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Honda researchers validate PM Index for direct-injection gasoline engines; gasoline quality matters

In a new paper in the International Journal of Engine Research, Koichiro Aikawa of Honda R&D and Jeff Jetter of Honda R&D Americas report that their “PM Index”—reported in a paper in 2010—applies well to direct-injection (DI) gasoline engines as well as to the port-fuel-injection (PFI) engines of their original study.

In the original study, Aikawa and Jetter, along with Takayuki Sakurai, also from Honda R&D, investigated the relationship between gasoline properties and vehicle particulate matter emissions in order to construct a predictive model. They individually blended various chemical species with an indolene base fuel, and then measured the solid particulate number (PN) emissions from each blend over the New European Driving Cycle (NEDC).

They found that aromatics with a high boiling point and a high double bond equivalent (DBE) value tended to produce more PN emissions. They also found that high boiling point components with low DBE values—such as paraffins—had only a minor effect on PN.

In Europe, a particle number emission limit for gasoline vehicles—spurred by the adoption of gasoline direct injection engines—is to be defined by 1 September 2014.

They also confirmed that low vapor pressure components correlated with high PN emissions, as might be expected based on their combustion behavior. Based on the findings, they constructed a predictive model they called the “PM Index” based on the weight fraction, vapor pressure, and DBE value of each component in the fuel.

They confirmed that the PM Index could accurately predict not only the total PN trend but also total particulate matter (PM) mass, regardless of engine type or test cycle.

Using hydrocarbon speciation data from a large number of gasoline samples from various countries, they calculated a PM Index distribution for each country. They then estimated that the highest PM Index fuel would produce 10 times the PM emissions of that of the lowest PM Index fuel.

They then concluded that worldwide PM emissions can be reduced not only through improvements in engine hardware, but also through improvements in fuel quality.

Their latest study builds on this base. The results from this study verified good correlation between the PM index and particulate matter emissions of a direct-injection gasoline engine, just as with the port fuel injection engine.

A significantly high correlation (R2 = 0.9644) was observed in the FTP-75 cold-start phase (Phase 1) in which the fuel influences are considered most evident. They simultaneously measured filter PM (PM mass) and verified its correlation with the PM index.

The correlation with PM mass was slightly lower than with particulate number, but it also had a good correlation with PM index. This indicated that the PM index will apply well to DI gasoline engines.

—Aikawa and Jetter (2013)


  • Koichiro Aikawa and Jeff J. Jetter (2013) Impact of gasoline composition on particulate matter emissions from a direct injection engine: Applicability of the particulate matter index. International Journal of Engine Research doi: 10.1177/1468087413481216

  • Koichiro Aikawa, Takayuki Sakurai, and Jeff J. Jetter (2010) Development of a Predictive Model for Gasoline Vehicle Particulate Matter Emissions. SAE Int. J. Fuels Lubr. 3:610-622 doi: 10.4271/2010-01-2115


Trevor Carlson

Excellent Research.

How does US gasoline compare?


Good question?


so am I shooting myself in the foot by pumping "richshaws fuels" into my prius instead of shell high quality gasoline even though one is 15 cents more a liter than the other?


For the last few days, a steady light wind from the South-West, has brought humidity, hot air (30C-31C), rain and lots of rolling low smog from Toronto, Detroit, Chicago, into our area.

Has Detroit started to burn the accumulated Petcoke in the adjacent power plants?

The wind should shift from the North-West by the weekend or early next week and blow the smog South-East, away from our area.


I wonder if BK4 would give HarveyE a thumbs-up for his completely off-topic comment.

At least half of the one-comment posts I see on GCC have just one OT comment by you-know-who.


PMs are part of the daily pollution we have to cope with?

Ways to measure or predict the volume is part of the solution?

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