Hello
(I don't own a Jag, in the stage of considering x-350.)

In several videos I have heard this guy saying that the SC in XJR (x-350) engages only when needed: I believe SC is engaged at all times, as it is (unlike turbos) mechanically linked to the engine itself. Am I wrong?

Cheers

 

You are not wrong.

 

The SC is turning with the engine at all times.
The BYPASS VALVE is used to recirculate intake air until boost is demanded.
There is no forced induction until the BYPASS VALVE closes and then the air is FORCED so technically it remains idle until required.

bob

 

Thanks a lot! (I am going to google more on the bypass valve.)

So in the video Valentin Cristea was not completely wrong either, only maybe not very accurate.
I assume he was trying to get across the following message "if your foot is light, forced induction can be avoided and you can drive almost-almost-economically with this car..."

Is it correct to say the valve closes only under HARD acceleration?

(Hopefully next week I will get to test drive x-358 V8 VDP, I am afraid it is not SC'ed though.)

 

I can't now find the description of the bypass action that I read but I got the impression that it just closes progressively with increasing RPM.

 

The only XJs with the SC are XJ R, XJ Super 8 and the rare Portfolio Edition.

 

The bypass valve ... yes found it ... its actuator is operated by the vacuum developed across the throttle valve; as the thottle opens the vacuum progressively diminishes and the bypass progressively closes.

 

Yes, I kinda go along with this, even though I read somewhere that what used to be called Vanden Plas was at some point "rebranded" to Super V8. But I believe that was limited to US.

 

Usually an SC car has a lower compression off boost than the equivalent NA (non-SC) car, and slightly worse MPG.

But.... if you're driving a V8 Jaguar and worrying about MPG.... really???

And worrying about it with an SC... nooooooo.

 

The X350 Super V8 was available from launch, basically a XJR with Vanden Plas interior. The Vanden Plas name was used in the US for N/A 4.2 X350 with upgraded interior, ect. Later there was a Daimler Super 8 launched in '06, however the Daimler name was not used in the US, due to licensing restrictions from Mercedes.

 

I was trying to understand what the remark "SC only kicks in when needed" meant, it was made just after the mileage was mentioned. (5:50 in the video)

 

Motorcarman's explanation is correct. When the engine is running so is the supercharger all the time.

When the engine is just idling or at low rpms the bypass valve opens so that there is much less to no boost . Also it opens when the accelerator pedal is lifted immediately after say a wot run.

So the supercharger even tho running all the time is not necessarily supplying boost all the time. Obviously it is when under hard acceleration.

 

Thank you folks

 

Well to be absolutely correct, there were a number of different X350/X358 with superchargers...

XJR
Super V8 SWB
Super V8 LWB
Super V8 Portfolio 2006
Super V8 Portfolio 2009
Daimler Super Eight
VDP Supercharged

The VDP Supercharged was the same spec as the Daimler for the US market, as previously mentioned the Daimler name was a legal clash with Mercedes...

Either way they are all relatively rare cars... worldwide sales figures;

Super V8 SWB, 1309 units
Super V8 LWB, 943 units (does not include the Portfolios)
XJR, 7316 units (includes the XJR Portfolio)
Daimler Super Eight, 853 units
VDP S/C and Super V8 Portfolio, 1277 units

Trying to breakdown the combined VDP S/C and Super V8 Portfolios

2006 Super V8 Portfolio, 265 units (confirmed)
2009 Super V8 Portfolio, about 300 units
VDP Supercharged, about 700 units

You should have more luck finding a VDP Supercharged in the US than a Portfolio.

 

Any Sovereigns with S/Cs ? (Or is that covered by 'Daimler' ?

Any LWB Sovs with S/Cs ?

Any LWB Sovs with S/Roof and S/C (well I can dream can't I ?)

 

Patrick the cat, is that not what a Super V8 is for?

Cambo, what is the difference between a US Super V8 and a VDP Supercharged?

 

Same difference between a Daimler Super Eight and a Super V8... not much lol

 

[QUOTE=Cambo;... worldwide sales figures;
Super V8 SWB, 1309 units
Super V8 LWB, 943 units (does not include the Portfolios)
XJR, 7316 units (includes the XJR Portfolio)
Daimler Super Eight, 853 units
VDP S/C and Super V8 Portfolio, 1277 units
.[/QUOTE]


Just ran across this thread - is the 943 Super V8 LWB the total production for all years? If so I didn't realize they were that rare.