In reply to a message from Eric Capron sent Tue 5 Nov 2013:
an option…not as original, IF you do not want the reduced
clearance due to dual pipes below the frame…a single very
large diameter pipe, as large as about 2 3/4 diam, can fit
thru the frame hole. A good shop with a mandrel can bend
pipe without pinching the pipe and can fabricate a collector
from the two manifold down pipes to go into the one large
single pipe. Then depending on what sound you want…no
muffler at all and add an Ansi dual pipe baffled end tips
(great sound !!) or add a muffler and the Ansi. (similar to
what was Abarth, Ansi has many various styles, chrome or
not). The large diameter single pipe will provide equivalent
or more exhaust than two single pipes. A=pi R squared.
Suggest try it without the muffler first…unless you know
that you just love a quiet Jaguar. On my OTS most everyone
loves the uncorked sound and the dog knows I am coming home
(thus so does wife) before I get there.–
The original message included these comments:
were sold (I think still are) as performance exhausts but it was the sound
everyone wanted.
Note that the XK firing order is such that the front 3 cylinders take
turns firing with the back three. With each set of 3 having its own
straight path for an identical length to the end of the tailpipe, the
sound produced is like two 3-cylinder engines running side by side with
the approximate sine waves of sound precisely timed to be out of phase
with each other so that they have the same pitch but are harmonizing
with each other rather than doubling the volume (amplitude) of one
frequency. This produces a richer sound than just one louder 6-cylinder
engine with a big pipe. Part of this precision in sound has to do with
the two exhaust paths being almost exactly the same length so that they
have the same sonic resonance frequencies (like twin organ pipes) to
make the harmony work in the most pleasing way to the human ear.
Note that with good harmony produced by the best in barbershop or
bluegrass, you can actually hear some notes that no singer is actually
singing - that’s the “harmonics”. They refer to it as a chord “ringing”.
Ask any barbershopper - it’s like the holy grail.
Add to this a “silencer” that consists of two perforated sections of
pipe passing side-by-side through perforated pipes in the chamber of the
outer shell of the silencer. This provides some mixing of the two notes
in the silencer that enhances the pleasing quality of the harmonics that
would be produced by one six-cylinder engine operating synchronously
with two 3-cylinder engines at half the rpm of the 6. What you end up
with is essentially music. The resonant frequency of the two paths
produces amplified sound at 1,600 and 3,200 rpm with quieter sounds with
harmonics on either side of those peaks. My favorite sound is at about
2,400 rpm with the lower volume but maximum harmony due to the added
amplitude of the harmonic frequencies.
It is not possible to produce the same level of musical quality if you
pump the exhaust of all six cylinders through one large pipe and then
divide that sound between two paths at the silencer. If you decide to go
with the 2-1-2 path instead of the straight 2 path with some mixing in
the silencer, you may never have the opportunity to compare the
alternative sounds over the operating range of the engine. In that case,
the good news will be that you will probably never have an opportunity
to compare the sounds to know what you might be missing.
One thing I certainly agree with is a FHC should have a single path for
the exhaust with a normal baffled silencer. Even with the hood up on the
OTS, the amplitude of the twin pipes is somewhat oppressive. It is best
experienced with the O for “open” - partly because the richness in
enhanced by the variety of sounds reflecting back from just about
everything - especially going through tunnels
So - I recommend straight-through twin pipes passing under the frame for
the best quality of music through the operating range.On 11/5/2013 2:54 PM, Nick53XK120S wrote:
In reply to a message from Eric Capron sent Tue 5 Nov 2013:
an option…not as original, IF you do not want the reduced
clearance due to dual pipes below the frame…a single very
large diameter pipe, as large as about 2 3/4 diam, can fit
thru the frame hole. A good shop with a mandrel can bend
pipe without pinching the pipe and can fabricate a collector
from the two manifold down pipes to go into the one large
single pipe. Then depending on what sound you want…no
muffler at all and add an Ansi dual pipe baffled end tips
(great sound !!) or add a muffler and the Ansi. (similar to
what was Abarth, Ansi has many various styles, chrome or
not). The large diameter single pipe will provide equivalent
or more exhaust than two single pipes. A=pi R squared.
Suggest try it without the muffler first…unless you know
that you just love a quiet Jaguar. On my OTS most everyone
loves the uncorked sound and the dog knows I am coming home
(thus so does wife) before I get there.
The original message included these comments:
were sold (I think still are) as performance exhausts but it was the sound
everyone wanted.
–
Nick53XK120S
Spokane WA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from Bruce Cunningham sent Tue 5 Nov 2013:
Just for the record, my 120 DHC had dual exhausts through the holes
in the frame, then followed up by glass packs and out twin pipes
with chrome ends. A beautiful look and killer sound. Very hard to
get it through sound tests at Lime Rock where we ran on Sundays.–
Dick West XK120DHC
Barrington, NH, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from OrganDoctor sent Tue 5 Nov 2013:
Just confirming a couple of things that were mentioned.
My NOS Burgess muffler purchased from Bob Zimmer in 1982 is
painted silver, has the words BURGESS and MADE IN ENGLAND in
bas relief letters on the can, and has an eight bolt flange
on the two pipe stubs on the inlet end. There is a bracket
welded on the outlet end for the frame hanger.–
XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
In reply to a message from Bruce Cunningham sent Tue 5 Nov 2013:
Bruce Cunningham’s description of the exhaust pulse
interface in the original style dual muffler is hands down
the best explanation I have ever heard.
I recall trying to explain my version of this exact theory
to a judge in Hingham district court when I was 16 after a
loud muffler ticket. I explained that all 120s were as loud
as mine.
He then asked how much I made at my after school job, and I
told him $36. He fined me $18 and told me not to ever drive
by his house.
It was over in seconds and I never saw it coming.–
The original message included these comments:
Note that the XK firing order is such that the front 3 cylinders take
turns firing with the back three. With each set of 3 having its own
sound produced is like two 3-cylinder engines running side by side with
the approximate sine waves of sound precisely timed to be out of phase
Add to this a ‘‘silencer’’ that consists of two perforated sections of
pipe passing side-by-side through perforated pipes in the chamber of the
Znalazłem twój post odnośnie XK 120.
Mam XK 120, który się grzeje, Wentylator oryginalny 5 łopatkowy z aluminium.
Dałem chłodnicę do przemycia, Silnik wygląda w układzie chłodzenia czysty.
Zapłon ustawiony.
Jakieś sugestie, co można jeszcze sprawdzić?
Czy również miałeś problem z grzaniem się silnika?
Andrew Warszawa 881483601
I came across your post regarding the XK 120.
I have an XK 120 which heats up, it has an original 5-blade aluminum fan. I have had the radiator flushed, The engine’s cooling system looks clean. Ignition timing is correctly set.
Any suggestions what else can I check?
Did you also have a problem with engine heating?
Andrew Warsaw 881 483 601
