Gearbox for supercharger

will it work???

it won't work. The gearbox would have to transfer a bunch of torque and horsepower, upto to 30 HP. The eaton should have a choice of pullies to adjust the pressure.

Since you are using a positive displacement, engine rpms don't mean anything as the compressor will deliver an exact match of the air you need (ok, close as the rpms increase the blowwer will slip and at the same time the VE of the engine will drop and nearly cancle out the air lost in slip of the compressor).

The best option would be to have a variable BOV. The wasted HP at economy will not be noticable. OH, you can do it all in one ECU and save the expense of two and switching harnesses.

"it won't work."

It did 50 years ago. why not today?

My first supercharger was a two speed centrifugal unit built in Conshohocken, Pennsylvania. Time has taken a toll on memory but I suspect it was a McCullough unit. Can't be 100% certain because I had lots of blowers back in the days. Paxton's, Roots type GMC blowers off of diesels.

I do remember that they were the blower of choice when Studebaker dropped one under the hood of a V8 Hawk and called it the Goldenhawk.

My memory of the unit was that the two speed unit had a bunch of ball bearings running loose in the nose. I remember fixing it but not much else.

Two speed drives were common. If anything, the passage of time, technology, modern lubricants and materials should make such a system even more viable.

Go for it!

L. J.

It won't work on a roots postive displacement blower. The one listed by Ken below is a centrifugal and because a centifugal obeys the fan laws you need to have it running at 10 times engine rpms at 1000 to 2000 rpm, than only 5 times rpm from 2000 to 4000 to get THE SAME BOOST PRESSURE ie the increased torque off the line that you get with a roots blower.

Again, your first was a centifugal, not positive displacement type. So apples to oranges here. What you need is a screw compressor with a variable caapcity control if you want minimum wasted energy and 100% varaiable boost (and torque). I use a Sullair or Frick in my business to move gases. They have a 100% continious variable capacity system on them. Of course the compressor cost 50% more than the standard.

The Studebaker Avanti used a paxton supercharger which was a subsidary or Studebaker at the time, 1962. The supercharger I believe was a centrifugal. I'll ask a friend in Tulsa who has an R1 and a R2, but the pictures look like they are and Paxton is famous for its centrifugal superchargers.

Antanov makes a dual-speed supercharger, a dual-speed alternator, and a dual speed pulley for use in driving superchargers.

Why 2 ECU's?

A single ECU should be able to handle the mapping load points you'll be running, also a controllable blow-off valve to alter your pressure from the SC with a single switch to the ECU to control the blow-off valve

Check out

MoTeC http://www.motec.com

Haltech http://www.haltech.com

Autronic http://www.autronic.com.au/

Wolf http://www.wolfems.com/

EMS http://www.enginemanagementsystem.com/

You can also modify an a/c compressor clutch to engage/disengage the blower entirely. What type of injection are you running? If its port injected, all you'll need to do is rig up an air bypass around the blower that can be opened when the blower is turned off. In short, it would be like the Mad Max police interceptor special with its switchable blower. Mercedes had a blown setup a few years back that did the same thing.

Guest above is on the right track. Have a look at the FORD Interceptor engine that was used in the movie MAD MAX. It had a positive displacement blower on it and was decoupled with a modified a/c clutch mounted on an idler pulley. The clutch was operated from inside the vehicle with a manual pull cable mounted on the shifter. This was done because of the premise of the movie. Gasoline was in very short supply after the nuclear holocaust, so the car was modified to have an "economy" setting but still have the blower to get away from the bad guys. It was a quick and dirty way to get an adjustable speed drive since they didn't have anything else to use back in the '80's. Have I got this right? Maybe somebody from down under can comment.

UFG

Firstly, thank you all for your input. I am very pleased to have found this forum.

Vicini, I think I get what you are saying, but the way I see it happening is I have a small two speed gearbox between the crank and M112, the gears of which I may even have to preselect before starting the car (not a real problem). The low gear probably gives no apparent boost at all over the rev range and therefore gives good fuel econonmy. The high gear delivers 9psi boost (the maximum I can have and not compromise the bottom end of the engine) The way I see it, the gear box itself will not experience any greater load than it takes to run the supercharger (you mention 30HP, is that what a decent size roots type needs?)

The gearbox's suitability is why I mentioned the engines operating rpm range (I know I didn't make that real clear), not the boost conditions. I have thought that if the gearbox had an rpm limit that it was constrained to (and if I have the room under the bonnet of the car) I could run small pulley on crank to big pulley on input shaft of gearbox, then big pulley on output of gearbox to small pulley on supercharger. This may subject the gearbox to larger torque loads, but will reduce its rpm. I would think that the adjustable speed drives I have seen in this site would handle more than 30 HP.

I've not heard of the variable boost screw compressors before and I am sure that affordability and availability where I am would be prohibitive.

I really like your idea of a variable BOV. I did not there was such a thing and I will be checking that out. It would certainly be a cheap way out. The only thing I dont like that much is that the supercharger will be running faster (and wearing out faster) than it needs to be, most of the time.

LJ, Thank you for the encouragement. I intend to chase this down as much as possible. I am not an engineer, just a Crane Operator but I really want to do something a little different. My wife and I have decided to do up a favourite older car rather than buy a new one and an "old school" theme with modern tech touches where we can, is the plan I first started thinking about having a two speed charger after reading in wickipedia where they describe the two speeders used in planes during WW2. You sound as if you may be familiar with such items

Ken, Many thanks for the Antanov link. Their two speed pulley looks a treat. As I understand it the ratios are 1:1 and 1:1.36. I dont know if these can be ordered in any other ratios but I will ask the question (maybe just run a heap of them in series )

I will be very interested to know the rpm that the input shaft runs at before switching ratios, and what pully size options there are. It would definitely be a help to bottom end torque if the right combo can be ordered to give me two distinct ratios that change back to the "low boost" gear at highway cruising rpm (1950rpm in my case)

The only downside I see with this is that it probably not manually controllable. So I cant flick a switch and have it hold one gear or the other as well as being automatically shifting. But thanks again. Just the to know such a thing exists is great. Cheers

Snaketails, Thanks for the links. Our car spends most of its time running on LPG (liquified petroleum gas. I heard somewhere that you guys in America use liquified propane? Ours is a combination of propane and butane, definitely not as potent as straight propane) We have a pretty high tech injection system (Prins) feeding our engine this stuff but the computer that controls it is pretty agricultural. It is just a piggy back add on to the petrol computer with very little tuneability. A company in Australia called Profire (www.profire.com.au) will have an ECU out in the new year that is specifically for my LPG conversion and will run both petrol and LPG and will be incredibly tuneable. I'm not sure if I will really need to have two of these to do the job, maybe I can flash tune the second lot of load points (over 1500 loads points in total, by the way ) but I am willing to buy two if necessary so I can have my two stage supercharger happenin'.

Guest and unclefastguy, Lol, as it happens I am from Down Under. I write you all from the town of Geelong in the state of Victoria. The Mad Max idea is great, thank you. I am wondering though if that would be better suited to a centrifugal setup that retains the naturally aspirated intake manifold. That way a diverting flap and an aircon clutch would be great. Superchargers that sit in the V of a V8 do so, in most cases, on a purpose built intake manifold that has very short runners. To somehow let air in under the supercharger (when it was turned off) in this case would result in very poor performance as the charge speed into the combustion chambers would not be what it was designed to be.

Thanks again to you all.

I look forward to any other comments as I chase up the possibilities you have given me.

The Anatov folks are pretty sharp, I think. They have a suit against Toyota for patent infringement, which looks like it might have some merit, to me (but I haven't researched it, nor do I have the legal acumen to really know). For the patent in question, the drawings show a positive displacement blower as one of several items to be driven by their continuously variable planetary transmission (which seems very similar to the transmission used on Priuses to combine electric motor and ICE outputs.)

I talked to Anatov a while ago about a transmission for my project vehicle, and as I recall, they are mainly an intellectual property company, so I think some (most?) of their devices do not exist as production units.

Another unit I looked into a little was the Gates two speed accessory drive.

I have no basis for saying this other than gut feel and conjecture: I'd guess that the "along for the ride speed" might be slightly over the speed that yields zero boost. Finding the optimum speed for that condition could require some fairly sophisticated modeling (or a dyno and a selection of drive pulleys, for experimentation.) In this article (which is not too bad, by Wikipedia standards) a blower efficiency map is presented, showing peak blower efficiency at a pressure ratio near 1.1.

Assuming you have multipoint injection and will be pressurizing a plenum, It might be simpler and more efficient to use air valving and ducting to provide. to paths for induction air, one bypassing the blower, and having the shorter, least restrictive path, and the other through the blower. Then a simple clutch would be used to engage the blower at will (with valving shifted automatically, presumably by boost pressure, or manually). With a two speed drive, there would be no speed at which the blower will not add heat to the intake air, reducing efficiency (if only from air stirring).

Fun project!

BTW -- ignore any advice that suggests that racing on dirt is better than racing on pavement: I've done both, and have concluded that dirt racing is for wooses who are afraid of a little death.

I had a brainstorm I guess. Why not stacked pullys like on my bench drill?

Hoping your not thinking I'm from Yanky land (and of course you know what that rhymes with)

Nah, I'm 35km the other side of Melb from where you are out near East Link

Whats "Prins" doub't its all that high tech (from my stand point) currently trying to save up for a Haltech or MoTeC, both around the $2200 mark ;o(

There used to be a company I think called "Gas dynamics" out at Pakenham that built injection systems for LPG, and for those who were running some sort of chargers.

2 ECU's is just a overkill, cause when a ECU is tuned, all the load points are mapped while on the dyno, and thats not just the fuel maps, but also the Ignition mapping too, covering all the load points will cover the low pressure from the SC in 1 region of the mapping to the high pressure mapping in the other region.

Unless you know the right people, Dyno time is still expensive ;o(

Yeah I did I didn't read under your avatar. Prins is a manufacturer of LPG conversion kits. The kits are imported by Parnell and installed under their name. And you are right, the computers are nothing special. Profire W.A. are a supplier of Parnell gear but they are nearing the end of the R&D of their own ECU which will run both petrol and gas.

I have always been under the impression that I would have to use all the load points for one region and therefore need another ECU, or at least a flash tuner to run a second full set of load points for the higher boost. But you give me hope that that will not be the case. Cheers. I'll give Profire an email and ask them.

Unless you are very familiar with this project, I would highly recommend this book; "Supercharged! Design, Testing and Installation of Supercharger Systems" by Corky Bell. It is available at Amazon.

I recently installed an M90 Eaton in a 97 Jetta VR6. I can honestly say that without the info, in this book, it would have been a bust. We have been driving it for 9 months now and it runs flawlessly.

The car runs great, has gobs of power and the mileage hasn't changed enough to worry about.

I can't recommend any book, any higher, than this one by Mr. Bell.

Good luck with this project.

for what it's worth... the eaton superchargers, especially the newest generations, have an internal bypass valve, which is activated via a vacuum-controller actuator (similar to the actuator on a turbo wastegate.

the m112 is available directly off an 03 ford mustang cobra, and the newer generation ford lightning pickup trucks.. they are very often swapped out for twin-screw compressors due to the higher power levels attainable..

now, as mentioned by another (can't remember who)... read "supercharged" by corky bell... VERY good read on supercharger systems... this will help you alot with the setup.

An eaton, being a modified roots blower, is VERY inefficient, especially at higher pressure ratios... if you expect to run more than 10psi of boost (which will be very not recomended on "stock" internals, especially at higher compression ratios), think again, and go for a better blower... and/or be prepared for HUGE parasitic drag on the engine. Also, keep in mind intercooling.

As for the "variable boost"... if you mount your throttle-body PRIOR to the supercharger in the intake stream (so... air flow would be thus... filter, throttle-body, supercharger, intercooler, intake manifold), when you close the throttle, the charger will be operating in a partial vac, and will require VERY LITTLE power to turn... this is where the internal bypass valve comes into play, it redirects a bit of flow from the exhaust side of the blower, to the inlet side, just circulating that air around a bit. When you go WOT, the bypass will close, allowing full flow from the outlet. Your fuel economy is going to be directly regulated by how well you can control your right foot :) there is a reason the eaton chargers have been chosen by ford, bmw (in the mini S), mercedes, jaguar, nissan, and now chevy (the new corvette "blue devil" runs a new-generation eaton)... they are reliable, and a great choice when wanting to keep fuel economy.

for what it's worth, my M90 requires something on the order of 40 HP to turn, when i am spinning it up near redline, with a 15psi boost pressure...

http://www.youtube.com/watch?v=dE0hytANSa0 for your viewing pleasure :)

Hello Crane,

First of all, Positive displacement blowers (unless they have changed) have to turn for the engine to run at all or you will need to duct air/fuel around them to use an electric clutch. The Mad Max design would not work unless the blower can spin freely to let the engine breath and they will turn but not all that freely. (take the belt off your blower now try to start it)

You could fabricate a sun gear with a electromagnetic clutch and an automatic transmission gear to change speeds but weight and cost would be counter productive.

How about a Tesla pump to a Tesla turbine closed loop,with a cross over valve to regulate flow. A little harder to design but much easier to scratch build, infinitely variable and no patent issues.

Brad

First of all, Positive displacement blowers (unless they have changed) have to turn for the engine to run at all or you will need to duct air/fuel around them to use an electric clutch.

this is true, however the clutched units (i am VERY CERTAIN) used in say the merc, freewheel the rotors as air passes by them. not to mention, the tolerances in an eaton blower are... well, lets just say "less than ideal"... i think you could send small animals & children through one of these.. without worrying about harming them at all... hence one of the reasons the eaton is so inefficient..

PLUS, again, a properly designed PDB system, will have the throttle UPSTREAM of the blower, so the amount of air that passes thought it, is fully regulated by your throttle.. combine that with the bypass valve in the charger (linking inlet to outlet), and you don't need to worry about freewheeling the charger to begin with.. the air that is needed can get around... OEM applications have been using these for YEARS in just that setup.

Really, never messed with Eaton.

The older roots used fuel to make the seal but now many now have a teflon strip. I would think the blower would restrict the intake to the point of losing fuel economy. The specs on the newer screw superchargers look much better but I doubt they will free wheel at all. (could be wrong never tried it) Tried to get a 671 home with a broken belt (frayed cutting into the hood). Ended up towing it.

Brad

Really, never messed with Eaton.

The older roots used fuel to make the seal but now many now have a teflon strip.

the eaton is just a roots, with a 60 deg twist in the rotors... pulls from the rear, outlets from the... side?/bottom? (all depends on how it's oriented).. the twist also got a bit more economy out of it.

far as i know, screw chargers can't freewheel @ all... but, like i said... bypass valve solves the problems, and throttling the INLET to the supercharger will give you the efficiencies you want.

Blink, Yes, that efficiency graph for the roots charger is very revealing. And for every day tootling around picking up the kids/shopping or open road cruising at highway speeds (over here that's 62mph ) a pressure ratio of 1:1 (or a theoretical zero boost) is exactly what I want as it will give me great fuel ecomomy and enhanced throttle response etc. Having the gearing option to run about 9psi when I want it (maybe only 10% of the time) means I'm not going to be too concerned about efficiency because I will too busy belting up through the hills.

Leaving the factory intake on and running a supercharger on an electric clutch with a "diverter flap" to switch the engine back to normally aspirated is an idea that is very appealing but only if I could do it with a positive displacement blower so I dont sacrifice low rpm responsiveness. And even that would be second best as we want the old school look of the snout and pulley poking through the bonnet. Arrgh!!

vicini, Lol! That is where all this started. I had decided to inflate the Fairmont instead of pulling it apart for a hot up. I had decided to go with 5psi and live with the inevitable compromise between power and economy when I was watching a machinist at work change the belt on a drill press. A conversation with him lead to looking at a Reeves drive in a heavier duty drill press which in turn led me here via Google.

Following that idea though; there seems to me to be a couple issues to be overcome for something that simple to work.

a) The length of the belt being appropriate for both ratios. I guess this could be done by having a small pulley on the crank, larger pulley on the snout for zero boost, and a larger pulley on the crank and smaller on snout for 9psi. Keep the difference between them roughly the same top and bottom with a decent spring loaded tensioner and in theory it would work well.

b) Changing pulleys on the run would have to be a bit like a push bike with a derailer of some sort (two of them probably; one top, one bottom, working simultaneously) that would push the belts laterally to the neighbouring pulley. The difference in size between the pulleys may make this more trouble than it is worth so manually changing the belt, assisted perhaps by a quick release tensioner, is probably the more practical way and would still be a relatively quick process.

c) The gap between the thermo fans on the radiator and the motor will need to be able to cater for twice the width of the supercharger belt. And the supercharger belt will probably have to be seperate from the accessories belt otherwise I would have to have double width belts on every item.

Hmmm, thanks for bringing it up.

Guest, Thank you very much for the book reference. I have ordered one. And since one kind turn deserves another, if you have ever wondered about the specific math of exhaust tuning, this book is one which will probably never be expanded on, except in its own re-editions; "Scientific design of exhaust and intake systems" by Philip Smith and John Morrison, likewise available from Amazon. A lot of it was over my head bit it will give the specific equations for things like primary pipe length etc, etc, etc.

Howling 60, Thanks for all that. Good to know a specific model of car that a second hand M112 can be got from. The only M112 that I have seen here in Australia that wasn't brand new was a top entry and a rear entry is essential for the look we want.

U V, Telsa pump sounds good but my fabbing ability would be pushed doing it myself and my wallet would be pushed having it done for me. And yeah, in the first Mad Max film (which was filmed around Geelong) the supercharger was a fake. The rumour is that it was an empty blower shell over the carb and inlet manifold of a stocker.

Crane, an unintended Thanks for the book lead,

I've played with or research about every other system but only understand the basics of exhaust tunning.

My knowledge of blowers is just getting other's to work right. Turbos on the otherhand...

The Tesla pump etc. is simple. The hardest part is the housing and it can be welded from flat stock. Have a machinist ream the bearings seats so they are parallel and perpendicular to the pump housing. Use over sized hoses to reduce back pressure (the biggest cost). Like gears, large pump small turbine/motor. Two T's to connect the pressure and return line with a valve between them to set your analog ratio. You could even plumb the valve to the cockpit. May have to try this myself.

Brad

a pressure ratio of 1:1 (or a theoretical zero boost) is exactly what I want

It might have appeared to be a typo, but I was proposing a boost of 1.1 (1.1:1) not 1:1, for the economy mode. I'm picking this only because it seems to be the point at which the blower is most efficient, and that I suspect that it might be better to run the blower at its most efficient rather that simply having it consume power as it "freewheels" (not too "free", I fear).

I get it Ken, if you must have a small drag (power lost or used) use it in a positive producing mode and not a negative consumption only mode.

What do you know this old dog is still learning tricks

Brad

great, thanks for the reply. You have come a long wy on this topic, in a circular manner. If you think about it, why not change the gears on the drive train. My car has double overdrive, 5th gear is .95 and 6th is .85 Red line 185 mph). Once in these gears mileage goes up, no fuss no muss. Want power drop to 3rd (redline 95 MPH max torque at 50mph).

Ken, Thanks for pointing that out. I will definitely run the "economy mode" at 1.1:1. I agree with your point on the efficiency and I think it would also be better to have a touch off boost than run the risk of having a touch of vacuum between the blower vanes and intake valves.

"You have come a long wy on this topic, in a circular manner."

vicini, Ha ha. It wouldn't be the first time. Yes, this thread of inquiry of mine has been very satisfying thanks to you all. The gearbox idea is probably doable with a lot of research and engineering but it would only reward my curiousity and would punish both the final available power to road and (more importantly) my wallet. The idea of two pulleys on the crank (three really, one for the accessories) and two on the snout of the blower is infinitely better if it wasn't for the idea of having to change the belt from one to the other manually, in the rain when I'm big on boost and short on fuel

So how about this:

Two pulleys on the crank, one big and one small. Two pulleys, in reverse of course, on the snout, except that they are both attached to two seperate electric clutches that are both, independantly attached to the input shaft of the blower. Two belts are permanently on these pulley pairs and the wiring is done in such a way as there is NO chance of both being on at the same time ( oh what a mess) That way a flick of the switch in the cabin stops one and starts the other, therefore changing the blower speed and fuel/ignition maps in a snap. These electric clutches will need to be the kind that allows the input shaft of the blower to pass right through and they will need to cope with up to, from above, 30ish horse power.

What do all think?

Can anyone suggest an appropriate electric clutch that I could check out?

Cheers.

"Can anyone suggest an appropriate electric clutch that I could check out?"

Haha. Global spec search: "Electric clutches"

2122 products from 121 suppliers

This should be interesting.

"Two pulleys, in reverse of course, on the snout,"...

Or, the two pulleys on the snout which are attached to the electric clutches could be the same size and all the difference in required blower speed be made up by the difference in size of the two pulleys on the crank. That would look better, particularly as we want the snout and pulleys lurking through the bonnet a little

one thing that just crossed my mind..... are you intending a v-belt drive, or a multi-rib/serpentine drive? (the latter i'm hoping, pretty sure v-belt isn't going to be happy w/that kind of power x-mission)...

also, what are you going to do for a belt tensioning system? to properly tension, you'll need a spring-loaded tensioner to deal with the belt deflection and the stretch that WILL happen as the belt heats up.

I honestly don't think you're going to be seeing any problems with a drop in fuel economy by leaving the non-clutched setup, running with a bypass valve... there is hardly any load when the charger is operating in a vacuum with the bypass opened up... also the old addage of KISS applies... (keep it simple stupid), clutches (especially multiple) = more things to break/troubleshoot. Just a thought, that's all.

Where did you see an M112 with a top entry anyway? i wasn't aware they ever made any like that, i would think it would defeat the purpose of the "modified roots" design of the eaton. just curious! I am hoping you'll keep ongoing photo records/etc of this build, i certainly want to see it progress!

Yes, definitely serpentine. The original idea of using a Reeves drive off a drill press was quickly squashed by the machinist I was talking to. He, like you, was of the opinion that a V belt would generate nowhere near the friction required to keep the blower going.

The tensioner was to be a standard supercharger item modified with an idler pulley big enough to bridge both belts, but I did not consider heat and there is every chance that the driving belt at the time will get hotter and therefore looser than the one just along for the ride so maybe I should be looking at a set up of two single idler pulleys tensioning the belts individually? Am I over thinking that one?

I probably should have described the top entry M112 I saw as a "rear entry from the top" as opposed to the lower profile "rear entry from the rear" (so to speak )

Here is the place to see the add. You may have to register.

http://www.fordforums.com.au/showthread.php?t=11224687

Yes 60, the KISS priciple may raise its ugly head and be completely inavoidable at some stage through this, but I am going to try and make it happen and I will be very pleased to post pics as the various bits and pieces come to hand.

Thank you for your enthusiasm.