The snout is just a shaft that connects the pulley to the driven rotor gear. There's no gears involved in the system other than the two rotor gears.

You are correct. I was thinking there was another gear wheel and of course there is not.

Helical cut gears have more tooth mesh vs. straight cut gears so they run smoother and make less noise. You could say they require less power to drive but I don't think it's enough to measure. The Teflon coating allows and tighter clearance so you get less 'slippage' between the rotor noses and the walls.

I think the porting gains were in making the blower run more efficient but it's still boost capped by the processor.

thats what i was thinking , changing the size of one or the other or both gear wheels would be catastrophic !

Yes but this is because of the addition of VVT to the S/C engines for the 2006MY, also the ECU was changed in 2006MY to a totally different unit, this is where the 10hp comes from, nothing to do with the supercharger itself.

EDIT

And since this discussion would be in regards to an X308 XJR, not the later X350, it's neither here nor there.

If a Twinscrew is not an option (because reasons) and you are going to stick with an Eaton, then my suggestion would be;

Get a Gen5 M112 from a 2006MY onward XJR, STR, XKR or XF SV8.
Put a "1.5lb" pulley on it, not a "3lb" which needs the snout machined.
Put a bigger pulley on the crank, since the pulley on the AJ26/27 was smaller than the later AJ33/34

Don't bother with porting or any of that stuff, not worth the money.

no the boost is not capped by the processor .
its capped via pulley sizes . hence you can up the boost with a smaller top pulley or a larger bottom pulley or both .

also bang on but you can't say helical gears use less power as that is not the case .
strait cut gears create no thrust therefore use less power . but are significantly louder .
most race cars use strait cut gears in there gear box due to the inherent power loss of helical . and gear box sound is the last thing on a race car drivers mind . unless theres crunching sounds .

you know its funny i was going to pull that supercharger for MY XJR

Heh, unfortunately it looks like it's gone now, it was there a lot longer than they usually are. Meant to pull the "v8 plate" and peek at the rotors, but life and other things got in the way... I already got a blower for mine from another STR there during the 40% off sale just needs needle bearings and fresh oil.

Hello everybody, I think that I have found an engine for my car. The engine comes from a 2001 XJR (like mine) but the engine was manufactured in may 2000. That means it has Nikasil lining. I have read a lot about the problem...but my theory is that the engine should be good since high sulfure petrol was banned in europe since 2000. However, there is no way to check if the car suffered heating problems.

What are you thoughts on this ? the engine has only 75'000 km's

Thanxs for your feedback

This doesn't sound like the most promising procedure since it states the engine is in the vehicle, but give this a read from Jagrepair.com ...JagRepair.com - Jaguar Repair Information Resource
Here's a related updated article.....http://jagrepair.com/NikasilandSulfur.htm

hi highhorse, I am not sure what you mean by "This doesn't sound like the most promising procedure since it states the engine is in the vehicle" ?

You had stated you found another motor, usually that means one that has already been removed and is sitting on a pallet or in a vehicle that is not functional. Since the stated procedure says its in a running vehicle is why I said such.