Running a TD05 with maps for a TD04 without exploding things!
 

Car is 2002 SVT with 1.8VVT engine.
It has high spec suspension and brakes and is my road car as well as being double driven (and hard) on track days with 15 minutes on and 5 minutes off.
The present engine is a very good but unopened 30,000 mile one. It's temporary pending my fitting a forged one in about two months.
Coolant reroute and BP4W head gasket.
Turbo will be oil and water cooled.
Decent ally radiator.
Undertray in place.
Some ducting.
Oil cooler - presently behind the radiator though.
Vented bonnet (BIG difference, including less front end lift over 100mph).
ECU is ME442 with switchable boost for a TD04, running either 9 or 13 psi for about 200 or 250 flywheel hp,
The TD04 is FUBAR and the engine is currently running really well normally aspirated.
I have a TD05 20g ready to put on. I'm told that will physically bolt on between the G19 manifold and downpipe.
I realise the 2.75" exhaust is not ideal for the bigger turbo but I'm not going to go any more than flywheel 275hp and the whole hotside is wrapped so hopefully back pressure won't be an issue.

Currently I have an unusual set of circumstances that mean it would be convenient and affordable to just put the TD05 on the unopened engine. The existing maps are for the old TD04 and limit the torque to avoid bending rods or breaking the then 5 speed gearbox (now replaced with a 6 speed).

Am I likely to get away with just swapping the turbos?

Or do I absolutely need to change the maps entirely?

Or just limit the boost? If I have to do that, is 10psi from a TD05 similar to 13psi from a TD04?

TIA

Bigger turbo flows more air at a given boost.
Pull 1-2° timing and add some fuel in the boosted cells, maybe ME can autotune those for you after richening it up for safety?

Thanks.

I’m looking for the car to be properly reliable, as I’ll be doing a track day nearly every week. Well I have no other vices!

So will I be helping reliability still further if I add a good water atomising system to reduce heat soak on the intercooler, but still tune for only 275 at the flywheel?

If I do that, is there any major benefit to using meth and/or anything other than tap water?

You will of course reduce the risk of detonation, especially when you are not using it for adding power. If it fails, you are just as safe as you are now, so there is no ill effect.

~ a 50/50 mix is what most guys use, but beware, that meth is a little lighter than water, it's like 45/55 IIRC, but it really isn't all that critical, when not tuning for maximum power.
You CAN use 100% water just for cooling, but tracking your car is so expensive, that I would mix some meth in