Accelerating from a red light

Markabele – Precisely. The acceleration rate is brisk because using this iMPG = ½ iMPH acceleration technique keeps the ICE nominally operating an RPM that is at or around the peak of the power curve, without requiring add-on, after-market instrumentation (tachometer, ScanGauge, etc) to assist in this fuel-sipping endeavor. This technique is for the Prius “Purest” driver who wants to operate a “Stock” Prius to achieve Max MPG using only its Factory-OEM instrumentation, not for the “Mod Kings” who choose to install add-on after-market instrumentation.

It is intended to keep you at the optimal operating point as you accelerate up to your desired travel-cruise speed and then lightly release the throttle pedal to cut-off fuel to go into the coasting-gliding-cruising mode. The iMPG = ½ iMPH technique facilitates achieving fuel economy gains because it burns fuel at a most efficient rate for the amount of propulsion power generated during the acceleration period-phase. It works to foreshorten the amount of time the gasoline engine is fired up and consuming fuel while giving you brisk acceleration up to your target speed during this Gas-Powered Period.

The Fuel Economy point here is: If you must go from Zero Speed (Dead Stop, 0.0 MPH) to your Target Speed (i.e. the 40 MPH you propose), it is best to do so with the gasoline engine operating in its most efficient mode for the shortest time.

Remember this Max MPG Fuel Economy Game is an incremental one. A short, brisk and fuel efficient acceleration followed by a long period of “INFINITE MPG” (XX.X Miles ÷ 0.00 Gallons => 99.9++ MPG) will deliver “$tellar MPG.”

Anytime the internal combustion gasoline engine is not running and you are moving down the road, you are getting "Infinite" Instantaneous Miles Per Gallon Fuel Economy. This "Infinite" Miles Per Gallon is displayed as 99.9 MPG on the Multi-Function Display (MFD) or Multi-Information Display (MID), as applicable. Conversely, if the ICE is running the Instantaneous Miles Per Gallon Fuel Economy will start converging on the 30-35 MPG fuel economy inherent to the ICE itself. Therein lays the MPG-FE Challenge.

A side benefit the iMPG = ½ iMPH Acceleration Technique is that you will beat most everyone off the line at a stop light (i.e. Corvettes, Bimmers, Subie WRXs, Duallies, F- 250/350, Ram 2500/3500 GMC 2500/3500 & Etc).

NOTE TO PRIUS v DRIVER-OWNERS READING THIS: For the new, 2012 Prius v Station Wagon, this iMPG = ½ iMPH operating point is conveniently reached and observed by keeping the top GREEN LINE on the HSI illuminated. This is the top "GREEN LINE" just before the "RED LINE" in the HSI Power Zone.

"Purest" OEM Prius "vee," "cee," 2G & 3G owner-operators like me apply the Foot Throttle Pedal Depression and "Feathering" iMPG = ½ iMPH - Transitioning To - iMPG ≤ 1.2 x iMPH Acceleration-To-Cruise Speed Technique Rule-Of-Thumb or skillfully manage Hybrid System Indicator Energy-Power Bar to aid them in keeping their ICE running in the Fuel-Economy "Sweet Spot" RPM zone of the engines's operating "Power" band during acceleration, and to fuel-efficiently converge on a steady-state travel cruise speed.

This permits driving fuel efficiently without having to use an added-on, non-OEM tachometer or other special external instrumentation like ScanGauge™ or CAN-View™.

Regular use and mastery of the foot throttle pedal depression and "feathering" control technique by "Purest" OEM Prius Hybrid drivers will pay them fuel economy dividends.

BOTTOM-LINE: Prius Hybrid drivers who accelerate from a dead-stop keeping at iMPG = ½ iMPH followed by efficiently transitioning to their selected steady-state travel cruise speed using these "Hybrid Smart" techniques will consume and waste less fuel on an overall Per-Tank-Full fuel economy basis.

If the techniques used by Wayne, Bob, and a few others work best for you to produce Max MPG, use them, and ignore the humble e-babbling pontifications of Master & Commander Hybrid Guru, me.

 

A slow acceleration increases the time it takes to get to target speed for your glide. It actually uses MORE fuel because the ICE is running longer. On the other hand, accelerating too quickly runs the risk of 'dumping fuel out the tailpipe'. The recommendation of targeting iMPG = MPH/2 is the best compromise available for OEM instrumented vehicle. If you have a Scangauge or other method to view RPM, the target range (for GEN II anyway) is 1400-2200 RPM during acceleration...also try to keep this RPM during highway speeds. See the excellent write-up by Hobbit regarding the Prius Sweetspot. Also check out his follow-up update.

 

Actually you want the peak of the efficiency curve, not the peak of the power curve. A compromise between getting to speed quickly enough to make the glide much longer than the pulse, without gulping too much fuel to get there.

And Wayne recommends a "brisk" acceleration for P&G. Not WOT but not egg-under-the-pedal either. LOD readings can help. Did this for years in my Subaru.

As for ScanGauge, I don't see any particular virtue in not using one. My goal is to save gas. If it provides info that helps me then I'll use one. I have one in the Prius because seeing rpm and gph and digital iMPG helps me. I don't have one in the Insight-I because I don't need it. And I'm not going to daisy-chain several ScanGauges on my dash because there's a limit to how much data I can absorb.

 

try search..it works.....

 

I would like to add to markabele reply.

Also which ScanGauge do you recommend?
I see 3 different ones ScanGauge II, ScanGauge-e and ScanGauge-d

 

AutoZone has them. You can give them a call. Not sure about the warranty. I would assume it wouldn't.

 

not too many posts because i use the search button....
try search........ is common statement from moderators not just on this forum

thread is about
"Accelerating from a red light"

so i hope we're back on track now

 

I just use the ScanGaugeII. I think they cost about $170 but you can get them cheaper via a group buy on cleanmpg.com

Installation costs nothing. You just plug it into the OBD2 diagnostic port at the bottom of the dash. I used velcro tape (included) to stick mine on top of the steering column just behind the steering wheel, and stuff the excess cable carefully into the area beside the steering wheel. Some people put them on the dash.

They shouldn't void the warranty because they only read data from the OBD system (except for clearing codes if your car throws a code and you manually use the ScanGauge to clear it). The two dealers I've had my Prius to for routine maintenance have said nothing about it. But if you're worried it's easy to just remove it.

It will display four functions at one time. The ones I use are RPM (mainly to see if the ICE is on), MPG (digital, easier to read than the vertical bar graph on the HSD), GPH (fuel flow: in warp stealth the ICE will be spinning but there will be no fuel flowing to it), and coolant temp. But if you are messing with acceleration rates you might want to see LOD (load). Incidentally, to get accurate MPG you will need to calibrate it by entering the amount of fuel pumped when you fill up.

Warning: My GF "borrowed" mine to use in her car so I ended up having to buy another.

 

Don't pay that price. Support this website by buying it from Danny in the PriusChat Shop, $159.95. Or get is a bit cheaper at cleanmpg (barely hidden as a membership fundraiser on the front page). Or wait for an Amazon.com daily special.

I did pay full price for my first one, when gas prices were higher and I was traveling in a much thirstier car without an mpg display. But by arriving the day before a long road trip, the fuel savings from that trip alone easily paid the difference. And it is still valuable enough to leave in that car, so my Prius got a new one.

 

Looks like Amazon has it the cheapest that I can find @ 159.99, it ships from and sold by Amazon.com, so no tax & free shipping (159.99 out the door).

 

On the topic of "brisk" acceleration from a full stop, is there any reason to think that this is hard on the engine over time? I have generally driven my 2001 Camry in a rather 'casual' manner (i.e. not Grandma slow, but not drag racing either) and my mechanic has said that the car is in remarkable condition under the hood and underneath the car.
What I am getting at is that I obviously would want the best engine efficiency I can, but I would not want to be abusive to the car either. Not saying that 'brisk acceleration' is abusive, but more asking the question if it is or not.
thanks

 

i've tried some of the methods....using scanguage... iMPG = MPH/2......and they are quick but certainly not burning rubber
the term "brisk" is subjective open to interpretation
but considering the prius engine is on only half the time..maybe there no problem
but thats an opinion i have

 

The Prius engine is also a much lower powered more rpm limited version of the Corolla engine. The engine below the Atkinson cycle head is nearly identical to Corolla engine, most of it's parts are Corolla parts. Corolla engines last just about forever whether they are flogged or not so the Prius engine doesn't make enough power or turn fast enough to hurt itself. That is a good thing for longevity.

 

WG is saying about 17mph because the Prius is using an Atkinson cycle engine which has weak low end torque compared to a conventional Otto cycle engine. WG advice uses the electric motor first for low power/torque to get the Prius pass the initial rolling resistance and avoids pushing the Atkinson cycle engine harder when low rpm/hi torque is needed to initally accelerate the car . The Prius' electric motors have good low end torque and when the SOC>55% there should be enough power to accelerate the Prius up to 17 mph on a flat road or going downhill. However, when going uphill the electric motors power levels (especially with lower battery levels) fall short early so its best to use Normal or Power mode before going uphill from a dead stop at a red light and start adding ICE power earlier at about at about 10-12 mph. At speeds over 10 mph, the ICE is more energy efficient than the electric motors. However, the ICE is harder to control/ modulate for energy efficiency than the electric motors. But more importantly Hypermiler like WG know its more energy efficient to conserve the vehicle's momentum/potential energy (anything in motion stays in motion unless acted upon by another force). ..and not to use the ICE or the electric motor

 

You must not have looked right here at the PriusChat Shop, where it is 4 cents cheaper, also with free shipping, and supports this site. And the other site I mentioned is twentyfive dollars cheaper, supporting another worthwhile (but competing) site.

And beware the Amazon.com is not sales tax free everywhere. Orders to five states (including mine, where the company is headquartered) already pay, orders from some Amazon partners pay in many more or even all states, and more states will shortly be charging tax: The Era Of No Amazon Sales Taxes Is Nearly Over. Small fish such as Danny likely won't get hit by these demands anytime soon.

 

This is a very interesting thread. My question Is around the distraction and difficulty of monitoring and adjusting to the iMPG guage. Can I achieve similar results monitoring my HSI in the HUD?
Ex.: accelerating high in ECO/ICE range without going into red?

 

Does PriusChat Shop charge tax? If not then it is pretty much the same price. If they do, then it is more expensive. The person inquiring and who I was responding to is in Nebraska and I am in Arizona. No tax in those states and not anytime soon will they be charging tax. Amazon charging tax in your state is irrelevant since I'm talking to you.

The other site you mentioned is a group buy. I don't know how easy it would be to get the amount of people to get a cheaper group buy so I went by if you bought it on your own.

With that being said, yes support the site. I'm not advertising Amazon. I just did a quick search of list of places selling it and forgot about the PriusChat shop. Our comments time were pretty close and I must of not noticed it till after.

I see you wrote "Or wait for an Amazon.com daily special." Why even mention that if you want to support the two sites you listed?