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Engine Modifications

The aim is to get as much torque as possible over a wide rpm range, this should help to make the driving experience better with relaxed performance.

Power target - 120bhp, 180Lbs torque.

Intended modifications:

1. Advance pump timing
2. Intercooler (corsa does not have one fitted)
3. Increased fuel/boost.
4. Improve Intake/air filter
5. Improve Exhaust (de-cat at minimum)

Pump Timing

Advanced the pump timing 2 degrees, had to buy an injection pump timing kit (DTI gauge and adapters).
Marked the crankshaft pulley 2 degrees before and after TDC:

The std settings are 0.5 - 0.6mm lift at TDC, checked it and it was set at 0.57 lift, moved it to 2 degrees before TDC and set the lift at 0.55, moving it to TDC the lift was now 0.65 so advancing the timing by 2 degrees increases the TDC lift by 0.1mm.

Intercooler

Time and funds are running low so I've decided to leave the intercooler until the car is up and running, don't want to do an econo rush job so better to wait until I have the time and money to do a good job.
The plan is to mount an intercooler in front of the rad with the inlet/outlet coming over the top of the rad (cutting the front panal a bit for clearance) so that they line up with the turbo, may need a custom intercooler which will cost a few ££££

UPDATE 26/09/08:

A member on the MIG forum has told of a brilliant solution they have done to help with induction temperature, when changing the air filter so that it connects directly to the turbo (bypassing the inlet manifold) the top half of the inlet manifold is made redundant, what he has done is made this into a charge cooler by filling with coolant, fitting a heater matrix in front of the rad and adding in a small electric water pump for circulation, so simple, clever and ingenious.
Chargecooling is more efficient than air to air intercooling and as small diameter hoses (heater hoses) can be used to connect the radiator to the inlet manifold it should be easier to fit/route.
Definately worth looking into in more detail :-)

Increased Fuel/Boost

Removed the white ring and hammered the dimple flat:

Removed the anti-tamper cover from the max fuel screw and turned the adjuster 1/4 turn clockwise, this is an initial setting until road setup.

Added the pipes for the boost controller:

UPDATE 26/09/08:

Have been reading about injection pump 'droop' which is I believe the reduction in fuel as the injection pump moves towards maximum rpm, to counter act this the max rpm can be increased (but of course care must be taken to not over rev the engine).
I have adjusted the max rpm screw (3 turns out) and this has definately helped to reduce the tail off of power over 3000rpm, I just need to remember to turn the max rpm screw back to the original position for the MOT.!!!

Improve Intake/Air Filter

I originally used a universal cone filter but this turned out to be to noisy, diesel induction noise is not as nice as a petrol engine as it just seems to drone all of the time.
So I modified the original airbox so that it could be mounted closer to the turbo, as the inlet pipework is so narrow I added a 3 1/2 diameter cold air pipe and a K&N panal filter, this has drastically reduced the intake noise with little if any reduction in performance.

UPDATE 26/09/08:

Now that I have been using the corsa for a while I think the turbo spools up slightly slower with the airbox compared to the cone filter, when I finally get around to sorting the intercooler I will make some further tweaks to the airbox to improve flow.

UPDATE 01/12/08:

Intercooler fitted, see the Updates page.

Improve Exhaust

Before sorting the exhaust and rather than running the totally standard system I have cut open the cat/particle filter and removed the contents, this will hopefully help to free up the exhaust flow until I get chance to fit a different system.

UPDATE 26/09/08:

Reading on one of the Vauxhall forums I came across a post by someone that for a laugh had removed the exhaust system from a tweaked 1.7TD, he said it boosted much higher/quicker which proves how restrictive the standard exhaust system is, this in now high on my todo list as it should be relatively easy to change with a worth while improvement, I am watching out for a suitable second hand system but if nothing pops up I will think about buying in universal exhaust parts (from Jetex) and making up my own.

UPDATE 01/12/08:

So far all of the exhaust systems have been to expensive so I have chopped the original one up a bit, see the Updates page.