Quote:
Originally Posted by N2oExpresS2k
Great info Ian, thanks for the bsfc numbers. Is it possible for the bsfc test to be performed with lean burn accounted for, or is that something that is typically done at wot?
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Yes it is possible to account for Lean Burn in a BSFC chart ... yes the BSFC is typically done at WOT ... which is how the BSFC chart ( attached bellow ) for the Gen-1 was done ... sense the OEM Gen-1 Insight will not enter Lean Burn anywhere near WOT , lean burn operation is not shown in that BSFC ... It is my wish list of things to do eventually ... unfortunately there are some complications.
- Requires a chunk of dyno time which is expensive... and a chunk of time.
- Average dynos do not have the means to do it... you have to:
- Find a better dyno with the means ... or
- Brings the additional the dyno is missing with you to an average dyno... or
- Setup your own dyno with the means.
The Average dyno gets most of their dyno time money from the 'high power' market ... not the high efficiency market... which means:
- Some are just plain not interested at all ... I've had some rude comments , some outright refusals ( "not in my shop" ) , some have even stopped communicating email or hung up the phone on me as soon as they realize it is energy efficiency testing and not some 500+ HP seeking muscle car driver.
- Even if you find one that is willing ... and you have the time and money ... you then need to figure out how much of the test equipment needed they have and how much you have to provide and operate yourself... Things you will need:
- Accurate fuel rate measurements ... how many grams or milligrams ( or liters or milliliters ) of gasoline per second or millisecond... have to quantify exactly how much fuel you are using , at what rate , and know what your error rate / accuracy is.
- Accurate fuel energy content measurement ... Gasoline as a mixture varies in energy content ... it averages ~13kwh/kg or ~9.7kwh/L but it can vary by more than 10% +/- depending on the specific mix you have on hand... that is too large or a variation for reasonably accurate energy efficiency testing ... and a more accurate energy content determination of a specific batch of gasoline would have to be determined to get the error rate way down from +/- 10%.
- Accurate Air to Fuel ratio measurements for the range larger than the Gen-1 Insight is able to run at ... Some people who have tested the Gen-1 Insight ICE with better AIR Ratio meters have seen as high as 25.8 to 1 Air to Fuel Ratios ... this is unique enough that many dynos just can't measure that lean.
- Accurate engine power output at lower power numbers than some dynos are calibrated for... we have a peak ICE of ~67 HP at the peak power point ( not the same point as peak energy efficiency ) and that is under Rich Burn conditions ... ( I've seen some reports of tests measuring it as Rich as 12.5 to 1 Air to Fuel ratios ) ... that is in the range of 1/2 the fuel rate in LB vs RB ... even with some efficiency benefits to LB we are looking at a dyno that needs to accurately measure power output well bellow 30 HP ... given the Power output graphs at WOT I've seen ( attached bellow ) we may need to go as low as ~5 HP.
The above is doable ... just needs time and $ ... what I would expect to see in general is a BSFC chart that changes with A/F ratios , V-Tech on or off , and our variable Ignition Timing, variable throttle losses ... I would expect a shift of the higher efficiency areas toward lower RPMs... and a bit of a jump at the line where the V-Tech goes into or out of LB , and into or out of RB.
The reduced friction would be an efficiency benefit but the throttle losses would reduce efficiency ... so I would expect the final OEM performance of highest point peak efficiency not to be much higher than OEM ~38% without modification to a un-throttled engine ( no small task ) ... but I would expect that higher efficiency area to grow in size and move to different Torque / RPM points as the engine kicks into and out of Lean Burn Mode ... and while in LB-Mode as our variable ignition timing changes and as the A/F ratio changes... Lean air to fuel ratios burn slower and our variable ignition timing advances some to compensate for this.
Oh ... one more thing ... if the IMA is attached during the test ... ideally it wouldn't be ... you have to compensate for any power / energy it adds from the battery ... something like MIMA could be used to remove almost all the IMA power/energy flow ... But a voltage and current sensor on the IMA motor outputs could be used to confirm it is close enough to Zero , or to quantify the IMA contribution to allow for it to be compensated for... otherwise if you are reading the voltage and current at the battery you are ignoring buffer capacitor effects and you have to compensate for the efficiency of the IMA system.
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Quote:
Originally Posted by Willie Williford
The next step will be "Direct Injection"........some of the new cars have it now.
(My opinion)
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Perhaps.
Although I see more room for improvement to be had in the waste energy recovery area ... even direct injection even at it's peak efficiency still throws away about half of it's fuel energy .... the most efficient ICE I've seen is only ~54.4% efficient ... and is still throwing away almost half the chemical energy in the fuel ... from ~38% to ~54% is only ~16% improvement ... vs our ~62% waste energy to ~46% waste energy ( at the ~54% point ) ... It just looks to me like there are just larger gains ( more energy ) to be had in the waste recovery area... although I'd be happy to take both
Gas Vapor system
