i am trying to learn as much as possible about these cars so i take in as much info as possible. one thing that is confusing me is that i see people mention ko4 turbos with other numbers after the ko4. can someone please tell me what those other numbers mean.

 

Its usually the trim for the compressor wheel. It denotes the size and angles of the blades in the turbine, and represents it as a rating number in units of the same housing size(k03, k04, T3, T4, etc.) Usually the bigger number stands for a higher flowing turbo.

For example a k04-20 flows more CFM at 10psi then a k04-15 flows at the same pressure.

I think I should also add these numbers change the spooling characteristics and the dynamics of the effective RPM range of the turbo.

 

did the 225 come with only one ko4 turbo or did the size differ?

 

Im pretty sure the 225 runs the same k03 as the 180. The trim might vary to get some of the extra power but Im not sure.

The k04 is an upgrade even for the 225.

 

oh, i thought the 225 came with a ko4 turbo and dual intercoolers and that is how it made its power.

 

Nope, the 225 uses a K04, the 180's are the K03. The 225 gets the added 45 Hp via the K04, stronger internals and bigger injectors.

 

Statement retracted, I did some looking around and they are different part numbes.

The 225 uses the same k04 as the S3, specifically the k04-20. That explaines alot, 45 hp is a pretty serious number but it didnt seem unattainable given 25-30hp just through better ECU management.

What kind of boost levels does a stock 225 run then? The same 10psi as the 180? Mine spikes to 12, and settles to 10.

The rods and pistons are different too? Im trying to figure they key differences between the 225 and 180 so when Im building mine I dont just upgrade to a hotter OEM motor. Pretty much a 180 with a dual exhuast, k04+proper software, fuel upgrades, and FMIC will produce around the same stock performance as the 225, right so far? And a performance ECU flash should push the k04 software up another 5-6psi or more? Then a true turboback exhuast, intake, intercooler fogger, MAF housing, etc. starts to actualy exceed the 225

Will the stock 180 internals hold to 325-350hp, because I know the stock 225 internals do. Would I need cams to support this kind of flow as well?

Would a k04-25(from the either the S4 or A4 Sport I believe) be better suited to that job?

Im looking for around 325hp at the crank. I thought a k04-20 with all the breathing/fueling mods I could think of, a GIAC program, FMIC and the boost dialed up to 18-20psi would fill the bill, now I'm not so sure.

 

Go with the K04-20, as I recall the -XX referred to difference in the inlet/outlet configurations. The K04-20 should be a direct fit to the stock manifold. I seem to recall that the 225 stock boost is 1.1 bar compared to the 180 which is 0.8 bar.

I know that from my experience my 180 went to 15 peak and 13 sustained with the chip. When I added the boost machine I am able to get 18 peak and 16 sustained.

I think the stock 180 internals should be good up to 300 HP. Any more than that you should plan on going to forged pistons and stronger rods.

A friend of mine has an A4 with the same basic engine as the 180 has and he moved up to a K04 without any problem. Well other than they kinked one of the oil lines so he blew that turbo up, plus and E05 before they discovered the problem when they were installing the Garrett. But even with the K04 he was making all kinds of power without any strain on the engine. With the K04 you can safely run around 18-20 psi boost and make a lot more than the K03 does at those levels.

 

i dont have much money too spend so im trying to do my muscle car tricks by removing restrictive items and adjusting screws and nuts. is there anything that i could just grab some tools and do to make any more power? i just went from the stock airbox to a cone filter and i have noticed a little more pep. i was thinking that it might be possible to push my boost up a little but then again i dont know crap about forced air.

 

Simply.. .spend the $500 and chip it. You might be able to increase the boost a little bit with a boost machine but without the software from the chip to up the boost and advance the timing you'll be pretty limited. The first thing I had done when I bought mine was to have an APR chip installed. I still have a "Stock" setting that I drop it into when I need to get smogged. Most of the time it runs with the 91 octane program and I have a 100-octane program in there for when I use race gas at the track.