I rode in a friend’s 7-series BMW the other day. All very luxurious and
everything
you’d expect. Except the motor seamed totally out of place. It seamed to
haul
the heavy BM along nearly as well as my V12 hauls the XJ but the lumpiness of
the V8 just seamed all wrong. Sure I appreciate the V-8 burble in its place
but it just doesn’t belong in a luxury car. The 60 degree V12 is vastly
superior.
Bmw’s 750il has a very well placed V12 in it. Being a DOHC, its redline is
lower than the Jag 12. At 4000rpm, however, you won’t need anymore thrust.
That car is a serious tank-rocket. I highly recommend taking a test drive
(for perspective) at your nearest high-line used car lot. And apparently,
Bmw has a new 12 coming out that is 60 degrees and 408bhp. See specs at http://www.ultimatecarpage.com/frame.mv?file=car.mv&num=934
Bmw’s 750il has a very well placed V12 in it. Being a DOHC, its redline is
lower than the Jag 12. At 4000rpm, however, you won’t need anymore thrust.
That car is a serious tank-rocket.
I’m not quite sure what you’re talking about. The BMW V12 in the
750iL is a SOHC 2-valve/cylinder V12. IIRC it was enlarged from 5.0L
to 5.4L in '96 or so when they changed the body style of the
7-series. There were two DOHC BMW V12s that I can think of; one in
the 850CSi and the other in the McLaren F1. On top of that, having a
DOHC motor doesn’t lower your redline. In fact, the better breathing
characteristics tend to INCREASE the potential redline. However the
actual redline is determined by a lot of other factors, one of which
is how many rpms the tranny can handle. That’s why most cars these
days have a redline of 6500 rpms; automatic trannies don’t really
like going much higher. Also, if you don’t believe that valvetrain
really doesn’t have a major affect on redline, I can build you a
small block Chevy (pushrod) 302 that will rev to 10,000 rpms just
fine. Could probably do 12,000 rpms. Those are motorcycle rpms out of
a pushrod V8.
Also the BMW V12 is vastly inferior to the Jaguar V12. There was
something about the blocks that didn’t react will with some pump gas,
so bye bye engine.–
-Ted
'82 XJ-S – 5.3L V12 '98 Volvo S70 GLT – 2.4L I5 Turbo
'93 GMC Vandura 2500 – 4.3L V6
New York City, NY AIM: FordCrusherGT Yahoo: Jag_Pushrod
Quite often, whether it’s doing a compression test or changing spark
plugs, the a/c compressor is in the way.
I WANT to modify the bracket, do a compression test-among other things.
Is there a way move the a/c compressor out of the way without letting the
freon out of my a/c system?
(snip)
Quite often, whether it’s doing a compression test or changing spark
plugs, the a/c compressor is in the way.
(snip)
By unbolting the mounting bolts and loosening the belts, you can tilt the
compressor up and forward, then rest it off to the side. This will give
you access to what is underneath it, without disconnecting the freon lines.
Tex Terry, II
86 XJ-S Coupe V12 GM400 DANA 2.88
Franklin, PA USA
I did change the hoses on the power steering. Thank you for all of the
good advice.
My engine is running like garbage right now-13.7mpg (in town). I
backfired yesterday. I think there is a miss or exhaust leak (or
something) because I can feel an irregularity in the idle. I fear I may
have messed it up when I overheated it.
I was reading through Kirby’s book which quoted the cost of a new one of
these engines at $10,000, but never mentions how much it would cost for
me to rebuild it myself. It would take some new learning, but I helped dad
build a couple engines growing up-so it shouldn’t be too much of a
stretch.
Assuming someone else does the machining, anyone know what it ought to
cost (in parts) to rebuild on of these engines? I would take it out and
assemble it.
The good news is that I will have a garage in about a month so I can take
time to do all of this at my leasure-rather than doing it in the parking
lot at work on a Sunday (like the P/S hoses).
I’m not quite sure what you’re talking about. The BMW V12 in the
750iL is a SOHC 2-valve/cylinder V12.
Ted, you need to click on the link he supplied where it gives the specs for
the new Bimmer DOHC V12. That will being you up to speed on it.
And please, guys, if we are going to be anal and snotty about labels, then
we need to allow others to do the same. To BMW afficionatos (I used to own
and LOVE an L7–though to be honest, my ex happily got the L7 and I happily
got the SIII VDP. My Jag is still running and her BMW is not…) a “BEEMER”
is the nickname for the motorcycle and “BIMMER” is the nickname for the car.
>Assuming someone else does the machining, anyone know what it ought to
>cost (in parts) to rebuild on of these engines? I would take it out and
>assemble it.
I spent around $2,500 to rebuild my engine including sending the heads out to be surfaced.“Robert J. Hill” robhill@physics.purdue.edu wrote:
Robert Woodling
'84 XJ-S sometimes you need pace
'97 XJ6 �sometimes you need space
always you need grace
'82 C27 Hull #5209
“Linnea Lee”
Monroe Lake, Indiana
Your favorite stores, helpful shopping tools and great gift ideas. Experience the convenience of buying online with Shop@Netscape! http://shopnow.netscape.com/
Also the BMW V12 is vastly inferior to the Jaguar V12.
Really! 300 b.h.p. and 332 lbs of torque (250 lbs from 1000 to 5900 r.p.m.)
of the 1987 BMW 5 litre V12 with catalysts doesn’t seem all that inferior
to me - in fact more like the other way round. Perhaps being lighter and
more compact than the Jaguar V12 are features that, by some yardstick, make
it “vastly inferior”. The greater mass of the Jaguar V12 helped endow it
with more refinement but did nothing for its performance, fuel efficiency
and ability to meet modern emission standards, so eventually contributed to
its demise.
The truth is both engines had good points as well as bad ones but really
the Jaguar V12 was good in its day but soldiered on a lot longer than it
was ever meant to simply because lack of funding meant there was no
replacement in sight - just as happened to the XK before it.
The later BMW V12 used in the McLaren F1 is in a totally different league.
There was something about the blocks that didn’t react will with some pump
gas,
so bye bye engine.<
I rather think that refers to the Nikasil problem which cost BMW dearly,
but actually the V12 used the Alusil process for creating hard wearing
surfaces in aluminium cylinders so was much more resilient. Subsequent
aluminium cylinder blocks with Nikasil plated bores (BMW 6 and 8 cylinder)
proved susceptible to corrosion and consequent rapid surface failure in
certain operating regimes with fuel having a relatively high sulphur
content. Jaguar have had the same problem on their V8 and like BMW have
abandoned the Nikasil process and reverted to conventional iron liners.
Ironically the low sulphur fuels that are now becoming common solve the
problem anyway.
It is a long story which I do not propose to expand on further because of a
forthcoming article about it all.
In reply to a message from Robert J. Hill sent Mon 29 Jul 2002:
Hi guys,
I’m new to Jaguars, but wondered if I could drop in here. I’m
thinking of using a Jaguar V12 engine or a project, but I’ve
heard rumours that the cranks can’t be re-ground when you’re re-
building an engine. Apparently this is to do with the nitride
coating (er, nitriding?) from the factory.
Is this true? If so, does it effect any specific engines, or does
it effect them all? I’m not quite sure just what V12 engine I’ll
be needing yet. I’m not sure if it’ll require a re-build at all,
but I was at the least thinking of stripping it, cleaning it all
out, perhaps lightly cleaning the cylinder walls (or a very light
hone), new rings, possibly new pistons, and new bearings if I
can. Oh, and gasket set and timing chain.
Thoughts? Ideas?
thanks guys,
Chris Waltham
Perth, Australia–
Big Chris
Perth, WA, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
I’m new to Jaguars, but wondered if I could drop in here. I’m
thinking of using a Jaguar V12 engine or a project, but I’ve
heard rumours that the cranks can’t be re-ground when you’re re-
building an engine. Apparently this is to do with the nitride
coating (er, nitriding?) from the factory.
I changed the bearing in my engine a couple of years ago (cost US$200
for the set). The old ones were down to the copper. The crank still
measured up to factory specs. Engine had done 200000km. Don’t worry
about the crank - it’ll almost certainly not need regrinding.
I’m not quite sure just what V12 engine I’ll
be needing yet. I’m not sure if it’ll require a re-build at all,
but I was at the least thinking of stripping it, cleaning it all
out, perhaps lightly cleaning the cylinder walls (or a very light
hone), new rings, possibly new pistons, and new bearings if I
can. Oh, and gasket set and timing chain.
All sounds pretty sensible. Though if your budget is tight, you’ll probably
get away with using the original pistons.
In reply to a message from Tony Bryant sent Thu 8 Aug 2002:
I changed the bearing in my engine a couple of years ago (cost
US$200 for the set). The old ones were down to the copper. The
crank still measured up to factory specs. Engine had done
200000km. Don’t worry about the crank - it’ll almost certainly
not need regrinding.
I heard a rumour that you can’t get undersized bearings. Is that
true? Did you require them, or were you able to use standard-
sized ones? From all accounts, the bottom-ends seem to be bullet-
proof, with other (albeit non-Jag) engines I thought crank re-
grinds - or, at least checking to see if one was needed - were a
matter of course.
All sounds pretty sensible. Though if your budget is tight,
you’ll probably get away with using the original pistons.
That depends how much they cost, I guess… I had a quick look,
looked like around USD$1500 a set (with rings). That’s a lot in
Australian dollars! So long as they look fine, is there
nothing wrong with using the existing pistons? But new rings
would be a good idea, right?
thanks again,
Chris.–
Big Chris
Perth, WA, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
All sounds pretty sensible. Though if your budget is tight,
you’ll probably get away with using the original pistons.
That depends how much they cost, I guess… I had a quick look,
looked like around USD$1500 a set (with rings). That’s a lot in
Australian dollars! So long as they look fine, is there
nothing wrong with using the existing pistons? But new rings
would be a good idea, right?
thanks again,
If the pistons and bores meet spec (not just look fine - you have to
measure them), you can reuse them. If the bore ovality, taper or wear
exceeds spec, you have the choice of fitting an oversize piston or
sleeving the cylinder and reusing the original. I just had this
problem with a Triumph Stag V8 and ended up with a set of oversize
since I would have had to sleeve 3 or 4 bores and that wasn’t cost
effective.
Even if the bores and pistons are fine, you will need to lightly
hone them and fit new rings (and the ring gaps will need to be
checked and possibly adjusted). Don’t even think about reusing the
old rings unless you like to take engines apart.
Once you have an engine apart, it’s false economy to scrimp on putting
it back together correctly and to spec, regardless of how much it hurts.
My current rule of thumb for engine rebuilds is $175 US / cylinder,
although I think that’s probably a bit low. It might be more
like $200. That would be around $2400 for the V-12, which is probably
in the right range.
cheers
Paul–
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software paul@AuroraGrp.Com | Unix & Windows
I heard a rumour that you can’t get undersized bearings. Is that
true? Did you require them, or were you able to use standard-
sized ones?
Since the crank wasn’t measurably worn, I replaced them with
standard sized bearings.
From all accounts, the bottom-ends seem to be bullet-
proof, with other (albeit non-Jag) engines I thought crank re-
grinds - or, at least checking to see if one was needed - were a
matter of course.
Only needed if worn beyond specs. Measure and find out for sure,
but unless you get a really high milage engine, I doubt you’ll need to.
That depends how much they cost, I guess… I had a quick look,
looked like around USD$1500 a set (with rings). That’s a lot in
Australian dollars! So long as they look fine, is there
nothing wrong with using the existing pistons? But new rings
would be a good idea, right?
The pistons are well designed and made by all accounts.
You might not even need rings - Get a leakdown test done.
Find out for sure.
Another option for pistons if you end up needing to replace them is that
apparently 2.6L mitsi 4 banger pistons (almost) fit. I can neither confirm
nor deny this rumour though…
So long as they look fine, is there