Building a hybrid turbo

[Oliver80]

Hi there I'm thinking about modifying my triple K k03 turbo, I'm proposing changing the impeller from a standard k03-03 to a k03-052 from a later model. At the moment it's on a aaz engine that's had about as much done to it as possible, I've had the head skimmed, ported and polished, I'm running high pressure injectors, I've replaced the boost pin and tweaked the pump, I've a 3" bore exhaust with a modded silencer. I don't want to change turbo completely as the k03 fits everything I've done, also I've heard there's not a lot of differance in power gain going to a k04, has anyone done something similar or know where I can source an impeller from..?

[Funbus]

What's your comfortable speed on motorway.
I don't think changing the impeller will increase much. There's only so much air can get through anyway.

[Oliver80]

Umm 70mph of course... It'll go higher, the speedo will say 75 and that's about 4000rpm, I'm running 225/75/17 wheel/tyre set up so I think my speedo's about 20% slow. It's not really top end I'm after as I'm limited to my gearbox ratios and that's my project for next year. The thing is, the turbo runs out of boost before I'm at top revs, I feel I'm wasting a bit of engine potential, I've tried to have a bit of a read up on turbo workings and I gather that increasing the inducer diameter whilst keeping the exducer diameter the same size will give me a later boost curve while not loosing any torque, I don't want to go for a larger k04 impeller as a 1.9 diesel won't produce enough exhaust fast enough and I'll get lots of lag.

[what2do]

I know sweet fA about this but what a whiff if fresh air, to have someone talking turbos, diesel and 'performance'. I hope you achieve what your seeking and the van whistles through the wind with much gusto

[Smosh]

I know sweet fA about this but what a whiff if fresh air, to have someone talking turbos, diesel and 'performance'. I hope you achieve what your seeking and the van whistles through the wind with much gusto

+1

[MGP]

Your main problem with the k03 is the hot side is too small to get much performance and keep the egt in check especially at high rpm's.
Your best bet is to sort out the gearing to get the revs down when cruising.
I went with a gt1549 turbo on my aaz mated to an audi a6 1.8 non turbo gear box so 70mph is about 3200rpm on standard 185r14 tyres.

[windy]

The best thing about the standard K03 is it spools up early, which is of great benefit on a heavy old van.

I have a feeling that anything that produces more boost higher up the rev range will likely lose that feature, which could be a problem on hills when changing up the gears & you initially find no boost to pull with.

[MGP]

Without going vnt the best you can ask for is a happy medium, unfortunately a small turbo and high revs just dont go together very well. If your planning a regear then then live with what you have till its done if not then a bigger turbo is the way forward.

[Oliver80]

Thanks for the relplies chaps have sourced a new core for a k03 so my rebuild should be started this week, just going to replace thi impeller wheel with the 052 one to start with and see what differance it makes, hopefully the spool time should be pretty much the same just a little gain I'm boost...