Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Pre-heating the Prius Transaxle and Engine for better fuel economy

bwilson4web · 03-21-2011, 03:46 AM

This past winter, I've observed a few warm-up tricks unique to our NHW11s:

30-40 seconds catalytic converter warm-up - during this brief time, gentle acceleration will clamp the fuel consumption at 0.60-0.70 gallons per hour regardless of speed. The NHW11 functions like an EV drawing as much power as a soft-foot can noodle out and often achieve ending speeds of 35+ mph (+56 km/hr) and an indicated MPG of 35-40 MPG (5.9 - 6.7 l/100 km). I suspect this is so the HC converter valve can remain closed at the expense of traction battery charge. Ignition is severely retarded.
"N" during warm-up, 0.30 gallons/hr - every time it coasts in "N", fuel consumption will run at this low rate regardless of vehicle speed.
"D" acceleration during warm-up, +1.50-2.50 gallons/hr - this needs to be minimized until the coolant reaches +60 C.

What I verified this past winter is this 'gentle warm-up' above 40 F (4 C) can keep my 10 mile (16 km) trip mileage in the 50 MPG range (4.7 l/100 km.) Anything less gentle and I'm looking at 40-45 MPG. But below 40 F, the block heater for 30-60 minutes became necessary for a 50 MPG result. I live in North Alabama which means afternoon temperatures below freezing is rare and I don't have a work, plug-in . . . but I know how to 'gentle warm-up.'

Personally, I want a Prius dock, a smart parking curb. But it has to anticipate my trip, a hard problem. It would be a lot easier if the car had a legitimate reason for being on ... say AC and waste heat for the house. Well we have a natural gas line to the house . . .

Bob Wilson

03-21-2011, 03:46 AM	#67 (permalink)
bwilson4web Engineering first Join Date: Mar 2009 Location: Huntsville, AL Posts: 843 17 i3-REx - '14 BMW i3-REx Last 3: 45.67 mpg (US) Blue Bob's - '19 Tesla Std Rng Plus Thanks: 94 Thanked 248 Times in 157 Posts	This past winter, I've observed a few warm-up tricks unique to our NHW11s: 30-40 seconds catalytic converter warm-up - during this brief time, gentle acceleration will clamp the fuel consumption at 0.60-0.70 gallons per hour regardless of speed. The NHW11 functions like an EV drawing as much power as a soft-foot can noodle out and often achieve ending speeds of 35+ mph (+56 km/hr) and an indicated MPG of 35-40 MPG (5.9 - 6.7 l/100 km). I suspect this is so the HC converter valve can remain closed at the expense of traction battery charge. Ignition is severely retarded. "N" during warm-up, 0.30 gallons/hr - every time it coasts in "N", fuel consumption will run at this low rate regardless of vehicle speed. "D" acceleration during warm-up, +1.50-2.50 gallons/hr - this needs to be minimized until the coolant reaches +60 C. What I verified this past winter is this 'gentle warm-up' above 40 F (4 C) can keep my 10 mile (16 km) trip mileage in the 50 MPG range (4.7 l/100 km.) Anything less gentle and I'm looking at 40-45 MPG. But below 40 F, the block heater for 30-60 minutes became necessary for a 50 MPG result. I live in North Alabama which means afternoon temperatures below freezing is rare and I don't have a work, plug-in . . . but I know how to 'gentle warm-up.' Personally, I want a Prius dock, a smart parking curb. But it has to anticipate my trip, a hard problem. It would be a lot easier if the car had a legitimate reason for being on ... say AC and waste heat for the house. Well we have a natural gas line to the house . . . Bob Wilson __________________ 2019 Tesla Model 3 Std. Range Plus - 215 mi EV 2017 BMW i3-REx - 106 mi EV, 88 mi mid-grade Retired engineer, Huntsville, AL