Through college, I liked science a lot, but didn't have the knack for chemistry and the upper levels of math, so graduated w/ a degree that didn't require these courses. Unfortunately, that's left me a leetle bit ignorant concerning the following matter! I've seen pic.s of the turbo glowing red. Does that not weaken the molecular structural integrity of the metal over time? I've seen some posts from people w/turbos w/cars over 100K miles w/ no probs., but on the other hand I've read posts concerning this particular reason is why some opt for the 2.8. <p> I'd like to chip, once I get my hands on the car, but am concerned bout goin .8 or 1 bar on which would be less taxing on the turbo and therefore longevity of the engine (wife has commanded that I WILL keep this car for 5-6 yrs)<br>Thank you in advance for your input!<p> 99.5 1.8tqms roof, trip, sport seats; Lt.silver/grey...hopefully in April.

Let me first direct you to the archives for the longevity issue. A synopsis is that the turbo is designed for 1bar from KKK, some people feel uncomfortable with higher levels of boost regardless, and some people sell chips that make less than 1 bar and use fear tactics to scare you.<p>It makes no difference what your choice is as long as YOU are comfortable. There has been one noted turbo failure on this list and a dozen (out of hundreds) wastegate rod failures on both chipped and unchipped cars (warranty item).<p>The turbo can glow cherry red (with or without a chip) because the exhaust impeller is encased in a "cast" iron housing that can take millions of heat cycles without problems. This is the part that glows. The vast majority of automobile exhaust manifolds are the same metal makeup and last forever. But yes, metal can heat fatigue and crack depending on the metal mixture and part design.<p>I predict you will be very happy with this car,<p>Erik

My father used to have a huge photograph that he loved... unfortunately, it was lost in a flood a year ago. It showed a Porsche 911/993 Turbo on a dyno at top end in sixth with the housing glowing on the top half of the print (visible) and the turbo track glowing in the bottom half of the print (infrared).<p>BTW, if anyone knows where another copy of the print is available, I'd like to get another copy... I'm sure it's a picture from Porsche's own photo facility and was done as a promo photo.<p>The real question is how well matched the turbo and engine are matched. Will the turbo overspin? Will the impeller be driven past limit? What is that limit? The K03 is a tiny turbocharger, and it's unlikely you'll seriously hurt the turbo before you hear the clickity-clack of a mangled wastegate rod. With the 1.8L engine, it's difficult to say the turbo will "never" suffer damage, but it is extremely unlikely if the turbo is being run at 1.1 bar, for instance. Now, if you bore the engine to 2.0 liters and try to swap pistons, rods, cams and crank without thinking to swap the turbo, you might have problems. Make sure everything in the system matches, you won't have problems.<p>Cameron

The turbo picture illustrates how the thermal output from the turbo can be huge, extreme enough to make the housing glow, without harming the system. But remember, you don't have a dyno in your Zuffenhausen back yard :-)<p>Cameron<br>

I own a 1.8T and I am not worried. You shouldn't be either. Right now though I am hungry and looking for foodenhausen.

Having worked on the "killer B" group B sport quattro rally cars in the 80's, I can tell you that the exhaust housing on the turbo gets to a "high orange" color, as do the brake rotors (discs). They do no suffer because of this, being made of cast iron or similar that has good heat properties and is able to heat up, cool down many times without harm.<p>Side note: once we moved to the sport quattro with 400 to 600 hp, we had to wear thin white cotton gloves to change the tires, as the titanium lug nuts (yes, the rally cars had studs installed for quicker tire changes)got hot enogh to burn your fingers and stick to the skin!!! Great to see a mud-covered rally car come in to mud-covered mechanics, all wearing white gloves !!!!

I agree completely,<p>But, this is not a theoretical discussion on my part. You sure could get more air to flow through the motor and make it overspin the turbo, but it would take thousands of dollars. This is not a function of the chip (in spite of what some believe) There are lots of designed-in final boost limiters on this motor from the hoses to the exhaust manifold.<p>The only real way to hurt the turbo is to use lousy oil/never change it. Same with the engine, and use low octane gas.

I worked on Porsche 934/935 and 962 race cars for many years. The KKK turbos were always glowing red - the housings themselves are very strong and not the issue. The weak link in a turbo charger are the bearings that hold up the impeller shaft. What tended to happen on the race cars is, the bearings started to go which meant the shaft was not spinning evenly any more and would seize, or break impellers. Over boosting would also tend to fling the impellers off the end of the shaft, or shafts would bend and impellers impact on inside of housing. Now we, would routinely run 1.6-1.7- 1.8 bar of boost in sprint races. The 935 originally came with<br>K27 turbos, on the 934 we ran a K36. In any event, the A4 is running at no where near the load we used to run, and also has water cooling now of the housing, so that helps a great deal. Another thing to remember, turbo's are relatively simple to rebuild, or cheap (in the overall scheme of things to replace).

Chris,<p>Don't think the turbo work harder with the aftermarket chips. The same amount of exaust goes throuth the blades. The chips control the amout of pressure that is going to the engine through the manifold. What will be stressed are the valves, pistons, rods, and crankshfaft. From all the inputs on this website,it would appear the 1.8T can take the additional strain. We have some agressive drivers here who would have discovered any weakness in the engine by now. <p>Enjoy the new chip.<p>Regards,<p>Reggie<p>98.5 2.8QMS

(nt)

I'm not a physicist, but a chemical engineer.<p>The turbo housing is a mild steel casting, so there is very little heat will do to it.<p>The real problem is the center bearing. The best way to roast this is to come roaring up to a stop then immediately shut the engine off. The turbo spins very fast and is essentially free-wheeling relative to the engine. The center bearing recives its oil supply (for lubricaiton and cooling) from the engine's pressurized system. After being spun-up it takes some time to stop spinning, while shutting of the engine immediately removes its supply of oil. The result is that the residual oil in the bearing will oxidize to carbon, which has very little lubricatring value and can "coke" the beearing causing it to sieze. When you plan on stoppng, try not to spin up the turbo, and turn the engine off last -- turn off the radio, close the sunroof, unbelt, open the door -- THEN TURN OFF THE ENGINE.