Positively Displaced

[Xnke]

Project ADD has struck...before the plumbing gets done the airbox will get built, then a new intake manifold will be constructed. (Maybe. Might run what I got till I get the new manifold on.)

[Xnke]

New injectors have been sourced, and the throttle linkage has been mostly worked out...I think I can get away with single return springs on each pair of throttles instead of the duals.

[Xnke]

Waiting on material to show up now, it'll arrive thursday. The new intake manifold will be a junkyard sheetmetal version of Monzter's spectacular CNC machined ITB madness, using runners that will be 10.5" from the cylinder head face to the end of the velocity stack, 1.5" ID, and angled up about 14* from perpendicular to the cylinder head face. It's going to be a tight fit, obviously, but it WILL fit in an S30, and a single-throttle version will be fitted to an S130 for a turbocharged application.

[Rob240z]

Hi Xnke,

 

I'm following this thread with great interest. What you've done so far looks great and has given me some ideas on my current build. I'm currently trying to figure out how I'm going to run a serpentine belt on my setup. After seeing how you have set up your pulley/tensioner I think I'm going to route mine similar to you. I've never seen a sliding tensioner like your doing. How does it work? All the tensioners I've seen swing in an arch.

 

My build is a little different, but there is a lot of similarities. The biggest difference is I'm using a rotrex c81 supercharger, but locating it in almost the same position you are. I bought a BHJ damper that has an 8-rib pulley attached to it instead of the v-belt pulley. I'm using an 8-rib alternator so I can line all the assessories up. I think this will give me a little space to the radiator and fans.

 

On your posts about estimating the horsepower your set up will make, my best guess is that you are being conservative. Corky Bell wrote a great book called "Supercharged! Design, Testing and Installation of Supercharger Systems". When I was planning my supercharger build I created a spreadsheet that used all the relavent equations from his book. I followed his workflow on designing my supercharger system in how it was applicable to what I was trying to achieve. There's a lot of good advice in his book, especially on avoiding detonation, which was my biggest concern. I'm not expecting my actual power numbers to come out exactly as calculated, but it at least was something to use that wasn't a blind guess and should get me in the ballpark. If you want the spreadsheet to play around with I'd be glad to send it to you.

 

Keep up the excellent work. I'm looking forward to watching this build and seeing the final outcome too.

 

Rob

[Xnke]

I looked at a serpentine belt configuration, but how are you planning to run the water pump? It won't work the same as it would on a conventional serpentine setup, since MOST of the ones I'm familiar with wrap rib side on the crank and flat side back around the water pump. I am running A/C also, so it wasn't going to work for me.

 

Anyway, this project is far from dead...just haven't been updating it here due to work on the manifold, which is down in the fabrication section.

[Rob240z]

This is a very rough sketch looking at the front of the engine.  My plan was to make a plate style bracket that holds the supercharger, alternator, tensioner, and extra wheel all in line with each other.

 

[Rob240z]

I just read through your intake manifold thread too.  You are a very good and resourceful fabricator.  Was that a fire extinguisher you used for the plenum?  I just bought a custom intake that was very similar to what I wanted.  If I had your welding talents I would have tried to make one too.

 

It's pretty cool someone else is doing a very similar build at the same time.  Different types of superchargers, but a lot of similarities. I think yours will be more torque oriented and my will build power at the higher rpms. 

 

This is the spreadsheet I used to figure out what blower and pulley sizes I needed.  I'm pretty sure this would work for yours too, just some of the variable values are different.

 

 

https://docs.google.com/spreadsheet/ccc?key=0AsePDCmbU5HudGhDSG5HYUtBbk5CVUtkNTl3RTdmc2c

 

[Xnke]

Keep in mind the actual locations of the parts...your alternator is drawn quite high on the block. You need to ensure you have at least 50% belt wrap around the crank pulley, and shoot for no less than 30% on your accessories. Also, serpentine belts are designed to be run at a VERY specific belt tension, or they WILL slip. The only reason I'm using a manual tensioner assembly is that I already check my belt tensions every week, and it was quicker to package. I would seriously consider a spring-loaded tensioner assembly. If you are using an serpentine belt, then the tension should be at a minimum 25lbs*8ribs=200lbs. Consider this when you build your tensioner and idler setups.

 

And yes, actually...that is two fire extinguishers that got welded together for the main plenum.

Edited December 8, 2012 by Xnke

[luseboy]

Ya serpentine's need a lot of pressure.  The belt tensioner on my mini cooper s (supercharged model) is quite hefty.  I put a smaller pulley on my charger and needed about a 4 foot bar and some heft to get it un-tensioned.  Would be interesting for someone to do a full serpentine conversion.  Seems like a lot of work for little gain to me, but hey, what do I know?  Is it possible to weld onto a dampened pulley? I have a powerforce crank pulley on my L28 and it only has 2 threaded holes on the outside... any way of attaching a serpentine pulley on the outside like you've done with the stock pulley?

[Xnke]

You shouldn't weld on something like that unless you know exactly what it's made out of. Call Powerforce and ask, would be my thought.

 

I had the tape on the car last night, getting an idea of what has to move where to get the drive belt on. The radiator needs to move 1/2" forward, or I need a thinner fan than the Hayden Trans-Kool that's on the car now. If the core support was flat, instead of having those 1/2" raised panels that the radiator mounts to, then I'd have just enough clearance, I think.

 

The radiator is a 240Z 3 row copper unit. I am pondering moving to a 280Z (taller) aluminum 2-row (thinner) radiator.

[Rob240z]

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.  

 

 

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

[Rob240z]

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

[Xnke]

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.

[luseboy]

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!

[Xnke]

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!.

[Rob240z]

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?

[luseboy]

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!

[Snailed]

... 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?

[Xnke]

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.

[Snailed]

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?