Turbo and Kompressor?

[vabboud]

true lancia toyed with the idea in their rally program, but computer technology of that time never permitted road going applications, the cost would have been prohibitive, and lanica even then could not charge ferrari premiums even for a "twincharger" now sold in a modest golf

[martinbo]

The key to VW's claim to innovation is not the mechanical combination of a turbocharger and supercharger but rather the dynamic interaction between the two. Previous forms of this design, particularly in aftermarket tuning, saw both the turbo and supercharger running in unison.

With VW's Twincharging technology (why the hell did they start calling it TSI as this is a mite confusing) there is an interplay between these two induction compressors that is electronically controlled. A clutch that engages the crank-driven supercharger pulley couples and decouples depending on the spool of the turbocharger, this makes for greater fuel economy and efficiencies as power normally sapped by driving a supercharger isn't lost at higher rpm. The effect of turbo-lag, naturally, is also negated. The interplay between the two is seemless and thus far undetectable by even the most sensitive of journalists.

[MoSs AMG]

why do i allways have the feeling that cars with superchargers are allways more reliable than cars with turbos?
somebody correct me if im wronge...

[MikeJ]

Originally Posted by MoSs AMG

why do i allways have the feeling that cars with superchargers are allways more reliable than cars with turbos?
somebody correct me if im wronge...

When driving a car with turbo, you should avoid high revs (having the turbo kick in) when the engine is cold, and let the turbo cool off (by avoiding high revs once again) before switching the engine off. Otherwise you might damage the turbo in the long run.

A buddy of mine has a Saab 9000 Turbo with 320,000 km on it, and he says the turbo is original and has never needed any work.

[Zonda]

Originally Posted by MoSs AMG

why do i allways have the feeling that cars with superchargers are allways more reliable than cars with turbos?
somebody correct me if im wronge...

Turbos generate alot more heat than superchargers do and therefor brake down easier.

[Snake Vargas]

Well, the hot exhaust gases run through one part of the turbo, which means they are subject to much higher temperatures, as well as heat generated by itself.

The supercharger is driven by a belt, so it's only subject to the heat it generates itself by spinning and by compressing the air.

However, intelligent use of turbos should be largely trouble-free. Factory manufacturers generally are aware of reliability and warranty issues and their effect on brand perception and profit, these days.

[martinbo]

Turbochargers generate no more heat than the exhaust manifold of a naturally aspirated car. It's the heat from the exhaust gas itself that heats the turbocharger (its manifold, turbine, lubricants etc.) to very high temperatures. These days turbocharger overheating is seldom a problem, though it certainly does still occur. A case in point was BMW's 320d red-dot turbo saga here in SA's high altitude regions a few years ago.

With modern electronics measuring the exhaust gas temperatures, turbo-overspeeding and overheating is prevented by limiting the boost pressure (and hence the turbine speed) via the wastegate.

The biggest culprit in turbocharger reliability remains the human factor: either overstressing the turbo from cold or not driving sensibly for the last 2 km in order to let things cool down. Turbocharger cooling is a still an issue and this pertains predominantly to the state of the lubricant (oil) running in the turbo bearings. It's quite simple, if you race your car all the way home, park it in the garage and just switch the engine off then the following is applicable.

1. As the oil pump runs only when the engine is running, the oil circulated through the turbo and sub-components no longer undergoes such circulation.
2. Oil changes its molecular properties and physical characteristics if subjected to very high temperatures for extended periods of time.
3. The oil in a highly heated turbo has nowhere to go once the engine is switched off and subsequently changes its molecular properties to that of a non-lubricating substance in an area where proper lubrication is essential: the bearings. Over time, subjected to such continuous abuse, the bearings eventually fail and the turbocharger shatters pretty little turbine blade pieces into the intercooler plumbing and possibly the rest of the induction system.

[donau]

Well put martinbo

[Snake Vargas]

They also have (generally aftermarket) turbo timers. They keep the cooling systems going after you exit the car, and turn themselves off after a little while.

That way, you're more free to drive as normal.

[martinbo]

Originally Posted by Snake Vargas

They also have (generally aftermarket) turbo timers. They keep the cooling systems going after you exit the car, and turn themselves off after a little while.

That way, you're more free to drive as normal.

Mmm yes, I've heard of them but haven't done much research into these "turbo savers". In my opinion, keeping the cooling systems running isn't enough. The turbo preserver would be most effective if it continued to run the oil pump after the engine had been switched off.

I met someone a while back who had such a turbo preserver fitted to his Isuzu pick-up; basically it kept the engine running even after the engine had been switched off and the vehicle was locked. Imagine the chagrin of South Africa's informal sector car guards upon observing one times departing driver and a still-running engine! Eek.

Snake, have you done any further research into how these aftermarket units operate?