Naturally Aspirated (NA) vs Forced Injection (FI)
NA VS FI as we call it, an age old debate about which one is better. Well let me put it like this to make things clear, naturally aspirated engine is a normal human breathing fresh air while turbo charged engine is like a man on ventilator. Air is being forced into his mouth, and it’s the same with the engines, rather its being sucked in by the engine itself. Well a doctor would say the first one is better, but as we know it, it’s not the same with cars. On the contrary turbo chargers give you more power, awesome levels of torque and make your day to day diesels worth driving or sometimes fun driving.
There is something about turbo's, the whining, the whistle, the sudden rush of torque from very low rpm, that makes you wanna drive them all day. But there is even a bigger something about the naturally aspirated cars, the freely revving engines makes sure you are on the redline in every single gear. That music of revving an NA can be understood by those who have witnessed a F1 race up close. Well if not, you better be watching one by next year, because F1 is going turbo.
Well yes it will be great to see turbo's whining and everything, but these days it seems like NA's are dying. Not only F1 but every car maker is going turbo, Eg The BMW M5 known for the beasty NA's under the hood has gone turbo, the days of the old BMW straight six will be missed, those engines were a blessing for the race of petrol heads. The brawny stalwarts are being phased out of Merc's line-up also in favour of a 5.5-litre turbo V8. Better economy and emissions, sure, but what about that glorious noise? The Zonda is soon to be replaced by an all-new Pagani, codenamed the C9. Rumours suggest it won't retain the Merc-sourced V12, but a boost-heavy twin-turbo unit. BMW’s earlier used to sell their cars by just the sound of those NA's, and people just bought them for it. That Magic seems to have been forgotten today.
Yes turbo’s does help in miniaturising the engines. Today smaller engines delivers higher BHP, you can easily accommodate them under the hood of a small car which makes them go fast, also helpswith emissions and efficiency of an engine, but that doesn't sound good. We don't want tiny little Fiat 500s with small turbo engines making them go mad, we want big cars with big engines, don't know why but it sounds manly to have big engines under the hood.
It’s not only about the engine size, but it’s also about the magic of an NA. Its a different feeling all together. You will know if you ask some racing drivers what a freely revving NA is like to drive. Its, it’s addictive, the sound the way the revs climb up, everything about a NA is addictive. Yeah turbo's are addictive too, I like the immediate shove of a turbo but when you're really on it, but the way they tail off just isn’t for me. They can help you make big power with a small unit, and those power figures can't be matched with the same displacement NA tuned to its best. But this all sounds a bit boring.
Another problem with any rear wheel drive turbo (with a bit of power) is that you need to be super careful mid bend. Whereas with a NA even one with a larger engine you can get away with more (not that you should be hamming on the power halfway round a corner anyway). Another thing is, you lose a lot of power spinning wheels and going no where, thanks to a high low end torque.
Next obvious question is ; Why no Supercharger – engines that are like the best of both worlds, the power is available from the start, the torque is there, the engine revs freely, but a supercharger is an engine killer. I seem to remember that the 5.5 V8 AMG units that produced about 500 BHP net were using over 70 BHP to run the supercharger at full chat and that extra power used to strain the engine and also consume lots of fuel, plus it doesn't feel the same as a turbo off the start nor is it any good on the redline like a NA. So I decided to keep it out of the discussion.
The NA's however, can be tuned in a manner that deliver all the bottom end torque and also rev freely up to top end rpm, plus sound magical the way they are supposed to sound. For example an Audi RS4, the 4.2L V8 gives 90% of the torque at 2250rpm. And Aston's One-77 is the most powerful naturally aspirated road car in the world, developing an insane 750 BHP from its 7.3-litre V12.
It’s not so that a turbo is not good, it’s amazing, (if one had the money) to have both, turbo and NA and one can use whichever suits the mood of the day! That will be the ultimate dream. But that dream might just be a little scary if all the car makers go turbo and ditch the old NA engines. I don't want that to happen, I want streets with a growl and not just whistle.