I took my time grinding on the nose. I did it in three steps leaving about 70 thousands of an inch for final careful hand fileing and belt sanding. I did it in two nights of about 2 hours each night.

 

I took more time but I did mine with the supercharger in place. I took some time to triple checked my clearance as I did not want to fit the pulley and realize it was binding on the snout

 

Hi all,
the last year I upgraded the upper supercharger pulley+KN filter (Jag XJR 2001). It resulted in maximum 13.8 PSI boost. Recently I upgraded the lower pulley which was custom made with diameter of 20mm larger than the stock. Guess what boost I'm measuring now? 14.2 PSI the maximum only while I expected a lot higher gains... However the car runs a lot more lively, a lot better throttle response and pulls like I expected.

Though my "butt dyno" feels the significant improvement I'm still curious why I'm getting only ~14PSI Boost? The blower exit gasket is new, blower outlet seals and clamps upgraded. Can it be that blower by-pass is leaking? Any other ideas?

 

You have H(eaton). Do not overdrive it too much. You get more power and torque at low rpm's but not more after 5Krpm. That's normal. Porting may help a bit.

 

Be careful when doing the lower pulley upgrade, I post the following tale in this thread as something that happens, remotely possible.

A friend had one installed, a few thousand miles later he had an unexpected loss of power steering, battery not charging warning, engine overheated with coolant level pegged in the dead red zone.

I asked him to start it, the SC belt ran intermittently, was the SC seized? looking down the front, the crank damper/pulley assembly was vibrating. I removed the belts and was able to unscrew the bolt with my fingers. It'd backed off. Looking at the threads, no threadlock was applied, old bolt re-used. If the engine had been run any longer it would have been destroyed, luckily he got away with another crank pulley, bolt and cone, the original cone had been heat blued and scared, along with the crank snout and the pulley face. Very lucky. Just make sure new cone and bolt parts are used to ensure a professional piece of mind job.

 

What belt are you using? what ambient temps are where you are? What gas do you use?
How are you measuring boost pressure?

I've read on here of an XKR (same engine) running near 18psi on a cold day, with a meth kit also. At this point it's useless as parasitic drive and heat losses on the 'blower max the power out - real improvements are made with a compressor type as against the blower.

If you need more power talk to Avos, he makes custom twin screw supercharger kits, with power up to 650bhp, with lower boost and negligible parasitic/heat losses.

 

@XJR-99
Yes I know all this. This is what I wanted - more torque at lower RPM. Inlet elbow, blower inlet and outlet are all a bit ported by myself.

@Sean B
thanks for the tale on the pulley fixing. I'll check the tightness this weekend and I'll try to get the torque wrench to use the proper force. I used the new bolt.
- I used the belt GoodYear 8PK1365HD (by that time I could not get the Goodyear Gatorback)
- fuel is 98 Octane
- ambient temp is ~20C (68F)
- I'm measuring the boost via OBD on mobile app Torque.
- I have also installed DevilsOwn water/meth kit and upgraded coolant pump to Bosh. During the winter planning to install additional coolant reservoir. All of them to beat additional heat.

I've already contacted AVOS but for the moment I can not afford his kit.

Do you mean the belt might be slipping? How to know if it is slipping? I do not hear any squeaking noise.

 

To resurrect this thread: I'm currently looking to buy a 2002-2003 XJR. Once I acquire the "right car", I will have the tensioner/gasket/water-pump/thermostat kit installed. At the same time, I would like to upgrade the lower pulley. My question: What would be the best brand (safest with most performance increase) pulley to get. I do not want to get into radiators, etc. Just a good, safe lower-pulley install. Mina? Powerhouse? EuroToys? etc.

Thanks!

 

tensioners in 03 will be the updated type.
waterpump also 02/3
thermostat on the R is an alloy not plastic item since 97'.

Powerhouse in the UK supply the larger diameter crank pulley. Cheaper than most. Just make sure you use a new damper bolt and the correct torque when fitting.

 

When I had my XJR done (I have subsequently sold it) I had both pulleys changed and the intercooler radiator and water pump uprated. I used PowerHouse parts and they were very helpful. I would recommend a call to them and form your own opinion. I was happy with their parts and service.

 

Hi
Any one can tell me if the mileage will decrees on the car at normal use if this upgrade will be made? I know it is a performance upgrade so the gas mileage is not important. In my opinion for my daily use this power is more then enough.
Best regards

 

Good day,


I'm about to go for the upper and lower SC pulley upgrade, larger intercooler and pump, and SC bearing rebuild.

Also need the secondary rail timing tensioners checked out. Didn't have them replaced previously and am wondering if they are cracked,...


Probably going to have my Jag mechanic do it all. Anyone have an estimate about how many hours this job will take?

Thank you.

 

Do the tensioners now, before you destroy your engine, and then plan the other work. There is no duplication of work between replacing the secondary tensioners and any of the other items, so no savings on labor.

 

The tensioners on my XJR ran me $850 with on oil change all inclusive.
The lower pulley is a straight forward affair, as it is a bolt on and should be no more than about 2 hrs. The upper pulley will require heating an removing the pulley, grinding down the snout and then heating and pressing the new one. Some people cut the old upper pulley in order to remove it. Either way, the upper pulley is more complex and time consuming.

I think you will gain great benefit by just swapping the lower pulley. It will give you some very useful mid range torque.

 

The primary one's that press against the chain have been replaced. That cost me about $1300. The rails on the front that only guide the chain were not replaced as my mechanic didn't think they needed to be,...

Is this urgent? Don't think this will destroy my engine,... and there is minor duplication of work.

 

if you keep the existing Eaton m112 S/C and change the pulley (s) -during normal operation up to mid to upper third load use mpg will NOT decrease appreciably. This is because an Eaton doesn't do internal compression work and is by passed at part load.


if you 'upgrade' to a twin screw or other such super charger (which are often more efficient) your mpg will decrease because even when they are by passed for part load use there is significant parasitic loss.

 

eric:
There seems to be some confusion here! I assume you know this, but for the archives-
You originally wrote, "secondary rail timing tensioners". That implies you refer to the tensioners on the upper chains, which are also called the secondary chains. In the later post, you implied that you were referring to the slack side rub bars on the primary chains.

You never addressed the chain tensioners (which are one piece for both the tight side and slack side) on the secondary or upper chains. Those are the ones that wreck the engine and to which rockland was referring..

 

Yeah, my terminology is bad. I meant the guides vs the primary tensioners.

 

Can someone explain me why to modify the snout and if how to do so?

 

On the stock pulley the pulley slips over the snout (shaft) of the supercharger. On the 3# pulley the inside diameter of the pulley is smaller than the outside diameter of the supercharger shaft. In order to get the pulley to slip over the shaft you need to reduce the diameter of the shaft.
Search the posts on this forum and on the XKR forum for information on how to grind the shaft