XJS fitted with big block chevy V8

[burblemania]

Hi All,

Anyone shoved a chevy V8 into an XJS in the UK?

Interested in converting an XJSC 4 seater into something with more balls, manual transmission and aural pleasure than Jaguar ever offered us.

Any comments / suggestions welcome.

Thanks

[richs2891]

Should be plenty of room in the engine bay as they used to have V12 in them. They also did the early hard top version in manual, my dad used to have one, on an old T plate. A are option, not many at all where made with manuals. It would have gone to the scrap yard by now, broke down loads as well.
Electrical connectors are rubbish as well.
LOl trying to do what jaguar never could by using a V8 ? (they tried to design their own V8 with a very narrow angle but never got it working properly)

[Fittster]

What does a V8 offer that the V12 doesn't?

[Tom74]

Wouldn't it be easier and probably cheaper to buy an XJS and an XJR and swap the oily bits? Supercharged V8 and even has the right badge!

[Byff]

Someone been watching Roadkill's Draguar?

[anonymous-user]

If you want a fuel efficient V8 that makes good power I suggest a GM LS3. Speak to Craig at Dynotorqe, he's done many V8 engine swaps

http://www.dynotorque.co.uk/index.php/

Edited by anonymous-user on Sunday 23 March 18:48

[NNH]

There's a firm called Jags That Run (jagsthatrun.com) with a lot of stuff for this kind of conversion, if you've not already come across them.

[Olivera]

Not sure why you'd bother, as most cheap chevy V8s will offer less power than the Jag V12, and the V12 can pretty easily be tuned to near 400bhp. Jag manual box should also be easily available.

Also regarding aural pleasure of an unsilenced V12:

https://www.youtube.com/watch?v=CJEROxhHdnk&li...

[J4CKO]

Fittster said:

What does a V8 offer that the V12 doesn't?

Smaller, more powerful, more tuning options, more robust ?

[Kev T360]

Byff said:

Someone been watching Roadkill's Draguar?

My first thought. There's did look good with the charger sticking out .

[PugwasHDJ80]

if you look around for long enough you'll stumble on an XJS with a four speed auto 4L80e

these have an adapter plate on them to make them fit the Jag V12, but without the adapater plate you could bolt up a small block chevy straight up.

All you'd need to do then is sort engine mounts, megasquirt for fuel and timing, and possibly gearbox control (aftermarket TCU would do the trick on a 4L80e)

[williamp]

J4CKO said:

Fittster said:

What does a V8 offer that the V12 doesn't?

Smaller, more powerful, more tuning options, more robust ?

You could say the same about a turbo 4 cylinder. But shouldnt everyone have a V12 at some point??

[eliot]

PugwasHDJ80 said:

if you look around for long enough you'll stumble on an XJS with a four speed auto 4L80e

these have an adapter plate on them to make them fit the Jag V12, but without the adapater plate you could bolt up a small block chevy straight up.

All you'd need to do then is sort engine mounts, megasquirt for fuel and timing, and possibly gearbox control (aftermarket TCU would do the trick on a 4L80e)

Not sure about that. The Jag TH400's and 4l80e's ive seen have a custom jaguar casting.
You may be able to cut the bellhousing of and fit a JW ultrabell - which attaches to the oil pump.

[Fire99]

I get the idea but I'm just not sure the power delivery of a Chevy V8 would suit the Jag, though I can see the appeal (and probable greater reliability)

Would the old supercharged straight 6 from the 'early' XJR not do the job? Engine is tough as old boots and it kinda suits a Jag's personality.

[cologne2792]

There was a V8 Diesel planned for the XJ back in the seventies but they don't like talking about it. We have a brochure though...

[XJ Flyer]

Olivera said:

Not sure why you'd bother, as most cheap chevy V8s will offer less power than the Jag V12, and the V12 can pretty easily be tuned to near 400bhp. Jag manual box should also be easily available.

Also regarding aural pleasure of an unsilenced V12:

https://www.youtube.com/watch?v=CJEROxhHdnk&li...

A Chevy V8 would arguably be able to provide more power for pound spent as the V12 does need a few serious modifications to make it provide a good output.Added to that is the fact that the Chevy pushrod motor is a lot easier to work on than the Jag engine.IE even valve clearance adjustment is a major job on the V12 let alone anything more involved.

Having said that in the V12's favour it sounds great with unsilenced exhausts and throttle bodies and a later 6.0 litre capacity engine from an XJRS etc is a good start point for good outputs.Putting a set of bigger liners together with the 6.0 litre's long stroke crank will take it to 6.8 litres and putting that with a manual box is probably less aggravation than going to all the trouble of sourcing a Chevy V8 and then making it fit.Also don't believe the bullst that the V12 isn't reliable as in most cases a good one is bullet proof so long as it's cooling system is maintained in top condition and it gets plenty of oil changes.All of which is why I've always stayed with the V12 option rather than bother with a V8 conversion.

Edited by XJ Flyer on Monday 24th March 01:52

[Coatesy351]

http://www.jaguarspecialties.com/v8_kit.asp

[PugwasHDJ80]

eliot said:

PugwasHDJ80 said:

if you look around for long enough you'll stumble on an XJS with a four speed auto 4L80e

these have an adapter plate on them to make them fit the Jag V12, but without the adapater plate you could bolt up a small block chevy straight up.

All you'd need to do then is sort engine mounts, megasquirt for fuel and timing, and possibly gearbox control (aftermarket TCU would do the trick on a 4L80e)

Not sure about that. The Jag TH400's and 4l80e's ive seen have a custom jaguar casting.
You may be able to cut the bellhousing of and fit a JW ultrabell - which attaches to the oil pump.

oh right- I know you've seen more than me

did think I'd seen a Jag one with an adaptor, but maybe that was one from the Rolls?

Isn't the bell housing unboltable on a 4l80?

[J4CKO]

williamp said:

J4CKO said:

Fittster said:

What does a V8 offer that the V12 doesn't?

Smaller, more powerful, more tuning options, more robust ?

You could say the same about a turbo 4 cylinder. But shouldnt everyone have a V12 at some point??

Used to drive my father in laws V12 Etype, always thought it was too much engine for an Etype, if not too much power, not all that smooth really, made a nice noise, generated way too much heat.

[jamieduff1981]

Can't you get something that already has one of those V8s in it? A V12 really is rather special and too good for downgrading to a Yank V8. It's kinda missing the point of the entire car.