big boost engine rebuild or not

[dub-disaster]

Don't you need a different map depending on how much boost you're  running?I thought that the fuelins would have to be different therefore different map that's why I thought of adding a second ecu.

[Tommo]

Yeah I must admit the K03's do seem cheap and readily available. But as they say if theres no lag then you have the wrong turbo. You can do what I did and fit a smaller turbine housing to a bigger turbo to make it spool up quicker (my 200sx turbo is on full boost by about 3500rpm). But with this you have to be careful sizing your compressor as too big and it could surge.

I would reccomend a garret off a rover 620/420 turbo, Although on a stock engine it may run into surge as it comes on boost lower down, you can prevent this by increasing the volumetric efficiency of your engine over stock (eg porting, BVH, GT manifold etc) Or increase your displacement (anything to get your engine flowing more air)

That setup would provide a much cooler charge at 20+ psi than a K03 would, meaning you can run more advance and a higher compression ratio, and produce a lot more power.

[Andy]

You can always open the diffuser gap up on the K03 to allow it to flow more air. No wonder the aqua mist works well on these cars as a K03 will be blowing pretty damn hot air at that sort of power.

Datalogs from my own car (1341cc, 9:1CR, stock head, K03-005, 'turbo' cam) suggest that at about 17psi inlet temps are no more than 10-15degC above ambient whilst ragging. I seem to remember seeing 55degC or so inlet temps when running more boost in an ambient of approx 20degC, but haven't found the time to map my own car on high boost yet so not got much data. I've not held it flat-out on the motorway to see what happens there though. Will report back at some stage! Don't think a K03 at 21psi on a 1.3 8v motor is worked as hard as you're implying though.

Aquamist works very well in general on the G40 engines if you're able to map the car to suit. At 15psi or so mapped without Aquamist my own car was slower with it fitted and working - though in fairness I was only injecting water, no methanol. Add the methanol, and the advance to suit and it works well.

I just thought that it decreased the turbos life as it was operating at the edge of it's limits? Any how I am thinking of running two ecus that I can switch between so I can have a 15psi for daily driving and better fe economy and a high boost one for when I feel like ragging it a bit more

You can always have a map done for 21psi, and then just adjust the actuator spring tension (or tweak your bleed valve or electronic boost controller) down to 15psi for daily use. You'll find that the map's not quite optimised for 15psi, but it should still be very driveable. Alternatively, we've got a couple of fancy chip sockets and chips in stock that'll allow you to run two different maps on a single Digifant ECU. Only downside is, you'd need to buy two maps!