Chips, the Stock turbo, and Compressor Maps

[Kor]

So I forced myself to learn how to calculate points on a turbo compressor flow map. Mostly this was to plan out what kind of turbo I think would be best. Eventually, not immediately, if you get me. Plus I was bored and no one is posting.

After learning how to do this, I decided to plot some points on a map of the stock K03 turbo.

So chipping is safe. It's been proven in the field by tens of thousands of cars. The benefits of chipping are well known. All this notwithstanding, when you look at the compressor flow map... holy crap.

Looks to me like running 15 or 16 psi puts the points right off of the map, especially into the higher RPMs. The temperature must be REALLY high and the efficiency so low... people talk about the reliability of a turbo upgrade, I can't possibly see how a new turbo is worse than the stock one!

So for everyone out there who is chipped, remember that scientifically speaking you are running your turbo WAY outside the specifications. I am gonna try to stay out of the high RPM range a bit more, and I can see why VW doesn't like chips now... not that I am gonna revert to stock anytime soon. Its all worthwhile... turbo can't live forever

[Klobi-One-Kinobi]

Good point Kris.

This was another reason I decided to upgrade my turbo. Hard to say how long my little ko3 would last at 17psi. Should be able to run bout the same boost on the new turbo with ease and with much more power.

Ad in my expired warranty (also just a ko3, not ko3 sport) and this upgrade was a no-brainer for myself.

If I had a AWW or AWP I might have just left it at a chip and exhaust, untill the ko3 sport went kaput. You guys get mad torque at a nice low rpm!

[Kor]

I wish I could have just watched the guys in C1 installing your Stage 2 turbo kit...

[Flanders]

how's the k03 sport at around 15psi?

(ie. what's the psi limit of the k03 sport where efficiency go tits-up?)

[Kor]

I don't have the maps for all the KKK turbos so I can't tell you specifically. But I am guessing that at 15psi were way out there even on the 'sport'.

[Flanders]

no kidding.

I'm going from hearsay but I was under the impression that the ko3 sports were good until 20+psi. I thought 1 bar was bang-on in the efficiency zone.

[Smartiepants]

Pfffff, they'll die out at like 18-19 at that point you are already pushing it to its limits. Look at a chipped persons car after they have driven hard, glowing red, look at someone else and it should be cooler.

[Kor]

Pfffff, they'll die out at like 18-19 at that point you are already pushing it to its limits. Look at a chipped persons car after they have driven hard, glowing red, look at someone else and it should be cooler.

Well they die out a lot sooner than that, you can't take 15psi to 6500 rpms...


Also, at some point the excess heat generated by the turbo because of the poor efficiency make the higher boost level useless. The point of boost is more oxygen. If you increase boost from 14 to 16 psi but the air gets 25% hotter, it will contain less oxygen and you will actually have less power. Just making up numbers there. I am not saying that this happens, but at such low efficiency levels the heat being produced IS very high. If I had a better K03 sport compressor map I could probably figure out exactly when this point is...

[1.8Trip]

I think the issue is because IC engines are really just air pumps and a turbo is a turbine driving a compressor to feed the engine more air, there is really only one aspect of a turbo that the engine cares about. That is the mass flow rate. lbs/min, kg/s ect. Mass flow rate is dependent on the speed that the turbo is spinning, the temperature and the pressure of the gas. With a given turbo, all of these aspects puts the operating point somewhere on (or completely off) the compressor map.

I just wanted to point out that boost pressure is not the only thing that matters when looking at turbos. In support of what Kor said, if you are trying to get 15 psi at 6500 rpm, you are in effect trying to increase the mass flow rate of the air entering the combustion chamber to the 30 lb/min range. I think our stock turbos do really well at 15 psi in the 3000 rpm range and that is what the VW engineers wanted when they designed our vehicles. They wanted a 4 banger that drives like a V6 with lots of low end torque.