1994 Jaguar XJS Convertible, 4.0L straight six
Kudos to those who designed this beauty...
... and to those who perfected it in the end
A GENERAL OVERVIEW
Performance mods:
The OEM air intake design (mainly the airbox,) seemed pretty obstructive, so I changed it by installing a large K&N filter under the left headlight and routing a 4" duct through the left wing straight to the Mass Air Flow Meter located before the throttle body. It is on this duct where the AutoMeter intake air temp sensor is located.
A good intake means little with a so-so exhaust to help it move the flow. Installed Magnaflow wide open, straight through mid-silencers and rear mufflers with no baffling or restrictions of any kind, ending with 3" pipes and nice size/shape Borla tips to complete the optimized flow-thru.
A WORD REGARDING THE HEAD PORTING
We had to go in to replace a suspect leaky head gasket. Once the head's out for this purpose, it's a given that you must not miss out on the opportunity to do the full head refurbish, including valve work, especially the valve stem seals. What I was not aware of, however, was to consider having the head ported, which involves subtle alteration of the airflow paths and of their surface texture, all done in a special flow bench by a highly specialized "guru" with the purpose of gaining a few more HP by optimizing flow. In fact, porting is extremely important to racing teams and, although it can significantly alter your power, the ruling body does not get involved, keeping it your own little secret. Furthermore, nowadays, Nascar racing teams are using high tech software methods in order to "document" the ideal porting for any given engine, thus not having to have any Guru start it from scratch every time. That's really no different from what you do when you store your music digitally: you do not lose any sound quality in the process the way you used to when recording on magnetic tapes because now it's all coded; you document a "code". Of course, my humble XJS' porting was done the good old way, which can take that guru a good 40 hours to complete, thus the steep price tag. On mass produced heads, the OEM cannot afford to invest what it takes to optimize the flow of each and every head they sell. For that, you need to perform the custom job that porting is.
So, here we have a newly refinished and race-shop custom ported head with heavy duty head gasket and all new seals, including new valve stem seals
The problem with the head gasket turned out to be a blessing in disguise
A new, more aggressively programmed chip from the Powerchip Group replaced the OEM chip in the ECU . The power gain was similar as that achieved with the intake-exhaust mods, but this one seems to be felt at slightly lower rpm's.
XK8 17" five raised spokes chrome wheels with correct Pirelli P zeros, much improve handling. I also believe that they look better on the XJS than they do on their very original XK8 …
This rear spoiler that you see above is an upgrade, as it came only with the 6.0L V12’s of the last three years (most likely due to the V12's assumed superior top speed capability; hmm... really?). I added the spoiler to improve the looks of the sometimes controversial facelift rearend. I, myself, used to prefer the pre-facelift rearend with the triangular lights at the corners, but I think in the end the spoiler did make a significant difference. It kind of changed the rearend overall look into more sporty and smoother flowing lines from just about every angle. However, I have the feeling that, among XJS owners, the rear end styling preferences will follow a specific trend: which is the kind that you own...
PUTTING POWER-GAINING MODS INTO PERSPECTIVE
Up to this point, all these performance mods pretty much belong in
the "soft" category level, meaning a little here and a little there. The big exception was the head porting job, which was not really "little" dollars wise because they had me sold on the top level job, just below the super-duper, pro-racing level.
Problem with all this is that, although performing these mods does wonders for the love ties between the owner and his/her beloved ride by means of spending so much "quality time" together (and $$$)... the actual performance and/or acceleration gains as a whole may not necessarily place you where you want to be, depending on where you're starting from. In my particular case, my gain on the 0 to 60 parameter was probably a compounded 0.8 seconds, which put my 0 to 60 at 7.0 seconds. This gain, however, is close to a full second, how bad can that be? The answer is that I may have just not been happy with the 7 seconds because in today's terms, that is grandma's performance. This is the reason why I considered a more serious boost arrangement.
The XJS is a Grand Tourismo (GT) car, and not necessarily a sports car. It was not conceived with power, or competition in mind (i.e. a Ferrari, a Corvette), but rather just as a nice touring, classy, machine. If you want power and performance, buy the right car; right now the sky is the limit. However, if you want to have your cake and eat it too, then you reach for a more serious source of power that will make your GT class tourer a true work of art. The softer mods described above do help, but they're not really enough to get you there.
Luckily, the AJ6 engine of 1993 and 1994 and the smartly updated AJ16 of ‘95 and ‘96 are believed to be the most bulletproof engines that Jaguar ever built, particularly in regards to the indestructible bottom end. This, here, becomes a crucial, vital point when you’re considering a serious power increase because, in general, engines that are not this strong will most likely require significant beefing up of some of their internals.
What I have done is to bless this car with two interesting
performance enhancements that come actually from the same
source: 1. All out 0 to 60
2. Everyday driving
DynoTune sensors, bottle and warmer
Now you see it...... ..... now you don't
First: The "Pull all the stops" feature. When placing (and keeping) your foot on the floor until you reach 60 mph you'll see that only 5.2 seconds have gone by. The factory advertised number for this feature was 7.8 seconds. So, this is 2.6 seconds, or precisely one third, faster (33.33%) on this popular performance feature.
Highpower Systems Int'l. Progressive Controller
Customized DynoTune overhead gauges close up
Second: Because this car's OEM engine and geartrain design makes it slow to react when you floor the gas pedal from a stand still, I've provided a short half second "pre-push" that's enough to get the engine to its best power-producing rpm's in an almost instantaneous fashion. When set on this mode (Green switch set to the UP position, top of the A pillar, left picture, below) it won't do 0 to 60 in 5.2 seconds, but it will respond much quicker during normal driving and only if you ask for it (i.e. go to at least 80% gas pedal travel). A 0.5 second shot is quite a short shot, and you don't necessarily do this all the time, so you do the math as to how little cost is involved.
AutoMeter gauges and AEM wideband AFR gauge
This whole thing is achieved by means of extra fuel and extra oxygen. As most car enthusiasts are aware of, these extra oxygen sources come from either a turbo charger and/or a super charger, or like in the case of my XJS (you already guessed it), a container under pressure: oxygen in the company of nitrogen, aka N2O. My other ride (an XJR) is S/C.
Highpower Systems Int'l pulsoids and injector
DynoTune overhead gauges
ABOUT INTERIOR UPGRADES
Over the years, I've added a few things here and there that were not original on this car, comfort and looks wise:
- Wood/leather steering wheel (OEM on later V12's XJS)
- Wood shifter knob (OEM on Celebration XJS models and also on XJR's and XKR's)
- Burlwood radio surroundings. Non-OEM, custom made; very rare.
- Locking center console with cup holders and enlarged storage room
- Self-dimming rearview mirror with compass and outside temp indicator (better than the factory one on my XJR)
- Relocated trip computer to the rear of the ski slope to make room for the digital sound processor that gained a home above the radio
-- The rest of what you see different inside my XJS has to do mostly with performance equipment monitors, such as the three gauges and switches on the A pillar, the overhead nitrous related digital gauges, the Electronic Nitrous Controller to the left of the radio and a set of nice looking, custom designed racing pedals.
IN-CAR-ENTERTAINMENT (ICE)
First, nothing remains from the OEM ICE in this car. In the trunk's right cavity, an 855 wrms set of 6 amplifiers, 5 of which in a stack of 4 Sony 100 wrms amps for each of the four midrange 6 1/2" Infinity Reference speakers; the 5th amp at the bottom of the stack is a 400 wrms Rockford Fosgate that feeds the 10" JL subwoofer in a sealed enclosure that I custom designed and built with two important parameters in mind: #1 The smallest possible depth size in order to have the least noticeable bulging out of the rear seat back cushion and, #2 Do this while sticking to the exact JL recommended sealed volume for this particular subwoofer (please, refer to the sealed enclosure subwoofer picture). In addition (and obviously), a correct size cavity had to be created inside the rear seat back cushion to fit in the assembly. For the dedicated and correctly aimed tweeters located at the bottom of the A pillars, a 55 wrms MTX amp is actually located inside that big case that hides the battery and conv. top stuff, basically behind the wall where you see that brown, mini cylindrical cigar humidor. Then, music is stored in the 40GB Kenwood Music Keg (removable hard drive), which in his day was state of the art stuff, but now getting dated and falling behind in technology (particularly, size) when compared to any USB driven mini external drive. The only thing that saves it is the perfect marriage to the Kenwood head unit. Regarding sound shaping, I still have that Pioneer unit in both of my Jags, which is a digital sound processor (cross-over, parametric eq and field sound effects) that I will keep until somebody makes a worthy and more technologically advanced replacement.
The video side
This add-on Sanyo GPS turned out to be a great multiple-use device for a very reasonable price. Obviously a full GPS system with voice prompt, it introduces a high resolution 7” TFT display to the system. It's also a DVD player (accepts any DVD) with an A/V input, meaning that I can play all of the movies that are stored in the 500GB hard drive (see pic that shows it behind the driver's seat). Sound, of course, goes through the full blown stereo system. I never cared for a screen covering everything when I’m only listening to the radio and that is why I don’t use those “pop-up screen” radios. When my display is not in use, I simply stow it away and lock it up in the center console.
Take all the time you want when eating that hamburger. Plenty of movies in that hard drive
LOCKED STORAGE
Jaguar provided no locking storage inside the 1994 XJS convertible, So, this means that if you want to leave the car outside the restaurant, or the wedding reception, or the valet parking at the show, etc. with its top down so the world can enjoy the inners of your special creation, you'll find yourself doing the tedious routine of taking all valuables into the trunk every time. After substantially enlarging the center console storage room, I replaced the lid with one from a sedan. It gave me a means to install a security lock and it added cup holders. Little filing and adjusting here and there, but totally doable.
Locking center console Cigar humidor, perks of driving a convertible...
Back in the old days at Crystal Cove Now by Ruby's at Redondo Pier, Friday nights
However, when they kicked us out of Crystal Cove, Ford's PAG Center, in Irvine, CA, came to our rescue. “Cars and coffee” has become easily one of the most diversified and sophisticated but, most of all, spontaneous weekly car shows in Southern Cal. You get to see really special stuff and many exotics there, I promise. If you're a local, or you're in town visiting, the show time should not really interfere with your itinerary because it starts early at 7:00am and by 9:00 am everybody’s gone. However, if you're showing your car, you better be there at least at 6:30 (yes, dark right now) so you get a spot of your choice. I've seen cars strolling around, looking for anything available as early as 7:15am, especially when some particular brand is being featured. And, don’t forget the great (“S”) coffee and their class kitchen breakfast. This, now, is like Crystal Cove on steroids...
Here, with wife Maria at a picture-taking stop during a local Club rally, up in the Malibu Hills.
