View Full Version : Car Guys: Naturally Aspirated v. Charged?
I have heard too much crap lately about cars being better somehow because they are not charged but get their power from pure displacement and other generic ways. I have heard that the Viper is not charged because Dodge wanted the car to be "natural"...... they figured they would be "cheating" somehow by putting a supercharger on there.
What kind of ridiculous logic is this?
First off, what is "naturally aspired"? I am pretty sure it simply means not charged. Assuming that is true, why is this thought to be "natural". i could make the argument that a compression ratio greater than 1:1 is not natural. at what compression ratio does the car become not naturally aspired?
Why can't a turbocharger or supercharger be thought of as an obvious component of an engine..... why can't it be thought of as PART of the engine? It is the obvious, logical thing to do...... shove more air in the cylinder. If speed is the goal, it is illogical to NOT install some sort of component that compresses air. get my drift?
Natural?! Makes no sense to me..... someone please explain what I am missing and why a car with computer chips and fuel injection is considered natural, but a car with a carburetor and supercharger is NOT natural. ironic?
Boo Boo Foo
01-30-2003, 07:38 PM
Ultimately though - it's all a moot point because internal combustion engines - by their very nature - are quite inefficient in reality. Only 32-38% of your fuel actually gets converted to mechanical energy at the drive wheels. By far the majority of potential energy in fuel is lost to your cooling system.
Accordingly, the question becomes - how much horsepower do you wish to produce? Regardless of engine displacement or design, the issue becomes one of "horsepower costs fuel - how fast do you wanna go?"
The sort of engine you use, at best, only effects about 6% of the potential energy in your fuel from turning into mechanical energy or not. Hence, ultimately it's all a moot point.
In terms of life span though - yes, a large capacity engine delivering 300 hp will outlive a small, highly stressed engine delivering 300 hp - every time.
01-30-2003, 07:42 PM
Moderator's Note: Off to IMHO.
01-30-2003, 07:47 PM
My opinion is that a supercharger is just one more component that can fail. If I want an awesome power-to-weight ratio, I'll ride my motorcycle. Or buy another Porsche.
01-30-2003, 07:50 PM
Originally posted by Fuel
First off, what is "naturally aspired"? I am pretty sure it simply means not charged. Assuming that is true, why is this thought to be "natural". i could make the argument that a compression ratio greater than 1:1 is not natural. at what compression ratio does the car become not naturally aspired?Compression ratio has nothing to do with being normally aspirated or not. A normally aspirated engine is one in which the intake manifold pressure is limited by ambient pressure. In other words, if you aren't using another force to cram air into the cylinders, it's normally aspirated.
i see, the engine breathes the surrounding, uncompressed air, so it's natural ok. fair enough. moot point, i agree.
01-30-2003, 09:02 PM
Forced induction can break stuff and it costs money. But, like any engineering problem, you can over engineer the crap out of the moving parts. That too costs money.
Other than money, nothing is wrong with super or turbo charging - ESPECIALLY if you run the car at any altitude.
01-30-2003, 10:58 PM
From my experience, a naturally aspirated engine is better than a turbocharged engine. One of the most notable differences that you will experience when driving a car that is turbocharged is turbo lag. It takes about a few mili-seconds (sometimes seconds on really old cars) for the charger to kick in and that is something that can be felt. This can be crucial if you are racing or you are being timed.
01-30-2003, 11:08 PM
Superchargers don't have turbo lag, but there are parasitic losses because you're driving the belt all the time. All engineering tradeoffs.
01-31-2003, 01:27 AM
I've spoken at length about my roomies car.
It has had 2 configurations to date... an all engine, and a Super Charger.
In the all engine work up, he had most of the bolt on, and quite a few internals changed. Intake/header/exhaust, Intake Manifold, Cams, cam-gears, ECU (chipping), wires and plugs.
Of course, he is cursed, so never got it tuned properly... it was quick. Mustang 5.0 eater. He kept it in that conficguration for about 6 months, then pulled all the parts off and had the engine tuned and cleaned.
He sold all the parts to his brother-in-law, and bought a Jackson Racing supercharger, with the 8lb pulley upgrade. Intake/HEader/Exhaust, cam gears, injectors, wires and plugs, fuel pump, ignition, ECU.... pretty much all the bells and whistles.
The car is fast. Really fast. He hangs with the Boxster, he eats Mustangs for lunch, he has smoked a couple of Z28's. Boosted is faster than N/A, at least in the configurations we've had.
Of course, his gas mileage is sucking, and he's badly in need of tuning again........
01-31-2003, 12:26 PM
One advantage to forced aspiration is that you get higher HP with a smaller motor...
generally, smaller motor means less weight up front, = better weight distribution,= better handling.
of course there are also the obvious acceleration and braking advantages to a lighter car as well.
01-31-2003, 03:09 PM
Is it possible that a NA engine might have a more advantageous torque curve than a *charged engine? Horsepower isn't just horsepower, if your low end torque isn't up to snuff, that will affect your performance.
01-31-2003, 05:00 PM
Since I care about long term durability I stayed away from Turbo'ed engines.
I don't know if a NA engine has a better touque curve. My friend's new WRX (2.0L turbo) totally kills my Matrix (1.8L NA). Turbo lag is very minor with his factory turbo.
I'm still betting that my Matrix will holdup better than his WRX though.
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