DbLog said:
It's not that the reading will be wrong. Pointless would be more accurate. Installing it in the downpipe won't let you know when engine parts start melting. Does anyone know of benefeits having the dung installed in the downpipe as apposed to in the manifold?
Ding ding ding.
You're cooking a turkey for dinner. You know that the turkey has to be cooked to X degrees for X minutes. You can put your thermostat in 3 locations.
1) IN the turkey. Right up next to where you want to take the reading.
2) In the oven.
3) Stuck to the oven wall.
Now all of the measurements are going to be accurate if you have a good thermometer. All the measurements are going to be able to get you what you need.
1) Take reading.
2) Take reading. Calculate thermal resistance of air in the oven. Calculate radiation / convection heat transfer between turkey surface and thermometer. Calculate thermal resistance of the turkey. Calculate how thick it is to the center of the turkey. Calculate center of turkey
3) All of the above + thermal resistance of the glass front of the oven.
EGT post turbo is going to tell you 1 thing accurately: Temperature post turbo. Unless you get the map lookup of how much heat is being rejected by the turbo, you won't know Pre turbo temps.
Say you have 2 identical engines with 2 identical post turbo temps: 1000F
Engine 1 is cold, the engine isn't even warmed up yet. The turbo is still cold. Meaning that it's rejecting 300F. So preturbo you're actually at 1300F.
Engine 2 is hot. It's in the hottest most part of Death Valley and has just completed a 5 hour straight drive, AC on high. Engine is already as hot as it's going to go so the turbo can only reject 50F, so preturbo you're at 1050F.
Your turbine blades are going to melt at 1200F. Where do you think you'd get more relevant information from? I mean you could always install one pre and post and then make a correlative map based on coolant temp, oil temp, ambient air temp. So you'd have a 2D lookup map, then remove the preturbo (who needs it anymore?). Glance at your post turbo gauge. 1000F. Then pull out your map you made, interpolate between the coolant temp and ambient air temperature on the grid, and ding, you have pre turbo temp.
Go to a Class 8 truck dealer sometime and look at their setups. Cat, Cummins, DDC, MBE, Volvo ALL have their sensors preturbo.
(Numbers were made up for illustrative purposes and not to be regarded as accurate)