock pulley.

Easy way to increase engine life, and I hear the engines tend to run smoother since you are not vibrating the hell out of the crank.

 

[phunky.buddha]

Originally posted by StyleTEG+Jun 11 2004, 11:10 AM-->

Speaking of the pulse dampener,

fluidyne is now selling street dampeners (along with the race ones, only the alternator pulley). Not that much lighter than stock, but it actually dampens the pulses better than the stock pulley.

Easy way to increase engine life, and I hear the engines tend to run smoother since you are not vibrating the hell out of the crank.

Good stuff! I still want all my accessory drives though.

Blanco@Jun 11 2004, 11:39 AM
Ok, here's a question along the same lines. How about the IB Spec lightened and polished crank? The site says it's not quite a knife edge.

Those are probably ok.

 

[StyleTEG]

Originally posted by Calesta@Jun 11 2004, 12:57 PM
Good stuff! I still want all my accessory drives though.

It comes with the ac rib and a removable ps rib (so you can keep both, or remove the ps if needed.)

Ok, here's a question along the same lines. How about the IB Spec lightened and polished crank? The site says it's not quite a knife edge.

It depends on where they lightened it. Micropolishing a crank is fine, it doesn't do much for weight but it cuts down on the excessive amount of oil that drapes the crank. The result is less windage and more power. But I wouldn't buy one unless I knew exactly where they took weight from and how.