My issue with it isn’t the pops and bangs necessarily, it’s more that it’s usually on a 1.2 Seat Ibiza that sounds rubbish

THIS.

It seems to be the thing for teens to do in Peebles, get an awful car, slap a big window banner on it saying ‘VAUXHALL’ or something, put a baked bean can exhaust on it so you can hear that terrible 90bhp 3-cylinder engine.

Oh, and slam it by cutting the coils so it bounces around on the road.

This is coming from someone who does own a 350bhp car that is a bit loud, and does pop on some downshifts.

I personally despise motorbikers. The number of bellends that fit a loud exhuast and then ride around with f00cking earplugs in under bloody helmet.

Also this 🙂

The Tweed Valley on a sunny day is spoiled by nobbers screaming thier 2-wheeled death machines up and down the roads. I always find it somewhat amusing that such a dynamic behavior is belied by what you see in leathers and under the helmet (i.e. static looking humans).

Having done a fair few natasp engines and done mapping from scratch… even good “tuners” are following methodologies that cannot possibly succeed in producing a correct engine map.

If you’re into a custom remapping, the most common natasp scenario is you’re trying to get fuelling and advance appropriate in a mapping vs throttle opening and rpm (alpha-N). If you have 16 throttle sites and 16 RPM sites you have 256 values for both fuelling and advance. The tuner will operate the rolling road to tweak the values at each site. The fuelling maps produced are always spiky. But the process fails because a recorded value at each site tells you nothing about the interpolation between sites. Just because you get a spike at one location (resonances) there is no assurance that the requirement you recorded was the actual peak. Should the interpolated fuelling as you progress away from the spike actually go up or should it go down?

The answer actually comes from data sampling theories. You’re basically attempting to reconstruct an analogue signal from digital samples. You cannot reproduce features above Nyquist frequency, so all the spikiness is actually useless information. Smoothing it all out is usually the much better answer.

This is not how the majority of car tuners think however, so the starting point from “tuning” is almost always a bad base map.

Next we get into the sticky world of compensations. These usually aren’t high up the tuner’s priority list but it is really vital to have effective and independent compensation for air and water temperature. Altitude compensation is also required but should be mathematically derived for alpha-N.

But the biggest issue is transients. These are genuinely hard to handle for all traditional injection scenarios (not so much direct injection) because the charge fuel mass is not a simple matter of the fuel from the injector getting atomised directly into the inducted air. Inlet tracts are a complex environment where there is a dynamic wetted area of inlet tract provides a major path for fuel getting into the charge. If you’ve had a production car tune with an overrun fuel cutoff, you have lost most of the wetted area and you need to over-inject transiently to provide enough fuel not to momentarily run lean and have a massive hiccough and kangaroo on throttle openings. All snap shut throttle transients tend to overfuel momentarily anyway for the same reasons.

Fuel has the other useful property of cooling down the combustion chamber. If you run too lean at too much power, the heat build up will tend to cause nasty detonatey things to happen.

Easiest way out of all these situations is to add fuel and disable fuel-cutoff on overrun so that is what most tuners do. Snap, crackle, pop.

Real car manufacturers have massive programmes to get their engine tunes calibrated and research programmes to introduce new technologies to work around the messy, swirly mess of internal combustion. This takes time and money and gets paid back by being replicated over as many unit sales as possible. It isn’t possible to do this stuff in the aftermarket.

But the aftermarket doesn’t give two sh*ts because the dumb punters are just crying out to be relieved of their money: make unfounded claim; violate all rules on pollutants and not killing catalytic converters and give ’em what they want… mail order, plug-in add-ons, bad boy noises and a sticker.

The banning of the internal combustion engine can’t come soon enough.

Peaslaker trying to baffle us by being too technical, can we stick to suck,squeeze,bang and blow

Wtf is over run? I’m assuming from the fact it needed a thread it doesn’t refer to the noise made by cars when they over run a corner and leave the road?

I assumed it was because the youngsters couldn’t afford cars equipped with the grown-up’s equivalent technology- Soundaktor, Active Noise Control, Active Sound Design etc etc

I understood a chunk of what peaslaker said (but it could have been better worded for the audience). And working on the durability / structural / suspension side there are similar under-developed junk “improvements” that aftermarket punters lap up.

The oem pops and bangs don’t happen during the events in a pass by noise test so they pass type approval. Or they’re on a separate button for “track use only”.

Peaslaker trying to baffle us by being too technical, can we stick to suck,squeeze,bang and blow

Reminds me of the Huey Lewis and the News monologue from American Psycho. Nobody’s going round Peaslaker’s for drinks later on, are they?

And working on the durability / structural / suspension side there are similar under-developed junk “improvements” that aftermarket punters lap up.

Isn’t that the same sort of thing as MBR who take something that, say, Santa Cruz have designed, ridden, tweaked, optimised etc and immediately decide they can improve it by slapping on a fork that’s 20mm longer as well as an angleset to slacken it off a bit more.

Thanks peaslaker

It is done by ‘remapping’ so the engine dumps fuel into a hot exhaust. It **** the exhaust and impairs the car’s overall performance.

An office colleague of mine (who understood these things) used to charge the local chavs £150 a pop to do it for them. Nice little sideline for 60-90 minutes work.

There’s a few around here but V8’s with stupid loud exhausts seem to be the new trend, I regularly see two black & one silver Merc, two black Audi’s & two older Jags booting it around the town – they can’t be getting much more than single figure mpg the way they’re being driven.

There’s a local crap fiesta going round with some sort of tune and a crap exhaust that seems to mimic shot gun bangs at all hours.
There’s a difference between a bit of over run crackle and actual bangs. Caused quite an annoyance lately.

My 450bhp V8 doesn’t do it

It does drop a tiny bit of fuel into the exhaust on downshifts though to make it sound like you are an awesome driver, which I’m not. Sounds nice though

*edit – DP

Nuffin new, my mates Severn Valley Motorsport Escort RS Turbo used to spit flames out the exhaust too. Proper rad shit an all that

That was because it happened whilst making the car faster. Modern cars don’t need that kind of tuning to go faster. Which means the bangs and pops are programmed in to the ecu by an old person and are therefore not cool unlike you mates RS turbonutterbast@rd.

It scares my dogs so for that reason the trend can f.r.o.

And yes, as a youth, me and my mates went through a stage of inappropriately exhaust’d crap cars so I can relate on some level, but these were just farty big bores and not likely to give old folk and animals a heart attack.

My issue with it isn’t the pops and bangs necessarily, it’s more that it’s usually on a 1.2 Seat Ibiza that sounds rubbish

rickon
Full Member

THIS.

It seems to be the thing for teens to do in Peebles, get an awful car, slap a big window banner on it saying ‘VAUXHALL’ or something, put a baked bean can exhaust on it so you can hear that terrible 90bhp 3-cylinder engine.

Oh, and slam it by cutting the coils so it bounces around on the road.

This is coming from someone who does own a 350bhp car that is a bit loud, and does pop on some downshifts.

just as annoying on a powerful car as on a 1.2 clio imo. More so sometimes, as the drivers are often old enough to know better.

There’s one such peenarse up the road from me with a C63s mapped to do this. Utter utter prick. He drives up and down the high street ‘impressing’ people by purposely blipping the throttle, making it go “bang bang-bang-bang” as he goes past.

The irony is that the car sounded great when he got it, really mean low V8 rumble. Now it sounds like the engines ****.

Now, if they could map them to sound like the 2011 EBD Renault engined f1 cars I might be interested…