muffler

[abstamaria]

Dear fellow-listers,

I note a lull on the List and, in case we are running out of topics, am
contributing this one to fill the gap.

Over the almost 30 years that I've had the Elan, my problem has been finding
the right muffler (silencer). I tried a shortened Cherry Bomb in the early
years, a Stebro, and a few custom-made ones thereafter, but was never
completely happy. My Elan notebook is filled with drawings of designs of
mufflers. My last installation was an all stainless 2-1/4" item from Tony
Thompson, which sounded good and, being very light, was consistent with the
Lotus ethic. However, it was a round muffler and didn't suit the cavity at
the back of my S4. It would probably look very good on an S1 or S2. Or a
26R, for which it was designed.

Last month, as I was working on bringing the Elan back to road-useable trim,
I spotted the spare mufflers I had from my Ducati 748R. I had changed to
carbon-fiber Termignionis and so had set aside the original items (also
Termignonis). These are oval mufflers with light stainless steel ends and
lovely, one-piece aluminum shells. The oval shape and length seemed to fit
the Elan. Upon disassembly (the silencer is held together by rivets), an
intricate baffled system with a perforated inner shell, all beautifully
made, was revealed.

I replaced the inner baffle system with a 2-1/4" s/s perforated tube, filled
the surrounding area with fiberglass, but left a bulkhead and a short empty
chamber at the rear end. I refitted the perforated inner shell and covered
this with the original fiberglass mat. I retained the original 2"diameter
exhaust stub exiting the muffler, but had a 5-inch long 2'1/4" diameter
extension pipe TIG-welded to this. Then I assembled the whole thing into
the aluminum outer shell. Except for the tail-pipe extension, It looks
original Ducati. Ducati pieces are generally very nicely crafted.

I installed the muffler, which is very light, over the weekend. It goes
nicely with the car. The concern is that the mufler might be too loud as
the overall volume is small, but the slight reduction of the pipe size at
the outlet should cut the sound a little bit, at least according to my old,
outdated book on the "scientific design" of exhaust and intake systems.

How does it sound? I still have to install the original matting under the
carpets and install the seats, so I have not started the car. Will let you
know.

Warm regards,

Andres
S4 DHC #8439
Manila

[Bill]

Andres

You said the question "How does it sound?"

I would be curious to know as well. The exhaust on my stock 1600 system
twists around the 360 degrees at the muffler and sounds great (slightly
muted) as intended but Lord only knows how much power is lost.

I picked up a motor cycle muffler to instal on my S2 project - straight thru
the rear - likely loud but only to be used for after midnite runs.

Bill

26/0358
26/4614


----- Original Message -----
From: "Andres B. Sta Maria" <***@***.***>

Sent: Thursday, August 04, 2005 6:54 PM
Subject: [LotusElan.net] muffler


Dear fellow-listers,

I note a lull on the List and, in case we are running out of topics, am
contributing this one to fill the gap.

Over the almost 30 years that I've had the Elan, my problem has been finding
the right muffler (silencer). I tried a shortened Cherry Bomb in the early
years, a Stebro, and a few custom-made ones thereafter, but was never
completely happy. My Elan notebook is filled with drawings of designs of
mufflers. My last installation was an all stainless 2-1/4" item from Tony
Thompson, which sounded good and, being very light, was consistent with the
Lotus ethic. However, it was a round muffler and didn't suit the cavity at
the back of my S4. It would probably look very good on an S1 or S2. Or a
26R, for which it was designed.

Last month, as I was working on bringing the Elan back to road-useable trim,
I spotted the spare mufflers I had from my Ducati 748R. I had changed to
carbon-fiber Termignionis and so had set aside the original items (also
Termignonis). These are oval mufflers with light stainless steel ends and
lovely, one-piece aluminum shells. The oval shape and length seemed to fit
the Elan. Upon disassembly (the silencer is held together by rivets), an
intricate baffled system with a perforated inner shell, all beautifully
made, was revealed.

I replaced the inner baffle system with a 2-1/4" s/s perforated tube, filled
the surrounding area with fiberglass, but left a bulkhead and a short empty
chamber at the rear end. I refitted the perforated inner shell and covered
this with the original fiberglass mat. I retained the original 2"diameter
exhaust stub exiting the muffler, but had a 5-inch long 2'1/4" diameter
extension pipe TIG-welded to this. Then I assembled the whole thing into
the aluminum outer shell. Except for the tail-pipe extension, It looks
original Ducati. Ducati pieces are generally very nicely crafted.

I installed the muffler, which is very light, over the weekend. It goes
nicely with the car. The concern is that the mufler might be too loud as
the overall volume is small, but the slight reduction of the pipe size at
the outlet should cut the sound a little bit, at least according to my old,
outdated book on the "scientific design" of exhaust and intake systems.

How does it sound? I still have to install the original matting under the
carpets and install the seats, so I have not started the car. Will let you
know.

Warm regards,

Andres
S4 DHC #8439
Manila

[gjz30075]

--- In ***@***.***, "Andres B. Sta Maria"
<abstamaria@s...> wrote:



Andres,

I found a pretty nice fit and sound with a Thrush Turbo from Jeg's,
part # 289-17702. Its got a 2" offset inlet and a 2" center outlet;
I'm running a 2" pipe so that's not a problem and any aftermarket tip
will work fine. The only problem is view of the oval end of the
muffler looking at the car from the rear, but no less offensive if
one had on the Sprint muffler. The size is 3 1/4" x 7 3/4" and 11"
long. The sound is nice and deep (more likely attributable to the 2"
pipe) and the price is right at $19.99. Hope this helps.

Greg Z
'72 Sprint