Quiet performance exhaust design

ElTorro

ElTorro

Commie bastard
Evening gentlemen.

Here is the question: is it possible to make a sensible sounding exhaust without sacrificing much performance? Engines in question are RB20/25s and SR20s.

I am sure that 3in straight through system won't be appreciated by my 7mil city at 4am, so what's the best way to quieten a straight-through exhaust note down abit? How many silencers, what type of silencers, some resonating shit? I don't want to look like a wanker with a large fuck-off fart can, plus cars that are quiet on low revs are more subtle and smart, so I'm looking at investing in a proper exhaust system.

Fine examples I'm looking at are stock M52/M62 BMWs. Engine is silent at low revs under a little load, but at 4k+ it comes alive and has a very nice tone. I know BMWs have smart exhaust, but what do you need to do with an old datsun to get the same effect?

Cheers,
Pete
 
the HKS silent power is meant to be good for up o about 400bhp and thats one silent exhaust, although the placebo effect may tell you differently
 
its more to do with the size of the silencer and what it is packed with. alot of the cheaper 'jap' silencers have no wadding inside them,they are just a length of perferated tube inside a larger tube.

the different 'boxes' do different things.the middle box takes out the low noise whereas the rear box takes out the high pitch noise.
 
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Putting a very long centre box in would be the best thing, it will quieten it down no end! If you wanted to be a little bit more showy then you could get one of those electric flaps inside the exhaust which opens and closes with the press of a button. Therefore you could have it very quiet when needed and then open it up when wanted. Mitsubishi GTO's Have them as stock! Perhaps you could grab one off a GTO breaking for fairly cheap.
 
Depends what you want. If you have no noise regs to adhere to, a simple flapper valve (like LOADS of standard cars have fitted) is the cheapest easiest solution- Quiet when you wanna be, loud when you open the flapper (can be at a flick of a switch).

Disadvantage there is flappers, just like exhaust bungs, are a restriction, so fuck your power and spoolup, so you cant have quiet and fast at the same time.

To go fast and quiet, and you can do that, even at mega power, it's silencers, as big and as many as possible. Straight through ones to not restrict flow at all, but proper ones, not these empty cheap Jap fart cans for sale. Simple as that really, nothing makes as big as difference as them, unsurprisingly.
I know of 600bhp cars, even a mid-engine one (so not much room for silencers) who can read 97db on trackdays. Still sounds badass, but not spastic loud.

Wrapping your exhaust in heat wrap makes a BIG difference (oddly) too. Anyone who heard my FC after I did that will know that. A big single turbo RX7, with just 1 small rear silencer and a ported engine and it was stupid quiet.

Finally, point the tailpipe at the floor. This is why you see a lot of race cars, esp rotarys, did this on my RX7 too (They call it Dolphin Tip or something gay in Japan, I called mine Elephant Cock, as mine was 5in diameter and painted matt grey, lol), like this, makes a BIG difference to how far the sound travels.

Fianlly, dont mistake LOUD sound with GOOD sound. VVT SR20s sound a bit wank for example, a loud can on em makes em sound worse. But quietening a car, especially if you do it properly as above, rather than just restricting it, makes it have just as nice/powerful a tone, just not to spastic loud it gets you in shit and makes everyone think you a cunt.
I know someone with an Audi R8 and he's put a stupid loud system on it. It sounds fucking wank and makes him look like a bell. Its louder, but the tone is waaay worse than stock, sounds like an old Rover V8 running open pipes.
 
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