eatcustard wrote:Stupid question
Why would anyone need to know the temperature of their exhaust pipe?
You don't on a standard engine, it is of no concern usually, more than likely make you paranoid but on a tuned engine it tells you how far you can push things without it going pop.
Thing is with a Diesel, they are throttled by fuel, the more fuel you add the higher then engine speed, they are unlike a petrol and you don't have lean and rich, well, I suppose you do but in a different way.
Diesels run "lean" at idle and only get somewhere near stoichometric at full chat.
To make a Diesel go faster you need to increase it's volumetric efficiency, basically get more power from the volume you have available to work with.
So, you increase the boost pressure (increase in boost pressure means you cram more air into the cylinder(s), which will result in more cylinder filling giving the potential for more power.....
.... but boost is no good without any fuel to burn with it, so you need to increase fuel also.
Several ways to add fuel, people seem to think that turning the fuel screw will "Make it richer", which it doesn't, it just basically moves the fuel map up a bit hence the increase in idle speed when you do so, hence why you have to then drop the idle speed back down again. And like i said earlier by turning the fuel screw all you have really achieved is an engine that will deliver more fuel at the top end of the rev range meaning that you can hold it in gear longer which will make it feel quicker.
but... more fuel means more heat created, more heat created will also increase boost pressure as the turbo works on heat not flow...
But, if you add too much fuel at the top end then the EGT will rise and if you go too far you may end up with molten pistons, not a good position to be in.
Any clown can give an engine more boost.
Any clown can give an engine more fuel, but if you have no idea how hot things are getting then you have no idea how long your engine will last or if your modifications are on the dangerous side.
Several ways to reduce EGT's, larger bore unrestricted exhaust (2.5" ideal for 1.6l to 1.9l)
Intercooling, or charge cooling.
Water injection.
Not add so much fuppin fuel!!
I read recently on here someone had nigh on 150 whp out of a AAZ but it went bang, that should give some clues.