Guest Terry S Posted July 25, 2002 Share Posted July 25, 2002 There has been much discussion on the US MKIV tech list about forged steel cranks so I thought I'd check with the guy who balanced my crank, & hey presto they are! Also the Yanks reckon the rods are too ! This all make me feel much happier, & explains why these cars can take such phenominal amount of power. You can all sleep soundly in your beds tonight;) Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted July 25, 2002 Share Posted July 25, 2002 Terry, did you have anything else done to your crank and rods other than balancing ? i.e. shot-peened or any other treatments. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 25, 2002 Share Posted July 25, 2002 Crank has been bladed, & both the crank & rods have been tuftrided & shot peened. Quote Link to comment Share on other sites More sharing options...
Mark Ayling Posted July 25, 2002 Share Posted July 25, 2002 Originally posted by Terry Saunders Crank has been bladed, & both the crank & rods have been tuftrided & shot peened. mm-hmm, uh-huh - yep, I know exactly what you're talking about Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 25, 2002 Share Posted July 25, 2002 Bladed? That's a new one on me. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 25, 2002 Share Posted July 25, 2002 Further lightening to the crankshaft can be achieved by blading the crankshaft webs. Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted July 25, 2002 Share Posted July 25, 2002 Originally posted by Terry Saunders Further lightening to the crankshaft can be achieved by blading the crankshaft webs. I thought our crankshaft's were already bladed ? Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 25, 2002 Share Posted July 25, 2002 To a fashion. Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 25, 2002 Share Posted July 25, 2002 Hmmmmmm....hmmmmmmmmmm.... So its a material removal process of some kind. I've seen crank webs with streamlined edges to reduce windage losses and oil aeration inside the crankcase but I'm kinda guessing that's not what you are talking about. Can you describe the blading process in more detail? Without wanting to speak out of turn here: Spot peening increases the fatigue life of a material by inducing compressive stress into the surface. The idea being that in order to initiate a crack, any tensile load first has to overcome this compression. A similar principle to pre-stressed concrete in fact. It can also remove machining marks which may otherwise act as tiny stress raisers in billet parts. Peening can be used for one-offs or low volume stuff but the "mass production" alternative for crankshafts is fillet rolling, where the radii between the main bearings, crankpins and crank webs are compressed locally on a dedicated rolling tool, producng the same effect in the material. Tuftriding: I'm guessing that's the same as or similar to nitriding? Its used for for increasing the surface hardness of the steel. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 25, 2002 Share Posted July 25, 2002 Originally posted by Darren Blake Hmmmmmm....hmmmmmmmmmm.... So its a material removal process of some kind. I've seen crank webs with streamlined edges to reduce windage losses and oil aeration inside the crankcase but I'm kinda guessing that's not what you are talking about. Can you describe the blading process in more detail? Without wanting to speak out of turn here: Spot peening increases the fatigue life of a material by inducing compressive stress into the surface. The idea being that in order to initiate a crack, any tensile load first has to overcome this compression. A similar principle to pre-stressed concrete in fact. It can also remove machining marks which may otherwise act as tiny stress raisers in billet parts. Peening can be used for one-offs or low volume stuff but the "mass production" alternative for crankshafts is fillet rolling, where the radii between the main bearings, crankpins and crank webs are compressed locally on a dedicated rolling tool, producng the same effect in the material. Tuftriding: I'm guessing that's the same as or similar to nitriding? Its used for for increasing the surface hardness of the steel. You have the anwers so why ask lol... Blading does exactly what you describe & obviously removes weight from the crank as well. The other two processes are used to strengthen the parts. Quote Link to comment Share on other sites More sharing options...
Guest Nick Harris Posted July 25, 2002 Share Posted July 25, 2002 How did they come to the conclusion that it is not a cast unit and is a forged unit! They look identical to the eye. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 25, 2002 Share Posted July 25, 2002 Originally posted by Nick Harris How did they come to the conclusion that it is not a cast unit and is a forged unit! They look identical to the eye. I assume that it reveals it's difference once machined. Quote Link to comment Share on other sites More sharing options...
Guest Nick Harris Posted July 25, 2002 Share Posted July 25, 2002 In the ''old days you could immerse the crank in oil and accurately measure the displacement then weigh the crank and gain a reading for the mass, however this no longer works as the use of hybrid materials is rife and this is no longer reliable. Machining would use the same cutters and it would be difficult to really be sure. If any car has aforged crank then every company out there would crow about it, does the sales lit say it is forged 'cos if it don't then it ain't. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 25, 2002 Share Posted July 25, 2002 there is sales literature in the States to back this up Nick Quote Link to comment Share on other sites More sharing options...
Guest Nick Harris Posted July 25, 2002 Share Posted July 25, 2002 Is that on MkIV.com? Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 25, 2002 Share Posted July 25, 2002 Not sure, it was mentioned on the US MKIV technical list which is where I picked it up from. Apparently it's common practice for Toyota, Honda & Nissan to install forged cranks that they think it's normal. There is also a US magasine singing te praises of these manufactures for this practice. Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 25, 2002 Share Posted July 25, 2002 The crankshaft section on MKIV.com is pretty scant compared to the other sections. The technical description of the engine mentions the material of just about every other component, but not the crank! The NCF section doesn mention that the pins and journals are induction hardened, and I'm not sure if you can do this with cast iron so it may be a clue. It probably would be possible to tell if it was a forging or casting by eye, but only by looking really closely. I think forged rods are more common than forged cranks but its horses for courses. A high output engine is obviously more likely to have a forged crank, and the I6 is a naturally "bendy" design so it makes sense. Casting will always be the first choice on cost grounds, if it can be made strong enough though. You won't find many engines south of 90bhp per litre with forged crankshafts unless its an unusually skinny design. The pictures on MKIV.com look like its a pretty stout crank, enough to look like it might work as a casting, but there's not enough pictorial evidence to say one way or the other. If someone in the States really has done the research then there's a good bet that it is steel. Quote Link to comment Share on other sites More sharing options...
Purplehaze Posted July 25, 2002 Share Posted July 25, 2002 Here in the US, there is a supra with 900RWHP with stock internals. Quote Link to comment Share on other sites More sharing options...
Guest Nick Harris Posted July 25, 2002 Share Posted July 25, 2002 American horses Quote Link to comment Share on other sites More sharing options...
Syed Shah Posted July 26, 2002 Share Posted July 26, 2002 Originally posted by PurpleHaZe Here in the US, there is a supra with 900RWHP with stock internals. For how long? The dyno run? Quote Link to comment Share on other sites More sharing options...
Purplehaze Posted July 26, 2002 Share Posted July 26, 2002 the guys on Supraforums.com, his name is Jesus. If you look at his sig, he has 904 RWHP on stock internals. Quote Link to comment Share on other sites More sharing options...
Syed Shah Posted July 26, 2002 Share Posted July 26, 2002 I've seen all this, but remember we measure HP in DIN, you measure it SAE, a 20% power difference, meaning hes really running, 720 REAL horses, and as I said, for how long? Quote Link to comment Share on other sites More sharing options...
Purplehaze Posted July 26, 2002 Share Posted July 26, 2002 I have no idea for how long, his car is a weekend car I believe. So, you guys measure HP differently huh ? So, if the M3 in Germany is measured at 333HP its actually more then the 333HP the USA M3 has ? Quote Link to comment Share on other sites More sharing options...
Syed Shah Posted July 26, 2002 Share Posted July 26, 2002 Yep, different measuring standard, which is why our BPU figures are lower vs yours. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted July 26, 2002 Share Posted July 26, 2002 Nick this is a quote from someone on the MKIV Tech list: "Mr. Okuma at GReddy once told me that Toyota and Nissan, in particular, use forged cranks so much, its considered no big deal, more of a standard than an exception. I also recall reading something to similar effect when Sport Compact Car magazine was building an SR20DET motor for one of its project cars; that is, making the same comment about Toyota and Nissan and including Honda in the mix when it came to forged cranks." HTH Quote Link to comment Share on other sites More sharing options...
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