New here, ... the physics of hypermiling?

[MinnesotaNice]

Originally Posted by NeilBlanchard

The one time that I coast a long time but leave the engine on is if the engine is still cold -- you need to bring it up to about 165F in my car to get it off of the richer mixture, so idling while coasting to warm it up seems worth it.

As you probably know, warmed up, newer cars with oxygen sensors go "closed loop" where fuel injection is adjusted based on the oxygen in the exhaust. When cold, they run "open loop" and inject an amount from the table... the "fuel map" (with actually many other adjustments). Lean burn is yet another mode but that's newer technology.

I'm under the impression somehow that wear and tear is high on a cold engine, and in Minnesota here,... sometimes that's 40F and sometimes that's minus 40F. I wonder if hard pulses on an engine not at operating temp is wasteful in terms of excessive wear.

Originally Posted by NeilBlanchard

And bump starting is probably better than using the starter, so if you have a standard, you can turn it off, wait a second and then turn it on again so that you can bump start it as quickly as possible, as needed.

Agreed. It seems safer too. Always do this, unless I get stopped at a light or something.

[brucepick]

I take a slightly different view on warmup in very cold weather. My preferred would be to have a good electric preheater that warms the block via the coolant. I don't have one so I have to deal with warmup in New England winter, which I admit isn't as frigid as the Minnesota winters.

Anyway, the engine runs rich when cold, we've already discussed that. So if it HAS to run rich, I at least want to get the most possible distance out of the fuel it burns while warming up. No warmup idling for me, except maybe if it's 10 degrees or less out there and I don't feel safe "using" the engine at those low temperatures.

So while warming up, especially in winter weather, I pulse and glide as aggressively as I dare. I really avoid idling whether rolling or not. I also avoid coasting in gear; that mostly slows the car down and doesn't do anything much to warm it up. I'm not a big fan of wide open throttle, or even of 60-80% open throttle. So I'm using moderate throttle when engine is running.

I use a grill block. That really helps speed the warmup process, and also enables the engine to reach and maintain full warmup temperature even in frigid weather. In winter I'd say about 90% of my grill is blocked off. Mine is removable chunks of gray foam pipe insulation stuffed into the openings that are about 2" x 5". The foam is layered up and bound together with duct tape. I'm working on something prettier but the nice thing about this setup is that I can add and remove chunks as needed.

I pay attention to the engine temp display on my ScanGauge. When the outside temperature changes significantly I need to add or remove grill block chunks.

[MinnesotaNice]

Thanks for commenting on this.

Originally Posted by brucepick

My preferred would be to have a good electric preheater that warms the block via the coolant.

Yes, I'm thinking that would have a lot of benefits and self-installed, they are only about $50. You just wouldn't want to run them all night like we used to when I was a kid.

The grill block is very effective I think.

Originally Posted by brucepick

So while warming up, especially in winter weather, I pulse and glide as aggressively as I dare. I really avoid idling whether rolling or not. I also avoid coasting in gear; that mostly slows the car down and doesn't do anything much to warm it up. I'm not a big fan of wide open throttle, or even of 60-80% open throttle. So I'm using moderate throttle when engine is running.

So you start EOC right away? I'd think full temp would take a good while at say 35 on city streets.

[MetroMPG]

Originally Posted by MinnesotaNice

In general, what features, describe an (market available or not) car best for Pulse and Glide as I describe it? (apart from "efficient hardware") A manual transmission with kill switch? Or turning key-in-ignition Fas ?

It would be as light as possible, very aerodynamic (both low frontal area & Cd), and have very low rolling resistance. All of which translates to less fuel required to accelerate (or climb), and less aero & rolling drag in order to permit the longest possible coasting distances. The engine power would be such that you just have "acceptable" acceleration rates (open to different interpretations) at high load/low RPM (minimum BSFC).

The mileage competition vehicles embody these goals to the extreme, eg:

2,757.1 MPG at Shell Eco-Marathon Americas


As for a road-going passenger car, for minimum fuel consumption in a pulse & glide scenario, find (or make/modify) one with characteristics as close as possible to these types of competition vehicles.

it seems current hybrids are not quite right. They're better for people who don't want to change driving behavior (so much). Or think about it.

Some hybrids are great for hardcore hypermiling because they are lighter, more aerodynamic, and have lower rolling resistance than comparable non-hybrids. Pulse & glide is a pleasure to do in a hybrid vehicle which is designed so you can control whether the gas engine is on or off and whether you are effectively coasting in "neutral" all solely through accelerator pedal position.

A small, light, aerodynamic vehicle with a manual transmission and a kill switch is the best non-hybrid alternative.

[Frank Lee]

Didn't #3 get 12,xxx mpg "equivalent"?

[MetroMPG]

Frank - could be. That one's from 2009 - I just grabbed it from the blog as an example.

[MinnesotaNice]

Originally Posted by MetroMPG

A small, light, aerodynamic vehicle with a manual transmission and a kill switch is the best non-hybrid alternative.

Has anyone ever discussed a microcontroller that controlled the clutch, injection and throttle allowing for say, a "pulse/glide" button (unkill, engage clutch- throttle up to 75% until speed is +3 mph and then "glide" (throttle down to idle, disengage clutch, kill until speed is -3 mph, repeat)? Like someone just said, if it were cycled quick enough, to perhaps maintain speed +- 3-5 mph it would "pass" as "normal".

[MinnesotaNice]

Originally Posted by MetroMPG

The engine power would be such that you just have "acceptable" acceleration rates (open to different interpretations) at high load/low RPM (minimum BSFC).

I'm actually kind of shopping for a replacement car. An engine swap is rather involved (but possible for me).

Any suggestions for a small engine and car? Loooowwww accelleration. I'm wondering what possibilities this has. No idea but guessing easy (bolt compatible) options are limited, and unplanned combinations involve custom machining and complexity.

[brucepick]

Originally Posted by MinnesotaNice

Thanks for commenting on this ...

So you start EOC right away? I'd think full temp would take a good while at say 35 on city streets.

Yes, I start EOC right away. And true, reaching full warmup would take a while on city streets, especially in a Minnesota winter. My house is only .72 miles from the interstate on-ramp so I'm in a different situation from what you're suggesting.

BUT you will get it warmed up a lot sooner if you set up an effective grill block.

Regardless, I'd start EOC as long as it's not so d**n frigid out that you're afraid to do anything but let it idle. We get plenty mornings in the 20's ºF here and I get rolling within seconds of startup, and EOC as soon as I'm not going uphill.

As I wrote a few posts back, the car is going to run rich till it's warmed up. No way around that. If it IS going to run rich, I at least want to get the max possible miles out of that quantity of fuel. So I'm going to EOC and whatever else I can think of to maximize it. Letting it burn more fuel than needed does make it run better once it's warmed up, but you're not getting any distance for that fuel you've burned.