MaxxMitchell

iTrader: (4)

I'm in the midle of disigning a custom supercharger using a compresure housing off of a turboed Grand Prix, and was planing on mechanicly driving it to simplify things. Now i got ball bearings that are rated at 50k+RPM but i dont know how i can drive it to get another 3:1 gearing. Got a 2" pully for the surpentine, so theres a 3:1, but another is needed to get 9:1 for a total of about 50k+ at redline. BTW this is goign on a little 2.8 so just looking for some cheap power

Ok now for the Question i have, what would handle that speed, thought about V-belts, but i know they would get unballanced and would probly fly apart, same with chain.

Looking at a company called boston gear, they are hardened steel gears, dont know what their max RPM is, but im sure they would be louder than crap, used them on other projects and they have great wear characteristics and are strong, But at those speeds no lubrecant would stay on them, and i dont know how loud they would get. Any ideas on if nylon gears would hold up?

here is a pic that ive drawn up in cad sofar, not too much time spent on the drawing jsut mostly the idea, this was with a V-belt idea witch i have found out will absolutly not work at these speeds

ede

i'm more of a dumbass than an expert, but i do work in a R&D lab and if it were me i wouldn't try for the goal in one step, i'd sort or work up to it. i ithnk with any gear or chain set up you'd need it to be in oil. my first thought would be a glimmer belt.

MaxxMitchell

iTrader: (4)

Hmm yea thought about the oil thing, i can seal it off and have the gears slosh in some oil, but im not sure how much would get pass the bearings and leak all over,but i guess if i set it up right one gear would run in the oil pool and then coat all the others.

But what is this glimmer belt, i have no experince with one, and could not find much on the net on what it is exactly.

ede

like a belt on a top fuel car, a cogged belt, actually there are better designs now wit ha sort of chevron look to them

MaxxMitchell

iTrader: (4)

OK now i know what ur takling about, my plan was to use a longer surpentine belt, the step it up again using the gears or some other method, got get my final 9:1, inorder to use that Glimmer belt i would needa new crank pully, then that adds more mass, and $.

92 zzz28

Would something like a ceramic hold up to that kind or speed? I would think with ceramic or a composite you wouldn't need much if any lubrication. I am just thinking out loud...

MaxxMitchell

iTrader: (4)

Dont now about the ceramic thing, im goign to ask a teacher at school, and then probly call IBT or MSC and ask what they sugest.

MaxxMitchell

iTrader: (4)

I think i found a solution, lol u may laugh but i think that it will work. Any one ever heard of the R/C car E-Maxx? Well for one thats where i got my SN but anyways, it runs a 2 speed tranny with nylon gears. Ive seen this tranny spent at well over 70k RPMs, and the nylon gears self lubricate and its a very strong set up with the gears being about 10mm wide. May sound funny but in first gear i can get a 1.78:1 then in second i can get 2.78:1 so a maunual shifting Supercharger .

Im just looking at the R/C tranny because i know its strong and i can even make it stronger with Hardened Steel idler gears, and the shafts are already hardened, and the RPMs that ive seen it pushed to i know it can handle what speeds im puting it to, and it should have enough strength to spid a little impeller if it can push a truck with some 6" Tires to 75mph with a dual brushless motor set up . Plus to build a new tranny is less than buying one Boston gear that i was looking at witch is about $45.

rjmcgee

Good luck.

I doubt those little gears will have the strength to do it. It will take power to not only spin it to 50k, but to compress air into the engine. I think you would be much better off doing a more conventional turbo setup.

MaxxMitchell

iTrader: (4)

Turbos take way too much work, Headers, valves, pipe lay out, and many other problemmatic things that i dont have the $ or the time for. The super, if it does work, would be much easyer to keep maintained, and alot less work to get installed, with little modification if any to motor. In the end i may just sell the compressure housing and impeller with back plate off promoting that its close to working.

But i am goign to bench test the tranny here soon, Do u think that its goign to be alot harder to spin the impeller in the housing, or do u think free spinning the impeller would give me a good idea on whats happeing.

I think im going to hook up an electric motor to the tranny, with impeller not attached, get an amp reading, then attach impeller and maybe get the housing close enough and see how the amps change, from there ill find out about how much HP ill need to spin it, then find out from stress stesting the gears if i can make it work Got a quarter to kill in school think i got enough time to do it all

dimented24x7

iTrader: (2)

Your going to need a good gearbox to do it. There are going to be some considerable forces on the driving gear and intermediate gears/planetaries or whatever youll be using since its an overdrive application. There are also problems with resonance and such at speeds that high. If things are off by jsut a little bit or if harmonics build up youll be in trouble. All the components taht are driven must be machined to close tolerances. Regular gears probably wont do it either, youll need close tolerance helical cut gears to comprise the gearbox. Of coarse, there will also be losses since its a gearbox. As for the belts, those might work. But again, there are going to be some forces involved since its an overdrive application that has to move a considerable ammount of air. Probably need to use a cogged belt. Another problem is that there wont be much boost built up at low-mid rpms since its a turbo impeller made for use in a turbo that spins really fast whenever boost is made.

dimented24x7

iTrader: (2)

If you want an idea of the forces youll be looking at, say, 6.5 ft-lbs of torque to generate 60 HP @50,000 RPM at the impeller. Say you want to build peak boost at 5k (speed at the input gear/pulley), that would requre a ratio of .1:1 so that would be around 65 ft-lbs of torque the box/belt would have to withstand. you could reduce this by useing a small idler pully on the cars belt line to help generate some of the overdrive. Id build a saftey factor of at least 2x into it, and be careful when testing! An impeller turning 50 grand is like a bomb if it flies apart. These are just pure estimates, of coarse. Youd want to look into it into more depth.

dimented24x7

iTrader: (2)

To expand this a bit further, a belt being driven by a 2.5 in radius pulley (about the same size as the crank pully, maybe its 6 in dia? Dont know off the top of my head) at the assumed speed of 5k rpms woudl have to endure around 300 lbs of tension to generate the needed torque. Oh, haev you also considered what will happen when you suddenly rev the engine? Its going to add alot of force into the equation to get that SOB spun up to 50k, lot of rotating energy stored up at that speed. Might be better to nose around for a super charger.

MaxxMitchell

iTrader: (4)

Good points, well im still going to tryout my little RC tranny, dont laugh at it, its a proven part to handle the RPMs that will be on it, as for handleing the torque, im not to sure but ive seen the truck pull me, thats with 6" Tires, and a Diff with a 3:1, havent figured the torque on it just yet, but im confident it will hold. As for applying the 300Lbs of pressure to the pully to keep it from what sliping? im giong to get at best 30% wrap on a 1.89" pully and yes the crank is right around 6" +- 1/8", The little tranny im using has that 2.77:1 ratio, spining it backwards, going to drill into the shafts of the tranny to roll pin in some couplers or inlarged shaft to support the pully and impeller. I do plan on spining it up to full speed before installing on the car, just to see if i got it ballanced.

As for shoping around for an actuall supercharger, $ comes to mind, and if i can do it for $250 and get a modest 4-6 PSI ill be happy, just to say that ive tried it.

As for the presesion thing on gears, if i was to build my own, i havent talked to MSC yet or IBT, or Small Parts, but if my little RC tranny blows or strips the gears or what ever happens to it, then im consolting them and maybe see what they supply and sugest from the manufacture on what to go with, Then comes the presision machining of the gear box halfs. Just alot easyer to go with something premade and proven to these speeds.

Oh and the inertia thing, when i rev, i would plan on the belt sliping, but the tranny gears themself are Nylon, with a Hardened final gear with all hardened steel shafts, initial start up should only really consist of the impeller its self and the surpentene pully witch weighs more than the intire tranny.

dimented24x7

iTrader: (2)

you have to keep in mind that there are going to be some really high forces if you want to start building boost or when there is a change of speed. Like on the order of several hundred pounds or more on the immediate drive/driven gear faces when there is a change of state. Those sorts of forces will tear the teeth clear off the nylon plastic gears and really put stresses on bearings plus there is also long term reliability to consider. In addition to that the turbo impeller wont build low/mid boost since its operation range is so high. A small cetrifugal SC would be better for what you want.

88 350 tpi formula

iTrader: (9)

I think the cheapest way is to go with a cogged belt like they said above this is how powerdyne does it. and they use ceramic bearings so no oil is involved

MaxxMitchell

iTrader: (4)

Well either way sounds like $ and unfortuneitly im out of it for a while, so project posponed