mp19fan

Wondering if someone could explain the principles of both to my young friend who recently acquired a rice-cooker (or rocket, as he puts it!) who is greedily absorbing as much car knowledge as his young mind will allow. Which would be more damaging to his engine ('94 Integra LS) and why? Thanks.

hapoo

a supercharger would be more damaging, what a turbo/supercharger does is force more air into your engine. A Turbo runs off of the exhaust gas thats given off, the gas powers the turbo and in turn forces more air into the engine, it has no side effects. A supercharger also forces air into the engine but its powered by the engine using a chain/belt. This method puts more stress on the engine and isn't as efficent.
More info: http://integra.vtec.net/turbo/

[Edited by hapoo on 03-13-2001 at 12:38 AM]

__________________

KoalaFD

That, I suppose, is the short of it.

Both involve forcing more air into the engine, which in practical terms, is a glorified air pump. More air means that you can burn more fuel and hence more power results.

The mechanisms by which these two do it are different.

Turbos, like hapoo said, have one wheel (kind of like a fan of sorts) on the exhaust side of the engine that spins when exhaust gases pass out of the block. This exhaust turbine is connected by a common shaft to the intake side which also has a turbine, termed the "compressor wheel". As the exhaust turbine spins, the compressor wheel also spins thereby forcing air into the engine.

Superchargers also use an compressor wheel of sorts but instead of being driven by an exhaust turbine, the wheel is attached via belt/chain to the main engine pulley and spins with the engine.

There are several pros and cons to each.

Turbos tend to have a higher ceiling of power. Theoretically, you can continue to increase exhaust gas flow (by burning more fuel) and this will increase the compressor wheel speed. There's not much of a limit provided the other components of your car can handle the boost.

Superchargers are run "mechanically" - as the pulleys spin faster and faster, more and more work is wasted until the point where the power you generate with the supercharger is balanced out by the power it takes to run it. Hence the ceiling.

The delivery of power is also somewhat different. In turbos, it takes a little while to "spool up" the turbines, giving you "turbo lag". As the turbo increases in size, this lag is usually more apparent manifesting itself in slow off-the-line performance coupled with neck-breaking force once you hit the right rpm. Superchargers, because of their mechanism, deliver pretty much even power right from the get-go and increase in proportion with the rpm (up to the ceiling mentioned earlier above, of course).

Also, it is sometimes a little harder to integrate an intercooler system with some of the supercharger kits that are out there.

In addition, as you get fancier, the boost level on a turbo can be controlled rather easily with electronic boost control and such so that you can actually control these parameters from inside your car. Since superchargers run off pulleys, most require a change in pulley to modify the boost pressure.

The debate as to which is superior has been going on for quite a while. I'm particular to turbos myself but I wouldn't say that it has no side effects. Any forced induction on an improperly prepared engine runs the risk of increasing air flow to levels that are too much for the other components of the car to handle and may cause detonation and blown engines. People, myself included, also like the smoother power delivery of the supercharger at lower rpms (around-town-rpms) more than the slow-fast of a turbocharger.

Done correctly, I don't see that either system should "damage" his engine. Done improperly, both definitely have the potential of doing so.

Blu

One of the upsides of supercharging is the failure rate. Turbos spin faster, and therefore are more prone to problems. Superchargers on the other hand are slower spinning devices, so they are a bit more reliable. Also, b/c of the high output of the turbo, car manufacturers tend to depend on the turbo for a disproportionate amount of power. If the stock turbo goes on a car, the decrease in power is more than just noticable. When a stock supercharger (yes, some cars actually use them) goes, there is a noticable reduction in power, but it is usually far from crippling.

Blu

__________________
Up above
aliens hover
making home movies
for the folks back home,

of all these weird creatures
who lock up their spirits,
drill holes in themselves
and live for their secrets

Ice-9

Beautiful explanation, Koala. I was thinking about writing something on it, but was too lazy to try to explain the whole thing.

Personally, I'm totally partial to turbos, but it's a personal bias, because I much prefer a higher top speed to a quick off-the-line burst. Also, if you want to go all out and set up a sequential twin turbo system, you can get some serious off-the-line power with a huge top speed.

__________________
Porsche. There is no substitute.

Ice-9
B-Works Productions
http://www.bworksproductions.com

helius

Don't turbos/superchargers tend to shorten the life of the engine? And is it true that you need to idle a turbocharged car for a minute or so (especially after some enthusiastic driving) before taking the key out of ignition? I've absolutely no first hand experience, and am just curious about things.

And is Buick the only major car company in North America that advertises their superchargers?

Sportzcoop

No car should just have either a supercharger or turbo put into it if it is stock. Either one could seriously damage the engine or other parts of the car if it is not modified in the proper order. According to Stillen Racing it goes a little something like this for a 1994 Integra
Stock 160HP
STAGE 1: Performance Exhaust 166HP
STAGE 2: Super Hi-Flow Intake system 173HP
STAGE 3: Twin Power Ignition 176HP

As you can see turbos/superchargers are not even listed as an upgrade which leads me to believe that adding either would cause permanent damage to a stock integra if major work on the car wasn't done first. Tell him to be wary and if he decides on one to make sure the place where he has the work done has experience or he might as well kiss his car goodbye.

OC

Turbos and superchargers still have a bad rap from the old carburetor days. Way back when a turbo or supercharger would shorten engine life because air/fuel mixtures could not be set correctly. Carbs are bad enough, but add forced air on top of them and you have an engine that won't last nearly as long as a modern engine. Engine technology has come a LONG way. Look at Jackson Racing. They make a very sweet supercharger kit for several Hondas and Acuras, and they do not shorten engine life at all. They have several of their own cars running their blower kit, many with over 100k miles and still going strong.

Look at all the factory turbocharged and supercharged cars today. Do you think that automakers would put out a car with a short engine life in this litigation-happy country? Audi and VW have turbos, Toyota has a supercharger, GM has a supercharger, Mazda has a supercharger, Nissan sold a bunch of 300ZX Turbos, Saab has had a turbo in their lineup for a long ass time, and so has Volvo.

My point is that a proper super- or turbocharger installation will NOT have a negative impact on engine life. The key word here is "proper".

-o

__________________
But what is adulthood except a delayed end-run around our parents' better judgment?
-- Peter Egan

*cough*

KoalaFD

Wow. Lots of posts... lessee...

As overclocked says, modern technology turbos and superchargers do not really shorten the life of the car provided it's done correctly. In stock systems like in the Audis and newer cars with their EFI, it's quite easy to make the car run safely on boost. The time people these days run into trouble is slappin' on a turbo onto their engines were were designed for high performance naturally aspirated (NA) operations - such as VTEC and other high compression deals.

Helius, in regards to the idling of the turbocharger, it will depend on the type of turbocharger. There are some turbochargers, reputedly the Audi A4 has one of them, that cycle coolant through the turbo to cool it down after the car is turned off. Why do you want to cool a turbo down? Since turbos are one of the fastest spinning things known to man (about 100,000 rpm!), they heat up quite a bit. If the car is shut off abruptly, then oil is no longer sent through the turbo to help cool it down and the thing effectively heat soaks leading to a process called "coking" which basically means that the spinny parts get covered in this nasty goo. Which shortens turbo life. So... people buy "turbo timers" that actually keep the car on for a preset amount of time after the key leaves the ignition to allow oil to continue to cycle through the turbo after the turbo is no longer actively generating heat. Now if you were just driving around and not really getting on the boost (like I often do since I'm off the freeway and in a residential area), then you don't have to idle very long since the turbo is not heating up much. But I digress. There are a lot of these little toys that go on turbos to try to extend their life and prevent problems - turbo timers, blow off valves, etc.

Sportzcoop, I think that Stillen doesn't list turbos or superchargers as an upgrade because they are often the "final step" or one of the most expensive upgrades out there. If you were Stillen and offered as your first step a $3-4k upgrade, I doubt you would get many buyers. Again, it's about doing things right. And planning correctly. For example, if he did decide to upgrade to a turbo kit, he would probably be throwing away that super hi-flow intake system; the turbo kits often come with one that fits onto the turbo. Planning well will prevent buying unnecessary parts and such as well as protect your engine and car.

mp19fan

Very cool, guys...thanks for the detailed info. This was exactly what I was hoping for. I know some stuff about TC and SCs, but not enough to make any suggestions. For now he has AM headers and exhaust, upgraded NGK wires (should he also upgrade to platinum plugs?), coil overs, adjustable shocks, 17" wheels on Nittos. I've been telling him to wait a bit before upgrading more stuff, but he's looking into more low-end torque. I just don't want him to do anything that will reduce the reliability of a good car. Ehh, but what can I say? He's having fun. Any other suggestions? Thanks.

nhbilly

Just my 2 cent..........you know going fast and straight gets boring after awhile. You want to focus more on handling. Damn ever raced in a SCCA event? So damn fun. Hitting and exit corner fast is fun.

KoalaFD

And this has exactly what to do with turbos and superchargers?

nhbilly

As Sherlock would say, If I could tell what he might think...then it would mean nothing I would assume.

Crazyace

if you change your oil at proper intervals, neither should harm. A turbo does need a little time to idle before shutting the car down, due to oil pressure. When you fly of the highway at 3000rpm, and shut the car right down, the turbo is still spinning. With the car shut down, thier is no oil pressure, so this is a very undesirable effect. Make sure you idle for 30 sec, then shut it down.

__________________
CrazyAce
Former News Dude

Got/Apex?

Blackbart

Dude the main thing that will shorten engine life is your right foot. The turbo or super charger will put more stress on all the engine components in the bottom end. But if the driver uses good judgement the engine should not be damaged. How much damage is done is controlled by you.

Just my 2 cents

__________________
What is the air-speed velocity of an unladen swallow?

bobber

The reason you need to cool down your turbo car after driving it is because the oil that circulates to keep the turbo running smoothly is extremely hot and just turning off the engine stops the circulation and thus leaving hot oil which can burn and spoil the turbo...thats why you wait until the engine cools down a bit ...basically the harder your drive a car the longer you have to wait after ... thats why they invented turbo timers that shut the car off automatically after a specified period of time so you dont have to sit there like a idiot.

__________________
bobber

KoalaFD

I thought I said that...

Of course, I used like 1000 words instead.


But that's the short answer... "coking".

Crazyace

Burning or spoiling your turbo? I would think that a lack of oil pressure is which causes damage, not hot oil non-circulating oil. All oil in the crankcase is pretty warm, circulating doesnt cool it that much. It cools when it's in the oil pan. The reason for letting it idle is the fact that oil pressure cuts out, not hot oil

KoalaFD

This is rather interesting because we're kinda saying the same thing. Perhaps we're both right...

"The A'PEX Timer is designed to keep the engine idling after the engine is shut down and the ignition key is removed. The purpose is to keep oil running through the turbo to cool down the center housing. This is particularly critical after a hard run, where the turbines can spin at over 200,000 RPM and reach temperatures as high as 900C...Extended and repetitive oil coking within the oil lines and center housing could result in clogging problems and damaged turbos." - A'PEXi

"The turbo's bearings rely on a generous supply of clean engine oil. All oil pressure is lost when the engine isn't running. With temperatures ... at the turbine shaft [of] 300-350C, a hard, destructive varnish or "coke" can form on the bearings or seals." - Greddy Performance

"This permits the engine oil to circulate through the turbocharger bearing housing, drawing heat out of the bearings and impeller shaft in order to bring the temperature down to a safe level before the engine is shut down." - HKS

Crazyace

Ya, were in the ballpark