Right another update i guess is needed...
It is still loosing coolant from the expansion cap when making use of 'some' of the extra torque, so i am pretty sure that the gasket has been compromised, so a strip down will be needed in the near future.
We have got a few ideas from some threads on .org as to what is the root cause, as it shouldnot be the fuelling directly causing the problem (butit might be we dont know)
So back to the update...
The thinking is that the exhaust housing for the GT15 family is far too small for what we are asking from it, and as such, the EMP (exhuast manifold pressure) is rocketting.... with the pressure high in the exhuast manifold it is doing enough to blow\compromise the gasket with the high boost from the inlet side.
So we are going to try and either tap the EM or use the EGR blanked plate and fit a pressure sensor, and just see what is what.
If the EMP is the root cause then there are a couple of options...
Either fit a custom external wastegate, with some pipework and a bit of a flex to join up with the decat - as this would basically show that the internal wastege on the GT1549 we have is not big enough to cope with dumping all the excess exhuast gases so we would be able to bypass the turbo completely and dump the excess pressure that way.
The turbo can still be controlled with the boost readings from the MAP as normal... although i am still thinking of getting a 3bar sensor fitted rather than the 2bar currently in use...
Or i will be going down a larger VNT turbo with electronic boost control, with a adaptor plate for the Exhaust manifold and a custom downpipe.
the later option is last resort, as i dont really want to detune the car (as it stands we think SDI's and remap is the most the turbo housing can take - so peak 250lbs ft and max 150bhp (or around 200lbsft at 4000 rpm), but i also dont really want to have the cost and the hassle of buying a new turbo and trying to sell the hybrid.
If we get the results as expected then i dont think that any-one will want to pay a decent price for a 'pointless' turbo either so it is a bit of a damage limitation excercise now!
So all is not lost, but it seems like it is still a way away from completion....
Any-one know where i can get my hands on a pressure sensor that can cope with up to 1000C, as all the ones i have found stop working after 250c
