Why doesn't some ingenious engineer or machinist or combination thereof come up with a set of rotor packs that will fit the eaton m112 case but operate under the Lysholm (twin screw) principle. We could then utilize existing cases with our only expense being a rotor pack and a newly designed air induction to use the rear inlet type in lieu of the top.

 

I don't know where they are with this; but, when JDM came out with the Magnum Powers blower case, there was talk of a future twin screw replacement for the rotor packs.

 

I was just thinking the same thing. It would probably be a lot cheaper and make more since then spending 3g's.

 

Not trying to be to much of a smart azz here but that would be like putting lip stick on a pig.

It would still be a 112 cu in blower for one, number two the twisted helix of the screw type rotors are the hardest part about making a screw charger.....thats were all the money goes and three if I'm not mistaken didn't you say make the stock case a rear entry.....I'm not going to touch that one.

 

Spend some time in School.. then in the field... and you'll understand that it would very much be like putting lip stick on a pig. Maybe like putting a SBC in a other wise stock yugo? The *case* that it's in just could'nt let the improvement really show it's stuff. Everything is a system. Whether we like it or not. Power adders are dependant on other parts to make it perform well.

Now, that's not to say that the stock eaton is "bad". It's not bad at all. It's an already tooled assembly (lower costs) and pretty much plugs into our application with some new intakes.

It's all about efficiency curves, support systems, and costs. Notice our Lightnings can be had for under $30K? That's a key factor as to what makes this truck so popular.

Rich

 

Although Screw is known and associated to bigger power increases, that doesn't always mean it's better. For instance some people don't know it, but they're running their Screw S/C's out side the MFG acceptable tolerances, "AND WRRNTY"

As said the diff is more related to larger displacement, (which is a must with a screw due to it's design). That doesn't mean you cant make a 112 cu in Roots kick ***.

If you'd really like to read some extremly technical diff between the two, I just did a story on it HERE

A few quotes from it.

Although the mathematics becomes involved the result is the screw rotor requires about a 17% larger unit volume to displace the same volume of air compared to a roots rotor of equal airflow capacity.

A very good article comparing a screw supercharger to a three-cycle Eaton supercharger was published in the June 2002 issue of Muscle Mustang and Fast Ford. In this article the test results comparing a screw supercharger at 9-psi boost to a stock Eaton M112 also at 9-psi boost was documented, the screw supercharger made 16 more hp under these conditions. Although significant these hp gains are not that impressive. It should also be pointed out that heat is generated within the twin-screw compressor because air is compressed within the supercharger causing the supercharger to become hot unless provisions are made to cool it.

All screw compressors are of an asymmetrical design having male and female rotors with the male having fewer lobes then the female. One popular screw supercharger has a 4/6-rotor configuration. The male rotor has 4 large lobes mating to the female rotor that has 6 large cavities or channels. Most of the air flows through the large channels of the female rotor since the channels in the male rotor are very narrow and have little volume. Since the male and female rotors are meshed they must turn in unison therefore the male rotor with only 4 lobes must turn 1.5 times for every turn of the female rotor having 6 cavities. For instance if the female is turning 18,000 rpm the male rotor must turn 27,000 rpm to keep up. The supercharger’s drive pulley is typically connected to the female rotor so the male rotor is turning 150% faster then the drive pulley in this example. Some screw supercharger providers limit their warrantee to 18,000-rpm pulley speed. Another Twin Screw supercharger manufacture has a 3/5-rotor configuration. This supercharger in order for the rotors to mesh properly has a 3 to 5 internal gear ratio therefore at a pulley speed of 18,000 rpm the male rotor must turn 30,000 rpm to keep up.

 

I don't see that as a story, looks more like an ad for a MP supercharger to me.

 

Working on it, and that's all I will say. It won't be a true screw design, sort of a hybrid.

A few years of Fluid Dynamics and a little bit of CAD design on my side...

 

Rotor pack redesign would only be one element; the blower discharge orifice would have to be redesigned, meaning people that have already ported the blowers would (not) be screwed, if you don't mind the clever pun. Also, the 4 silencer ports would have to be plugged, meaning welded.

 

If they come out with a twin screw rotor pack then would the cost still be under a KB? i mean 1,700 for the nose and case. That leaves the screw rotors needing to cost less than 1,300 to make a magnum a cheaper twin screw. But say they are like 700-800 you could make a stock eaton scream with some mods to the case like already mentioned. I guess time will only tell since i have no clue how much the rotors might even cost.

 

Well ya kind of : o )
But the facts are a screw design does spin one side faster than the other, and with the Pulley Combo's some are running, that may be outside the acceptable range, (which would explain why some of the cases look like a screw after minimal use, no pun intended, ) And when comparing both "at the same lb of boost", there really isn't a world of difference in power with one over the other, even when the Screw has a much larger displacement.

The power is made by using more boost in a more efficient way, both a Screw and Roots is capable of doing that. What I learned from that article was a screw does it by spinning one side 1-1/2 times more than the other, with the Magnum Powers, you simply do it by running a larger lower Pulley, the end result is the same, your spinning it more internally, and the case design for both allow you to do it at a much lower inlet temp (maybe as much as 1/2 the temp on a Magnum) where as the Screw design may in fact make more heat "under normal daily driving conditions" in which 95% of my driving is.

If I can reach my goals for 1/2 the price, stay with the reliability of a Roots design, and keep inlet temps down, I'm sticking with the Roots design Thank You, especially when it's advertised to spin efficiently up to 24000 RPM,

 

If you believe that, you have definitely fallen over the edge. (Well, that's a bad statement, we all know you are over the edge already.)

Pulley a KB for 15psi and pulley an MP for 15psi on the same engine. The KB will make more power.

On a BUILT engine buying a MP might make sense if you are going to run some HIGH boost with it. On a stock block either stick with a ported blower or get a KB and pulley it for 15psi. At the 15psi level, the KB will kick the MP's butt even with the MP pushing 17+ psi and the KB at 15.

 

Keep me posted on your findings. I am interested in how it works out.

 

I'd be the first to say I'm totally out of my mind, hehehehe
and soooooooo misunderstood

Yes the KB will have some more power, it'll also have 1 screw turning 1-1/2 times faster than the other one, so to compare apples to apples you would need more Pulley on a Roots, which is where a Mag is designed to work best.

 

I was a pump engineer for 6 yrs.. and have been on 5 different high end cad systems for 13 yrs.. Believe me... the gains don't warrent the costs using the stock casing.

Just my 2 cents, Rich