Hey guys,

I was just wondering. If a 1994 Jaguar XJ6 has a supercharger, is it possible to add one to an 84'? If not, is there other posiible ways to add more power, say 50 more horses to my kitty cat?

 

It depends on how serious you are and how much you want to spend, how big a project you want.

Here's a few things you can do for free

Note: this tip can help all XK 6 cylinder engines. However, it is particularly pertinent to the XJ-6)
To enhance the low-end performance on Series 1, 2, and 3 XJ-6, do the following:
After adjusting the valves, advance the cam timing 3 degrees by setting the ignition timing pointer on the vibration dampner at 6 degrees before T.D.C. and set the cams as if the pointer was on T.D.C.

FI cars come from the factory set too lean and with too slow response on the air flow sensor. Breaking off the potting compound to get in and make these adjustments is rewarded with 0-60 times decreased by a second and a half, and no problem passing emissions either.

There are a couple of modifications that every XJ6 should get. The steering rack is held in with wimpy foam rubber bushings; sliding in a couple of washers to limit movement transforms steering response. XJ6's are famous for cooking their transmissions. This is due to inadequate cooling of AT fluid in the radiator; an aftermarket transmission cooler should be installed. Every 6 cylinder Jag engine needs tappet guide hold-down plates installed at 40k miles. Any car without these will make horrible knocking sounds even at idle. Installation is an easy two-hour process. All XJ6 catalytic convertors clog at 70-90k miles. Replace or ream it out, or you will lose the head gasket at 100k miles.

Inflate the tires to maximum. Take out the heavy spare tire in the trunk.

Buy a K&N air filter and install it.

If you want to experiment and have some technical ability, www.hydrogen-boost.com has a system for fuel efficiency but also performance that can be installed for under $800 I believe. This is probably better than a supercharger.

If you really want to dig in,
think about replacing the old transmission with a GM TR700 with overdrive. It will extend the life of your engine. The Borg 65/66 were bad. The heavy flywheel they used made things smooth, but robbed horsepower.
Find a 1982+ v12 HE engine. You'll get better fuel mileage that the old 6 cyl, and slightly better performance. Or really go to the extreme, and put in a manual transmission. All of this could cost thousands of dollars for the manual.

Remember, the XJ will never be a truly quick car, it's just dragging around too much weight-so unless you want to gut it, you're going to have to accept that.

 

that is some useful information....... glad I came across that because the 85 I bought is more sluggish than my 91 Suburban that is almost twice as heavy. but it leaves a few questions.

1. how do you adjust the valves? is it like adjusting the valves on a chevy small block?

2. I have no problem using a TH700r4 (prolly have a couple laying around) but how is it adapted? who makes the kit and where do you
get it?

3. are better gears availible for the rear end ......... 2.98 seems a little tall for a 30% OD transmission (TH700r4)

4. where do you get tappet guide hold down plates?

5. and the final dumb question ................... If a TH700r4 can be adapted than can a tremmic 6spd for a corvette be adapted?

 

John's Cars (I used to have the URL but don't any more, so you'll have to Google them) has a kit that includes everything for a conversion to a T700 except the transmission itself.

Similarly, if you google Tremec (or Keisler) with XJ6, you'll find that they have bellhousing, etc., kits for 5- and 6-speed transmissions including the pedal sets and clutch hydraulics. I think the price runs around $6000 these days. But that includes the tranny.

Jim T