More and more car manufacturers are developing sophisticated safety systems for their cars. With anti-lock bakes, airbags and traction control seemingly just about everywhere, it's a major component of today's cars. I can remember when the first generation of airbag-equipped cars was released here in Australia, how so many people poo-pooed the whole idea (just like when seatbelts were introduced). However, that scepticism was quickly steam-rolled when airbags began proving themselves capable of saving lives in the real world. Following this success, Volvo (amongst others) then came out with their SIPS (side impact protection system) which locates a sausage shaped airbag between the driver's side and the B-pillar/door in the event of a side-on impact. It's a pretty clever development isn't it?
But I couldn't help laughing when I saw a brochure for the current 7-series BMW which sports no less than 8 airbags - 6 of which were positioned around the front passengers. The cutaway picture showed all 8 balloons deployed, making the gorgeous interior of the luxury saloon look more like the company car for Bozo the Clown. Whilst I'm sure this system is of high technical merit, the idea of BMW contracting the services of a balloon-bending clown to front their airbag safety team amused me somewhat. What's next? Maybe a dog-shaped airbag for fluffy little Pookie riding along on the rear parcel shelf?
Ahh, but seriously, the awareness of vehicle safety really has increased dramatically in the last couple of years. But as I recently discovered, there are still some exceptions though....
A few days ago I found myself pulled up a few cars back from a stop light in the middle of peak-hour madness. Sitting patiently, I saw the lights change to green and prepared to move off the mark - but, much to my anger, there was no movement. Grrr. Expecting to see a broken down junker stranded in the middle of the intersection, I peered down between the cars in front. And there, before my very eyes, was the most bone-headed and dangerous thing I've ever seen on the road. A mid-50s guy (old enough to know better) was working hard at the wheel, struggling his way around a 90-degree corner - with the steering lock still attached! He was able to turn the wheel only about 1/5 of a turn, and completion of the painfully slow manoeuvre took about three reverse-back attempts - making it the world's first nine-point 90-degree turn!
No, I don't suspect he'd just stolen car because not only would a thief be smarter than to drive off with the steering lock still in place, but there was also a young child perched up proud on his rear booster seat! What a dimwit was this bloke! And not only was it incredibly dangerous for the driver and the young tot, but what about everyone else sharing the road with vehicle of oh-so-limited maneuverability? Looking away in horror, I noticed the wide-eyed expressions on the face of nearby motorists who had also caught a glimpse. I guess all you can do at a time like that is thank God for modern vehicle safety systems. They're a 100% necessity when there're people like that around!
Now it's time to really stir up some trouble. Who out there believes engines (naturally aspirated or force inducted) perform the best with some amount of back-pressure downstream of extractors? Please, send me an email if you have undeniable proof - preferably in the form of a dyno-graph. Just make sure that in any case the engine had been re-tuned (fuel and ignition) for optimal results from each set up. I've noticed this back-pressure topic has been pretty well flogged on our tech forum, but I thought I'd flog it a little more just for fun.
A friend of mine bought a naturally aspirated 1983 3-cylinder Charade as a temporary run-about while his other car was being repaired. But even with its mechanically sound engine, the 1-litre trio certainly still needed to be stirred along in revs to keep up with normal traffic flow. Purchased for only a few hundred dollars, the car needed to be brought up to scratch with some maintenance the previous owner had neglected to do - and the first item on the list was the replacement of the exhaust.
Driving along one night, the front flange of the system separated along a weld line and fell to the ground, creating the world's loudest 3-cylinder Daihatsu. On the way home, he noticed how much slower the car felt just about everywhere in the rev range. And as many people know, a loud car usually feels faster because it sounds like the engine's pushing out more power. So for it to be louder and feel slower, it must certainly be down on the factory's huge 30-odd kilowatts. The next step saw a 2½ inch system (with a single straight-thought muffler) bolted to the standard engine. And despite "expert" opinion to the contrary, the motor did benefit from the big system; it's just that people generally think a 2½ inch system on a 1-litre three cylinder is over-kill. Compared to both the standard system and the non-existent system, it revved out better and picked up torque everywhere.
So what does all this mean? Well, we know the factory 1½ inch system gave poor performance but quiet running. The straight off the flange exhaust gave monstrous noise and dropped off torque. And the 2½ incher gave acceptable noise and the best performance. That's where most people would draw their conclusion that some back-pressure is needed.
But what we don't know is the effect the non-existent exhaust system had on the engine's running conditions. More than likely, such a huge increase in exhaust gas flow confused the poor un-tuned carburettor and, in turn, created improper air/fuel mixtures. On top of this, the new peak and average combustion pressures probably required revisions to the ignition settings. So with some more development and tuning to suit, any higher flowing exhaust can make a improvement to your car's performance.
Further to this, and moving to the other extreme of the financial spectrum, you don't see Formula One cars hung with a tailpipe of any substance. That's because they know downstream of extractors, headers or whatever you want to call them, there is no need for back-pressure.
Let the emails begin - but, please, only if you have hard evidence to back you up!
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