are yall gonna make me give up my secret? dont do it to me... ok ok ill say it since anyone that has a FF and MM mag has read it anyway... look up rotrex.... they are frictiondrive planetary gear style setups... very quiet at idle and they are able to spin way faster than a gear driven unit making them quite small... mount that lil buddy on the botom of the motor... run some tubing up in the stock location... a lil methonol injection to keep an inter cooler out of sight and bam sleeper supercharger.... ok so its not that easy, but thats the fundementals of the plan...

-me

 

Just looked up Rotrex and I can definitely say that I had never heard of either that company or that type of forced induction system. Seems pretty interesting, but I'm going to have to do some more research on that one before I can give a true fact based opinion. By the way, how soon do you plan to do your install? I've very curious to see how that plays out for you.

 

i dont know... i would like to do it asap... ive considered doing it on my stock motor so i can try to get a kit together for it, maybe try to put it out on the market in small quatities... right now i got no money and it would prolly cost around $5k to do... soooooo that is really a hiderence... one of my buddies has a 99 cobra and he is thinking about the same thing since there are vitrually no mounting kits out for these things so we might go in together and do it all at the same time...

-me

 

I have heard of Rotrex SCrs but only, I think, on small light plane applications - they are small and lvery light and syet generate a lot of boost for their size, so they work well in that application when those characters are critical.

I will be interested to see just what happens with one.

I am not dissing the idea (I like it) but want to make a couple of points. Like most complicated devices the engineering for superchargers is a tradeoff among desired characteristics, and although you can get high boost and volume with small chamber size by using very high RPM, that alone will not exactly replicate the performance of a larger unit operating at lower RPM. My favorite example here is the Magnusen (which I once owned and loved on a stock block vette) which is similar in design to, but much smaller than a Weiand 6-71, but runs at about 2-3 times the RPM to generate similar boost levels. However, it generates more heating and has a more exponential boost curve than the Wieand: 6 lbs of Magnusen boost will not perform as well as 6 lbs of 6-71 boost. Of course, here the size makes a big difference on where and how you can fit it.

Where I am going is: the same ought to be true for the Rotrex versus, say, a Vortech, etc: I would expect it to build boost mostly at the high end and with a of heating of the incoming air, so if it were my project I would work hard to fit an intercooler, preferably a big water cooled one if I could, or an air to air one with an added alcohol spray cooling.

 

yeah there is alot more thought that needs to go into this... but i think it would be cool to do... but like i said $$$ is a problem... im not sure about the heating... and the car market is starting to use them... i think nissan and bmw are working with them... and i understand about the boost being developed at higher rpms... that is a slight issue... hmmmmm something to ponder... like i said all just ideas that i would try if i had infinate cash... and i will prolly try in the future, but right now... it hard to say when it would happen...

is constant boost bad? lets say that you could develope a constant 6 psi... like with an electic unit... is that bad... does the curve need to climb? if not you might be able to use damn whats the name (where one pulley grows and the other shrinks as rpms increase) to give you like a constant rate of boost, or atleast keep the superchager spooled at lower rpms... you kno for example at 1000 rpms its spinning at 20k and at 6500 its only spinning at like 35k (backwrds from the way pulleys are mormally used, but im sure it wills till work)... so you dont over boost, but you have boost down low still...

keep the questions comming yall are bringing up good questions... and being a mechanical engineer i like to try to solve problems...

-me

 

Yeah, I have really wondered about using an adjustable radius pulley, somehwat like in a cheap CVT to make an adjustable pulley on a SCr. You could run it so it provided lots of boost down low but did not overboost up high, etc.

My Sears riding lawnmower has two such pulleys in its transmission (many small riding lawnmowers do, particularly those made by MTD ) and I took it apart to study the pulleys (I had to anyway because the damn thing never worked from day one -- kept throwing the belts, so I had to take it apart and modify it anyway). One complication with this idea, is that a 'vette sized SC requires between 50 and 100 HP at max RPM and boost, and I think the best of these moving radius pulleys with a normal "V" belt will handle is about 35 HP.

 

i might be wrong on this, but i think the power required on the rotrex unit is quite a bit lower... so it might come in under the hp load that the cvt can handle... there has to be something wrong with the idea though... other wise someone else wouldhave done it...

hmmm maybe a duble unit kinda like a turbo set up... one geared to pull hard on bottom thats on a clutch and dissengages when boost is too high... another that spools up to the right rpm range for the top end... :shrug: but that pretty much defetes the purpose of the size... i guess you could always gear a single for loow end response and just waste gate the excess on the top end...

-me

 

The HP required to turn a blower is pretty much the same (within 30%) regardless of SCr type -- they are just big air pumps and while some designs (usually the large chamber, low RPM ones) are more efficient than others, no design will do significantly better than the others. Most Rotrexs I've seen are for smaller (2 liter) cars and probably require no more than 30 HP tops. A Rotrex than can blow something serious into an LS V8 will need to have at least 50 HP (my back of the envelope computation for high efficinecy at just 4 lbs of boost, the minimum that would make any positive difference at all). It might be possible to make the pulley system work to that level but not much more, and they would need to be pretty big pulleys (and belts) -- it might not be light or small.

 

so we are basically facing the delima of moving volume... without volume we dont have pressure... because our motor gasp for sooo much air... IFF these tings are as compact as they say they are... i would almost be willing to run a dual setup... one mounted low on each side of the motor... (dont know whats down there now might re consider this when i know). surely 2 of these things could handle a v8... damn it i dont know... and maybe they have started branching out with some bigger models... it was in ford builder and they were saying you could easily make a kit for a stang...

without 9 or 10 psi its not even worth it... i dont know... thats y i would do it if i had infininate cash... so i could try it out and see what worked best...

-me

p.s. im getting sleepy and cant think...

 

ok so im thinking mods for next winter when the car goes int he garage...

CAI... trying to find a cheap ls6 intake... underdriver pulleys... different rockers (advice here)... short throw...

that should be enough to keep me entertained and infront of my buddies cobra till i deside what im doing in the long term... how much you think i need to save up for all this and yall have any other lil things that need to be added to my list? you know if i could get her up 25 or 30 horse from stock... just something to give me a lil jump im cool for now... well untill my buddy strokes his camaro... then i will prolly not be the fastest on the block anymore...

-me