XJR S/C whine ...
 

I am hunting a power-problem on a Daimler Super Eight, and start to suspect it is the S/C not functioning.
Seeing the below video, at what RPM does the S/C whine become pronounced, clearly noticeable over the engine sound?

From the get-go, you can hear the noise on that video clearly - from 7 seconds in it's right there. If I have time today I'll shoot a video but have to visit my father in hospital so no promises.
The whine is from the straight cut gears running twice engine speed, and it's noticeable when you role the throttle via the TB cable with the bonnet is open.
Sounds like the SC is goosed?


Here's a wonderful flat-out Eaton, any excuse to post this video again ;)

The question remains for you XJR drivers; at which RPM do you start to hear the charger coming in?
Finally the weather is clearing, and tomorrow I will give it one final full acceleration, listening if I hear the S/C on this car.

Sean, I still don't get how a S/C can be goosed.
Less boost, yes, but hardly anything?
(by the way, checked the boost valve, but seems to work perfectly :().

Eric, how about you make and post a video of the engine revving bonnet up so we can at least hear what this engine sounds like? Have you dropped the belt off and checked for play?
The only way I can describe the SC noise is like a Kazoo! rising and falling with engine revs.

I wonder if it's belt slip? A destroyed coupler?

In that video it mentions the hood insulation is removed which makes it sound louder than it would otherwise.

On mine I never noticed a particular RPM where it becomes loud, throttle input makes more of a difference in sc whine volume than RPM does.

I completed my new findings in the original post.

https://www.jaguarforums.com/forum/x...5/#post1785306

I know it is hard to judge on a YouTube video, but maybe you can have a listen to the sound at acceleration, and judge you hear the S/C?

Appreciated!

SC sounds fine.

That's what I thought as well ... so now the million dollar question is why the car behaves like a slug?
I am still thinking the boost valve, as it is the easiest explanation to loose boost on a functioning S/C?
Or can old / bad plugs and the sensor really take so much power away without showing any other hickups or problems?

Check the TP% at full throttle with a scan tool, just checked the brothers new purchase X308 3.2 1998, TP was no more than 69%, adjusted the outer cable and achieved 100%. Different car now :)

Yeah, I saw your thread, always a good move.
I actually did this as one of the first things, got it up from ~70% to 96% at full throttle, but it did nothing to the main problem of a lack of power.

Install a boost gauge to the SC outlet cover's vacuum line and measure the readings.

Mine now only reads 5psi max , so we might have similar issues ;)

Update: Spent yesterday afternoon with the owner courting several possible repair shops, and decided we will work with UK guy and his American/Taiwanese business partner, doing a lot of road cars like Mustangs and the like.

Will bring the car in for a final check next week, but basically I am sourcing a rebuilt S/C (plus a million other parts ..).

I saw several companies in the UK and in the US offering replacements, but any suggestion is welcome, and if anyone has a left-over in the garage, let me know, I might be interested :).

Is the problem with the SC for sure? Not second fuel pump offline? Maybe talk to Lawson @ powerhouse, once they get the sc off you should know what route to take and then make the call on either rebuilt or get the kit to refurb.

I have to agree with Sean; check fuel pumps. More insidious would be failing coil packs. All went wrong on my XJR: secondary pump, an A bank coil, then a B bank coil. power loss from the coils felt similar to loosing the pump, but got much worse (as they died more) over time.

Yeah, with my limited experience, but after a lot of ruling out, I am rather sure it is SC related.
Both pumps are working fine, cross checked as well, pressure stays up.

These things are hard to diagnose, let alone for you from a distance, on a forum, based upon my crappy English, but the main issue here is that the car drives beautifully.
If there should have been a hard-spot, some reluctance, a dip during acceleration, a burb, or something like that, I should suspect an item as mentioned.

However, the car drives like a Jag should, smooth, shifting correct, it goes through the RPM range super smooth, it picks up without an issue, nothing.
It is just that it should all that with a punch, and it doesn't ...

I unfortunately don't have the facility nor the time to do this work in my underground garage for him.
So I can't dig deeper one-item-at-the-time, as I should have liked.

And to prevent the car waiting for weeks outside for parts at the indy, we have to think a bit ahead.
As we all agreed yesterday that the S/C makes various noises at various places, we decided to take the leap and buy parts and a replacement in advance (this pending a boost test and opening up the S/C next week as a final test).

I will let you guys know, your help was much appreciated.

PS. I did a OBD2 Torque Pro run, and measured the power as I did on my own XJ8, but with the XJR input.
I know it's only a very rough calculation, but both using MAF, and the direct result came out just under 300HP.
That confirmed my initial thoughts rather well, it drives like a XJ8 :).

Wow your engine sounds extremely quiet in that video compared to mine. Not the SC noise, but the rest of the mechanical noises of the engine. I'll have to get a video of my blower as well (which I suspect is worn and I have a replacement waiting on bearings and free time).

you really should put a boost gauge to it for this diagnosis . before buying another or removing its blower .
as low power can be many things .as stated . check both fuel pumps are running .
this can be done via obd .
also clogged catalytic converters are well known to do this al so .

[QUOTE=Sean B
The whine is from the straight cut gears running twice engine speed,


are you sure ? my twin screw SC has angle cut gears and screams like a meerkat also!

i thought the sound was the rotors cutting wind and allowing the sound back past the TB when open , most of my scream came from the air box not the blowers gearbox. ?

oh year that is boosting you can not only hear it but see it ,
if you disconnect the blower belt then do that lap again you will be lapped repeatedly , these things are super gutless with out boost .

[QUOTE=Datsports;1790443][QUOTE=Sean B

are you sure ? my twin screw SC has angle cut gears and screams like a meerkat also!

?[/QUOTE]

@Data trust me - it's the gears :) Bevel cut is more civilized, but still creates that distinct noise and it travels.

I'd hold off buying another charger until all the basics are checked, it's easy to blame the SC but they're a simple thing with not much to go wrong and when it does you definitely know about it in noise. The worst thing is putting all faith in replacing a part only for it to behave in the same way. More diagnosis required.