Anyone know about cars?

[ReverseLunge]

Is turbo charged and super charged the same thing?

[jBirch]

No.

Turbo chargers use the back pressure from the exhaust cycle to power a turbine that compresses air for the intake cycle. The turbo has to "spin up" when you mash the gas, a phenomenae known as "turbo lag" and slows you down on drag strip type applications.

Super chargers use a motor that's run off a belt powered by an electric motor to compress the air for the intake cycle. They generally don't suffer from turbo lag and so respond to increased throttle demands better. But they are bulkier, more expensive and more prone to failure.

While both do the same thing (increase HP by forcing more air into the cyclinder), they accomplish it differently.

Hope this helps.

[jBirch]

An addendum to that last...

Superchargers are most commonly run off a belt from the crankcase, not an electric motor. Though there are superchargers that are run this way, it's just more usual to see the power come from the engine instead of a secondary power source.

Hope this helps.

[ReverseLunge]

Thanks and why is it that you know everything?

[D+F+P=Hadouken!]

Originally Posted by ReverseLunge

Thanks and why is it that you know everything?

Cause he's got mad skillz.

[SouthPaw]

Also, lots of turbochargers tend to not be street legal, mostly because of what it does to your exhaust I believe, while most superchargers are legal.

[latenight]

That's odd, because you see a lot more cars stock with turbochargers rather than superchargers

[HillBilly]

but most companies are barely legal, no?

[jBirch]

Originally Posted by SouthPaw

Also, lots of turbochargers tend to not be street legal, mostly because of what it does to your exhaust I believe, while most superchargers are legal.

This is untrue, as far as I know. Boost (turbo and super) does, indeed, make it harder to pass emissions tests sometimes, as the exhaust temperature is higher and the compression less complete. Moderate levels of boost usually work just fine on stock cars, regardless of whether that boost is derived from a turbo charger or a super charger.

In order to boost really high though, you need to have a free flow exhaust system (so you don't get back pressure on the cylinder), and the biggest constrictor in the exhaust path is the catalytic converter. Removing the cat conv makes a huge difference but also makes it illegal to drive as a regular car since you spew crap like crazy. Further, the higher the boost, the higher the octane for the fuel (so that you don't get premature combustion). If you boost past a certain point, you can't run on "pump gas" any more, as no pump sells 100+ octane fuel. It's a matter of degree, that's all, not a matter of design.

In fact, in racing applications, you more often see non-street legal cars with superchargers, then with turbo chargers (where boosting isn't banned outright), because of the aforementioned turbo lag. It's the braking and accellerating that makes racing interesting, not the constant high speed. As soon as you have to slow down and then speed up again, you have turbo lag. Turbo lag = slow at low revs = stupid in a race car that has to brake then accelerate (or accelerate from stop).

Hope this helps.

[mollusk]

The main point of turbo/super charging is to increase the volumetric efficiency of the cycle. By having the incoming "charge" at a higher pressure you can put more air and fuel into the cylinder and hence have a greater rate of energy release (increased power) for a given engine rpm. One problem is that compressing the air quickly (so that it approximates an adiabatic process) raises the temperature of the incoming charge and that increases the combustion temperature. That is good for efficiency, but bad for production of NOX (oxides of nitrogen). Turbocharging (increasing pressure) with an intercooler (lowering the temperature) is an option to get better volumetric efficiency without raising the NOX emmissions too much. (There will be a tendency to higher NOX at higher pressure due to recombination reactions being more favorable at higher pressures.) In practise supercharging is used to get a large boost in pressure and turbocharging for a lower boost in pressure. Large pressure boosts require very sturdy mechanicals or lead to a short engine life. If all you need is a few seconds to go 1/4 mile, then long engine life isn't a real issue.

[SouthPaw]

You can get by the emissions test with a supercharger without taking out the catalytic converter, just gotta get a tuned exhaust header to create a vacuum that sucks the exhaust out. Works just as well, if not better, and will still pass smog tests.

And I agree, would never put a turbocharger on my car, supercharger is the way to go! =D

[AdventureDiva]

wow jBirch...that was hot

i love car talk

~Rachael~

[Soldier]

That's, just...wrong...

[Epee_Pox]

Originally Posted by SouthPaw

You can get by the emissions test with a supercharger without taking out the catalytic converter, just gotta get a tuned exhaust header to create a vacuum that sucks the exhaust out. Works just as well, if not better, and will still pass smog tests.

Yeah, but it sure it tough to get the backpressure just right when fiddling with the exhaust either way, and unless you are really careful you start losing all that lovely horsepower you did this for in the first place.

[jBirch]

You're just saying that because Racheal thinks it's hot. Any time you've got pistons and o-rings, exhaust manifolds and headers, racks and crank shafts, you've got yourself a dirty conversation. Especially when you add grease to a hot chick into the mix.

And my wife thinks car talk is hot too. Especially in the garage. *grin*

[Epee_Pox]

guess i'm doubly lucky then. i married a gearhead.