Modifying exhaust from under car to side exit

norma · Post by **norma** » Thu Feb 07, 2008 10:50 pm

Going to start a new thread (for those that are interested) about converting my 'under-slung asthmatic pea shooter style' smoke-exit into a proper sized, side exit jobbie....
Bear with me cos the light at the end of the tunnel was temporarily turned off - it appears to be re-lighting now though

Antnicuk · Post by **Antnicuk** » Thu Feb 07, 2008 11:46 pm

i'm listening

I am doing it the way around, i have a 3 inch side exit but need to add a rear silencer as rotary engines are too loud.

I'm interested in the route from the side to the back of the car.

norma · Post by **norma** » Fri Feb 08, 2008 3:50 pm

Step 1:
Get Wunoff (in this case) to make a silencer to my spec (with a little help and advice from Rob

)

Pay them about £250........

norma · Post by **norma** » Fri Feb 08, 2008 3:51 pm

Step 2:
3 weeks later, recieve said item.......

norma · Post by **norma** » Fri Feb 08, 2008 3:54 pm

Step 3:
Ok, this is where you need a stiff drink first....
Cut a bloody great big hole in the side of your car

norma · Post by **norma** » Fri Feb 08, 2008 3:57 pm

Oh, and after spending £30 on various saw blades, the winner (by a mile) is:
http://www.screwfix.com/prods/10553/Bla ... lade-300mm
absolutely brilliant, straight lines, doesn't catch and doesn't wear out either - and at under £4-00!!!

norma · Post by **norma** » Fri Feb 08, 2008 3:59 pm

Step 4:
Offer the box up.....

spend next 3 hours fettling the dam hole (!) to make it fit properly....

norma · Post by **norma** » Fri Feb 08, 2008 4:04 pm

Step 5:
Go on Ebay and purchase some Kart exhaust bobbins, M8 female one end and male the other.
Then bash a couple of bits of stainless until they look almost presentable and get someone gifted (who can weld the stuff) to attach them for you.....
If you can do it yourself - then you're a smart arse

norma · Post by **norma** » Fri Feb 08, 2008 4:07 pm

Step 4.5:
oops! forgot to add, cut out excess amounts of probably structural fibreglass so that the exhaust runs no where near any.
Then spend a day adding fillets and bits of ally in a vain attempt to get some strength back around the front of the rear arch and also the rear of the front arch...

norma · Post by **norma** » Fri Feb 08, 2008 4:12 pm

Step 6:
Attach bobbins to exhaust and (in my case) through the sill to give the box plenty of support.
I then used a sill plate to help spread the load of the 2 countersunk stainless hex bolts I used to bolt through into the bobbin.....

norma · Post by **norma** » Fri Feb 08, 2008 4:14 pm

Step 7:
Start adding copious quantities of Rally design heat reflective fabric, get glue stuck to fingers and clothes and tools but not to fabric

norma · Post by **norma** » Fri Feb 08, 2008 4:18 pm

Well, thats as far as I've got (in 3 months !) ... will up date more as and when it happens.
Got a guy lined up to weld the manifold for me and just waiting for the steel tubing to arrive...
More random pics for you......

stylussprinter · Post by **stylussprinter** » Fri Feb 08, 2008 7:11 pm

Wrong way up I'm sorry to say though

They will tear off after not too long due to weight and engine torque

What's required is just ONE bracket bolted to the exit end of the silencer via the bolts holding the rear end and tailpipe on. Half moon shape 25mm wide then welded to that a 25mm leg sticking out parallel with the ground with hole drilled into it. That then sits on top of a bobbin which itself sits onto a bracket parallel with the ground and bolted through the passenger seatpan

Bobbins are designed to take weight NOT hold it

Having two brackets will be a fight with the engine flex and ultimately the engine will win

norma · Post by **norma** » Fri Feb 08, 2008 7:23 pm

stylussprinter wrote:Wrong way up I'm sorry to say though They will tear off after not too long due to weight and engine torque What's required is just ONE bracket bolted to the exit end of the silencer via the bolts holding the rear end and tailpipe on. Half moon shape 25mm wide then welded to that a 25mm leg sticking out parallel with the ground with hole drilled into it. That then sits on top of a bobbin which itself sits onto a bracket parallel with the ground and bolted through the passenger seatpan Bobbins are designed to take weight NOT hold it
Having two brackets will be a fight with the engine flex and ultimately the engine will win

You reckon Rob? I would have thought that just one bobbin on the side would actually put too much stress on the manifold ....?
There's loads of flex left in the silencer and they are 8mm bolts so not weedy.
I'll beg to differ - but if they do shear, I'll happily confess and bow my head in shame

stylussprinter · Post by **stylussprinter** » Fri Feb 08, 2008 10:02 pm

The tighter you fix the silencer the greater the stress on the manifold . Also bolt size is irrelevant -- it's the bobbins that hold the weight and they normally fail at the metal/rubber join when hung as opposed to compressed

clubstylus

Modifying exhaust from under car to side exit

Modifying exhaust from under car to side exit

Bobbins ?

Re: Bobbins ?

stress