Greetings and some Q's from a new -04 owner

Hi all,

Bought a -04 Prius used a couple of months ago. Had to fix left rear brake which was dragging (the brake piston or whatever was rusty and got stuck), otherwise good condition.

We have had some real tough weather here, temps were at -37C (that's -35F) when I got the car in the first morning. It started without any preheating. Gotta love a "starter engine" that can push the car to 50km/h, hehe. Just earlier that week a diesel with 2h preheating didnt start up in -30ish degrees.

Of course the mileage in that kind of weather driving short city trips (maybe 8km one-way) is crappy... But the stuck brake also contributed during that week, so ...

Attached is a pic of a short drive of 32km where I messed around with high speed P&G, over half of it was around 80-90km/h approx, the end half had a truck ahead that went probably just over 80 so 75-90 or so. Started with an almost empty battery bank, ended higher, and the mileage was going down (read: up) so steady state I was probably under 4l/100km doing that. Weather near freezing at 4C. Not bad I guess.

The 3rd gen prius motor seems to be better optimized, oh well cars just cost too much in Finland (we have a semi-illegal in EU cartax added on top of everything =P) so went with the older gen. But few questions, mind you I have read tons (I tend to do that) so am looking for quite spesific info, have probably read already general info :

15kW - 30kW power range, I use 111km/h on OSD as a marker for "level ground no wind" approximation for 15kW, that about right? The prius gas pedal is straight "power modifier" type of pedal, not torque, right? So same pedal% should be 15kW at any speed, or thereabouts?

Instantaneous fuel consumption at that 15kW times two should approximate the 30kW pedal position pretty well? I'm getting about 5l/100km for the 15kW steady state speed, maybe a smidgen less. So looks like the 30kW is quite deep pedal position. Can I also use the motor sound as a "over 30kW" notifier? I can sense/hear a slight change in the tune of the motor when going over some rpm point, probably when the burn cycle changes to "more power less economy", is that near the 30kW mark anyone know?

How well can I use consumption / speed * 100km/h to approximate from instantaneous consumption the 15-30kW range for acceleration? Starting from 50km/h that'd be around 10l/100km instantaneous for 15kW? Oh and basing all this 15-30kW to the graphs with best fuel/kWh production rates. Physics is easy, conservation of energy etc., so anytime gas motor is working staying at 15-30kW = best. Rest of the time, well, ya know.

Hmm had one more question ... oh yeah. Aside the ScanGauge stuff (gotta read up on how much that costs etc.), do you think it'd be hard to make a LED light marker that lits up green when based on stuff the ScanGauge also measures the motor is at the 15-30kW range, or out of fuel injection altogether? So that it would not be lit when fuel injection is happening but motor is not running at optimum power range? I guess if the ScanGauge doesn't cost toooo much it would be a nice toy.

PS. I tend to try to travel at 111km/h now so can use cruise control. Also keeping the pedal pressed somewhat near the power required for that, so that in downhills it accelerates. In uphills since we don't have very steep hills here cruise control is okay as 30kW is easily enough for our "hills" (okay, we have no hills here, really).

PPS. And forgot the pic.

PPPS. And 1 more question: does the engine warmup higher idling speed "work less wastefully" if I try to run the battery down when ending my previous drive, so that it also loads batteries when heating up? So more load during the slow crawl to higher speed roads?

 

Hmm now that I think of it more, I think the first half was more like 80-100ish, remember some 100+ speeds. Was following a car, so had quite long pulses after dropping behind a bit then pulsing near, definitely some 100+ there. I'd guess the other car was going average 90ish km/h.

 

Answering my own question about the end-of-drive and startup (S1). Found the info that the motor tries to stay within "long" cycles so that the heat from burnt fuel stays longer inside the motor before exhausted out, and even uses the battery a lot at the beginning to remain within low rpm.

So I guess the answer to that question is no, it is not a good idea. The higher the battery at end of drive, the more the motor can keep low rpm till it heats up to S2.

I'm not quite sure what to take away from the fact that older posts (here, CleanMPG) had a <50MPH sweet spot (IGN 14 threads), whereas the newer ones mostly talk of the 15kW sweetspot. The 15kW sweetspot I can definitely understand based on the brake-spesific fuel curves. The IGN 14 threads though ... wonder if that info is still thought to be valid. That would be nice for 50MPH road limit roads, no need for high speed gliding just accelerations with 15kW then lean burn (75mpg or 3,1l/100km instantaneous, that won't keep the speed up but won't have to mess with getting into glide either) slow deceleration till need for 15kW again.

Driving 100km to home today so will test out a "6+3l/100km at 80" rhytm: 6l / 100km burns and 3l / 100km lean burn glides starting from 80km/h and erm going somewhere up of 90 with the 6l burns.