Jaguar 99 XJ8 Vanden Plas with GM LS1/4L60E Conversion
 

Hi all, this is Andrew from Jaguar Specialties. I posted here before about some of our latest LS conversions into Jags, and wanted to put up some pics of one of our latest installs (my own car).

Note- I'm not trying to convince anyone to do anything or badmouth the stock drivetrain, just show what's possible for these models.

This is a 99 Vanden Plas sedan and this car now has a basically stock 2002 Camaro LS1 and 4L60E trans. As you can see it's a great fit and the build uses all of our standard conversion kit parts including our unique GM-Jaguar CANBUS interface (that interface is the key to the conversion- without it, an install like this wouldn't be possible). The car is set up with full emissions (we're in California) with stock (GM) cats, stock GM cast iron (high flow) exhaust manifolds, and a 2 1/2" mandrel bent exhaust. It runs and drives beautifully. One little trick on this car has to do with being able to use an earlier Jag XJ6 differential with higher (numeric) gears. The stock ratio on the car was 3.08; the earlier unit is a 3.58 and that makes a big difference in how this (nearly 4100 lb) car pulls off the line. That diff change is only possible due to some specifics of how the conversion handles the driveline- you could not make the same change with a stock XJ8 drivetrain. Overall, it's smooth, reasonably quiet, and very comfortable. And on from every angle, inside and out, the car looks and operates exactly as original. All of the gauges read properly with no warning lights or messages, the shifter works perfectly with the GM trans (including the J-gate feature), the speed sensitive steering is fully functional, and the climate control also operates properly (including the automatic temp control feature). If you didn't open the hood, you'd swear the car is stock.

This type of conversion could be done on any 98-03 XJ8 model using nearly any LS engine (including the truck 4.8 -5.3-6.0 versions) and the 4L60E/4L65E trans. And the cars themselves are ridiculously cheap to buy- a nice sedan such as this one with good cosmetics and major mechanical problems generally sell for $1000-$2000- they're a giveaway. Put in the LS and you've got a fantastic car to boom around in. And the performance potential is limitless. On a most basic level, this conversion costs (using a good used GM drivetrain package), all told, would be similar to the cost of a rebuilt Jag engine alone. Email me for more info.

Note- we offer a similar conversion for the 97-02 XK8 and XKR 2 door convertibles and coupes too. And we are (right now) building a 6 speed manual transmission version of the XK8/XKR conversion- that will be a kit offering soon...

Here are a few pics- I hope you like them.

https://www.jaguarforums.com/forum/a...ine=1382906460

https://www.jaguarforums.com/forum/a...ine=1382906460

https://www.jaguarforums.com/forum/a...ine=1382906460

https://www.jaguarforums.com/forum/a...ine=1382906460

https://www.jaguarforums.com/forum/a...ine=1382906460

Very clean looking install. Impressive work, sir.

What's not to love?
 

THAT is one CLEAN installation!

Any plans on offering a T-56 on the X308 platform?

I see an LS7 / T56 in an XJR as a cool option!

Stewart

Manual trans........
 

Now what would be the ultimate M5 fighter....

For the moment, no plans for manual trans X308- I need to get the manual XK8 out there- big draw on that one.

But never say never- it's possible. Much of what we've learned rigging up a clutch pedal and hydraulics on the XK8 could possibly transfer over to the XJ8 as well.......

Do you think there would be decent interest in something like that? I've had maybe 4 or 5 calls on it over the past 2 years that we have been selling the XJ8;LS conversion kits.

Dunno about "decent interest', but it's something that I'd seriously consider.

That said, the beauty of the J Gate shifter, and everything else being fully functional has really got me thinking.

I've seen MANY Jaguar Chevy V8 conversions over the years, but NOTHING that looks this clean and NEVER have I seen a conversion that was so COMPLETE and well thought out.

Congratulations!

Stewart

I would absolutely love a T56 in my XJR, however I don't have much interest in taking the Jag plant out for a Chevy one (no offense to the Chevy guys)

I won't do this to my current XJR either.

She is in too good of shape to butcher.

However, I see MANY XJR's for sale with bad engines or transmissions for CHEAP!

An LSx / 4L60E transplant makes a lot of sense, and frankly, opens up a whole new world of cars that I previously would NEVER consider buying.

Those pics posted above have REALLY got me thinking about this conversion.

Stewart

JaguarSpecialties,

Just sent you a PM.

Stewart

My buddy and I have talked a few times about this swap. It seems like it would be relatively straight forward. I think the first step would be to loop the CAN line out of the TCM and see how everything else reacts. That would give you a good idea of what signals would require substitution. The next biggest headache after sorting the electrical end would be the shifter/console alignment and finding a suitable quadrant. The bellhouse and driveshaft should be pretty simple. I got my XJR for pennies on the dollar, not scared to get a little crazy with it.

Other Completed XJ8 and XK8 Conversions
 

I'm not going to post the link here, but we do have pages on our website devoted to completed XK8 and XJ8 cars, done both by us and customers. There you can see a variety of these cars, done with both the all aluminum LS1's and also the (much less expensive) truck LS engines. PM me for more info.

These conversions have been very popular, filling a need between these extremely reasonably priced cars (when broken) and getting back on the road. It's not for everyone, but so far, those who have been interested have been very happy with the results.....

Cool, and especially impressive that you got all the secondary proprietary Jag functions working too.

What are the performance specs? Faster than a stock XJ8? Faster than an XJR?

Very nice conversion, very clean. Thanks for posting.

installation
 

Thanks for posting, this is a great option for, what would otherwise be, dead cats!!! Can you also handle the install and/or do you have someone that you work with in NorCal for the installations? Thank you!

That is really super cool. I couldn't stomach someone "destroying" a perfectly nice Jaguar for no good reason, but that's a great option for a car with a timing chain or transmission failure that, in all likelihood, would otherwise end up in the junkyard.

I'm really curious about a few things:

1. Have you successfully smogged one of these in California? It's should just be an "engine swap" run through the BAR, but IIRC the donor motor must be from a same year or newer car, correct?

2. Do you guys sell the parts to do the work, or is this a turn-key only product?

3. Why'd you go for the 4L60 over the 4L80, or the 5L40/6L50 option? Cost, complexity, or something else? An X308 with an LS and a 5- or 6-speed auto would be a pretty nice cruiser.

4. Seems like you have a handle on GM powertrains... do you do any non-Jaguar work?

It would really depend on the motor. A base LS1 would probably yield performance in the middle of, but closer to, an R than an 8. But the beauty of the LS motors is how interchangeable their parts are - swapping heads, intakes, throttle bodies, etc. can yield pretty widely varied results and these motors, by and large, can be built for big power pretty easily.

FWIW, the car I had before the '03 XJR was an '07 CTS-V with a 400hp LS6. Ultimate power was on par with the R, but it made so much torque at such low RPM the end result was a much quicker car. Frankly, I was slightly disappointed at the performance of the XJR coming from the CTS-V, but of course when talking about variations of 400hp it's all rather academic. Both cars make so much power that actually using it on the street simply isn't possible. I had the V out at Infineon a couple times, and suffice to say the car was capable of a lot more than I was. I'm fairly certain the Jag is the same. ;)

Additional Info
 

To answer a few of the questions that have come up:

1) Smog- Yes, our 98 XK8 prototype with 2004 GTO LS1 went through the BAR referee and was approved as it sits. That car runs full emissions, including the original GTO cats and the referee as good with it. The VDP here is also to go to the referee sometime soon- it also is set up with full OBD2 emissions

2) What we sell are the kits and related parts to do these conversions- we don't actually do any work on customer cars. However, we do have associations with a number of different shops around the country that do these conversions for our customers, using our parts. So if you're looking to have it done, we probably know of a shop near you that can help.

3) The 4L60 was used primarily because that is the trans most often found behind the LS engines. Most of our customers buy and install good used packages, and the 98-02 Camaros and 99-03 4.8/5.3 trucks are the most frequent donors. All run the 4L60 or 4L65. That's not to say the other options won't work. We do have one customer who installed a 2010 Camaro LS3 and 6L80E into his 98 sedan- although that's not a package we specifically support. With his tweaking of our parts, and some special work on our interface, it was/is a viable conversion. That car has been running/driving for a year or more now.

4) Sorry no, we only do work on Jags- those are the cars I like the best. They have, in my opinion, the best combination of style, performance, value, and potential.

Just a side note on performance, particularly of this car: one of the reasons this car feels quick is the diff. Because of the way the driveline is handled in the conversion, we can use the diffs from earlier XJ6 models that have more aggressive ratios. In this case that 3.58 (instead of stock 3.08) makes a big difference. On the freeway at 75 the car only pulls 2400 rpm in overdrive, and around town, it's pretty snappy. If this were the lighter SWB car (like an XJR or standard XJ8) that weight savings would go even further to performance. (That diff swap is not something that would be possible with the stock Jag drivetrain, due to the stock driveline architecture)

I hope that helps- let me know if you have other questions.

Andrew
Jaguar Specialties

That's awesome. I'm pretty excited about the possibility of an LS-powered XK8 coupe with a manual transmission. That'd be neat!

Update- 99 VDP with GM LS1 - 1000 miles later
 

Thanks to everyone who was following this thread- I wanted to add an update since the last post.

We have now nearly 1000 miles on the conversion and all I can say is it's fantastic. The car runs and drives beautifully- it's smooth, reasonably fast, and still definitely has the comfortable feel of a big car. On the scales, it comes in at just around 3900 lbs (2100 front, 1800 rear, with a 1/4 tank of gas)- no lightweight for sure.

Also, the car has gone through the California BAR Referee process and is now fully California legal (with full OBD2 capability). So from this point on it is (in the eyes of the state) just another car out there, and can be registered and driven with the conversion. And if it can pass California's strict emissions rules, it can pass anywhere...

Please let me know if you have any questions. In the mean time, I'm busy fixing little things, adding new shocks, and we may have our sway bar bender make up larger diameter front and rear bars to test out.

Thanks

Andrew
Jaguar Specialties

HI,

Just to clarify, a customer cannot give you a car for you to do the conversion, you only sell the kit for someone else to do so, correct?

Converting a Jag.....
 

To answer your question, no and yes.

No, we don't actually do any customer work here- only prototype design and development. However, we are associated with many professional shops around the country that use our kits/parts for conversions on customer cars. So depending on where a prospective customer is located, we probably have an associated shop nearby who can do the conversion. And there are a few in California as well....

Thanks,

Andrew
Jaguar Specialties