johnd-mkiv Posted February 12, 2007 Share Posted February 12, 2007 I have been speaking to a few people about having this done some saying its worth doing others saying it will give little gains, just wondering what your experiences and knowledge on this would be. worth doing or not? Quote Link to comment Share on other sites More sharing options...
Al Massey Posted February 12, 2007 Share Posted February 12, 2007 another blonde moment! what do you mean? Quote Link to comment Share on other sites More sharing options...
johnd-mkiv Posted February 12, 2007 Author Share Posted February 12, 2007 http://www.importperformanceparts.net/imports/knife_edging.html Quote Link to comment Share on other sites More sharing options...
Al Massey Posted February 12, 2007 Share Posted February 12, 2007 cheers in the know now Quote Link to comment Share on other sites More sharing options...
uk-rich Posted February 12, 2007 Share Posted February 12, 2007 i had this done during the re-build, seems a worthwhile mod Quote Link to comment Share on other sites More sharing options...
SUPRASUZUKI Posted February 12, 2007 Share Posted February 12, 2007 If your cranks out, why not? Gains are probably minimal but it's directionally correct. Not sure if this is true for Supra engines, but generally speaking. Quote Link to comment Share on other sites More sharing options...
johnd-mkiv Posted February 12, 2007 Author Share Posted February 12, 2007 If your cranks out, why not? Gains are probably minimal but it's directionally correct. Not sure if this is true for Supra engines, but generally speaking. The £380+vat bill that comes with it, if its not worth doing ill spend it else where. The crank will be balenced either way Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 12, 2007 Share Posted February 12, 2007 I wouldn't even consider it. It's strictly race engine only, and getting it done properly can be tricky. Far FAR better places to spend your money. If you have a spare 400 plus to spend put it towards a steel crank rather than messing with the stock one, IMO. Quote Link to comment Share on other sites More sharing options...
SUPRASUZUKI Posted February 12, 2007 Share Posted February 12, 2007 The £380+vat bill that comes with it, if its not worth doing ill spend it else where. The crank will be balenced either way Cheapskate:d Quote Link to comment Share on other sites More sharing options...
johnd-mkiv Posted February 12, 2007 Author Share Posted February 12, 2007 I wouldn't even consider it. It's strictly race engine only, and getting it done properly can be tricky. Far FAR better places to spend your money. If you have a spare 400 plus to spend put it towards a steel crank rather than messing with the stock one, IMO. Cheers chris;) Quote Link to comment Share on other sites More sharing options...
johnd-mkiv Posted February 12, 2007 Author Share Posted February 12, 2007 Cheapskate:d Quote Link to comment Share on other sites More sharing options...
SUPRASUZUKI Posted February 12, 2007 Share Posted February 12, 2007 You'll miss that 2-3bhp y'know;) Quote Link to comment Share on other sites More sharing options...
Digsy Posted February 13, 2007 Share Posted February 13, 2007 In any engine, oil is always draining down into the pan from the top and being sloshed back up from the bottom. When the counterweights on your crank hit the oil, you get loss of power. In addition, you also get loss of power just from spinning the heavy crankshaft around. Knife-edging will reduce power lost from hitting the oil and also takes off several pounds of weight from the crank. You get higher RPM and better reliability. The first bit about the crankshaft hitting oil particles in the crankcae is correct. Knife-edgeing (or "blading") the crank can have a measurable effect in reducing parasitic losses from this (known as "windage losses"). I'm not so sure about the power loss from just spinning a heavty crankshaft around. Because the material removed will be at the extremes of the crankshaft counterbelence weights, there will be a measurable reduction in inertia, so the engine should accelerate a little bit faster. I think its debatable whether this would be noticable, especially if you still had a stock flywheel hanging off the back. % wise the inertia reduction for the entire cranktrain would be pretty small. As for higher RPM and better reliability, you might get a slightly higher RPM, but beter reliability you definately won't. Taking mass off your crank will reduce the in-bay primary balance and affect your oil film thicknesses. Its usually hard enough getting sufficient mass into a crank counterbalance that there is unlikely to be excess material there that can be removed willy-nilly. Quote Link to comment Share on other sites More sharing options...
SUPRASUZUKI Posted February 13, 2007 Share Posted February 13, 2007 I believe the GSXR1000 uses a knife edged crank as standard, so they're making their way into 'road' engines aimed at high performance. I know this is detracting from the decision (mechanical or financial) for the Supra engines, but just adding to the discussion. Quote Link to comment Share on other sites More sharing options...
Digsy Posted February 13, 2007 Share Posted February 13, 2007 The GM L850 2.2 and 2.0 litre engine series all have knife edged cranks, so its on "cooking" engines, too. Don't get me wrong - its a really neat feature if its designed in from the word go, but it can be difficult and the benefits are marginal so a lot of OEMs don't bother. Quote Link to comment Share on other sites More sharing options...
paul mac Posted February 13, 2007 Share Posted February 13, 2007 my perception of knife edging a crank was purely for a very high power engine in an effort to wring every last hp from it in conjunction with a zillion other mods, would look good on your engine spec in your "garage" though;) Quote Link to comment Share on other sites More sharing options...
Terminator Posted February 14, 2007 Share Posted February 14, 2007 Don't most of the mental power guys in the US use stock cranks. If so it does not seem to slow them down . In my VWR race engine good for (USA) 1000RWHP the crank is the only stock moving part. Given what has been said, if the engine is in bits anyway, you may see very small gains, however the same money spent on turbo mods may see higher gains. Given the choice I wouid go for turbo modifications. Quote Link to comment Share on other sites More sharing options...
johnd-mkiv Posted February 14, 2007 Author Share Posted February 14, 2007 Thanks for all your help people, I think im going to pass as im not after massive power (yet ) I dont think ill benefit from it Quote Link to comment Share on other sites More sharing options...
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