Xnke Posted December 11, 2012 Author Share Posted December 11, 2012 Belt orbiting is the effect that ALL belts have, it's kinda like how pizza dough gets flung up in the air spinning and stretches out into a circle. The belt is "flung" outwards, away from the belt path, which lessens the belt wrap around all the pulleys. Quote Link to comment Share on other sites More sharing options...
luseboy Posted December 11, 2012 Share Posted December 11, 2012 Reasoning behind not grosely over-sizing belt would be the already discussed problem of room in the bay. Would require shifting the engine back, right? Perhaps cost (not sure how much that'd cost), availability of belts/pulleys, and tensioning problems. All things that can be addressed but not very easily. Also I'd worry about wear on the crank from leverage on the end of the pulley. Quote Link to comment Share on other sites More sharing options...
Xnke Posted December 11, 2012 Author Share Posted December 11, 2012 The reason *I* am not using a wider belt is that I don't need one, all the pulleys I can find for this supercharger are 6-rib, and in my setup, the belt would interfere with the fan if I went wider. It already interferes with the fan, but it's a fixable amount. Quote Link to comment Share on other sites More sharing options...
Snailed Posted December 11, 2012 Share Posted December 11, 2012 Belt orbiting is the effect that ALL belts have, it's kinda like how pizza dough gets flung up in the air spinning and stretches out into a circle. The belt is "flung" outwards, away from the belt path, which lessens the belt wrap around all the pulleys. Oh, I misunderstood what you were saying. I thought it was an oscilation set up by the non-linear resistance of the supercharger. That does make sense though, I'm surprised that it's an issue at the fairly low mass of the belts and the high tension but clearly it is. Interesting stuff. Quote Link to comment Share on other sites More sharing options...
Xnke Posted December 14, 2012 Author Share Posted December 14, 2012 Think about the belt velocity, too. on a 6.25" diameter drive pulley, at 5000RPM, the belt is moving at a speed of 8180 linear feet per minute! This is with no belt slip at all...11452 feet per minute is the speed at 7000RPM. That's ridiculously fast...2.1 miles per minute...129 miles per hour! At 129 miles per hour, I think you'd be stretched pretty good too. (to calculate belt speed, 6.25"*pi=19.634" circumference...19.634/12=1.636 feet per rotation...1.636*7000=11452 feet per minute...11452/5280 feet per mile=2.1 miles per minute...2.1*60 minutes= 129 miles per hour) Quote Link to comment Share on other sites More sharing options...
Snailed Posted December 15, 2012 Share Posted December 15, 2012 Wow, yeah, that's pretty fast. That's on a pretty small crank pulley too. So you need to try and reduce the long runs between pulleys and use enough wrap to counteract the forces of belt orbit? In the case of timing belts (much slower belt speed per rpm) do you think it's possible for the belt to be effectively shortened on the tension side and dynamically change cam to crank timing? I always wondered if the aftermarket timing belt idlers were necessary even on 9-10k rpm engines. Quote Link to comment Share on other sites More sharing options...
Xnke Posted December 17, 2012 Author Share Posted December 17, 2012 The belt speed depends on the driving pulley's circumference, and the RPM. Belt orbiting is a lesser problem for thick belts, such as V-belts, than it is for flat belts, such as poly-v, flat, or cogged (timing) belts. To combat belt orbiting, you would ideally have idlers or driven pulleys on alternate sides of the belt, such that the belt would wrap over the driven pulley, then over the idler on the backside of the belt mid-span, then over the drive pulley, and under an idler, again on the backside of the belt mid-span, then over the driven again. This way, the belt does not bend the same direction twice consecutively, and belt orbiting is better controlled. Quote Link to comment Share on other sites More sharing options...
Xnke Posted January 5, 2013 Author Share Posted January 5, 2013 WHOOO! The cam specified for the supercharger application from Isky will be mailed out monday morning. Hopefully a bunch of welding supplies will be here by then and I can complete the intake manifold soon; so I can fix the exhaust leak on the header and get a properly muffled exhaust in place. This time I have access to a 4-post lift to do exhaust fitting. Things will be slowing down soon, though, my day job is getting iffy. *Most* of the parts are made; and I need to make sure to hold enough cash back when I get paid again to grab another set of companion flanges from Cockerstar; I might have to make a new set of axel adaptors to get rid of a vibration in the rear of the car at 70MPH. Quote Link to comment Share on other sites More sharing options...
Xnke Posted January 22, 2013 Author Share Posted January 22, 2013 Hangin' in there...too cold to get any real work done in the shop lately. Have a lot of the details worked out on the intake manifold, getting that side project finished up now. Back to radiator clearance, I've settled on the MkIII Supra radiator for the 7M-GE, as it is *very* close to fitting between the frame rails and is half as thick as the old copper core Datsun unit. It should cool the engine effectively, but the only sticking point is the width...it's a VERY close call as to whether I'll be able to slide it between the frame rails or not. 25 5/8" wide at the widest point of the lower tank, states the manufacturer, but we'll see when it gets here. I may have to notch the front frame rails to accept the lower tank crimp, as this is an aluminum radiator with plastic tanks. If it really just won't fit, well, I'll cut the tanks off and weld on aluminum tanks. That's a last-resort type option, though. Quote Link to comment Share on other sites More sharing options...
Xnke Posted January 30, 2013 Author Share Posted January 30, 2013 Little progress has been made lately; Mostly on the intake manifold. Finishing up the fuel rail mounting points and finish-machining the rail itself, fitting a few small vacuum ports, and the throttle linkage are what's left on the manifold; but then there is still the wiring harness to build, radiator to fit up, and the crank damper has to be sent off for rebuilding. That list above will get the super installed and drawing filtered air from the engine bay...Not the final product. In the end, I want the super to draw filtered, cool, high-pressure air from either a factory-style hood vent in the factory 77-78 location, or the cowl area. If a pre-filter screen is fitted then drawing cool air from the wheel well is also an acceptable option. Even after all that; the car would be drivable with the super...as long as I kept civil with it! The currently installed transmission sounds worse every day, whining and carrying on. The clutch currently fitted is a 225mm OE unit, and does a fine job as it sits; however I will install a lightweight chrome-moly flywheel and a 250mm full-disk organic clutch, instead of a 225mm copper-ceramic puck clutch that won't last as long and won't have as nice of street manners. Yes, copper-ceramic clutches can be street-driven, I've driven one a few times and had little trouble out of it, but it simply isn't necessary at the expected torque levels. (I am expecting 275ft-lbs average, we'll see when it gets assembled!) An OEM-style organic disk, coupled with the larger diameter plus higher clamping force of the intended pressure plate, should yield OE-style clutch life, disk engagement, and pedal feel. A 240mm ZX turbo clutch would likely do the job, but I would rather only install one clutch, and just the extra 10mm of disk diameter brings with it approximately 20% more torque capacity. I'd hate to install the ZXT clutch, then once the tuning is done be hamstrung with a slipping clutch. Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 6, 2013 Share Posted March 6, 2013 (edited) I knew I could find this if I looked hard enough. Setup sent the car sideways at will... In 1997. I forget who it was, but someone flamed me because they were "doing something nobody has done before" ( Centrifugal SC on L28) and was not enamoured itch my "it's been done"... They wanted proof. Here it is! Car would break pulleys at the key way. Use a double key, and thick hardened washer with proper bolt TIGHTENED PROPERLY and with Loctite 608 Cylindrical Parts Locker on the shaft, with 242 Blue n the bolt. Looseness on the drive pulley will kill it. Edited March 6, 2013 by Tony D Quote Link to comment Share on other sites More sharing options...
Xnke Posted March 6, 2013 Author Share Posted March 6, 2013 Awesome! I have a KA crank bolt on order, with a proper thick washer machined and hardened to RC38-40 from 1045 to match. I think the double-keyway would weaken the damper more than it would help, given that the damper doesn't have all that much wall thickness to begin with. As we've said in the past, any time you rely on the keyway to lock the damper in place, it's going to fail...proper clamping force should be what retains the damper. I'm thinking along the lines you are...Loctite 608 to fix the damper in place, increased thread engagement from the longer KA bolt, and higher clamping force from the thicker, stronger washer that doesn't flex combined with a nominal increase in tightening torque. Also, I've been reading about the oil slinger causing a loose damper condition, have you had that issue Tony? Supposedly the oil slinger frets on the pulley, disintegrating and suddenly causing a loose damper condition. I'm still running one, as I've not had any issues out of it yet. I'm thinking when the damper gets swapped out, I'll pluck it out of there if it is showing any kind of wear at all. Quote Link to comment Share on other sites More sharing options...
Rob240z Posted March 6, 2013 Share Posted March 6, 2013 (edited) I've never seen that one before Tony. Thanks! I'm building a centrifugally supercharged L-engine now and I've done lots of research. There isn't much out there. Xnke build is the best I have seen by far for documenting any supercharger build. Thanks Xnke! I'm mounting my supercharger in the same location as the one in your picture Tony. I have only seen one other L-engine with a centrifugal supercharger. It mounted it where the air pump is stock. It was a race car for sale on this forum in December 2010. It was carbureted too. Members name is teamz. Here is the link: http://forums.hybridz.org/index.php/topic/96891-73-240z-track-car-supercahrged-g-force-t5/ Quoted from his for sale ad. Looks like a sweet car. I wonder where the car is now and if it ever sold? This is my one owner 73 240Z track day car. It is in "as raced condition". The last time it was on the track was Oct 09 and has had nothing done to it since then. the body is good but has some repairs done. The drivetrain is sound but not freshened so should be looked at. The car is well sorted and very fast on good tires with a good driver. I am located in southern Wisconsin. Asking $15000.More pic's are available. PM or email dave@klondikecheese.com. 2010.11.10 73 Datsun Procharger 2.JPG 2010.11.10 73 Datsun Engine Bay 2.JPGENGINEProfessionally built L28 motorF54 Block 88 mm boreEagle H beam rodsJE custom pistons 10:1Arizona Z Car oil panCanton 2 qt Accusump w/electric valveN42 head professionally portedSchneider custom ground camREV valvesIsky valve springs and keepersProcharger C1 supercharger - 18 lb boostExtra supercharger pulley for 12 lb boostATI Super BalancerAZ Car 4 brl intake manifold modified to single planeHolly 390 cfm HP carb professionally built and modified for boost applicationAZ Car intercoolerMSA 6/1 header3" exhaust w/Brzezinski race mufflerAZ Car radiatorFlexalite dual electric fanMSD 6AL ignitionMSD Blaster SS coil 2010.11.10 73 Datsun Fuel Pump.JPGFUEL SYSTEMSummit 10 gal aluminum fuel cellAeromotive A300 fuel pumpAeromotive 13301 regulator w/boost referenceDual fuel filters 2010.11.10 73 Datsun Front Underside 2.JPG 2010.11.10 73 Datsun LR Suspension detail 1.JPGDRIVE TRAING Force T-5 transmission spur gear dog ring 2.94 ratio with .9 overdrivePro 5.0 shifterQuartermaster 8 1/2" rally clutchQuartermaster button flywheel w/Datsun flexplateAluminum driveshaftR200 3.90 CLSD differential with upgraded clutch packs280Z stub axlesModern Motorsport CV axle adapters300 ZXT CV axles with custom length axle shaftsCCW 17" X 9" wheels w/Hancook Z214 275/40 C-50 tires 2010.11.10 73 Datsun LF Suspension 1.JPGBRAKES AND SUSPENSIONAZ Car 4 lug Wilwood big brake kit front and rearUpgraded Wilwood GT 48 front rotorsWilwood dual master cylinder brake and clutch pedals w/balance barWilwood brake balance bar adjusterAZ Car lower control arms front and rearAZ Car coil overs w/camber platesBump steer spacers 2010.11.10 73 Datsun Interior 1.JPG 2010.11.10 73 Datsun Interior 4.JPGINTERIOR AND SAFETY8 point roll cageUltrashield Pro Road Race seatG Force 5 point harnessFirecharger on board fire extinguisher systemPainless 8 circuit race car harness P/N 50001Autometer tachometerAutometer and Accutech gauges 2010.11.09 73 Datsun L Side 1.JPG 2010.11.09 73 Datsun Front.JPGEXTERIORXenon front air dam with functioning brake ductsBRE style rear spoilerZG fender flaresLexan rear windowMSA headlight covers 2010.11.09 73 Datsun Rear.JPG*Slight right rear bumper damage Edited March 6, 2013 by Rob240z Quote Link to comment Share on other sites More sharing options...
Rob240z Posted March 6, 2013 Share Posted March 6, 2013 Hi Tony, Do you happen to have any other pictures of this setup? I'm trying to see how the supercharger is mounted and how the belt is routed. In your picture I can see a serpentine belt and possibly a tensioner or idler pulley, but the picture is hard to see. Do you have a higher resolution version of this picture you would share? I'm curious what the solution to the water pump pulley was. Thanks, Rob Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 6, 2013 Share Posted March 6, 2013 Muahahaha ha! Aluminum"engine plate" style mounting of SC with 3/4 wrap and ability to run above 15psi. Serpentine belt on aux pulley in front f standard pulley (ATI or BJC better choice) Water pump stayed on standard V Belt as did alternator. Serpentine was "forward" those two pulleys. As for "double key" I mean axial position. The Japanese commonly DO NOT use woodruff keys on the high performance motors, they use a SINGLE key way and fully cut key in the crank snout. This gives TREMENDOUS area to,take orchestra should anything come loose. It's not so much a "torque transmission" reasoning on high rpm NA engines, but a ay to prevent damage from the woodruff keys wobbling and eating up your expensive prepped crank! For torque transmission, though, a single key is nice and functional. Double keys is one step below pulling the crank to make the key way fully through all front-end components. There are reversal forces here on-off throttle, add driving a 45HP compressor demand and you see a full key way is good idea (or double keys) The problem with slinger s "embedment" it can squash or peen out. Once that happens compression clamping on the pulley lessens, and that sets up the dynamic whereby the bolt comes completely loose or he key way then wobbles because the pulley can start "working"on it. The slinger IS NOT a hardened component, it's simply stamped sheet metal. As little as 0.003" embedment can SERIOUSLY lessen tension on the fastener and consequently face-clamping forces (the reason for thick washer!) The problem with the stock L-Crank Washer is its thin and flexes. That flexing is what pens the slinger in the first place. Flexing is just like embedment in terms of tension load on the fastener...compounded by the fact that it's now putting cyclic loading on the fastener as well! Not good... Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 6, 2013 Share Posted March 6, 2013 The only reason I have this photo is the owner died and the entire car is for sale. Remember I rode in this car sometime in 97-2002. Not a lot of hi-res digital photography at that time. My Sony filled a diskette with four "high res" 1280x960 photos at that time... Quote Link to comment Share on other sites More sharing options...
Snailed Posted March 6, 2013 Share Posted March 6, 2013 This may not apply to the crank and pulley design on the L, but I'll throw it out there for review; On the V10 Mopar engines I have installed superchargers on I drilled two 1/4" holes, 180 degrees apart, through the pulley and into the crank snout about 3/4". Roll pins were then hammered into the holes. These are not keyed from the factory and most of them rely on a ~30mm bolt that is torqued dry (I believe) to 250 ft/lbs, which came loose on stock Vipers frequently anyway. I'm not sure if roll pins are the best way but I did it to six Vipers and they are all still together, some making over 1000whp. I have done this on a 6.1L Hemi also. Quote Link to comment Share on other sites More sharing options...
Xnke Posted March 6, 2013 Author Share Posted March 6, 2013 (edited) I have a spare crankshaft here that will be getting prepared for eventual insertion into the next engine, which will be specifically built for the supercharger application. The crank has been magnafluxed already, and has minor wear marks from the rear main seal. The front snout will be converted to a single key system before it goes in. I am looking into machining the rear of the crankshaft as well, to fit a 36mm snout on the back of the crank to more positively locate the flywheel...this is commonly done in japan by a few different methods, but I am not sure which method I will choose yet. Still not sure what you mean, Tony, I can't think of any way to "double key" the crank pulley without removing the crankshaft to machine it. I used to have a hand-operated keyway slotter, kind of like a drawknife but it was sized for SBC applications. it took A Long Time, but you could key the crank snout in the car with it. Edited March 6, 2013 by Xnke Quote Link to comment Share on other sites More sharing options...
Xnke Posted March 7, 2013 Author Share Posted March 7, 2013 Snailed, You mean drilling from the front of the crank, back alongside the crankshaft, and driving a roll pin into place? Now I understand. That can be done! Quote Link to comment Share on other sites More sharing options...
Snailed Posted March 7, 2013 Share Posted March 7, 2013 Snailed, You mean drilling from the front of the crank, back alongside the crankshaft, and driving a roll pin into place? Now I understand. That can be done! Yes, that's what I mean. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.