monte383sbc Posted February 27, 2008 Report Share Posted February 27, 2008 Well iam building a engine and i was woundering about the knife-edged crank compared to the stock crank, would there be any addvantages for the knife-edge crank like oilling and how about rmp wise or idleing, o ya how much h/p do u think stock crank and rods could hold safely? cuz i dont wana gernade it lol... thanks matt Link to comment Share on other sites More sharing options...
idriftnaked707 Posted February 27, 2008 Report Share Posted February 27, 2008 before i built mine i was thinking about doing the same thing but just like you i didnt know what the advantages were and kept it stock. Link to comment Share on other sites More sharing options...
JustPaus_88TSi Posted February 27, 2008 Report Share Posted February 27, 2008 http://www.starquestclub.com/forums/viewtopic.php?t=43970 I've heard the rods are okay to 550-600rwhp.. I doubt you will hurt the crank. Link to comment Share on other sites More sharing options...
Tim_C. Posted March 13, 2008 Report Share Posted March 13, 2008 There was a reputable StarQuest mechanic in Florida (forgot his ID, but it isn't Shelby I'm talking about) who said there was substantial gain from knife edging. This guy used to be on here all the time, and was one of the original members, but I can't remember his Username? He did it to his, and said he wouldn't build another one without doing it. Link to comment Share on other sites More sharing options...
Edde Posted March 14, 2008 Report Share Posted March 14, 2008 There was a reputable StarQuest mechanic in Florida (forgot his ID, but it isn't Shelby I'm talking about) who said there was substantial gain from knife edging. This guy used to be on here all the time, and was one of the original members, but I can't remember his Username? He did it to his, and said he wouldn't build another one without doing it. Just a wild guess - could have been Ryan aka pumpedtsi. Link to comment Share on other sites More sharing options...
TopDawg_43 Posted March 14, 2008 Report Share Posted March 14, 2008 I run a knife-edged crank. And I LOVE IT!!!! :hmm3grin2orange: My car revs really fast. Between the crank, header (Chads), and my flywheel I have very little (if any) turbo lag. When I turn the boost up, my car will spin the tires while rolling in 3rd gear. The only problem I had was finding a clutch that could hold the torque. The low-end torque goes through the roof! And it spins really smooth at high rpms. Link to comment Share on other sites More sharing options...
TopDawg_43 Posted March 14, 2008 Report Share Posted March 14, 2008 http://www.starquestclub.com/forums/viewtopic.php?t=43970 I've heard the rods are okay to 550-600rwhp.. I doubt you will hurt the crank. I think this is the updated link for the one listed above http://www.starquestclub.com/forum/index.php?showtopic=43970 Link to comment Share on other sites More sharing options...
Tim_C. Posted March 14, 2008 Report Share Posted March 14, 2008 Just a wild guess - could have been Ryan aka pumpedtsi. Yes, that is him! Can't believe I forgot his username! Link to comment Share on other sites More sharing options...
Edde Posted March 14, 2008 Report Share Posted March 14, 2008 Yes, that is him! Can't believe I forgot his username! I remember everything He sure has built enough 2.6's to know! Link to comment Share on other sites More sharing options...
JustPaus_88TSi Posted March 15, 2008 Report Share Posted March 15, 2008 I think this is the updated link for the one listed above http://www.starquestclub.com/forum/index.php?showtopic=43970 Oh crap.. That means that since we just switched to the new forum layout, we lost every single link that's been posted in threads for the last six years.. :character0269: Link to comment Share on other sites More sharing options...
TurboRaider Posted March 15, 2008 Report Share Posted March 15, 2008 How about putting some numbers to this MOD? Say you take 7 lbs off the crank and the effective distance from the axis of rotation is 5". 7 lbs = 3.2 kg 5" = .127 meters The moment of inertia of the weight removed is 3.2kg*(.127m^2) = 0.051 kg-m^2 Assuming 500 RPM per second engine acceleration: (kg-m^2/sec^2) = .051 kg-m^2 * 52.4 rad/sec^2 = 2.7 N-m or 2 lbs-ft of torque Ths is how much torque the mass would have taken away from accelrating the car if your changing the RPM at 500 RPM second. To put a HP # to that figure at 5000 RPM it would be: 2(5000/5252) = 1.98 hp Since you are sweeping an RPM range to get the effective HP you need to do some calculus since you would need to figure out the area under the curve of the RPM range you use when accelerating. Also remember when reving in neutral the RPM's per second are a lot higher so the effect of the reduced mass is a lot more noticable. In that case it may be more like a 5X differance that what I calculated. However most races are done in gear (even on a Honda) so the 2 hp figure is a bit more realistic of the improvment you will see when you are racing. :lightingzapA: Let me know if I messed up on my estimates of weight removed that the distance from the crank centerline so I can update my calculations. 5" seemed to be the average distance of the material removed and 7 lbs seemed to be a decent number as well. If I can get my hands on the moment of inertia of the ballance shafts it would be interesting to do the same calculations. Kevin C Link to comment Share on other sites More sharing options...
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