In reply to Chris_V: Does the BMW have replaceable cylinder liners like the Jaguar? If so the secret to power is in the pistons.. The early V12's have only 7.8-1 compression but fantastic heads. Bore the cylinders out to about 95-96mm and with a stock crankshaft you wind up around 7 liters.. increase the compression to about 10.5 to take advantage of modern fuels and you are 1/2 way to 450-500 horsepower.
The Jaguar factory ran the stock V12 up to 7800 without valve float or other problems. The stock camshaft is designed to haul a 4200 pound car plus a couple of sets of golf clubs and 4 people around.. I'm sure BMW is the same. There are aftermarket camshafts that will make power at higher RPM. Or you can send your camshaft to Isky or Crower and have them grind decent lift and duration on the stock camshafts for a lot less. Isky even sells good springs in case yours need replacement.
Now toss that BMW or Jaguar into a nice light chassis and reap the rewards of massive torque and lots of horsepower.
frenchyd wrote:
In reply to Chris_V: I often find whole Jaguar V12 cars on Craigslist's for $500 or less and I've purchased running Jaguar V12's engines and transmissions from V8 swappers for as little as $50 when it's time to clean out the garage..
I'm interested in the BMW V12. Can you tell me what does it weigh? Width and length? Is it like a Jaguar capable of 7800 RPM in stock form? Crankshaft Forged etc? What about transmissions? While the Jaguar uses a GM turbo 400 or it's overdrive version the locating dowels make swapping in a manual transmission relatively easy.. A common trans swap is the T5 but you can buy an undrilled aftermarket scattershield and pretty much swap whatever transmission you want.. I have a Tilton scatter shield for a Sienz dog ring
I've never seen a STOCK Jag V12 turn 7500 rpm. the BMW V12 redlines at 6000 rpm in stock form, but with a tune and exhaust can turn to 7000, which is plenty with a 6 speed manual behind it. It can also be overbored with new sleeves/liners to 6 liters, and put out 650+ hp in N/A form, but a number of people have twin turbocharged them to that output at the smaller displacement.
The BMW V12 is a much newer engine in much newer cars, which is part of the reason the cars in running form cost so much more than the Jags.
The BMW V12 longblock, as used in project cars like I posted (and the 240Z/Ferrari GTO replica that was posted by a member here a couple years ago) weighs in at about 400lbs (or little less. iv'e seen figures for the longblock as low as 340lbs), according to every source I can find. It's basically an aluminum BMW 6 cyl with an extra head. Which puts it a little lighter than the Chevy LSx engine.
Listen, I love the Jag V12 and it's possibilities, but it's a big, heavy lump and it's not the only game in town for an inexpensive V12, especially for engine swap projects.
so, for the BMW, why can't you shave/deck for a bit more squeeze? I know it will mess with your cam timing (and possibly advance one bank while retarding the other) since the chain now has a shorter working distance, but that seems easily solved with adjustable cam gears.
Also, the BMW does have SOHC and rocker arms to articulate the valves, could a person not just make rocker arms with a slight change in ratio for bigger lift? I know that hurts top end since the ramp rates go up so much though.
People say the heads are pretty bad on the BMW (especially the exhaust side), but i've never looked myself.
Honestly, for the BMW, it seems like forced induction and engine management is the way to go for cheap power.
from: http://forum.roadfly.com/threads/7593544-M70-engine-weight-finally-got-it
Finally got around to weighing a M70 engine today and here is the results.
Engine complete with:
A/C pump
Alternator
P/S pump
Oil filter
Fan and clutch
Starter
Flywheel, clutch disk and presure plate
Exhaust manifolds
Engine wiring harness
Motor mount brackets, no rubber mounts
560 lbs
Weighed on a digital scale with a 2000 lbs rating
So if it is 560ish fully loaded, remove the 4 exhaust manifolds (50lbs?), A/C & P/S pumps (30lbs?), Flywheel stuff (40lbs?) and fan (5lbs?) that gets back to 435ish for the longblock. Seems reasonable I think.
What about Mercedes m120 engines? I've seen a few go for $1000 on CL. Especially the early to mid 90's. They came with about 380hp from the factory in the sl600 and 400hp from the s600.
$850
$900
And I know there are a few threads on the MS forum about using MS on them with success.
In reply to rcutclif: The weight of a Jag V12 is 730 pounds but that included the cast Iron exhaust manifolds, PS pump, Fan, torque converter, flywheel, starter, and a really heavy (and big) Alternator.
If I subtract those we're at? 605 pounds? (using your weights) Yes that's still heavy but the crankshaft alone must weigh well over 100 pounds..
As for milling the heads for more compression, The early Jag has no combustion chamber (Huron head) and the later HE like the BMW shrouds the exhaust valve for better part throttle fuel mileage so not the performance choice.. In addition you would need to mill the head enough to take a link out of the timing chain which then generates all sorts of complications..
Finally The BMW, Jaguar, and Mercedes Benz are all designed for the big sedans used to carry 4 fat old people around and a couple of sets of golf clubs.. so the camshafts make peak torque at low RPM, The port Valve sizes are rather small, and all of them give up power for smooth and quiet.
Maybe the aftermarket supplies bigger valves, higher compression pistons, and high lift, long duration camshafts Like Jaguar does.. I haven't researched BMW or Mercedes Benz
In reply to yupididit: Jaguars 4 valve per cylinder heads used on their modern 6 cylinders have the same bore spacing and bolt pattern as the V12's 2 valve heads.. the factory and a few others have swapped 4 valve heads onto the 2 valve production engine if you really want performance potential..
In reply to Chris_V: Of course you haven't seen a stock V12 at 7800 RPM first off due to the extremely mild camshaft it's all out of breath long before that would happen and second the computer won't let it get there. 7800 RPM was seen on the factory Dyno's (source AJ6 Engineering) I'm pretty sure the stock Jag V12 is redlined at 6500 RPM. I'll check and get back later..
The Jaguar has cast Iron sleeves which makes it like an old tractor. You just push out the Iron sleeve, chuck it into a lathe, and bore it to whatever size you want.. (It's safe up to about 96mm from the stock 90 mm)
I used Aries forged pistons but Cosworth has a really interesting piston crown that reportedly is worth more power. Plus that big forged crsankshaft is easy to increase stroke. On my engine I used Chevy con rods and went from the 2.30in rod pin down to 2.10 of a Chevy and wound up at 84mm stroke.. 96mmx84mm times 12 and it was cheap to do..
In reply to frenchyd:
McLaren and Pagani (untuned m120 in the c12) thought it fit to use BMW and Mercedes v12 engines as their basis for super cars. So I'm going to say the performance potential is equal to if not better than the Jaguar. I like all 3 to be honest. All can be had for decent cheapness and can ran using MS. I'm not comparing them to jaguar but more so giving more options that have great starting power potential. A 400hp stock v12 is a pretty darn good starting point in my opinion.
Toyota made a v12 too. But, it was a japan only motor and it doesnt like boost in stock form.
In reply to yupididit: The reason I prefer the Jaguar V12 over Mercedes and BMW is the low cost of power increases it offers.. I spent less than $300 and turned a 1975 XJS V12 into 500 horsepower. (2 junkyard Saab turbo's with intercoolers plus a $85 FMU)
My XK-E race car used Aris Pistons at about $50 each and offset ground and welded crank to get to 7.3 liters (445 cu.in.) Isky and Crower both have a nice selection of profiles to grind the stock camshafts but if ultimate power is called for rather than power on a budget a Kent camshaft is the solution..
I can buy valves from Summit racing intended for Chevy's and modify them for the Jaguar..
The computer is easy to trick into giving you however much fuel you want, without needing to reprogram it etc.. With a distributor controlling the spark, it's simple to change timing..
That's cool if you want to go for the "500hp" dreams. But, the BMW and Mercedes v12 can be a drop in and megasquirt fun at stockish power and still be fast enough for 95% of us without figuring out pistons, valves, and built bottom ends.
Plus the m120 sounds mean as hell with exhaust modifications.
I think it's berkeleying awesome you've modified your v12 with junkyard finds. For some reason I'm more attracted to such builds and projects than those folks with crazy $ money to do top of the line top brand parts builds.
BTW there have been a lot of jag v12+th400 combo's for $500 on my local CL.
Frenchyd and all,
What an interesting thread! I have two XJ-s V12 and a XJ v12 sedan that I paid $250 to $300 each. I am very interested in hotrodding the V12 in one of the XJ-S and have been gathering parts for the project.My plan follows the build from seasoned Jaguar engine builder and racer in Australia who sent me the details of his built.
Use the pre-HE heads (flatheads) modified with bigger valves (something you can't do with the HE heads). Bore the cylinders to 96mm and use custom pistons. This will yield 6.0L or close enough. Custom ground cams, bigger intake plenums with the TBs facing forward and proper ducting for fresh air. Fuel and ignition were handled by an aftermarket ECU. Manual tranny and a numerically higher posi rear end.I am sure there are more details but that is all I remember now. He said the engine put out over 500hp and was geared to cruise at 186 mph. This car was built for a Cannonball run.
What I find the sticking point for me is the ECU. I have two friends, one races a FOx body Mustang and is a software developer by proffession. He scrapped the MS in his race car in favor of a Holley system. My second friend is an EE and he is STRUGGLING to make MS work on his 260Z with an LS1. Now if these two guys who are much more technically savy than I am I don't stand a chance of making MS work on my JAguar project. Units like Motec or Halltech are out of my reach. Are there any other alternatives? I want to have a distributor-less ignition system plus be able to control the fuel.
Very interesting discussion on the BMW and MB v12. I am a fan but will have to put those into the future when I one comes available at my price range.
frenchyd, How do you get an XJ-S down to 2300 lbs from 4200 lbs? Details please since I am going to pursue that route. Because I live in Texas I NEED to have a well functioning a/c.
fortee9er wrote: My second friend is an EE and he is STRUGGLING to make MS work on his 260Z with an LS1. Now if these two guys who are much more technically savy than I am I don't stand a chance of making MS work on my JAguar project.
EE doesn't mean understands the nuances of engine sensors and tuning.
It's been some of my experience that EE doesn't necessarily even mean real-world experience. (Yes, in THEORY the ground plane is the same everywhere... if you ignore a bunch of things)
Besides, I am gung-ho MS but if I were swapping a GM V8 into anything, I'd use the OE computer and wiring. They're all supremely hacked. $650 for the HPTuners cable/software suite gets you everything you need.
In reply to yupididit: Please realize I'm a computer luddite. The idea of buying a Megasquirt and programming it to work with the Jaguar V12 scares the heck out of me.. Friends who have tried it either haven't ever got the car running again (they were probably more terrified of computers than I am) or if they have got it running haven't found significantly more power.
Unlike more modern engines Jaguar has a distributor so timing still is a matter of timing light and manually turning the distributor.
on my Jaguar V12 i use the SDS(simple digital systems) Calgary Canada, works fine for me!
had it since 1994, but upgraded 3 times, lot of advancements in engine control systems,in past 20 yrs.
i still use the factory distributor, but a modified advance curve(GM weights and springs). Crane ignition box 700.
hi-output coil.
if i were to do it today,i would set up a crank postion sensor system,and/or EDIS.etc. but whats the point been 21yrs and still doing fine? if it aint broke dont fix it!
OK in the beginning, it was a lot of experimentng with the socalled fuel map, but little by little its finally real close to perfect,about 95-97% correct!
my engine is a 1978 XJS V12, standard bore and stroke, hi-comptession pistons,9.2-1, total rebuild, oversize valves inlet&exhaust 3mm, ported heads, EXTRUDE honed inlet manifolds and plenums(nice). big K&N filters.
ported factory exh.manis.ceramic coated in and out, large custom pipes all the way thru, no cats etc. set of CRANE cams middle of the road performance level, i like torque for the street, and they will go 6500-6700rpm before starting to fall off, truthfully i rarely drive around at 7000rpm!!LOL.
course a lower final drive ratio and a better 4spd auto transmission, along with a final calibrated weight of 3375lbs helps a lot!
Hi Ron,
Good to see someone, with hands on experience,from the JagLovers site over here.
In reply to fortee9er: Forget civilized to get a XJS down to 2300 pounds you need to build an all out race car.. Examine every bit and part to shave ounces.. Eliminate, do without, punch holes (and then dimple to put strength back in) use aluminum or carbon fiber for fenders, doors, hood, and trunk.
In reply to rcutclif: If BMW has the weight of their V12 down to 435 pounds, then their six cylinder must weigh 240 pounds? A V12 has two times nearly everything.. 2 heads, 2 6cylinder blocks, 2 times as many pistons, connecting rods, crankshaft throws, intake manifolds, exhaust manifolds, etc..
frenchyd wrote:
In reply to fortee9er: Forget civilized to get a XJS down to 2300 pounds you need to build an all out race car.. Examine every bit and part to shave ounces.. Eliminate, do without, punch holes (and then dimple to put strength back in) use aluminum or carbon fiber for fenders, doors, hood, and trunk.
I have thought about composite body panels but I have not seen any being made or offered for sale. Do you know of a source?
frenchyd wrote:
In reply to yupididit: Please realize I'm a computer luddite. The idea of buying a Megasquirt and programming it to work with the Jaguar V12 scares the heck out of me.. Friends who have tried it either haven't ever got the car running again (they were probably more terrified of computers than I am) or if they have got it running haven't found significantly more power.
Unlike more modern engines Jaguar has a distributor so timing still is a matter of timing light and manually turning the distributor.
I understand. I'm an wiring idiot. Luckily I know a guy who is a MS master and will set me up if I ever need him for a price that's well worth it.
I was just throwing other options out there for the folks.
In reply to fortee9er: I just make my own.. it's not all that hard. Buy some fiberglass.. Coat the part you want copies with a release agent and make a splash mold.. Now buy some Carbon fiber and make your part.. Plenty of examples on the net for you to learn from..
If you are serious I'll walk you through it and provide you with a few tips and pointers.
In reply to yupididit: Sit down and do a little pencil work.. Price a Megasquirt, plus the cost of sorting it out and then be honest about what sort of power to be gained.. A stone stock Jaguar, how much more power will a Megasquirt gain over the stock system?
