Well, I needed to add a beverage. Let me just clarify a couple of things.<p>1) First let's talk about volumetric efficiency. Yea, I know, a big word, but one of significant importance to the discussion of Turbos. (Sorry, 2.8 owners, go get two turbo's or and S4 or a SC, then the discusion will apply). Boost really has nothing to do with power, all it is is a measure of how much PRESSURE exists in the intake manifold. Power is more associated with how much air you can pump through the engine, not just the pressure that is providing the air. This is why, with Turbo'd cars, the more volume of air the better, not just the pressure. As they say, more CFM's is better. Too bad I forgot what CFM stand for, oh well, it's how much air you move, not it's pressure.<p>2) The problem with the K03 and the K04, is really this issue of efficency. The inlet is only so large and the outlet is only so large and the impellers only turn so fast, you get the picture. BTW, the pressure you run on the manifold has NOTHING to do with how long the turbo will hold up (I've seen postings about 1.0bar and wastegate breakage). They are related, but not the way people think. Better put, to get a given pressure with a K03 or K04 for a given engine rpm, you have to spin the wheels faster and faster.<p>There is a strange thing that happens when you spin (or fly) an object faster than it's designed to be. It will actually stall because it physically can't move the air or better put, cut the air, it get's in it's own way. This is just one problem with the K03 and K04. The other is really a physical thing, because they are small turbos, their parts are small too. Boost usually translates to heat and heat is a turbo's worst enemy.<p>You can see why this comes full circle, it's not really the boost, it's the fact that for a give amount of heat, there is only so many parts that can dissipate that heat. Heat is bad and breaks down the chemistry of metal and well, you can loose a turbo that way.<p>The other way you can loose a turbo IS tuner related. If they are running too lean in a given table, or too much timing, or too much boost, you will have high EGT's. This is that heat thing again. One last comment, it's heat that breaks wastegate rods, not boost, but you can see how they are intertwined.<p>Bottom line, you want performance it's a combination of many things, pressure, volume, temperature, etc. You have to think of it as a continum, if you are going to put more air in, you have to provide a way to get that air out. That's why it's a combination of how much air you can suck, blow, burn, and pass. And intake, turbo, combustion, and exhaust are all critical to making it work for a give amount of power.<p>3) I do have to be a little frank. So hang on an don't blame me; a) If you are looking for more power, really looking, don't go and find a million ways to say it's bad for the engine. There are no two ways about it, if you want more power, you're putting more load on the engine, bottom line. Can this lead to something that will break, YUP, but so can hitting that pot hole at 55MPH!<p>4) There is no magic that says you can add power and not add wear and tear. I wish it were true but it's not.<p>Oh, well, epistle number 4 is on it's way!!!<p>Alan

I believe CFM is a measure of flow...Cubic Feet (volume of air) per Minute

tn

The FAQ needs to be broken down into multiple topics..it has TOO much information now. Ack! <p>Steve S.<br>97 2.8QM

I guess the old saying "Horsepower kills engines" is the answer after all. Great research here and I hope it trickles into the FAQ eventually, though this process seems to take a bit especially with all the activity trying to get S4 and Germany information posted (in other words don't be discouraged if this doesn't show up in the FAQ immediately, it's great material and should be made accessible on a long-term basis).<p>One question for you though, from your research what do you think the effect of work on the manifold would be? Larry Victor and a few others, including myself, have nearly isolated extrudehone as the most appropriate process for working on the manifold, but because the process is legally protected the price is relatively high. From what you have learned (all four volumes worth plus more), would you say one of the following two statements is true, justifying this work?<p>* The gains from work on the manifold will be great and almost any earthbound price is appropriate given the extreme gains<br>* The car's drive system is so unbalanced without work on the manifold that powerplant output and/or lifespan may suffer and this work is nearly neccessary due to engine imbalance that might occur without this type of work<p>If either of these is true, I think most 1.8T modification people would consider this modification more seriously, but it seems to be a subject of controversy comparing the stage systems among tuners. What are your thoughts on the issue?<p>Staying away from chip and warranty debate for the next lifetime,<br>Cameron

Good topic Alan, you've raised some interesting questions. I'm feeling mechanically inclined tonight, so let me take a stab at a few things:<p>On 1)<br>What you are interested in is mass flow rate. This is a function of pressure *and* volumetric flow rate. A pressurized intake system simply makes the air more dense, so you get more oxygen per "breath". And more CFM, less restriction means increased volumetric flow rate and faster "breathing".<p>So more CFM is good. More pressure (and density) is good. More of both and you'll beat the //M3s :) Just make sure your engine management system is aware of what's going on and can get enough fuel for the increase in air.<p>On 2)<br>Don't exceed the max pressure (and thus RPM) your turbo was designed for very often, and you shouldn't worry about 'grenading' your turbo.<p>Like any pump, your turbo has an efficiency curve. Staying close to the peak operating pressure to minimizes pumping losses. Unfortunately the optimal turbo size may be large and slow to spool up... Yet another tradeoff. I like Toyota's solution on the Supra, a small and large turbo in series.<p>Pending no manufacturing defects, if you keep your turbo within designed operating temperatures it should last a long time. What are these? I don't know, but I'd imagine they are published somewhere. If not, with enough beer, the right engineer may tell you. <p>On 3)<br>Your car will break if you use it. The real questions are "what part?", "when?" and "how expensive will it be?". You can double the forces/temperatures on some things and they'll fail 0.00001% sooner. Other things will fail immediately if you work them a few percent harder. Whose job is it to have answers to these questions regarding your A4? Audi and reputable tuners.<p>Hope this helps... Have fun, drive hard, and let us know how your mods work out. <p>AJL<br>98 Passat 1.8T<br>