Quote:
Originally Posted by BillGrissom
Wow. How are you measuring 39 mpg? The current EPA figures for my 1985 300D is 19 mpg hwy, though I get ~22 mpg. I hope you aren't naively going by the markings on the fuel gage for consumption and the odometer for distance. Use the calibrated pump at fuel stations by measuring from fill-up to fill-up. For distance, use highway mileage posts or a GPS.
The turbocharger recovers exhaust energy, so disabling should make the engine less efficient. Diesels run WOT all the time, so a turbocharger is an ideal match. Some people who have added a turbo to 60's gasoline engines claim it improves mileage slightly. That is hard to believe since boosting the inlet pressure only to drop it across the throttle plate is a waste. Might be a very minor improvement from adding a little energy (heat) to the inlet air.
|
The turbocharger is not a magical free energy device. It creates a huge exhaust restriction in order to spin up the turbine. If the engine can breathe enough air without boost for a low load situation (aka cruising on the highway) theres no reason to maintain that exhaust restriction. Keep the waste gate wide open until you put your foot down. Lets say >30% throttle angle for example.
I'm thinking about reusing an old Megasquirt 1 controller to do a few things on my diesel. Not fuel injection obviously but if I can get RPM, throttle angle and manifold pressure signals to the MS box, it can easily control the waste gate any way I want to, PWM water meth injection proportional to engine load and RPM, turn on/off the electric cooling fans at any temp I want... etc. It can also take inputs from an EGT sensor, wide band O2 sensor (Bosch LSU 4.9 designed for diesel), coolant and intake temp sensors etc. Its on the back burner after I get the 5 spd swap and #17 head sorter. I spent too much time messing with EFI. Not having all sorts of multi color wires and zip ties all over the engine bay just doesn't feel right.