Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Turbo Diesel mod, open turbo fully for better coasting.

Tesla · 03-17-2012, 09:10 AM

My vehicle has a VNT (Variable Vane Turbo), it adjusts opening to match engine air requirements. A while ago I was doing some investigations on engine braking on steep downhill runs, my ECU opens the turbo fully at 3,000rpm, I noticed I had good braking till 3,000 rpm, then turbo would open up and it starts to run away. As the Turbo is the biggest restriction in the exhaust, I thought this may be useful for getting better economy, so I put together a temp set up where I could to either open or close Turbo fully depending on need, worked well, but as I was doing lots of other trials didn't do this consistantly. I am in the process of setting up a more permanent design with a microswitch on the throttle and some air solenoids to control the turbo actuator, this way I will be able to have either engine braking or free coast when throttle is off, most of the time the switch will be in the free coast position.
Those with a waste gate turbo may be able to open wastegate fully to coast or close it for engine braking.

03-17-2012, 09:10 AM	#1 (permalink)
Tesla Master EcoModder Join Date: Feb 2012 Location: Australia Posts: 355 The Truck - '02 Nissan GU Patrol ST Thanks: 5 Thanked 76 Times in 50 Posts	Turbo Diesel mod, open turbo fully for better coasting. My vehicle has a VNT (Variable Vane Turbo), it adjusts opening to match engine air requirements. A while ago I was doing some investigations on engine braking on steep downhill runs, my ECU opens the turbo fully at 3,000rpm, I noticed I had good braking till 3,000 rpm, then turbo would open up and it starts to run away. As the Turbo is the biggest restriction in the exhaust, I thought this may be useful for getting better economy, so I put together a temp set up where I could to either open or close Turbo fully depending on need, worked well, but as I was doing lots of other trials didn't do this consistantly. I am in the process of setting up a more permanent design with a microswitch on the throttle and some air solenoids to control the turbo actuator, this way I will be able to have either engine braking or free coast when throttle is off, most of the time the switch will be in the free coast position. Those with a waste gate turbo may be able to open wastegate fully to coast or close it for engine braking.