For all those now asleep - ZZZZzzzzz.......
I'm going to leave this stuff for now and get a real life...!
cheers.

 

Not much benefit of putting a LYS2300 on a C32/SLK32
Here's a copy of a post I just put on over at the SL55 and C32 Forums.
Originally I was looking for rebuild advice at the SL55 forum so I could get a cheap 2300 and refurbish it for the SLK32, but now I'm really wondering about the gains.
It is same info as per my previous posts below - but worded a little differently.

..........
What I've learned so far is that both the 1600 and the 2300 are very similar except for...
1) The front snout of the 2300 has an additional gear set in it to drive the main rotor to; 6200 x 155/91 x 1.35 = 14,288rpm + the meshing gear to drive the 3 lobe rotor to 5/3 x 14,288 = 23,813rpm
2) The front snout of the 1600 on the SLK32/C32 only has the mesh gear - but the main rotor is driectly driven by the pulley to; 6200 x 155/74 = 12,986rpm + the meshing gear which drives the 3 lobe rotor to 5/3 x 12,986 = 21,644rpm.

So you can see the 2 have very similar specs in relation to the bearing speeds - so I would safely assume they are of very similar construction. I was originally under the impression the 2300 was spec'd differently, but I'm not thinking that any more.

When you work out 2300 cc/rev versus 1600cc/rev
I'm currently assuming the /rev is per rev of the pulley shaft.
If you assume 1 rev of the main 5 lobe rotor (female/cavity) does this 2300/1600cc
1) for the 2300 you only have to turn the pulley 1/1.35 times to make one rev of the female rotor
2) for the 1600 you have to turn the pulley 1 time to make one rev of the female rotor.
So the 2300 has an internal 1.35x advantage.
If it didnt have this internal gearing, it would only do 2300/1.36 = 1700cc/rev against the 1600 which does 1600cc/rev.

The other key difference I've established is that looking at the 2 units in the engine bay, the 2300 has the teflon coated male/3 lobe rotor on the other side (drivers LHS). This is because it is driven through the additional internal gearing set in the snout, whereas the 1600 has it's 3 lobe male rotor on the drivers RHS because the pulley direct drives the 5 lobe rotor.

Now for constructability - if I was manufacturing these for profit - to minimise costs - I would use the same rotor profile but just cut one longer/shorter to fit.
This leads me to belive there is maybe only a 10% difference between the lengths of the 2 rotors - the 2300 being 10% longer.

Externally - I measured my rotor case at 220mm and from comparable scaled photos I've measured the 2300 at 278mm. But I havent taken into account bearing beds and the like - hence why I am chasing the actual measurements to confirm the hypotheses above.

It was all very interesting 'cause I started out fantasising about the effect of replacing the 1600 on my SLK32 with a 2300. I was thinking efficiency improvements and air flow. But if they are very similar rotor designs/profiles, the gains would be minor. The main difference between the isoentropic charts would be that the 2300 is simply a 1600 stretched out by a ratio fo 1.35 + 10%.
In the end, the rotor bearing spec and rotor balance tolerance/harmonnics may limit the gains and you end up with only a minor benefit of a 10% volume increase per main rotor rev. A similar effect could be had by simply increasing my crank pulley by 10%.

It has been a time consuming but I think a beneficial hunt to say the least.

I need these rotor dimensions....please someone!
............

 

A bit of an update.
Seems a little bit of an anti-climax (for moi) after hours of research but....

The rotors in the IHIS105 and it's bigger brother....the IHIxxxx (still don't know the designation - help appreciated) are different;
- at 183mm v 223mm or about 22% (infered from the pictures previously but removing the clearance for the bearing journals). Given my error in measurement, they may have made it even simpler and made them 7" (178mm) and 9" (229mm) which would point to a 29% length increase. However.....
- they also have different a helix setup. Strangely enough I've established they both go for a rotor twist along the complete length of the female rotor (5 lobe) of 180deg. More than likely a predetermined key performance sweet spot for IHI, and
- the rotors seem to be of equivalent diamater in each unit - around 127mm for the high speed 3 lobe and 105mm for the 5 lobe. Again this may possibly be simplified to imperial dimensions by rounding to 5" (127mm) and 4" (102mm).
- They seem similar, but I'm yet to confirm if the lobe profiles are the same - I suspect so, they appear to be from all the picks I've reviewed.

The interesting thing here is that the female rotor in each still only does half a twist (180deg), just over a longer length. So given the rotors are effectively rotating at the same speeds in each unit and the rotors are similar diameters, the added capacity is driven by the rotor length and I guess it's ability to draw/screw more air, rather than capture/bite more air.

- as mentioned before, the teflon, high speed, 3 lobe rotor is on different sides for each. I've established this is because the female 5 lobe rotor is to be the driven rotor in each case.
I did read somewhere that one rotor likes to drive and the other gets driven by the air.Will add if I find the link again.

- another thing of note is the large difference in the discharge ports, the SL55 unit being almost twice the area as the S105. You can also see the different rotor pitch in the "silencer plates" and how they are cut at different angles. I did find a port job done on a C32 SC over at the MB forums, to remove some of the material, but I'm not sure of the benefits.

- from all this deduction - if you look at tip speeds of the 3 lobe rotor, at 127mm and a stock SL55 at 23,813rpm you get 158m/s or 520ftps. If you crank it to ~17,000rpm with a 65/178 stacked arrangement on a SLK32/SRT6/C32 - the 3 lober is getting to 28,000+ territory and you're hitting the 617ftps, 423mph or 188m/s.....I guess speed is a relative thing.

I could add some pictures...will see.