V12 engine mods, cheap

In reply to mguar:

its a 1987 block, plus ive also got the t5 cobra transmission on it aswell capable of holding 425ish

In reply to mguar: corvair haha

i know all about the HE ive just about memorized kirby palms book. i know you can pull 400-45 hp out of the he block with stock heads, im just concerned about losing my midrange power, i was thinking of getting piper mild cams, 20hp engine retuning with aj6 throttles, i have removed the cats and have high clow downpipes with 0 flow reduciton units, im building the growler style intake to match the larger throttles. what do you guys think of this plan? 20 hp from the cams 20-30 from the throttles, rumor has it 15% from the intake but idk if i belive that. the 2.5 in pipe is like another 20 no ac, plus you also have to factor in the high horsepower from the new transmission because its far easier to spin than the turbo 400. thats my plan any suggestions?

In reply to mguar:

Thanks for your posts Mguar,

Impressive amount information about the Jag V-12 engine!

I'm currently in the process of Megasquirting a '96 6.0L to replace the (tired) 5.3L in my '84 XJS.

I've been considering doing a quad throttle-body set-up (2 factory TB's per intake) for the 6.0. Your thoughts? (The '84 5.3 and '95 6.0 TBs are the same diameter).

Regards,

BK

Hmmm. CL has an '85 for 850.00. Cranks, no start. Hmmm.

cwh wrote: Hmmm. CL has an '85 for 850.00. Cranks, no start. Hmmm.

I'm thinking about it too: http://grassrootsmotorsports.com/forum/grm/mguar-you-are-a-bad-influence/45237/page1/ I wish MGuar wouldon come back for a visit again.

The V12 out of the BMW 750i is just as reliable as the BMW I6 times two. I'm just sayin. The Jag is a...Jag.

Must ... stop ... reading

Damn. Now I find myself wondering if a Jag V12 would fit into a TR6. It would be like two Triumph motors with only 100 lbs. or so more weight.

Zaguar been done before: Zaguar Article

In reply to HappyAndy: It's been a while but I'll answer a few questions brought up. The early V12's had either the Jaguar 4 speed or the Borg Warner automatic (Yuk!!!) . About 78-79 they switched over to the Turbo 400 but not just any Turbo 400. The bell housing for Jaguar was unique and the internals were very heavy duty parts (Tow Trucks- ambulances) usually, although I've taken some apart and found the cheap lighter duty stuff. (It's possible they were installed by a trans shop instead of the proper pieces..)

The good news is that B&M parts fit and work. However the really great news is that the dowel locations make using bell housings from people like Tilton simple. Transfer punches locate where to drill holes go. Always use careful measurements to adjust for depth and check for alignment. Even with aftermarket kits. Now you can pretty much bolt any strong 4/5 or 6 speed manual gearbox.. Don't fall in love with 5 or 6 speeds unless you are looking for a cruiser. 5th and 6th speed are almost always overdrive and with the common 2.88 final drive ratio at anything above an idle you are in speeding ticket territory..

The final drive is massively stout..as long as it's in good condition it will handle anything. Stock though the rear suspension has a few shortcomings. It sits on needle bearings that while cool, work too short of an arc and all the load is felt through one or two little needles.. Replace with brass bushings for a cheap effective fix.. The whole rear suspension rides and works really nice but racing calls for a different approach. It's mounted on rubber. That solves the geometry conflict between the arc of the suspension and the arc of the trailing arms.. However when fat sticky tires and real power get together well let's say a different approach works better.. Instead of the trailing link pointing forward it is moved in at about a 45 degree and pivots about the center of the inner arc of the lower suspension arm. Then the whole cage can be rigidly mounted with a notable improvement in cornering power. The earliest Jaguar XJ-S had a 7/8ths front swaybar and 9/16ths rear sway bar Later they went to 3/4 inch and no rear sway bar.. For Racing one inch in the front is better, adjustable of course. while depending on various factors the 9/16ths rear might still work.. Obviously mushy rubber mounts give way to aluminum (install a grease fitting please). Believe it or not the stock springs will work if the right shocks are used.. but the big XJ12 sedan is stiffer

Finally my favorite shopping place for Jaguar stuff is the local junkyard. Shop where you see an old rusty sedan or two and don't be fooled into paying a very high price for anything.. V12 engines are worth $300-$500 although you often see much higher prices asked. Few know anything about the cars they have and almost no one knows how to interchange Jaguar stuff..

In reply to BlownKitty: Sorry but I hope you haven't wasted your time on the quad intake idea. Stock it has 1200 CFM and you want to double it to 2400 CFM? Ferrari and Aston Martin don't use quad intakes on their engines.

Here's a much cheaper solution.. The stock air cleaner flows nearly nothing and it's sucking hot air right off the radiator. Cut the stock air horn off. Buy some of that flexible aluminum dryer hose (4 inches?) Gently bend it to draw cold air from in front of the radiator. Another way is to take a hole saw to the low beam headlight bucket. The high beam can be ducted to the front brake calipers for cooling the brakes diving into turn 5 at Road America, Elkhart Lake

In reply to Timeormoney:

OOPS wrong!!!! The high compression of the HE and turbo chargers will cause melted pistons.. Use the early flat head for maximum flow potential, the 7.8 compression pistons to make the engine live without buying $12 a gallon racing fuel. Now put that all in the HE block so you'll have a transmission that will survive.. The HE was designed not to make power but to get better fuel mileage.. The combustion chamber looks exactly like the stove bolt Chevy Six of the 50's and early 60's

And if you want the benefits of the 6.0 litre engine, use the early (1971-1980) heads and custom pistons.. Since you are making custom pistons go all the way and bore the sleeves out to 96 mm (from90)

In reply to calvindoesntknow:

Cheap power tricks..

Cut off the air horn on the aircleaners, Duct air to those with as big a tube as you can.. 4 inch flexible aluminum dryer hose works easily. Pick up cold air from in front of the radiator..$20.00

Eliminate any mufflers you can get away with..$10.00

Make sure the distributor works properly.. many of those I look at are not properly lubed and as a result frozen. or the vacuum advance/retard leaks.

While it won't make more horsepower the difference between a properly working distributor and most Jaguar distributors is night and day.

Now the final thing is what luxury can you do without.. Stock the XJ-S is about 4200 pounds. A Race car can get down below 2700 pounds.

The horsepower of the stock V12 isn't impressive but it's torque is.. and 300 horsepower with all that torque will move 2700 pounds around in an extremely exciting fashion.. 4200 pounds? Blaaahh!

In reply to HappyAndy: It's still running around here. I see it every so often. I'll take some pictures next time I see it.. It's not pretty but seems to be pretty bullet proof..

Since the boost gauges came from the same junk yard one read less than 6 PSI and the other was over 8..

unevolved wrote: I think the big question everyone's wondering is what's the smallest, nimblest chassis these can be easily swapped into?

I'll just leave this here...

https://www.youtube.com/watch?v=jZLnrOeu0KE

I don't think that's the easiest swap, but .

Next mod for that car, a Flying Miata rollbar.

By the way, how expensive or normal do the Jag V12s cost to maintain?

In reply to frenchyd:

Welcome back forum member who may, or may not be Mguar. I hope things go better for you this time around. J still occasionally do a V12 search on CL. Some day I will have a V12 Jag.

Everything ive ever heard about the jag v12 is that they are hand grenades, and the best mod for one is to replace it with something that start. So is that not true?

gearheadmb wrote: Everything ive ever heard about the jag v12 is that they are hand grenades, and the best mod for one is to replace it with something that start. So is that not true?

Sounds like you have been talking to the same guys who argue sbc vs sbf over a budwiser.

In reply to gearheadmb:

The motors have a few issues that can cause serious problems (Cats and some of the ignitions) but there is a HUGE user sourced book available for download that explains how to fix those. Once it is well sorted and you bin everything that says Lucas on the car (joke), the biggest issues is that vast quantities of fuel that these motors eat.

I'll just leave THIS here...

edizzle89 wrote: I'll just leave THIS here...

Oh great, a Challenge-worthy V12 near where I live. You people are a bad influence.

In reply to maschinenbau:

oh trust me its gone though my mind more then once, but im looking into other options right now

How durable is the V12 Jaguar engine? Open one up and you'll swear it was designed by the guy who builds 5000 horsepower top fuel engines. (only with 4 extra cylinders)..

The flaw is that people who can afford them new don't know how to read (the maintenance manual) and wouldn't do anything more than maybe change the oil.. Then they get tired of paying a premium to have the dealership change the oil and start going to the cheaper places to have work done..

Now those guys aren't trained and don't know for example that you have to oil the distributor. That the pause in shifting is nothing more than a $3.00 part that came loose (probably because they had the trans fluid changed at the same cheap place. By the way it's a common Turbo 400 problem that there has been a fix out for decades. Normally that Turbo 400 is well built and durable if the fluid is changed properly.

If you do read the maintenance manual or spend the time learning to do the work you'll find they are simple, straight forward engines (& cars.)If you can count to 8 it's really not that much harder to count all the way to 12. The only flaw is that there is a pretty good chance Ignorant wrench benders have messed things up or neglected important things.. When I say ignorant it's important to understand what the word ignorant actually means and not it's pejorative connotation. I'm ignorant about a lot of things, computers being one of them. Rarely in my life have I heard a mechanic admit ignorance and seek help.. The guy who does swallow his pride and go looking for information is the guy I'd trust to work on anything as complex as a Jaguar.. In short if the proper manuals don't come out it's time to leave..

In reply to maschinenbau:

I've purchased similar as low as $500. I recently passed on a 1994 convertible (with V12) for scrap metal prices.. It was filthy but solid.. Nope it didn't run but that might have been as simple as a dead battery or as complex as a blown head gasket.. Had it been on a trailer I could have used to get it home though the temptation would have been great to drag it home to add to my collection..