Lotus Elan

Quieter Exhaust

PostPost by: david.g.chapman » Tue Apr 12, 2005 6:45 pm

NOTE THIS POST HAS BEEN SENT TWICE (SAME AS QUIETER EXHAUST FOLLOW UP)
Some weeks ago, the old mild steel silencer on my +2 had to be replaced, and I opted for a stainless steel rear box from CN. There was quite an increase in noise from the car as a result. Cruising at motorway speeds was getting wearing!

I had heard of a possible solution from this forum, where an MGB bomb was mounted further up the exhaust system. I decided to follow this lead.

I have used the MGB bomb from MGOC spares (part number SSMG121T), and mounted it just in front of the rear box. The bomb entry and exit pipes are 45mm ID, and one end will fit nicely over the rear box pipe section, which normally fits over the centre pipe at 41.5mm OD. You have to use an adaptor sleeve at the other end to fill the gap - I made mine out of a section from the old rear exhaust.

I also fitted an addional "baffle" in the tail pipe of the new rear box (2.5 inches ID!).
This baffle is made from a 5 inch length of old 41mm pipe closed off at the rear, and is mounted up against the narrower pipe coming out of the box itself. I drilled enough holes around the wall of the "baffle" pipe to equal the area of this narrow pipe.

NOTE THIS POST HAS BEEN SENT TWICE (SAME AS QUIETER EXHAUST FOLLOW UP)
Result - Nice sporty exhaust sound below 3000 rpm, and quiet cruising at motorway speed, wth a 4 speed box! The exhaust note is now on a par with wind noise. There is no discernable loss in power I can detect.

Ground clearance is still OK as the bomb diameter is 80mm. You just have to mount everything close to the chassis.

So if you have a stainless exhaust and you want a quieter Elan for ?50 - try it!

Dave Chapman.
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PostPost by: john.p.clegg » Tue Apr 12, 2005 8:52 pm

This reminds me,did someone post recently that they needed some stainless "wool" to pack their silencer??
I think i may of found a supply

John
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PostPost by: rickf » Wed Apr 13, 2005 5:31 pm

Extending the tailpipe to just past the rear bumper, as I saw in another post, reduced the exhaust noise at speed to where I could listen to the radio. The addition of foil backed foam heat/sound insulation under the carpets and on the cabin side of the filewall reduced the noise from a number of sources and mede the car feel more "solid."
Cheers,<br>Rick<br>1972 Elan +2
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