Yes, retaining your points would require a bit more planning and careful engine selection. I get the impression from your post that you have not driven a proper Lump. The ride and smoothness can be retained with proper engine selection and a few minor considerations. For example a stock fuel injected LT1 or LS engine is almost as smooth as the V12 and probably on par with the I6 but I've only driven an I6 once. The proper handling and driving dynamics which we all love can be retained by using AJ6 front springs. Both the LS and Lt1 are very similar in weight to the I6 and may actually be slightly less heavy because over head cam I6 engines usually weigh a bit more that CIB V8s. I can tell you from experience the set back position and low center of gravity of a compact CIB V8 enhances handling dynamics noticeably. When you remove 450Lbs off the front axel you are certainly going to make dynamics such as handling and braking improve.


As for noise the V12's have a distinct growl many enjoy. I believe this is the case because the exhaust manifolds sit very close to the frame rail and transmit a muted exhaust note in to the cabin. A v8 convert moves exhaust manifolds a bit farther away from the frame rail so the growl is still there only a bit less so.


I've seen shakey lumps with poorly tuned carbs burning my eyes and clacking away because the exhaust pipe was hitting the frame. I'm not an advocate for workmanship like that.

 

I've seen the same, SS.

In my experience/observation the hatchet job conversions are suffering the inevitable rate of attrition. I see 'em languishing on Craiglist, Auto Trader, etc. fairly often for very little money. Usually, it seems, they've met the fate the the owner was trying to avoid with the engine swap in the first place.....sitting out behind the barn rotting away. Who knows why. Unresolved problems with the conversion? Problems with the rest of the car? Chev engine eventually wore out? I reckon most end up in the scrapyard but presumably (hopefully) the V8 conversion delayed that fate for a few years.

Gradually, but increasingly, though, I'm seeing really nice Jags with beautifully done conversions. Very sanitary work with good results. Sometimes these come up for sale with the seller remarking 'many thousands spent'.....and, looking at the result, I have no reason to doubt it. But these cars begin to stretch the notion of a V8 conversion being a 'practical, low cost' way of keeping an old Jag on the road.

Obviously a lot would depend on how much is paid for the conversion kit + the Chev engine and trans. I really don't know what the going prices are these days.

I'm rambling.....

Cheers
DD

 

I absolutely think you should stick around, comment, ask questions, and contribute things you've learned through your experiences, which the rest of us may not have run across, and just become part of the vast knowledge pool that is on this forum.

 

Well hopefully this is fading away a bit. New LS1 swaps require a bit more knowledge and attention to detail than a rusty 350 with a carb. It seems like these examples are from the 80s and 90s mostly and represents the work done back then they same way most unrestored cars from the 60s and 70s weigh 200lbs more than stock because every dent and ding is smeared in bondo instead of properly repairing the panel

 

i would like to see you post your project and progress as well.

i would like to see someone create a nicely done conversion. the biggest problem is most v8 conversions you see out there are hack jobs.

if it was me doing it i think i would find a replacement engine vrs a swap but I'm not against you swapping your car.

 

ICS you can argue all day because it is your opinion but a V8 cannot match the smoothness that a V12 can just like a V6 can't match the smoothness of a v8. Its physics.


then again you believe pushrods are the future...

 

V12's with a power stroke every 60 degrees certainly are smooth no question about that. However modern V8's with coil on plug and sequential fuel injection are very smooth too and can rival a batch fire spark jumping distributor based v12. Not as smooth perhaps but real close. I owned a 6.0 Jaguar V12 and 6.2 LS motor at the same time so I was able to directly compare them.



Doesn't matter what I think I'm not an automotive engineer. Over the years I've owned many more OHC motors then pushrods. But the fact are the facts. GM's newest LT1 push rod V8 make mores HP over all and more HP per LBS that BMW's latest twin turbo V8 by more than 10%. There are other sophisticated engines that make great power too but the BMW was the only one that got close to the new LT1. How long will push rods solider on...I don't know but it's amazing to me what GM engineers have been able to accomplish using push rods.

 

A very interesting discussion. I thank everyone for their contributions, it's made me much more aware of the disparate interests of the members of this forum. I too love the thought of having a V12 Jaguar, and that was my wish for many years. It wasn't to be, but that's quite OK. There are many automotive conversions and "upgrades" that I don't personally like, low-riders with flashy paint and lots of chrome for instance, but I've ALWAYS appreciated the thought and passion put into them by their owners. It's the same with engine transplants, I don't always understand the reasons driving them, but I do appreciate the efforts they represent.

I look forward to hearing more of the OP's story, and seeing pictures, and encourage his future participation here.

And to those stuffing huge engines into little cars, be careful! I lost a friend when his cute Sony micro-truck spun, rolled, and burned. It was a beautiful job, but turned out to be his last.

Steve

 

Good read. Strong opinions. Repairs or swaps - neither are inexpensive or happen at the snap of fingers. My 12 was smooth, even on 11 cylinders. Leaky plug wire. Jumped the chain on the jack shaft, came home on a back of a wrecker. I'm old school, so BBC was my choice. Where would we be if no one every put a engine a surrey or Henry didn't race the 999?

 

How about leaving it at this?

Some guys like the Jag engines, expend the necessary effort, time, and money to make 'em run sweetly and reliably, and meet with success.

Some guys like the V8 engines, expend the necessary effort, time, and money to install 'em in Jags, and meet with success.

'You can't argue with success'



Cheers
DD

 

Doug,

If this forum ever appoints an ambassador it should definitely be you

Care to address the current situation in the Ukraine?

 

Yes you can...some fools argue with success all the time, just look at our congress.

 

yay Doug

 

spend some time drooling here ....

Photos of Modified Sports Cars

 

"...every V8 swap I have ever seen meant the death of the car…"

Allow me to afford you a view of that might bump your percentage a little…

Jaguar V8 Kit

 

geoffsxjs - Don't forget to remove all the V12 badging when you're done!

Keep it real.

 

My 1990 XJS with 32K miles is all factory and I'm leaving it that way... Original and unrestored is the way to go.

 

"I wanna put an LS1/T56 setup in it", with all due respect I suggest you buy a Corvette.

 

Tee hee. I love politics....but not on a car hobby forum. I get plenty of it elsewhere, including my own immediate family....which is a real mixed bag. Family get togethers are a real hoot .


Cheers
DD

 

And presumably a splendid example




Well, sure, that's *one* way to go.....if you have a Jag in fantastic condition. Easy decision.

I'll bet a month's pay that even the most ardent V8 conversion fan would advocate that a gorgeous, low mileage, original Jag with a sweet running Jag engine should be lovingly preserved and maintained as-is.....and would NOT advocate that the engine be swapped.

Cheers
DD