AudiWorld Tech Articles



Tech Article Title Author Date
A4 K04 turbo upgrade Don Pavlik 2000

In the never ending quest for more power I present to you...

The K04-015 turbocharger

From the outside there is no visible difference between stock and the K04.   I'm told it's what's on the inside that counts -- a more efficient turbine which allows higher air volume at the same boost pressure.

K03 cold turbine

K04 cold turbine

As you can see there is a difference between the turbines.  I don't know much about turbo design but the K04 seems like it has a more aggressive blade pitch.   Seems like it would take a bigger "slice" of air while rotating.   Just a guess.

The K04 sounds distinctly different from the stock K03 unit. Any 1.8T owner who has been running a 0.8 or 1.0 bar chip and has a sharp ear would be able to tell something was up the first time you spooled up some boost.  While the K03 has a "ffffweeeee" sound the K04 has a higher frequency "swsssss" sound.   Even with the stock ECU you can hear the K04 at 7 lbs of boost.  The K03 with a stock ECU is completely silent at 7 lbs.  The K04 whistles like it means business... even at 5 psi.  I find myself easing into the throttle just a little now and then to hear it spool... cool sound.

The 235hp turbo kit I purchased included:

  • K04 turbo
  • all required gaskets, bolts and washers
  • software
  • air filter
  • the vendor claims an exhaust is not required for 235hp

I've also installed Bosch Silver F2CS spark plugs (purchased separately from elsewhere) which are a cooler heat range to help curb detonation.

 

The K04 turbo install

 

It's right... finally!

If you've been following my K04 turbo installation saga you know I've had months and months of problems with the upgrade --  4 months of problems to be exact.  I had no end of trouble with the car.. it just wouldn't run correctly and performance was nowhere near the claimed horsepower.  We just couldn't get the software right.   The vendor kept their nose to the grindstone and eventually found the magic combination that makes my car purr... or should I say growl.  

The 1.0 bar chip upgrade from stock is a much more dramatic improvement overall than a K04 upgrade.  However, the K04 turned my car into feisty beast that charges hard as low as 2300 rpm and makes it presence known until 6,000+ rpm.  Driving around town and on the freeway it slaughters most traffic with or without a downshift when you lean on the skinny right pedal.  4500+ performance is good and the power drop-off experienced after 5000 rpm with the K03 turbo and 1.0 bar chip is gone -- the car has a satisfying pull until you bump into the rev limiter.  No increase in turbo lag with the K04.  I like this setup it was just a long road to get to this point.

But, if you had visions of showing your tail lights to that pesky ///M3 you see on the way to work every now and then you'll need just a little more out of the little 1.8T unless you catch the guy (or girl) gawking at themselves longingly in the mirror, the M3 is equipped with a slushbox (a sin for sure... they deserve to get dusted) or the other driver is just not on the ball.  My car is fast but it's not quite into the ///M3 neighborhood.
Comments from Steve Brown:

Well, Don came over on Saturday & was brave enough to let me drive his car (my last three vehicles were autos & my manual experience comes from my fathers TR4A & his MGA (no syncros to get back to first!).  Anyway, I'll let him tell the tale of how he got the car to where it is now, but I'll tell you, his car is now (1) fast, (2) stable, engine wise, throughout the rev range, (3) fast, (4) fun, (5) fast.  

The car gets up and moves! (He might try to say there is a bit of hesitation as you spool up the turbo off the line, but it's MINOR). Cruising at anywhere from 25-60 (no place for HIGH speed test), you could basically aim the car & GO, RIGHT NOW!

My humblest apologies to Don's clutch, getting moving & 1-2 were VASTLY different from a 75hp 30 year old car. 

Wow...I realize now two things: (1) The 1.8T is an amazing piece of work, (2) I'd be completely in debt modifying one if I had it.

There is a turbo whistle, but I only noticed it when I was outside the car. The car sounds like a MACHINE, but not at all offensive (still stock exhaust).


A consolation: My horns are WAAAAAY louder than his.

Donp: [That's for damn sure... I was shocked!  Really loud!  I need these!!]

Steve
98.5 2.8

Testing I've done so far has resulted in 1/4 mile times of 14.61@93.30 mph and 0-60 runs of around 6.01 seconds.  These were the first runs I'd done with this configuration -- I suspect I can shave a tenth or two off of these times once I learn the powerband of the car and where to shift to squeeze out the most performance.  If so, that would put me in the high 14.40s or 14.50s.  That aint bad for a 3600 lb car with a 1.8 liter engine.  I have not had time to do in-gear testing yet but I suspect those times will be good too.  Yes my friends I've now got a sleeper -- A mild mannered looking A4 with a split personality.  My goal has been accomplished.

Update:  Since my initial 14.61 1/4 mile run I've done additional runs.  My best time so far: 14.49@95 mph.

I did find that the car runs perfectly with the stock (ie. factory) prom installed.  I wanted to verify I could run the stock software as I heard that the car would not run correctly with a K04 -- mine does just fine.  Smooth (albeit slow) factory power right up the the rev limiter.

The Bottom Line

Do I consider the upgrade worth it?  Would I do it again?  Yes and yes.   Although, I don't think I'd be so patient the next time.

If you are one to expect an upgrade to be truly an install, drive and forget ordeal I suggest you do your homework before you take the plunge on an upgrade of this type.  I've done heavy duty engine upgrades and such before and they always have a few rough spots... it's just the nature of high performance.... this one was no different.

Here's some interesting (and somewhat puzzling) information based on published dyno data for stock, chipped and chipped with a K04 turbo.  The puzzling part is the stock dyno pulls indicate the engine was performing above the factory claimed horsepower and torque.  Was this engine really performing above average or do we have dyno error or some other influencing factor.  Personally, I adjust the numbers based on what stock should be knock off a few HP and LB-FT as some kind of crude normalization -- I suspect would be reality numbersNote that this data was "eyeballed" off of pictures of graphs so this data is  probably not entirely accurate.  Repeat: Assume these numbers are very crude (and potentially inaccurate) data.  I don't want any email telling me my numbers are bogus or misleading... I worked with what was available just to get a ballpark idea.  You might say bad data is worse than no data at all... probably true... but since I did the work for my own curiosity I figured some others might care to see the info too.

Dyno Data

Torque: Stock v Chipped v K04 Chipped

 

Change

RPM

Stock

Chip

Turbo

stock v chip

stock v turbo

2500

160

185

209

25

49

3000

160

222

245

62

85

3500

160

230

255

70

95

4000

160

235

255

75

95

4500

160

227

252

67

92

5000

158

212

242

54

84

5500

147

185

223

38

76

6000

135

160

200

25

65

6500

118

136

175

18

57

7000

-

92

135

-

-

 

Horsepower: Stock v Chipped v K04 Chipped

 

Change

RPM

Stock

Chip

Turbo

stock v chip

stock v turbo

2500

75

90

100

15

25

3000

90

125

137

35

47

3500

108

155

170

47

62

4000

123

180

195

57

72

4500

138

195

216

57

78

5000

151

200

230

49

79

5500

155

195

235

40

80

6000

155

185

230

30

75

6500

146

172

220

26

74

7000

-

155

180

-

-

 




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