FE hit cuz of cold weather starting.
#1
FE hit cuz of cold weather starting.
I'm still not exactly clear on why my FE suffers in cold weather. I think it has to do with two reasons
Anyone have similar experiences?
- Colder / Denser air requires more fuel per same volume of air, hence the use of cold air intakes to up engine power.<
- Lowered volume of air in my tires due to colder air.<
Anyone have similar experiences?
#4
Re: FE hit cuz of cold weather starting.
Gil,
Your Engine and catalytic have to warm up before the system can optimize MPG. This happens in the frst few minutes of your trip. This causes low MPG at first which is then averaged out on longer trips. If your commute is short, you'll see a large hit to your MPG.
Another factor on very cold days is your use of heat to keep you warm. This cools the Internal combustion Engine (ICE) and limits the systems ability to run electric only which reduces MPG in low speed driving (there's plenty of heat generated at high speeds).
JeffD
Your Engine and catalytic have to warm up before the system can optimize MPG. This happens in the frst few minutes of your trip. This causes low MPG at first which is then averaged out on longer trips. If your commute is short, you'll see a large hit to your MPG.
Another factor on very cold days is your use of heat to keep you warm. This cools the Internal combustion Engine (ICE) and limits the systems ability to run electric only which reduces MPG in low speed driving (there's plenty of heat generated at high speeds).
JeffD
#5
Re: FE hit cuz of cold weather starting.
Digraph, don't feel too bad because cold weather affects every car/ICE out there not just hybrids. Just think of those poor SUV/Hummer folks that think they're getting 10mpg when in reality its only about 8....
#6
Re: FE hit cuz of cold weather starting.
Originally Posted by digraph
I'm still not exactly clear on why my FE suffers in cold weather. . . .
Anyone have similar experiences?
Anyone have similar experiences?
Bob Wilson
#8
Re: FE hit cuz of cold weather starting.
Hi,
The reason I ask is cold temperature performance is somewhat vehicle dependent. Folks have rediscovered that what works in one hybrid electric won't necessarily work in another. So if I suggest preheating your traction battery, you'd probably answer, "Say what?"
I forgot to ask, manual or automatic?
BTW, have you visited "CleanMPG.com"? They have a lot of gas experts and share our interest in vehicle efficiency across a broader range.
Bob Wilson
Originally Posted by digraph
Actually I have a 2.0 L gas VW. But I figured the ICE physics was the same. I'd probably be considered a hypermiler, by pure ICE standards for such a heavy/inefficient car
I forgot to ask, manual or automatic?
BTW, have you visited "CleanMPG.com"? They have a lot of gas experts and share our interest in vehicle efficiency across a broader range.
Bob Wilson
#9
Re: FE hit cuz of cold weather starting.
Cold weather has benefits for gas engines. First of all, your engine will provide more power when colder since the cold air flowing into it will be more dense which will result in more fuel being packed in with this dense air to keep the air-fuel mixture properly balanced. This will result in more horse power output.
This effect is like a very mild form of turbo charging as more air can be packed into the engine cylinder when it is cold and dense. Air reduced by 30 degrees is equivalent to 1 PSI of turbo boost. With cold weather you get this effect for free.
Intake Air Temperature
Toyota and most automakers take advantage of this effect by placing the engine air intake at the very front edge of the engine compartment under the hood to avoid pulling in hot under-hood air into the engine. The table below describes the relative power loss expected by a gas engine as outside temperatures increase:
The second advantage of cold weather is that the engine can run on lower octane fuel before experiencing engine knock. Thus, when the temperatures are in the 30's for instance, you can notch down to a lower grade of gas without reducing gas mileage and performance. I typically use premium gas in spring through fall and mid-grade in winter (Chicago area)
This effect is like a very mild form of turbo charging as more air can be packed into the engine cylinder when it is cold and dense. Air reduced by 30 degrees is equivalent to 1 PSI of turbo boost. With cold weather you get this effect for free.
Intake Air Temperature
Engine Power Loss
Example Power Output
20C
%0
224 hp
40oC
3.50%
216 hp
60oC
7%
208 hp
80oC
10%
202 hp
100oC
13%
195 hp
Example Power Output
20C
%0
224 hp
40oC
3.50%
216 hp
60oC
7%
208 hp
80oC
10%
202 hp
100oC
13%
195 hp
Toyota and most automakers take advantage of this effect by placing the engine air intake at the very front edge of the engine compartment under the hood to avoid pulling in hot under-hood air into the engine. The table below describes the relative power loss expected by a gas engine as outside temperatures increase:
The second advantage of cold weather is that the engine can run on lower octane fuel before experiencing engine knock. Thus, when the temperatures are in the 30's for instance, you can notch down to a lower grade of gas without reducing gas mileage and performance. I typically use premium gas in spring through fall and mid-grade in winter (Chicago area)
#10
Re: FE hit cuz of cold weather starting.
This forum word processor doesn't seem to handle tables well. See legible table below from my last post:
... Air Temp......Engine Power Loss......Engine Power Output
........20 F............................ 0%............................ 224 HP
........40 F......................... 3.5 %........................... 216 HP
........60 F.............................7%.................. .......... 208 HP
........80 F.......................... 10%.............................202 HP
......100 F.......................... 13 %........................... 195 HP
... Air Temp......Engine Power Loss......Engine Power Output
........20 F............................ 0%............................ 224 HP
........40 F......................... 3.5 %........................... 216 HP
........60 F.............................7%.................. .......... 208 HP
........80 F.......................... 10%.............................202 HP
......100 F.......................... 13 %........................... 195 HP