Hi there I have a defender 90 with a discovery 200tdi engine I'm wanting to gain more speed and poke out of it I've already got a straight through exhaust and had the turbo turned up I havnt had the pump turned up as the guy I had the engine off says ( you dunt wanna do that ) I dunt know why and didn't explain so why would that be? And wot other mods can I do thanx
Your in the wrong vehicle.
I would suggest you don't want to turn it up much because it will end in tears. How much have you turned the turbo up by? There are upper limits, you will have fitted a boost gauge, so what is your manifold pressure at max boost?
200tdi is a strong engine, but start tinkering with it and you reduce reliability and increase the chances of HGF, overheating etc...
There are 3 academic adjustments on the injection pump (I have explained in great detail on here somewhere so it's on the forum somewhere) basically getting it right is a combination of all three settings, you can't just turn up one and that will be it because it doesn't work like that, there is the low manifold pressure fuelling, part boost fuelling and max boost fuelling. There is also the max fuel but this isn't as good as it sounds, turning this up will increase revs, heat and smoke. The engine shouldn't be tweaked to give higher max revs because the engine can't cope with much more.
If you turn up the low fuelling you get a bit more on acceleration from 1st gear before turbo kicks in, but this will cause smoke issues so you need to then adjust the rest of the pump to suit - part boost gives better pull in the mid range and max boost will allow max fuel sooner. But if you don't have a machine to calibrate it on then you are going to be doing it by smoke levels and how it drives, each time putting it back together and trying it again. Problem with this method is if you don't have extra gauges like exhaust gas temp or boost pressure etc, you don't actually know if these tweaks have had adverse effects on the engine.
If at any point there is black smoke, the "tuning" has not been effective and it's just getting too much fuel for the air at any given time, increasing boost even more will decrease engine life...