Audi's 4 cyl engines are some of the sweetest 4 bangers on the planet. The 1.8T started out with 150 hp, then it was bumped to 180 which is adequate for our roads. Then came the TT 225 the only Audi with this engine.

It is my understanding with the 225 they used forged connecting rods and crank, a bigger turbo, revised engine mapping and a performance exhaust (standard tuner tricks) to get the extra hp.

Does anyone have more details about the difference between the 180 and the 225?

 

You summed it up nicely!

The 180 has a K03 Turbo and 225 has a K04 Turbo with higher stock boost pressure of ~14psi.

 

In addition to what you stated, there were the following changes (from memory, I may forget a few); although, not all the differences below are for power increase:

- Improved exhaust (visually you can differentiate by the dual tips at the rear)
- Larger fuel injectors
- Dual (vs. single) SMIC
- Forged pistons
- Rod - 20mm wrist pin vs. 19mm
- Higher boost - 225 = 14.7psi, 180 = 11psi
- Compression is 0.5 lower, for lower cylinder pressure from higher boost
- K04 20 series vs. K03 Sport turbos
- 6-speed vs 5-speed
- Block walls and coolant passages a little thicker

The performance differences are really just the turbo, injectors, boost, remap, and maybe a couple hp from the exhaust changes. One could argue the dual SMIC is a performance enhancement when heat becomes an issue, but it would actually reduce maximum power due to additional pressure loss.

 

Thanks guys:
So does the TT 225 have some sort of variable valve timing? I thought I read somewhere that the new TTS has it.

 

The AMU engines are non-VVT (up to 2002.5), and the BEA engines are VVT (2003+, with a few 2002.5 - I think from 11/02+). In MKI TT's, VVT is for emissions and does not offer any power gains. However, the cars that came with VVT also came with a wide-band 02 sensor, which allows finer tuning when getting a custom ECU remap; and thus, more power.

 

Wow:
I had no idea that I had a BEA engine. Do you know what system they used to get the VVT, is it a dual lobe cam or something like that? At about what RPM does it change?
Thanks

 

I'm not 100% sure, but I don't think it's a dual-lobe cam, just an adjustable tensioner unit. Unfortunately, the VVT in question is not for performance and offers no gains. I think it is only for startup/idle.

In short, don't get too excited - the only appreciable difference between the AMU and BEA is the latter having the wide-band O2 sensor. The wide-band will allow you to hook a gauge up and get accurate readings; and, would also give a bit more tune-ability once you get into BT tunes. I think APR got an additional 13hp (crank) on their Stage III+ kit.

 

boo.......i have a AMU engine

 

So a manual 180hp will only be a 5speed, and the 225hp is a 6speed?

 

A little off topic, but does anyone know specifically what I must do to run a k04 turbo on my 1.8T? (170bhp/173tq) I'm running stage 1 Revo right now, making 205bhp/240tq.

The way I see it, my choice would be to either

-Upgrade to stage 2 Revo on existing turbo, with a couple bolt ons like exhaust (which I have sitting in my garage, but hate) and intake, and diverter valve;

-Upgrade to k04 turbo and keep stage 1 Revo, or

-Upgrade to k04 turbo and stage 2 Revo + bolt-ons to support the stage 2

Suggestions?

Andrew