New guy here but I've been reading for the last few days and trying to lurk-n-learn but I thought I would go ahead and ask...

I've got an 82 Jaguar XJS that already has a tired SBC swap w/ 700R4. The swap is at least 12-15 years old and the engine overheated on me Monday.

I'm hoping to swap in a stock LM7 w/ Edelbrock dual-plane manifold, MSD controller, 600cfm Edelbrock carb (already on the Jag) and an Edelbrock 2215 cam. Maybe LS2 valve springs. No room for headers so I'm thinking 2010 Camaro or CTS-V exhaust manifolds run through the existing mufflers...not sure of the pipe diameter.

The 82 had 262Hp/300ft-lb when new and did 0-60 in 7.8 seconds with a TH400 and 2.88 gears. It weighs 3979lbs.

Desktop Dyno 2003 with what I believe are the right flow numbers for the LM7 heads shows me 306Hp/372Ft-lb with my planned combination.

Do the DD numbers sound right?

What kind of numbers can I really expect? Any ballpark figures on 0-60 with a 700R4 and 2.88? I'm not looking for a 1/4 mile monster or a dyno queen but I would like something significantly better than 1982 performance.

 

Welcome to the board!

First off, I would recommend buying a motor and trans mount kit specific to the XJS. It will save you a lot of headaches that are totally not necessary. They're worth the money, which in the scheme of a conversion, isn't much at all. JaguarSpecialties is the manufacturer - you can probably google them and go from there.

On my 1985 XJ6, I used a set of LS2 Corvette manifolds flipped to dump forward. (The forward angle is very slight.) This allowed me to stay inside the unibody frame rails and also put the exhaust outlet in a place that did not interfere with the steering shaft. I know your car is an XJS, but it is similar to my XJ6 in that particular part of the engine bay.

Check out my website - maybe it'll help keep you from reinventing wheel after wheel!

http://www.buyrcars.com/jag.htm

 

FastKat: Thanks for the reply. I've already read through your build (very nice BTW) and my resources and goals are a little different than yours. I want to put an LS in place of an existing SBC so the mounts are already there.

I went to look at a 2k3 LM7 I found on local CL. What a disappointment. It has 16Xk miles, according to the salvage yard guy, no documentation. The driver's side coil packs were gone and no accessories were included. They wanted $600!

Another local yard has 2 LM7s with unknown mileage for $325 each and just the long block. They have another LM7 with 74k miles, no accessories and a "lite engine fire." Every other place locally wants $750-$1000 for their long blocks.

I'm severely tempted to just get the 260HP SBC crate from Jegs, swap in some $700 aluminum heads and call it a day.

 

Put another SBC back in!
You'll be running in a day.
Jarhead

 

That SBC might be a good idea. Swapping in an LS-based engine creates some pretty significant obstacles. Using your existing mounts, there is no OEM LS oil pan that will allow you to install an LS engine in the same place as the SBC. If you use LS-to-SBC adapter plates that move the engine a little further back, you will need to shorten your driveshaft and rethink/alter/remake your transmission mount crossmember. Moving the engine back will also create some significant exhaust manifold problems - I doubt any off the shelf manifolds or headers will fit.

Although I am all about new technology and the LS engine family, the SBC would be the lower-cost, easier, and faster alternative.

 

Anyone ever seen this much sludge in the pan of a 60k LM7?

That is just all I could scoop out before my glove tore.