EGT

Which Motor?

Will also be a different value pre or post turbo... the 1hz is prone to cracking between the valves if things get too hot!! The early t/d cruiser is not as tolerant to heat as the later multivalve due to injecter position in combustion chamber.
Andrew

Hi Burnsy,

I've spent quite a bit of time chasing recommended maximum EGT figures. You'd think the turbo manufacturers would be keen to make these figures available, but not so. Most American sources I've seen recommend a maximum 'upstream' temperature of either 1300F (704C) or 1350F (732C). A reputable South African site recommends 720C and I've adopted this as a reasonable 'middle ground'.

Please note that these are 'upstream' figures and, in my opinion, this is by far the best place to measure EGT (that is, in the exhaust manifold near the turbo-charger exhaust turbine inlet). The upstream temperature is that which the turbine casing, the turbine blade tips and the wastegate 'see' and which causes cracking and erosion when it gets too high. The temperature at the exhaust turbine outlet ('downstream') will always be a LOT lower than the upstream temperature, especially at high load.

I have measured just shy of 190C temperature drop across my engine's turbo under full load conditions. That is, if the upstream temp were 720C, the downstream temp would be around 530C - and this is therefore my recommended maximum downstream temperature. It also seems to coincide with the recommendations of several aftermarket turbo installers. The problem with downstream measurement is that the temperature drop across the turbo varies from engine to engine and is always changing with engine load.

Hope this helps,
Ian

Does it really matter if the probe is pre or post turbine? After all, if you have been advised of max. permissable temps in either position, then that is what you drive by. Trick is knowing, these temps, not one position versus the other? Both are indicators of different temperatures and both require knowing the different values!