Depending on the drive train losses, we might have passed the 600
BHP mark on a 4.0 XKR with our twin-screw conversion.

We actually where able to pull 470 rear wheel horsepower, and using
a 22% drive train loss figure (for some a common loss for automatic
cars), you come to 603 BHP.

We have learned from this dyno day and taking the conditions of
that day into account, we are confident that the next miles stone
of 500 rwhp (641 bhp) might be very feasible without major engine
modifications...

Very exciting stuff (at least for me and a small crowd ;-).

Regardless of drive train loss, the rwhp is imho already immense,
not to forget the torque (with 22% drive train loss at 4300 rpm 626
lbf/fft or 849 nm).

Here the dyno graph and some more info can be found:
http://www.maxperformancecars.com/index.php?option=com_fireboard&Itemid=53&f unc=view&id=2707&catid=3

Andre.

 

Can the other drivetrain components, such as the trans, handle such an upgrade in engine power?

Doug

 

im looking into aftermarket power upgrades also on a 2000 xjr, wanted to know how you achieved this!!
nick

 

@CB00JAGUAR

I am developing this together with my partner Bill MacLeod in the US, he may be known for making an X-pipe exhaust system for our cars. Both of us are actually enthusiasts, and we where united as we both were very disappointed with the performance upgrades available. Later we joined forces, and now we are working hard to see if we can make a kit out of this and offer to fellow enthusiasts ;-). We have actually already converted a couple of cars. The core of the change is ripping out the Eaton supercharger and replace that with a Big Bore KB twin-screw unit. Of course there are more parts surrounding this, and that can support higher hp numbers like an exhaust. You can PM me if you are interested further.

@SeismicGuy

The drive train is pretty strong and can handle higher horsepower figures, however not sustained power runs at these levels. Normally I drive with about 430 rwhp (it is just a pulley change to select the boost level you want, a 5 minute job), and I have used this for 10’s of thousands of miles already without any issues (sued the power a lot ;-)). Occasional peak power can be handled, but all with care, so make sure oil temp is good before using the power. Racing is of course something else, I doubt a constant power if these figures can be handled for long, but an occasional ¼ mile and street driving looks to be ok.

In the event you like to race it, we could strengthen the gearbox (at least the Mercedes one).
@stkxjrtech
The 4.0 XJR can have the same treatment ;-), hope the above gives you some idea of what we have done, otherwise you can pm me for more info.

Andre.

 

Avos,

I will imminently be saying goodbye to my 95 Vette and replacing it with a 2005 XKR. Even though I am far from a young gearhead anymore, one of the things I liked about the Vette was the plethora of performance upgrades to play with, ranging from very cheap and simple (e.g., air intake upgrades) to more complex (e.g., valve train upgrades such as higher ratio rocker arms).

In anticipation of the getting the XKR, I was browsing around the net and did not find much in the performance upgrade department except for an improved air intake from a couple of vendors, pulley upgrades to get more boost from the supercharger, and cat-back exhaust upgrades. I will probably want to get the improved air intake since these are fairly cheap and easy to install. I was also wondering about the supercharger pulley upgradesare these fairly cheap and easy and effective?

Thanks,

Doug

 

Hi Doug,

You will find mixed results from changing pulleys, my experience wasn't good. You do feel some added midrange, but I didn't gain any top end. The Eaton is already at is max efficiency, and by turning it faster, you will not only create more heat (hence some say Heaton), but also consume more power from the engine just to turn the supercharger. That whole experience has inspired me to look for a performance improvement that really does work, and has evolved even beyond my original expectations now.

Maybe if you would just do a modest increase, and improve also on your air cooling it might work a little to just change the pulley. Remember that the Heaton will also heat up the intercooler systems, so when that is cold you might get a nice hp number (like in winter, or the first pull/power run you do), but once the system is heated up, you will have lost hp again.

The twin-screw creates much less heat than the eaton, and also uses less engine power to turn, which is a win win situation. But even there I can recommend improving the stock intercooling parts, as that is an inherent weakness for any water to air cooling system.

Andre.