Teach me some more about Jag V12s

Google turns up everything from "they're a pile of junk" to "the greatest engine ever built." I found very little on blueprint specs. (I'm kinda the king of finding off-the-shelf pistons and rods to make a beefy rotator on a budget)

also, in searching for Jag V12s I saw several of the BMW V12s (5.4L) in a vaguely similar price range.

Don't worry about ancillary parts; much of the intake, exhaust, etc will be fabbed or altered. I'm thinking a megasquirt with individual throttles kinda thing. I'm looking for reliable hardware - block, heads, valvetrain, ignition (if I need it) etc.

Basically... looking for a V12 as a build project. Suggestions?

http://ls1tech.com/forums/conversions-hybrids/1643786-v12-ls1-build.html How good are you at welding aluminum?

I have an 89 750il here which could go cheap to a GRM'er...

curtis73 wrote: Google turns up everything from "they're a pile of junk" to "the greatest engine ever built." I found very little on blueprint specs. (I'm kinda the king of finding off-the-shelf pistons and rods to make a beefy rotator on a budget) also, in searching for Jag V12s I saw several of the BMW V12s (5.4L) in a vaguely similar price range. Don't worry about ancillary parts; much of the intake, exhaust, etc will be fabbed or altered. I'm thinking a megasquirt with individual throttles kinda thing. I'm looking for reliable hardware - block, heads, valvetrain, ignition (if I need it) etc. Basically... looking for a V12 as a build project. Suggestions?

http://www.topspeed.com/cars/car-news/top-secret-v12-supra-ar78395.html

I've seen a few Toyota V12 projects.

Based on my experience with my XJS, I'd say they they are basically great motors that suffered from poor ancillaries. They generate a LOT of heat that tended to bake rubber and plastic causing failures in cooling, ignition, and fuel injection. This would cause overheating and fires.

Once the motor had overheated it was virtually worthless since the heads would warp. A rebuild was prohibitively costly.

If you start with a good motor and replace or rebuild virtually everything attached to it and upgrade the cooling system it might make a good candidate for your swap. BTW, I have no knowledge of the later 6.0 engines built in the Ford era. The design changed somewhat, but I don't know if that helped the other issues.

It's an elegant little engine wrappped up in a Rube-Goldberg machine.

I could never understand the high cost of engine rebuild parts since so many of the cars ended up needing new engines. Jaguars reputation would have been much improved if they had not been so greedy in the owner's time of need.

Guy I know with an Esprit SE builds V12's as a hobby. Any V12. He says the stock Jag V12 bottom end is good for 1K HP.

We used to have a resident Flounder-er here that knew them really well. He doesn't seem to be on here anymore.

SyntheticBlinkerFluid wrote: We used to have a resident Flounder-er here that knew them really well. He doesn't seem to be on here anymore.

I believe it was mguar? Would be worth a search to find some of the old threads. I'm pretty sure he was banned.

Dr. Hess wrote: Guy I know with an Esprit SE builds V12's as a hobby. Any V12. He says the stock Jag V12 bottom end is good for 1K HP.

That sounds like fun. A little megasquirt and a couple turbos :)

Basil Exposition wrote: A rebuild was prohibitively costly.

It has wet sleeves, right? One of the nice things about that is that you can make sleeves in darn near any size/thickness/bore you want (with obvious limitations). Piston, pin, ring, and rod selections can usually then be sourced from chevy, ford, or other cheaper sources.

MrJoshua wrote:

SyntheticBlinkerFluid wrote: We used to have a resident Flounder-er here that knew them really well. He doesn't seem to be on here anymore.

I believe it was mguar? Would be worth a search to find some of the old threads. I'm pretty sure he was banned.

I believe that was his name yes.

I'll just leave this here:

http://www.youtube.com/watch?v=M9I7GWllPFY

And this:

http://www.youtube.com/watch?v=c5jtf83eKGs

Also the beginning of loosecannon's build thread on his jag powered MG has some interesting info on the Jag V12.

Pretty sure I met mguar on another car board from which he was also evicted. He knew a lot but not very politely.

bearmtnmartin wrote: Pretty sure I met mguar on another car board from which he was also evicted. He knew a lot but not very politely.

I think he was on the Chumpcar forum but was also kicked off.

Here's what I've never understood. The Jag I-6 is known to be a reliable and smooth power plant. You stick two of them together ... suddenly it's the most unreliable engine in the universe. How does that happen?

In reply to LanEvo: Wiring. IIRC, the V12s lack grounding or the wiring they used for grounding was no good. Something along those lines.

Also, Lucas electricals didn't help.

LanEvo wrote: Here's what I've never understood. The Jag I-6 is known to be a reliable and smooth power plant. You stick two of them together ... suddenly it's the most unreliable engine in the universe. How does that happen?

Because they have no relation. The V-12 is not to I-6s combined.

spitfirebill wrote:

LanEvo wrote: Here's what I've never understood. The Jag I-6 is known to be a reliable and smooth power plant. You stick two of them together ... suddenly it's the most unreliable engine in the universe. How does that happen?

Because they have no relation. The V-12 is not to I-6s combined.

Dear lord! Can you imagine how massive and heavy that would be?

Ditchdigger wrote:

spitfirebill wrote:

LanEvo wrote: Here's what I've never understood. The Jag I-6 is known to be a reliable and smooth power plant. You stick two of them together ... suddenly it's the most unreliable engine in the universe. How does that happen?

Because they have no relation. The V-12 is not to I-6s combined.

Dear lord! Can you imagine how massive and heavy that would be?

what do you think BMW V12s are? they are two I6s with a common Crank and case. They have double of everything else.. including the computers to run them

ronholm wrote: I have an 89 750il here which could go cheap to a GRM'er...

Go on....

Hey, Curtis, you're like an hour from me. I see BMW 8 series with the V12s on Craigslist and Autotrader from time to time...

Also, the proper way to use stand-alone engine management on many V12s seems to be to treat them as two separate inline sixes.

I spoke to Matt at DIY Autotune regarding MS to run a BMW V12. He'll set you up. I backed out of projet due to the cost/difficult to run a manual trans.

mad_machine wrote:

Ditchdigger wrote:

spitfirebill wrote:

LanEvo wrote: Here's what I've never understood. The Jag I-6 is known to be a reliable and smooth power plant. You stick two of them together ... suddenly it's the most unreliable engine in the universe. How does that happen?

Because they have no relation. The V-12 is not to I-6s combined.

Dear lord! Can you imagine how massive and heavy that would be?

what do you think BMW V12s are? they are two I6s with a common Crank and case. They have double of everything else.. including the computers to run them

Same with Ferrari's

As I understand it, the original Jag V12 was built from the parts bin with XK6 heads and such, but deemed to heavy and complicated for a race car, and too unrefined for a luxury car, so it got heavily re engineered with single cams and such.