What are the differences between the 225HP version of the 1.8T engine scheduled to appear in the TT and the current A4(just management or parts as well)? Would it be too difficult to achieve such horsepower from an A4 1.8T engine by just using whatever modifications Audi made? Would it be too silly to expect that such an upgrade could be available someday from our dealers? <br>

http://205.252.248.99/intro/intro3_2.html<p>This is to the TT Introduction on our Audi-TT site (www.audi-tt.org).<p>In short, it look like this engine has a larger turbo and a different air-flow system.<p>With a chip and larger turbo, I think that it would be easy to get to 225 on the A4 engine. Don P has put in a new turbo, and he has a pretty good write-up about it, but I don't have his web address handy right now.<ul><li><a href="http://205.252.248.99/intro/intro3_2.html">TT 225hp engine</a></li></ul>

The following info was pulled from the VWVortex web site:<p>"This 225hp (165 kW) turbocharged engine achieves a specific output in the Audi TT Coupé that many a full-blown sports car of recent years would be proud to claim as its own. This level of performance explains why the engine's compression ratio of 8.9 : 1 is extremely high for a turbocharged unit."<p>"To permit this high performance to be achieved reliably, the 1.8-litre engine has been fairly extensively modified. The pistons, connecting rods and big end bearings have been uprated to accommodate the higher combustion pressures. The double-mass flywheel and the clutch have also been modified to match the changed performance characteristic. The intake manifold, turbocharger and exhaust manifold are of entirely new design."<p>"The 225hp (165 kW) engine is equipped with two charge-air intercoolers, through which the Type K04 turbocharger forces air into the combustion chambers. The airflow path is quite different from the 180hp (132 kW) version, and together with a larger air cleaner ensures that the temperature of the air reaching the engine is only about 30°C higher than the ambient temperature. This is equivalent to more than 80 % charge-air intercooler efficiency, and keeps the engine supplied with an optimum flow of oxygen-rich air. Maximum boost pressure at the intake manifold can reach 2 bar."<p>My guess is that you could bring your A4 150 HP engine up to 225 HP by purchasing the Audi parts (eventually)...but you'd be looking at some major $$$$.<p>Andy Hedin

Well, the specific out of 225hp is easy to achieve on the 150hp 1.8T with a new chip running 14psi, a bigger turbo, exhaust and intercooler. However, the internal improvements to the 225hp version would allow for much higher boost levels than the 150hp 1.8T. According to Audi, the 150hp 1.8T can withstand max boost of 15psi without internal mods and still be reliable. The 225hp 1.8T engine can withstand 29psi or 2 bar. If you look at all the chips currently available for the 150hp 1.8T, none go above 15psi. You will be able to achieve much higher hp figures with the 225hp 1.8T than the 150hp version