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Xnke

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I didn't realize you were using a manual tensioner.  I couldn't see the back of it and thought you were maybe using some kind of spring or something else to make it into an automatic tensioner assembly.  

 

Yes about alternator being high. My drawing was very rough.  The crank and water pump pulleys are drawn much farther apart than in reality too.  I think a good wrap can be achieved by placing a idler pulley in between and to the left of the crank and water pump pulleys as long as the top of the idler pulley is above the bottom of the water pump pulley and the bottom is below the top of the crank pulley.  The size of the idler can be increased to get more wrap.

 

I'll explain my thought process even if it's flawed as to why I decided to go with an 8 rib serpentine conversion on my engine build:

 

The supercharger comes with and uses an 8 rib pulley.  

 

I have always planned to use an automatic tensioner as every other centrifugal install I've seen incorporates one into the supercharger bracket and I just assumed there was a good reason every serpentine belt system I've seen does.

 

I was planning on upgrading my original 240 alternator to one with more amps so I figured why not just get one that has an 8 rib pulley on it anyway. My work van has a 100 amp alternator with an 8 rib pulley that seems like it would work fine.  Since I already have to make a supercharger bracket, I figured why not make it to hold the alternator too.  That way I can position it where I like.

 

I wanted to run a quality damper and was looking on BHJ website and noticed they make an 8 rib damper that lines up exactly where the original crank pulley does.  So I bought it.  

 

The only thing left is the water pump pulley conversion which shouldn't be to hard.  Originally I was going to buy the electric water pump from MSA, but I have been seeing conflicting reviews about it and have decided not to take the risk.

 

It seemed like converting everything to 8 rib serpentine was the right choice.  But after seeing your setup, it probably would have been easier to add an 8 rib pulley to the end of the crank pulley and run the supercharger on a separate belt system.  Making the supercharger bracket would have been easier.  But I have already purchased the the BHJ damper, and it wasn't cheap, so I think I should continue as planned.  The other benefit is the clearance to the radiator and electric fans isn't a problem with this setup.

 

I am a little worried though that the high tension from the serpentine system will be to much for the water pump shaft.  Do you think the water pump can handle it?

 

This is a picture of the BHJ damper I bought if you haven't seen it before.  

 

post-11209-0-09887000-1354990083_thumb.jpg

 

http://www.bhjdynamics.com/index.php?main_page=product_info&cPath=10&products_id=238

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I was worried the 3 row radiators looked to deep too when I was looking.  This is the one I just bought last week.  It is a 2 row with fans.  I read here on hybrid that Champion radiators are good.  The Champion 3 rows are rated at a much higher horsepower according to this ebay seller though. 

 

http://www.ebay.com/itm/190751782300?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

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I am familiar with it; and as long as you recognize that when your supercharger eats a belt, you'll loose your waterpump at the same time, and you're OK with that, then there is no reason to not run the single serpentine belt.

 

As far as the water pump pulley goes, look at the KA24DE pulley in the pickup truck, or the VG30E. Might find something to fit there.

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What about having a remote electric water pump as well as some sort of serpentine one?  That way at least you had some backup to stop the engine from overheating... The mini cooper s uses a remote water pump in conjunction with one driven by the timing chain (If i remember correctly, been a while since I went on the mini forums).  Maybe you could just have one that you could switch on in the event of a belt breakage?  That pulley is really cool though!

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Won't run long, since your alternator is also out of the loop...the battery can't hold a running vehicle plus an electric fan plus an electric water pump too...Look at the current requirements. You do NOT want to exceed the capabilities of your alternator!.

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How often would you say a supercharger eats a belt? I was thinking I might have some belt slippage to deal with. I didn't consider that I would be going through belts very often. If that is something that happens frequently maybe keeping the supercharger on a seperate belt would be the smarter thing to do. BHJ makes a v-groove pulley that bolts to the front of the crank pulley. I could use that to spin the water pump and alternator. I was hoping to use it to spin an AC compressor if I decided to install AC at some point in the future though.

 

What do you think of MSA electronic water pump?

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I don't think it should be relied on even to limp the car home, but I was thinking simply in the case of it throwing a belt, just to keep water moving after you turn the engine off/when you're pulling over to the side of the road to avoid excessive overheating.  Even in stock form it wouldn't be possible to drive the car with a broken belt, at least for very long.  In a Z-car it isn't over-pretentious to assume that a belt change on the side of the road would be possible if nothing else broke in the process, so at least this way it would give you the opportunity to simply install a new belt and be on your merry way again, albeit with a drained battery but at least your bearings would be intact! Make sure you make a limiter for that tensioner though, as if that belt does break, it wouldn't be too hard for that thing to take out the closest pulley, and possibly ruin an alternator, the timing cover, your supercharger, and itself in the process, leaving you stranded.  As you said, it's a lot of force required to tension a serpentine correctly!

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... and as long as you recognize that when your supercharger eats a belt...

They do that way to much it seems. I have installed and tuned a bunch of bolt-on aftermarket setups and it seems like most of them at least develop slipping problems later on if not shread belts. Maybe a cogged belt like this Vette I just finished?

post-11686-0-62763200-1355181583_thumb.jpg

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The problem is that the supercharger usually gets a small diameter pulley installed on it, and people don't think about belt wrap and tensioning. That's why superchargers eat belts.

 

Look at the SII GM3800. That's an M90 supercharger, driven from the same belt as the entire accessory drive. The crank pulley size was upped to a little over 7" diameter, specifically to allow the supercharger pulley to be sized to 3.8". This allows as much belt contact area as possible while still retaining the six-rib belt and the required supercharger drive ratio. (I think it was the series II, could be the series I. One of the two uses the same drive belt, the other series uses a belt specific to the supercharger.)

 

You have to figure the load on the belt, too...at full-song the M62 draws 36HP, plus another 3% or so in belt loss. Call it 40HP and be safe. How much contact area do you need to transfer 40HP? Now, since you know the amount of belt contact area you need, figure the amount of belt wrap you need on your chosen pulley diameter...figure out the area of belt contact based on the amount of belt wrap. Is it enough to transfer your 40HP? No? Then either increase belt width, belt wrap, or driven pulley size. Is it enough now? Yes. Now look at the belt orbit. When operating a roots-type blower produces a pulsating load. This pulsing is what causes the belt to slip, eventually...but the path to slippage makes a stop at belt orbiting. Right now, I'm looking at a potential belt orbit problem in my setup, the long unsupported span on the tension side of the belt (the high-side, coming down to wrap around the crank on the driver's side of the car) would tend to push outward, away from the idler and toward the driver's side of the car. This would be a good location for a second idler assembly, to shorten the unsupported span. Otherwise, this long span will be the major cause of belt wear; even if it isn't enough to justify engineering a new idler.

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I never knew it was called "belt orbit". So belt orbit does not get started (as readily?) on a centrifugal setup I assume? I still have seen some belt problems with these but I would think it was more a function of smaller drive pulleys, less belt contact, and the increased work you are asking the belt to do, as you mentioned.  I think people do try to address getting enough belt wrap, at least you hear a lot of talk about it on forums and from guys with cobras that don't perform when they need to.  Wouldn't it be wise to grossly oversize the belt and not always be on the edge of...the road haha.  I'm a reliability whore, sorry for all the questions.

 

What about belt wear? Do you have figures on how the coeficient of friction changes. Is it a flat line that suddenly drops off or maybe a gradual decrease after inital seating of the belt?

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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.

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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.  

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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.

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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.

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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)

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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.

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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.

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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.

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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.

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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.

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I knew I could find this if I looked hard enough. Setup sent the car sideways at will...

 

In 1997.

 

post-380-0-21119000-1362577370_thumb.jpg

 

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 by Tony D

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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.

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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 [email protected]

attachicon.gif 2010.11.10 73 Datsun Procharger 2.JPGattachicon.gif 2010.11.10 73 Datsun Engine Bay 2.JPG
ENGINE
Professionally built L28 motor
F54 Block 88 mm bore
Eagle H beam rods
JE custom pistons 10:1
Arizona Z Car oil pan
Canton 2 qt Accusump w/electric valve
N42 head professionally ported
Schneider custom ground cam
REV valves
Isky valve springs and keepers
Procharger C1 supercharger - 18 lb boost
Extra supercharger pulley for 12 lb boost
ATI Super Balancer
AZ Car 4 brl intake manifold modified to single plane
Holly 390 cfm HP carb professionally built and modified for boost application
AZ Car intercooler
MSA 6/1 header
3" exhaust w/Brzezinski race muffler
AZ Car radiator
Flexalite dual electric fan
MSD 6AL ignition
MSD Blaster SS coil

attachicon.gif 2010.11.10 73 Datsun Fuel Pump.JPG
FUEL SYSTEM
Summit 10 gal aluminum fuel cell
Aeromotive A300 fuel pump
Aeromotive 13301 regulator w/boost reference
Dual fuel filters

attachicon.gif 2010.11.10 73 Datsun Front Underside 2.JPGattachicon.gif 2010.11.10 73 Datsun LR Suspension detail 1.JPG
DRIVE TRAIN
G Force T-5 transmission spur gear dog ring 2.94 ratio with .9 overdrive
Pro 5.0 shifter
Quartermaster 8 1/2" rally clutch
Quartermaster button flywheel w/Datsun flexplate
Aluminum driveshaft
R200 3.90 CLSD differential with upgraded clutch packs
280Z stub axles
Modern Motorsport CV axle adapters
300 ZXT CV axles with custom length axle shafts
CCW 17" X 9" wheels w/Hancook Z214 275/40 C-50 tires

attachicon.gif 2010.11.10 73 Datsun LF Suspension 1.JPG
BRAKES AND SUSPENSION
AZ Car 4 lug Wilwood big brake kit front and rear
Upgraded Wilwood GT 48 front rotors
Wilwood dual master cylinder brake and clutch pedals w/balance bar
Wilwood brake balance bar adjuster
AZ Car lower control arms front and rear
AZ Car coil overs w/camber plates
Bump steer spacers

attachicon.gif 2010.11.10 73 Datsun Interior 1.JPGattachicon.gif 2010.11.10 73 Datsun Interior 4.JPG
INTERIOR AND SAFETY
8 point roll cage
Ultrashield Pro Road Race seat
G Force 5 point harness
Firecharger on board fire extinguisher system
Painless 8 circuit race car harness P/N 50001
Autometer tachometer
Autometer and Accutech gauges

attachicon.gif 2010.11.09 73 Datsun L Side 1.JPGattachicon.gif 2010.11.09 73 Datsun Front.JPG
EXTERIOR
Xenon front air dam with functioning brake ducts
BRE style rear spoiler
ZG fender flares
Lexan rear window
MSA headlight covers
attachicon.gif 2010.11.09 73 Datsun Rear.JPG
*Slight right rear bumper damage

 

 

 

 
Edited by Rob240z

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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

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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...

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