CP

I'm wondering because I've been reading a discussion on a Subaru board about the compression ratio in the new WRX engine. Seems that Subaru has added a tumbler valve in the intake manifold to improve low-end torgue in that motor by disturbing the airflow. The compression is a low 8:1. But it looks like it also restricts airflow at high engine speeds. The link has a picture of it.

I was wondering if the Audi engineers had to deal with this problem too, or if the compression in the 1.8T is high enough that it is a non-issue.<ul><li><a href="http://www.i-club.com/ubb-files/Forum30/HTML/000142.html">TGV discussion</a></li></ul>

Jimmy Pribble

9.3:1 according to Model Guide (hint).

leechiahan

why you ask still dont know?
is it some thing important?

CP

I was trying to spark a discussion about this tumbler valve thingy.

DustysA4

but I've read in the past that that A4 1.8 has an air pump that aids in keeping emissions down when the motor is started up. It is there because the cat isn't hot enough yet or something like that.

Is this the same thing or something similar?

Also the new subie is running like ~14.5 pounds of boost so it is not wonder that the compression is so low. Personally I don't know why Subie claims to compete with Audi when they have a 2.0 and run much more boost. They aren't even in the same class IMO. Don't get me wrong, I still like 'em=)

®ob

The air pump you refer to runs while the engine is cold blowing more oxygen behind the ehxaust valves. When the engine is cold, the cats aren't hot enough to fully get rid of all emmisions. A bit more oxygen in the mix and that helps burn of the emissions when the engine is cold.

Leszek

I think the European 180hp A4 has an 8.5:1 compression, but Europeans know how to rev their engines and don't mind loosing low end torque for higher hp

Leszek

I believe Subaru knows that most most people who purchase a WRX will want to modify it to get more power, especially since STi is not available here. Subaru therefore decided to make this engine bulletproof for high HP/high boost applications. With 8.0:1 compression you can safely run 22psi on 91 (US) octane gas. You loose low end torque, but you can most likely get 300HP without modifying engine internals.

Bollinger

There are some 180HP 1.8Ts in Europe. In the UK the last two years the Quattro version of the 1.8T has been 180HP. In the rest of Europe all 1.8Ts are 150HP. Don't know what happens with the new model.

Europeans know how to rev their engines because they are used to crappy little engines that you have to rev to do anything with. Audi offers the A4 with a 1.8L normally aspirated engine in Europe. In some countries it's also available with a normally aspirated 1.6L engine. And it is a luxury car.

Many cars in Europe take about 14 secs 0-60.

Jenner

I can find more info about it if this is what you are asking about.