Conference terri::cars_uk

Is it legal to use a "straight through" silencer on public roads?
Will it be unbearably loud?  Will the neighbours stop talking to me?

What will the effect of a straight-through exhaust be on the engine
(eg performance, mpg, engine longevity), which, coming from a boring old Sierra,
was presumably designed to work with a baffled exhaust?

Scott

	When I first fired up the Marlin, it had just the side pipes, it
	sounded like a Vulcan bomber and the flames were around 2' long.
	A good box should create a low pressure zone that attempts to pull out
	the exhaust (at the very least it should not create any back pressure).

	So, I guess it depends if you like being conspicuous or not...

	Dave

    
    On road-going 4-strokes straight through pipes are just a noisy bore, &
    will not make the vehicle significantly faster at all. Even racing
    machinery being pushed below 110db is not suffering a noticeable (in
    feel) difference.
    
    Racing 2-strokes are quite different, but you're not likely to see those
    in your average commuterbile. Silly little boys on 50cc mopeds tend to
    lose performance with badly designed expansion chambers, but boys will
    be boys ............
    
    Pal of mine has an XK120 with straight through pipes in 1/8 inch
    copper! Loud, but deep. No tinny reverberation, but at least he takes
    it on the road very rarely -- but sounds great at a sprint.
                                                

Perhaps I'd better clarify what I mean.

I don't want the car to annoy the neighbours, but I want it to sound like a
sports car and not a Ford Sierra.  I was recommended to get a straight-through
silencer to achieve this purpose.

This looks, externally, exactly like an ordianary silencer box.  The difference
is if you look in one end you can see out of the other.  The baffle structure
is around the edges.  Pretty picture time:

      __________________                      ______________________
1)   |XXXXXXXXXXXXXXXXXX|               2)   |XXXXXXXXXXXXXXXXXXXXXX|
_____|XXXXXXXXXXXXXXXXXX|_____          _____|_ _ _ _ _ _ _ _ _ _  X|_____
                                                                 | X
_____                    _____          _____ _ _ _ _ _ _ _ _ _ _| X _____
     |XXXXXXXXXXXXXXXXXX|                    |XXXXXXXXXXXXXXXXXXXXXX|
     |XXXXXXXXXXXXXXXXXX|                    |______________________|

"Straight through" silencer;              Ordinary silencer; the exhaust gases
XXX is the baffle material                must pass through the baffle

3)
_______________________________

_______________________________

Straight through pipe; no baffle!

My query is what will the difference in volume and "timbre" of noise be between
the three systems?  I assume racing cars have (3)?

Most production car exhausts have a "silencer" box and a "resonator" box.  What
is the difference between these in terms of construction and function?

Scott

    So much about Janspeed and Perry exhuasts, what about Ansa Marmite
    exhaust? It's supposed to be high performance stuff from Italy. Has
    anyone had experience with this? like on Alfa cars.
    
    Feedback please!
    
    	TTH
    

    Never heard of Jetex? Where is it from? Is it good, compared with
    Janspeed, Ansa...?
    
    Well...
    
    	TTH

>    Never heard of Jetex? Where is it from? Is it good, compared with
>    Janspeed, Ansa...?

    I always thought they made those rocket engines that you put on model
    planes ! You remember, the ones that you lit and they ran for only a
    few seconds. Thinking of which that principle has been adopted by a
    few motor manufacturers.

    Alex :^)    

    Ansa exhaust comes ready to fit on various makes/models of cars. I have
    one tried out (fitted by the workshop sales guy) and it proved to be
    smoother in rev on my Alfa 33 1.7 Cloverleaf. Well, not the entire
    exhaust system, only the tailpipe with muffler/baffler. The exhaust
    looks beautiful, stainless steel chromed! I'm tempted to try the entire
    exhaust system including the manifolds. Costs around S$400/- or ~140
    pounds. Is that cheap or expensive? Will that really help add more
    power and better fuel consumption? Has anyone of you had this fitted
    and how was it?
    
    Incidentally, I had K&N air filters fitted the other day when the
    performance has been markedly good. However, it's too noisy when
    accelerating hard; the car seems to have lost the "Alfa sound"!
    
    		TTH

    They were also used in model racing cars - Jetex made the whole kit.
    Great fun.
    
    Jeff.

	I also played with Jetex engines while a yougster. The fuse was also 
very useful if you were into making large bangs with other chemicals 'nuff said.

	I haven't seen them around for 15 years. I don't know if they are still 
available whether they were felt to be unsafe, the company went bust or what. 

Nigel

    I expect the kids started sniffing them ...
    

    
    I seem to remember it being difficult even to breathe near burning JETEX,
    let alone sniff it (no I didn't try) !!
    
    Didn't it give off ammonia or something ?

    combining the original topic - brands of exhaust systems
    	with the sidebar topic - childhood reminiscing
    
    1.	are Abarth mufflers still made?  I had one (bought in Rome) on
    	my 1967 Fiat 850 Spyder.
    
    2.	Are Stebro mufflers still made?  I HAVE one on the 1969 Elan.
    
    -Barry-
    

    I sent my car for servicing today. My service adviser recommended a
    combination of Ansa for manifolds/extractor and Janspeed tailpipe for 
    the exhaust system for my Alfa 1.7 carburetter. He said this will give 
    smoother rev and boost performance. How is this true? Has anyone 
    experienced with such a combination?
    
    Janspeed is rather expensive, though!
    
    	TTH