Data with & without Block Heater anyone?

80-100F seems about right if you're waiting any length of time (like driving down your driveway) to take a reading. If your car's been sitting overnight in those ambient temps, the thermos contents will be cooler than what's in the rest of the system. The thermos dump normally occurs almost immediately after starting, transiently dropping the system coolant temp. Take a look immediately after startup. I've seen it anywhere from about 110F to 140F then.

(Actually, it's puzzling to me why there's so much variation. It doesn't seem to depend on OAT. I've been thinking of posting this in a new thread, but maybe the EBH experts can help both of us. Hobbit? FireEngineer? Others?)

But I digress. I haven't paid as much attention to how low it drops as to the initial temp, but I know I've seen it below 100.

As for tips, consider blocking your grill to conserve the heat the EBH provides. Between the two, you will have earlier and more frequent opportunities for ICE-off glides if traffic and route conditions allow.

What are your typical conditions, BTW? Speed? Terrain? Number of lanes? Traffic volume? Expected slowdowns or stops (e.g, predictable traffic, red lights, stop signs)? Give us a little description and maybe one of us can offer tips specific to your commute.

 

Definately block the grill!! Its one of the cheapest mods available, and its certainly effective! Not as much as the EBH, but complements it nicely, and only takes a few minutes. I think your temps are in the "normal" range and your EBH is working properly. I see slightly higher temps, but my grill is blocked.

the mileage on my first 5 min. bar has increased from 20-25 mpg up to the 40-45 mpg range. A drastic increase in my book. I've used 3 tanks since FireEngineer did my install, and am averaging 52.8 as of this afternoon. Thats up from about 45 mpg before the EBH and grill block.

I'm currently experimenting with my commute, trying alternate routes to and from in order to assess the route for best mileage. Even one or two are longer, but here in the mountains, I'm looking for the flatest route, fewer hills.

 

Zen, it looks like you've tried, or at least are aware, of most techniques that might help. I have some specific comments below.

I think my answer is take another route with fewer lights even if a bit longer...and block the grill.

You're on target with both. When traffic and road conditions do allow ICE-off glides or EV mode (see below), your warm ICE will be more willing to comply.

I'm still experimenting with alternative routes and occasionally finding ways to fine tune the drive. Some may be longer, so I'll try one a few times and compare the average MPG to the old route to make sure that overall fuel consumption drops. I enjoy the challenge of pushing the numbers higher, but I keep the big picture in view.

My commute is your typical suburban nightmare:
-7 or 8 miles
-50 mph roads (jammed with cell-phone jabbing SUV drivers who get upset if you don't "jackrabbit" start)
-13 traffic lights in one 3 mi section (who planned this???)
-none are synchronized (no way to predict...other than if you see a green one in the distance, hit the brakes because you'll never make it...) only once in the 4 years have I made it from end to end without a red light!
-one hill out of the neighborhood, but more or less flat

That's tough. Hobbit's work suggests that mid-speed ranges are the least efficient. So it looks like you're forced to accelerate, cruise for a period of time at this inefficient speed, then lose all that wonderful kinetic energy when you get hit with a sudden red light. Is that about it?

You didn't say how you're monitoring your coolant temp. Can I assume it's a ScanGauge? If so, watch your RPM and keep it below 2300 or so as you accelerate. You'll still find you can accelerate at a pretty good pace (unless you're working up a hill), fast enough to keep most would-be tailgaters at bay.

If you can't find an alternate route, work on learning the timing of the lights. Though they may not be synchronized, you may find individual lights to be predictable. Anticipate their change and begin your slowdown, as traffic allows, when you see a stale green.

P&G doesn't work well since lights are too close to get much glide, and generally >41mph...but I try stealth glide/glide that when I'm not tailgated.

So you obviously know about P&G, and it looks like you've explored its capabilities and limitations. One thing I've been doing in these conditions is "pedal-feathering" EV mode (no EV button) to extend a glide or maintain speed for short distances -- both below 41 MPH of course -- or as the sole source of propulsion for closely spaced red lights. For example, if I see a stop light in the distance that I expect to be red for me, but it's too far away to begin slowing without inciting road rage, I apply enough pedal to induce EV mode. On level terrain the car will actually accelerate, and maintain speed on an ever-so-slight uphill. I'm careful not to deplete the battery too much, and I do this only if I know subsequent driving will likely recharge it.

On the consumption screen I seem to get something like:
25 40 50+ without the EBH
35 45 55+ with it

That's pretty respectable.

I only have 1000 mi on it (the prius)...so both it & I need to be broken in a bit more.

Agreed. Keep practicing and have patience. It's taken my car's driver over a year to get really broken in!

Finally, if you haven't already done so, check out CleanMPG. The focus there is on maximal fuel economy regardless of vehicle. Lots of helpful folk there too.

 

<div class='quotetop'>QUOTE(zendriver @ Apr 5 2007, 10:43 PM) [snapback]418578[/snapback]</div>

It must be your zen, vibes, or whatever: Today I speculated basically the same thing and tried a different tactic on the first part of my morning commute.

From the driveway I turn onto a two-lane road, mostly hilly, 45 MPH limit, for about a mile and a half. It's in a mostly rural area, but with moderate traffic as folks from outlying subdivisions use it as a commuter route. Even with the EBH, the ICE is usually not warm enough to cut off, so I've been using a hill-country, cold-ICE variant of P&G: maintain speed or accelerate up the hills (whichever happens with RPM kept within its target range) and ICE-on glides down, keeping top speed below 41 as traffic allows (not always possible). On the glides I've often dropped it into neutral, which assures that the ICE stays at the lowest RPM and burns as little fuel as possible. At the end of the mile and a half is a stop sign, and by then the ICE is usually warm enough for an ICE-off glide up to the intersection. From there I turn onto another road that's ideal for P&G: less traffic, more level.

Today's change: Again keeping the RPM in its target range, I accelerated to as high a speed as possible, while staying safe and avoiding tickets (the locals like moving radar). I maintained it with a lower RPM, but still within the target range. I used ICE-on glides again to moderate speed as needed. Of course I got to the next road segment and its P&G opportunities more quickly. The net effect: My first five-minute MPG was close to 50, as high as I've ever seen it first thing in the morning. It served the added benefit of not worrying about holding up traffic behind me.

After reading your original post, I've also been watching my coolant temps after the intitial reading to see how low they go after the thermos dump. Yesterday it started at 128 and dropped to 100, OAT about 40. Today it started at 104 (actually the lowest I've seen it with the EBH, which makes the 50 MPG five-minute reading even more impressive) and dropped to 83, OAT about 30. This seems to validate your findings.

 

<div class='quotetop'>QUOTE(zendriver @ Apr 4 2007, 08:47 PM) [snapback]417934[/snapback]</div>

Do you live in Elk Grove? You described my town 100%. I hate it.

 

<div class='quotetop'>QUOTE(zendriver @ Apr 6 2007, 11:05 PM) [snapback]419168[/snapback]</div>

"Pulse and Putt" .... hhmm, you may be on to something!

You're right on target about reaching the P&G road sooner as a contributor to the 50 MPG segment. I should have mentioned that in the previous post. And yes, I get to stage 4 before the first five minutes is up, as long as the grill is blocked.

Whether this improved the trip MPG is hard to say. Intuitively you'd think it would. But between the weather swings we've had recently (morning lows anywhere from 30 to 60) and widely variable traffic conditions in later segments, it's hard to compare.

I agree about avoiding the cabin heater. I've found that it really pulls the ICE temp down during ICE-off glides or at idle. So during our coldest stretch this winter I just bundled up and skipped the heater until the ICE was fully warm. Then I only ran it during steady ICE-on operation or in bursts during pulses (the steering wheel button makes that quite convenient) ... or when my fiancee was in the car!

Some miscellaneous comments about your recipe:

I'm reluctant to modify the oil viscosity as long as the car's under warranty. It's probably not a problem, but I'd prefer not to risk it, nor to have to change it sooner than prescribed only because of the weather.

With speeds <41 during warmup, consider neutral for an ICE-on glide. Bob Wilson (in his NHW11 Prius) and Hobbit (in his NHW20) both have reported good results with this.

For cruising, the low end of RPM efficiency is probably lower than 1700 and somewhat speed-dependent, according to Hobbit. He suggests it may be as low as 1200 at lower speeds. See this somewhat technical but very informative paper for more.

Seems we've strayed way beyond the topic of the original post, haven't we? But it's your post, so I'll keep running with it.

 

zendriver,

I think you've got it!! Now just do it and practice, practice, practice.

And for the winter a switch to 0W20 oil does get you about a 2MPG gain at 30 degree temps.

Wayne