Very strange v12 engine number

Just purchased a 1983 uk v12 he, it was originally owned by my father feom new till 1989 under warranty it had several new engines. The joys of a leyland car!

The engine number was never updated with the dvla, and the current logbook is showing what appears to be the original.

The car has had alot of modifications, including a getrag 5 speed conversion. Twr suspension, stainless wxhaust and headers etc. One owner was a speed freak and got caught at 160mph plus he was apparently obsessed with getting this to go faster!

Now im suspicious the DVLA have the engine capacity as 5707cc. Due it having a few private plates i cant get mot histpry to find when this change happened, or if its a misprint.

However, the engine number has thrown me, its 100% this

12MR84 i have photos and its absolutely clear.

No other numbers present, now 4 very sharp people and an inspection camera have verified this?

Unfortunately at some point the build plate has gone, so that cant help…
But in the box of spares i have have 3 ECUs , im guessing that this has been bored and mapped.

The cars plate now is umo526y it was 3721pg…

Any help would be appreciated.

I plan to give the car back to my sad for his 70th birthday later this year.

1 Like

My first thought…perhaps meaningless…is that replacement engines are numbered differently than than originals?

Cheers
DD

Thats my thought!!! But then google would have “something” about that, and some postings on forums are now 20 years old, so it would have been mentioned.

Im wandering if ive possibly got a very early pre he engine, given the guy was a speed freak and owned specialist jaguar garage.

Or its a lister/twr/panther/marine engine…

Its truly strange.

It seems strange that someone has bothered to contact the DVLA and notify them of a non-standard engine size, but not a different engine number. Number 1 suspect would be an early TWR engine, but it would be a later fit to that early chasis. Lister went a lot bigger in capacity, I don’t think they would have bothered with a 5.7L. I think the same with the marine and spitfire re-bores, mosty over 7.0L.

I’m not in the UK at the moment, so I don’t have physical access to my XJR-S, documents, and other references. But I would guess that my 6.0L engine, from TWR, has an official JaguarSport engine number being a 1992 car. I can check in a few days if it looks like yours.

Just done some googling - Most references for a 5707cc V12, is a Lamborghini engine from the 1990s. Hmmm… maybe they chose the same 87.0 x 80.0 mm bore and stroke? :thinking:

The very early listers were 5.7s. Apparently its an easy conversion with a bore out and off the shelf pistons…

The plot thickens as in the boot of spares i have 3 ECUs…

Ive a feeling looking at the headers ot may have aj6 parts…

Ive found a load of mot’s from 1993 and 1994 it appears the capacity changed then, and the mot was done by the owner of a jaguar specialist in preston, who also owned the car…

He knew his stuff, so im strongly suspecting ive got a special engine here…

I may need to take.it to someone like aj6 …

More curious information. A Lister 5.7 could be a good bet, but the mid 1990s seems like a late modification for an early engine. Maybe try Simply Performance for some advice, I know he has a Lister. Do you have a problem that you need to fix, or just want more information?

Can you not contact Jaguar heritage trust, they may have some info… it sounds like you have a car that I am trying to emulate…