Forgive me if this has already been posted. I haven't had time to hang out here lately, but thought some would find this interesting. We had hoped that the '10 emissions would show improvement, as several of the later/larger Toyota hybrids actually had emissions performance even better than the Prius. Thats not to say that the Prius was ever bad, just that technology continues to improve. Anyway, it would appear that hope was well founded, as I found the CARB emissions testing data for the '10 online. Here is the quick summary, with the new Insight data as well: Vehicle: --------- CO ----- NOx ----- NMOG --- Rating 2010 Prius ------ 0.04 --- 0.003 ---- 0.005 -- SULEVII AT-PZEV 2007 Prius ------ 0.10 --- 0.010 ---- 0.009 -- SULEVII AT-PZEV 2010 Insight PZ - 0.30 --- 0.010 ---- 0.005 -- SULEVII AT-PZEV 2010 Insight B3 - 0.20 --- 0.010 ---- 0.021 -- EPA T2/B3 2007 Civic Hyb -- 0.40 --- 0.010 ---- 0.004 -- SULEVII AT-PZEV All units g/mi 2010 Prius improves CO output by more than 2x, NOx output by more than 3x and NMOG output by almost 2x vs. its gen 2 counterpart. Insight apparently to be sold in a low CA emissions and higher rest of US emissions versions. Prius looks pretty impressive compared to Insight, although this is not necessarily the whole picture just the basic numbers. Also interesting to note how the 2010 does on evaporative emissions w/o the bladder. Vehicle: --------- 3 Day --- 2 Day --- Run Loss - Vapor Recovery 2010 Prius ------- 0.20 ---- 0.28 ----- 0.00 ----- 0.01 2007 Prius ------- 0.16 ---- 0.14 ----- 0.01 ----- 0.00 Looks like evaporated HCs are a little higher, though still low enough to qualify for partial zero emissions status. Looks like the bladder was helping, but enough people complained and/or it cost too much so Toyota killed it. Somewhat unfortunate, as there are many out there who argue that evaporated losses are becoming the dominant air pollutant from gasoline vehicles. For example, using the numbers above if you drive the Prius every 2 days, its evaporative losses will be equivalent to driving an extra 10,304 miles/yr from an NMOG standpoint (0.28 g/test * 365 days / 2 days/test / 0.005 g/mi). In many urban areas NMOG (HCs/VOCs) seems to be the leading smog generator, so that elevates their importance. Nice to see the running loss number come down though, that was a pretty significant contributer on the previous gen. With the tailpipe NMOG number down, and running losses down, the new model should still be net lower in overall HC/NMOG output. The B3 Insight's NMOG output is kind of bad news for urban VOC limited areas that don't get the CA version, although the Insight's evaporative numbers are more like what the old Prius' were. Of course both of these vehicles are still much better than most on most of these numbers. '07 Prius Data: http://www.arb.ca.gov/msprog/onroad/cert/pcldtmdv/2007/toyota_pc_a0140560_1d5_pz_hevge.pdf '10 Prius Data: http://www.arb.ca.gov/msprog/onroad/cert/pcldtmdv/2010/toyota_pc_a0140657_1d8_pz_hevge.pdf '10 Insight Data: http://www.arb.ca.gov/msprog/onroad/cert/pcldtmdv/2010/honda_pc_a0230491_1d3_pz_hevge.pdf http://www.arb.ca.gov/msprog/onroad/cert/pcldtmdv/2010/honda_pc_a0230489_1d3_b3u2_hevge.pdf Certification report sites: CA: Subject Top Page: On-Road New Vehicle & Engine Certification Program EPA: Annual Certification Test Results & Data | Cars and Light Trucks | US EPA All in all a pretty impressive effort by Toyota in my opinion! Rob
Impressive indeed. Thanks for sharing that. I think all of us can live with that slightly higher vapor emissions if the fuel guage actually works and we can use the entire tank capacity! We should start seeing a LOT of 700 mile tanks with the usable gas and increased FE.
Thank you for the info. I would very much like to see the evaporative emissions data on the Prius version without bladder that we have here in Europe. It would be nice to see how far they have gone from the [still] current generation to the new 2010, both without bladder. No doubt the cooled EGR system is contributing to a lot of these IMPRESSIVE numbers, avoiding rich mixtures altogether.
Prius has never run rich mixtures, even w/o cooled EGR. What is interesting is the NMOG numbers on non-CA Insights compared to the CO2 numbers. Any thoughts on that? Less catalytic converters? Lean burn?
Oh I think they do, are you sure they don't? How does the Prius solve the problem of exhaust gas being too hot at high rpm and possibly damaging the catalytic converter? Typically the mixture gets richer to cool down the exhaust and prevent damaging the catalytic converter, and I don't think the Prius is any different in this regard. I even think I have read something about it here recently... or was it on Yahoo PTS... possibly from Bob Wilson? Easy to find: http://priuschat.com/forums/prius-h...her-mileage-better-interior-2.html#post819957
It has been well documented that Prius ICE's run stoichiometric through the entire range. They don't run lean due to NOx emissions, and they don't run rich for HC emissions/economy.
Yes, normally that's the case. But at high load/rpm even the Prius has to put the mixture a bit richer to protect the catalytic converter. That is one of the main advantages of the new 2010 Prius and one of the reasons you have better MPG on highway. The inert cooled exhaust reuse back into chamber helps lowering the exhaust temperature and thus protect the converter without spending more fuel in doing so. I really don't have data with me, as I don't have a scanner on my Prius, but you can find several posts everywhere about this. Here's another good one: http://priuschat.com/forums/prius-main-forum/58551-ice-efficiency-prius-vs-insight.html#post797086 Also, our dear friend Bob Wilson has a lot of data and has recently posted on PTS these lines about this advantage on the 2010: 2) cooled exhaust gas recirculation - dilutes the fuel-air mix at high power settings to avoid having to use an enriched mixture to keep exhaust gasses cool enough for the catalytic converters. I'll send him an email and ask to chime in here, I'm sure he as well documented data on this subject, if I know him at all
Story here where they attempted to Turbo a Gen II Prius - the problem they had were they tried everything they could to get mixtures to stray from 14.7:1 (and eventually met success). Turboing A Prius
RE the above "evaporative emissions w/o the bladder". I read this post earlier today, and just arrived back from the gas station filling up my current car - Lexus RX. ($2.02 reg in Orl FL. As I'm filling, I looked down at the nozzle and there was no evap recovery mechanism - as a matter of fact that round rubber anti-splash thing was missing. So, my thought was...wonder how much evaporative emmisions are produced each fillup compared to (what I believe are miniscule) emmisions by the Prius? I know every little bit counts when it comes to pollution - and I will be doing my part when I get MY Prius. Oh, I see some of you posters state your MPG data. I don't mean to flaunt mine, but 19.2MPG over the past 235 miles. Take THAT!:brick: Also re the bladder. I took care of MINE while at the station...
Very interesting, really, but I think this is not the point here. They were trying to impose higher (richer) mixtures and to control them at their will. That's what it was failing on them. One thing is to try to fool the Prius into very high rich mixtures, and that I believe it is not an easy task at all. Another thing is to deny that the Prius itself uses slightly richer mixes when temporarily protecting the catalytic converter. I'm not saying you can force the Prius into extremely richer mixes like they wanted on that turbo. I'm saying the Prius will go slightly off the stoichiometric lambda 1 rate when needed. Again, I'm off base here since I'm not the one with the data. I'm trusting somebody else's analysis, because I trust them. Just let me ask this one for you HTML: if you believe the Prius never goes higher than lambda 1, then how do you think it protects the catalytic converter from burning itself out?
I see your point, but you either have high exhaust gas temps from "lambda 1", or higher catalyst temps from throwing additional unburnt HC's. At what point does one supersede the other? A 2005 Dyno test where the mixtures stayed pretty consistent, as seen on the dyno plot. http://priuschat.com/forums/prius-main-forum/24869-2005-prius-my-chassis-dyno.html
I had not discussed this much here but here is one of my BSFC charts from a high speed trip in my NHW11. We share the same engine block but some changes in the control laws and I have a maximum rpm of 4,500: You will notice there is distinct step from 3,800-4,000 rpm that I believe corresponds to a change in the engine control laws. This would be the most likely place where fuel enrichment begins to occur out to 4,500 rpm. In an ordinary Otto cycle engine, the efficiency peaks near the red-line as the throttle plate losses go away. In this case, the efficiency fall off suggests something else and fuel enrichment is a likely candidate. I'll have to reconfigure and go out again with my laptop to record new data to give a definitive answer. I'd like to do it after my spring tune-up. Bob Wilson
I think you made a small typo there, the unburnt hc is cooler than burnt ones, hence the cooler exhaust gas, it's unburnt gasoline. Now we're talking! Thank you so much for pointing this out! Yes, indeed I stand corrected and understand your point. Either the data is not measured well (can it be?) or you are right and in fact the air:fuel ratio is strikingly constant! Thanks for putting me straight :rockon:
