Jaguar 4.2 Supercharger upgrade

[NormanD]

I'm sure Lawson does, email him, say NormanD gave you his details

[e-mail]
Phone: [phone]


The other person to talk to is Tom [e-mail]
0118-976-2899

He can suply and fit the KenneBell twin screw supercharger
That will give one hell of an improvement

Edited by NormanD on Monday 31st March 22:33

[Tame Technician]

Basically its goes like this.

6% smaller top pulley, £130 ish, no machining required, approx 1.5psi boost increase. No need to remap the ECU, it will adapt and fuel trim its self to fuel correctly at the level of boost.

http://www.ebay.co.uk/itm/150915402983?ssPageName=...


10% smaller top pulley, £130 for the part but additional cost as the nose of supercharger needs to be machined or ground down. Approx 3psi more boost. Also as I understand it no need to remap the ECU,but more power gains can be had if you do.

http://www.ebay.co.uk/itm/Jaguar-XJR-XKR-S-Type-R-...


Next step is the twin screw as Norman points out, but if you have a 4.2 engine this option is likely going to cost more than the car. Have seen it on american jag forums for $6k.
http://www.eurotoysltd.com/catalog/product_info.ph...

I have to wonder, if lower compression pistons or high spec bottom end might be required to put up with the increase boost from the twin screw. Charge cooler might need upgrading also and a remap will definatly be required, maybe different higher flow injectors to make the most. But they say extra 200bhp is achievable.

[Tame Technician]

charge cooler upgrades bigger more efficient rad

http://www.ebay.co.uk/itm/Jaguar-XJR-XKR-Uprated-P...

And higher flow pump

http://www.demon-tweeks.co.uk/motorcycle/water-pum...

I'm sure some one does a kit with both, and the pump correctly rated this was just the first one google found.

[NormanD]

Tame Technician said:

Next step is the twin screw as Norman points out, but if you have a 4.2 engine this option is likely going to cost more than the car. Have seen it on american jag forums for $6k.
http://www.eurotoysltd.com/catalog/product_info.ph...

I have to wonder, if lower compression pistons or high spec bottom end might be required to put up with the increase boost from the twin screw. Charge cooler might need upgrading also and a remap will definatly be required, maybe different higher flow injectors to make the most. But they say extra 200bhp is achievable.

EuroJag uses a 2.1Lt TwinScrew, TLJaguar uses a 2.6Lt TwinScrew

I have that on my XKR, now problems with the bottom end
And as TT says, a lot of extra Horses

[a8hex]

Is there much point without also replacing the backend to a limited slip diff?

[Tyre Smoke]

Just jumping in here, I have done the smaller top pulley on my Rangie, with the machining done to the nose of the Supercharger, and it made quite a noticeable difference. Not sure the gains from a twin vane charger would be justifiable on a big ol' Rangie (cost vs performance).

One thing though, I've decatted the Rangie which makes a 25% difference for the better in fuel consumption and another increase in both power and torque, however I have the engine management light on. This is due to the lambdas picking up no cats. First off, I thought the ECU wasn't picking up any noticeable change in emissions from the pre-cat lambdas and the post cat lambdas (obviously!) so blanked off the post cat lambdas holes in the exhaust and left the lambdas in fresh air. Still the same problem. I guess I'll have to get the ECU remapped to cure this? i.e. not pick up the emission settings?

Any other ideas, chaps?

Apologies for the hijack.


Just for info, I have a MOT friendly garage.

[NormanD]

a8hex said:

Is there much point without also replacing the backend to a limited slip diff?

Yes I've also got a Quaife LSD as well as a Manual gearbox

TLJaguar can supply that as well

[Tame Technician]

Tyre Smoke said:

Just jumping in here, I have done the smaller top pulley on my Rangie, with the machining done to the nose of the Supercharger, and it made quite a noticeable difference. Not sure the gains from a twin vane charger would be justifiable on a big ol' Rangie (cost vs performance).

One thing though, I've decatted the Rangie which makes a 25% difference for the better in fuel consumption and another increase in both power and torque, however I have the engine management light on. This is due to the lambdas picking up no cats. First off, I thought the ECU wasn't picking up any noticeable change in emissions from the pre-cat lambdas and the post cat lambdas (obviously!) so blanked off the post cat lambdas holes in the exhaust and left the lambdas in fresh air. Still the same problem. I guess I'll have to get the ECU remapped to cure this? i.e. not pick up the emission settings?

Any other ideas, chaps?

Apologies for the hijack.


Just for info, I have a MOT friendly garage.

If you let the down stream lambdas dangle, they log a different code like signal too low or something, but you still get the light.

You need to have someone who is handly with electronis make up a litle circuit board that turns the 12v lambda heater signal into a 0.5-0.6 volt constant voltage to feed back to the ecu.

Or they make mini cats they fool the sensors, but you need a lot of space down by the down stream probes for this.

http://www.bigdaddiesgarage.com/mini-cat-cel-fix.h...

[Tyre Smoke]

Thanks for that!

Off to do some research!

[NormanD]

Tame Technician said:

Or they make mini cats they fool the sensors, but you need a lot of space down by the down stream probes for this.

http://www.bigdaddiesgarage.com/mini-cat-cel-fix.h...

I know someone that has fitted then

They didn't work

[Tyre Smoke]

For anyone who is interested, I think I have a solution for the EML being lit. Total cost via Ebay £5.82. Will need a bit of soldering, but here's the plan:

Assuming you do want a 0.5 DC voltage, then the correct way to do this is a resistor, a zener diode and a trim pot (variable resistor). A 560ohm 1/2w resistor from the nominal 12v supply connected to a 1.5v zener diode which is then connected to the ground side. A 500ohm trim pot is then connected across the zener diode and the output voltage taken from the centre of the trim pot and ground. The pot can then be adjusted to give a suitable output between 0 and 1.5v

I'll let you know how I get on.

[Tame Technician]

Sorry I perhaps should have said before, the ways i listed were cheap trick, the correct way to get rid of the light is the have the ECU remapped and programmed to ignore the down stream sensors.

Regarding the electronics trick, Just remember the cars battery voltage wont actually be 12v, with the engine running it might be as high as 14.

But the ecu wants to see a nice flat line from 0.4 to 0.6 ish.

[Tyre Smoke]

Yeah, hence the variable resistor. Reckon on about 14.4v running.

When turned off via fault code reader, the EML takes about 20 - 40 miles to come back on, so my (useless) logic would say set the electronic foolery to give 0.5v steady at engine running 14.4ish volts.

Less than 2 pints of beer to see if it works or not.......

Also, probably a bit more room in the Rangey to fit the electronics in.

Once again, apologies OP for the hijack.

[s1v8esprit]

Tyre Smoke said:

Yeah, hence the variable resistor. Reckon on about 14.4v running.

When turned off via fault code reader, the EML takes about 20 - 40 miles to come back on, so my (useless) logic would say set the electronic foolery to give 0.5v steady at engine running 14.4ish volts.

Less than 2 pints of beer to see if it works or not.......

Also, probably a bit more room in the Rangey to fit the electronics in.

Once again, apologies OP for the hijack.

Update please did this work out?

[Piersman2]

s1v8esprit said:

Tyre Smoke said:

Yeah, hence the variable resistor. Reckon on about 14.4v running.

When turned off via fault code reader, the EML takes about 20 - 40 miles to come back on, so my (useless) logic would say set the electronic foolery to give 0.5v steady at engine running 14.4ish volts.

Less than 2 pints of beer to see if it works or not.......

Also, probably a bit more room in the Rangey to fit the electronics in.

Once again, apologies OP for the hijack.

Update please did this work out?

Yep, I'd like to know as well. My last XJR (a 2008 4.2) spent 2 years in my ownership triggering the cats warning light every few days. No one could find any issues or reason for it, changing the cats out eventually didn't even make any difference. Mind you I believe the later cars were a more stringent emissions standards than the earlier ones and more prone to erratically triggering these warnings. It might make the 'tricking' of the ECU with electronic trickery easier on early cars.

[Dodsy]

Piersman2 said:

Yep, I'd like to know as well. My last XJR (a 2008 4.2) spent 2 years in my ownership triggering the cats warning light every few days. No one could find any issues or reason for it, changing the cats out eventually didn't even make any difference. Mind you I believe the later cars were a more stringent emissions standards than the earlier ones and more prone to erratically triggering these warnings. It might make the 'tricking' of the ECU with electronic trickery easier on early cars.

Probably the gasket around the air inlet to the plenum. I had exactly this problem when the XJR was under warrantly. A quick poke around showed lots of soot around the gasket so clearly leaking and letting in unmetered air.

But the Jag dealer knew better - Under warranty it had new Catalytic converters and all new Lambda probes (up and downstream) on both sides. Then they replaced the whole induction system. Then I think they changed the injectors and coilpack(s) .

Light still coming on and they said the computer had run out of ideas. I suggested they change the inlet manifold gasket as I had suggested at the outset, couple of pence of rubber and bingo problem solved