Higher-Octane Gas Could Improve Fuel Economy

[Caleditor]

Nice article.
I think that I have stated this many times. This is the opposite of installing an EGR valve.

bob-facscetti.jpg

DETROIT – Vehicle fuel efficiency could be improved significantly if the U.S. would shift to higher-octane gasoline, Detroit Three powertrain chiefs tell attendees at the SAE World Congress here.
The rationale is simple: Higher-octane fuels burn more predictably and allow automakers to design engines with higher compression ratios. Higher compression ratios yield more power per combustion event and more power-dense and efficient engines.
Conversely, low-octane gasoline can detonate unpredictably in the combustion chamber and create engine-damaging “knock.” Programming spark timing to avoid knock and keeping compression ratios lower robs horsepower and efficiency.
U.S. fuel has a research octane number (RON) of about 91, while Europe has a standard of 95 RON or higher. That’s a huge difference to engine experts. If automakers could stop designing engines to avoid low-octane engine knock, engine efficiency could be improved by as much as 5%, Bob Fascetti, vice president-Powertrain Engineering at Ford tells SAE attendees.
“We have to design for regular fuel (91 RON in the U.S.). If we could get 95 RON fuel at the pump like Europe, if we could get higher compression ratios, we could get big benefits,” Fascetti says.
The idea hardly is unprecedented. The U.S. mandated European-style standards for ultra-low sulfur content in diesel fuel in 2007, resulting in dramatically improved diesel engines and emissions.
“Our (octane number) is too low,” Bob Lee, vice president and head of Engine and Electrified Propulsion Engineering at Chrysler, tells reporters on the sidelines after his presentation. Lee’s estimate for fuel-economy gains is slightly lower, but he says, “I’m giving up 2% or 3% (in fuel efficiency) just to go from 95 octane to 91.”
Higher compression ratios are beneficial in many ways, Lee says, such as improving the efficiency of Atkinson-cycle combustion strategies.
Steve Kiefer, vice president-Global Powertrain for General Motors, also says he supports a move to higher-octane gasoline.
The three powertrain chiefs have spoken about moving to higher octane at technical conferences and in Washington, where the Department of Energy is well aware of the benefits, but have not said much publicly until now.
“I can’t say we’ve actually lobbied together, but it’s a common-sense thing. If we had a single-octane fuel that was higher, then we can take advantage of that for the customer, we can implement higher compression ratios and we won’t be knock-limited on the fuel,” Fascetti says. “It’s win-win for the innovators as well as for the customers.”
dwinter@wardsauto.com

http://wardsauto.com/vehicles-techno...e-fuel-economy

[Fast355]

Nice article.
I think that I have stated this many times. This is the opposite of installing an EGR valve.


DETROIT – Vehicle fuel efficiency could be improved significantly if the U.S. would shift to higher-octane gasoline, Detroit Three powertrain chiefs tell attendees at the SAE World Congress here.
The rationale is simple: Higher-octane fuels burn more predictably and allow automakers to design engines with higher compression ratios. Higher compression ratios yield more power per combustion event and more power-dense and efficient engines.
Conversely, low-octane gasoline can detonate unpredictably in the combustion chamber and create engine-damaging “knock.” Programming spark timing to avoid knock and keeping compression ratios lower robs horsepower and efficiency.
U.S. fuel has a research octane number (RON) of about 91, while Europe has a standard of 95 RON or higher. That’s a huge difference to engine experts. If automakers could stop designing engines to avoid low-octane engine knock, engine efficiency could be improved by as much as 5%, Bob Fascetti, vice president-Powertrain Engineering at Ford tells SAE attendees.
“We have to design for regular fuel (91 RON in the U.S.). If we could get 95 RON fuel at the pump like Europe, if we could get higher compression ratios, we could get big benefits,” Fascetti says.
The idea hardly is unprecedented. The U.S. mandated European-style standards for ultra-low sulfur content in diesel fuel in 2007, resulting in dramatically improved diesel engines and emissions.
“Our (octane number) is too low,” Bob Lee, vice president and head of Engine and Electrified Propulsion Engineering at Chrysler, tells reporters on the sidelines after his presentation. Lee’s estimate for fuel-economy gains is slightly lower, but he says, “I’m giving up 2% or 3% (in fuel efficiency) just to go from 95 octane to 91.”
Higher compression ratios are beneficial in many ways, Lee says, such as improving the efficiency of Atkinson-cycle combustion strategies.
Steve Kiefer, vice president-Global Powertrain for General Motors, also says he supports a move to higher-octane gasoline.
The three powertrain chiefs have spoken about moving to higher octane at technical conferences and in Washington, where the Department of Energy is well aware of the benefits, but have not said much publicly until now.
“I can’t say we’ve actually lobbied together, but it’s a common-sense thing. If we had a single-octane fuel that was higher, then we can take advantage of that for the customer, we can implement higher compression ratios and we won’t be knock-limited on the fuel,” Fascetti says. “It’s win-win for the innovators as well as for the customers.”
dwinter@wardsauto.com

http://wardsauto.com/vehicles-techno...e-fuel-economy

I moved to E85 on the 06 Hemi Ram and 2012 5.6 Titan after finding that they were knock limited on pump premium. MBT was higher than 93 octane could support without detonation. Both engines are under 9.8:1.

I found gains of up to 20 ft/lbs in parts of the torque curve and a peak to peak HP/TQ gain of about 6%. Fuel consumption increased roughly 25%, however cost analysis compared to pump premium was within pennies either way. E85 was over $1 cheaper per gallon than 93. I like the extra HP/TQ and cleaner running engine, so I stuck with E85.

On the Titan I was actually able to alter the intake valve timing advance tables to advance the camshaft at a lower rpm, increasing overlap and advancing the ICL, increasing overlap and the dynamic compression ratio at lower RPMs to make even more torque.

[RobertISaar]

i feel that this would require some really specific things to happen successfully, mostly because of the average driver having no clue what the hell is going on underhood. they'll save 3 pennies a gallon for known-junk fuel rather than a top-tier station and they'll usually drive out of the way to do it as well.

[Fast355]

i feel that this would require some really specific things to happen successfully, mostly because of the average driver having no clue what the hell is going on underhood. they'll save 3 pennies a gallon for known-junk fuel rather than a top-tier station and they'll usually drive out of the way to do it as well.

We had a customer do just this, kept throwing the CEL light on in a new Murano. They were buying premium fuel, but it was still a poor grade of fuel. The RVP was too high causing the engine to run too richly and thus the code.

[RobertISaar]

weird, i wouldn't think relatively high pressure fuel injection would be that sensitive to RVP.

[1project2many]

The RVP was too high causing the engine to run too richly and thus the code.

So too many light end distillates are causing rich operation? That isn't a direct correlation and seems a bit tough to pin down. If valid, investigate faster combustion bringing reaction nearer to completion prior to valve opening and subsequently less unreacted O2 in exhaust stream.

[brian617]

U.S. fuel has a research octane number (RON) of about 91, while Europe has a standard of 95 RON or higher. That’s a huge difference to engine experts. If automakers could stop designing engines to avoid low-octane engine knock, engine efficiency could be improved by as much as 5%, Bob Fascetti, vice president-Powertrain Engineering at Ford tells SAE attendees.
“We have to design for regular fuel (91 RON in the U.S.). If we could get 95 RON fuel at the pump like Europe, if we could get higher compression ratios, we could get big benefits,” Fascetti says.

This statement is false. While European fuel is labeled at the pump with RON numbers US fuel is labeled with octane numbers reflecting the formula RON+MON/2. Here is a link to an article explaining just that.

http://motocrossactionmag.com/mobile...-MO-10984.aspx

Besides that, octane numbers are not a real good measure of fuel quality. Things like the distillation curve and specific gravity have more to do with how a fuel preforms than a simple octane rating.

[Caleditor]

This statement is false. While European fuel is labeled at the pump with RON numbers US fuel is labeled with octane numbers reflecting the formula RON+MON/2. Here is a link to an article explaining just that.

http://motocrossactionmag.com/mobile...-MO-10984.aspx

Besides that, octane numbers are not a real good measure of fuel quality. Things like the distillation curve and specific gravity have more to do with how a fuel preforms than a simple octane rating.

The article came from wardsauto as listed and it is from the SAE congress. Maybe I can get the information from a friend that attended

[1project2many]

Besides that, octane numbers are not a real good measure of fuel quality. Things like the distillation curve and specific gravity have more to do with how a fuel preforms than a simple octane rating.

This is why off brand fuels can be all over the map. Meeting octane rating is a very small part of the picture. Mixing diesel and ethanol can produce a fuel with correct octane, but good luck getting it to perform well.

[Caleditor]

GM's Service Information (SI) has 2016 vehicles listed already in the drop down boxes. We are less than 10 years out with the 54.5 mpg standards. They are going to have to figure this out soon.

[1project2many]

You're looking at real world numbers closer to 40mpg. I believe it's doable. My turbo Sunbird has achieved 36 with my wife driving. I also believe we've lost ground. The two Aveos we have use smaller version of the same engine in the Sunbird yet they achieve mid to high 20's on the highway! What??? Our 2001 Malibu was also high 20's. Not impressed when cars of the '90s were high '20s to low '30s with V6 engines and Chevy Sprint / Suzuki Swift was in the '40s.

Look for different NOx controls so autos can move toward higher intake mixture temps. Stop playing HP wars and build cars that get good mileage. Put Vroom-Vroom go fast into a different category and let buyer pay for privilege of going faster and using more fuel. And no more "cash for clunkers" that wipes out used car market!

Here's something to think about. The 99-02 Chevy minibuses in our fleet achieve roughly 9-10 mpg on average with the 5.7l engine. Those buses were also available with the tiny 4.3. The tq/hp ratings of our 5.7 are 330 / 245 and they move the bus along just fine. When I spec out a new bus the only engine I can get is the 6.0 which is generating average fuel economy numbers in the 7-8 mpg range. The 5.3 is rated for 338Tq/315hp, more than the L31, yet GM won't supply that engine in anything larger than a single wheel chassis cab.

Ford likes to do the same with the 6.8L V10 but with enough fighting you can get the smaller engine. Ford has the bus builders convinced that asmaller engine won't survive in a dually chassis with 10,000lb gvw but we've got vans with 200k and the 5.4 is still running just fine. And the fuel economy is 2-3 mpg better. While that may not sound like much, in a fleet using over 20,000 gallons of fuel a month that 2-3 miles per gallon is worth money.

[Fast355]

You're looking at real world numbers closer to 40mpg. I believe it's doable. My turbo Sunbird has achieved 36 with my wife driving. I also believe we've lost ground. The two Aveos we have use smaller version of the same engine in the Sunbird yet they achieve mid to high 20's on the highway! What??? Our 2001 Malibu was also high 20's. Not impressed when cars of the '90s were high '20s to low '30s with V6 engines and Chevy Sprint / Suzuki Swift was in the '40s.

Look for different NOx controls so autos can move toward higher intake mixture temps. Stop playing HP wars and build cars that get good mileage. Put Vroom-Vroom go fast into a different category and let buyer pay for privilege of going faster and using more fuel. And no more "cash for clunkers" that wipes out used car market!

Here's something to think about. The 99-02 Chevy minibuses in our fleet achieve roughly 9-10 mpg on average with the 5.7l engine. Those buses were also available with the tiny 4.3. The tq/hp ratings of our 5.7 are 330 / 245 and they move the bus along just fine. When I spec out a new bus the only engine I can get is the 6.0 which is generating average fuel economy numbers in the 7-8 mpg range. The 5.3 is rated for 338Tq/315hp, more than the L31, yet GM won't supply that engine in anything larger than a single wheel chassis cab.

Ford likes to do the same with the 6.8L V10 but with enough fighting you can get the smaller engine. Ford has the bus builders convinced that asmaller engine won't survive in a dually chassis with 10,000lb gvw but we've got vans with 200k and the 5.4 is still running just fine. And the fuel economy is 2-3 mpg better. While that may not sound like much, in a fleet using over 20,000 gallons of fuel a month that 2-3 miles per gallon is worth money.

Hands down the old L31 is a better truck engine than the 5.3 or even 6.0. The reason GM does not offer the 5.3 in a bus is lack of low end torque. But what do they expect with a smaller displacement engine and gigantic ports.

While the actual design is over 10 years old, my Titan does as well as any V8 fullsize truck on the road on gas, especially around town.....The reason, lots of low and midrange torque that keeps you off the throttle in daily driving.

I mention this because my sisters 14' 5.3 was rated something like 22 mpg. and my Titan 18 mpg. We ran the same trip, have almost the same size tank, got almost the same range, and both got 18-19 mpg running 70-75 mph. Pretty sad that GM fuel economy does not even come close to advertised.

[1project2many]

No torque, but the anemic 4.3 was available with loose converter in one ton applications. We're in town, stop and go, so not much help no matter what size engine or where torque production is. BSFC is maximum at peak torque so I'll take a loose converter and power vs torque to move along.

I will say that shop truck with 6.0 pulls stuck buses all day long without breaking a sweat. I can get reasonable mileage on the highway if I keep it below 70. But as soon as I hit a couple of lights there goes the economy.

Currently rebuilding 5.7 engine for bus and trying HT383 cam. Nice experiment for an otherwise stock vehicle.

[Fast355]

No torque, but the anemic 4.3 was available with loose converter in one ton applications. We're in town, stop and go, so not much help no matter what size engine or where torque production is. BSFC is maximum at peak torque so I'll take a loose converter and power vs torque to move along.

I will say that shop truck with 6.0 pulls stuck buses all day long without breaking a sweat. I can get reasonable mileage on the highway if I keep it below 70. But as soon as I hit a couple of lights there goes the economy.

Currently rebuilding 5.7 engine for bus and trying HT383 cam. Nice experiment for an otherwise stock vehicle.

Just my $.02, I would try a set of 1.6:1 full roller rockers rather than the HT383 cam. The HT383 cam has a bit more overlap than the L31. But it will be interesting to see what happens.

I have the 4.3 converter in my 4L80E in my G1500 with the 5.7.

Not sure where you have seen that BSFC was highest at peak torque??? BSFC is often LOWEST at peak torque and falls off on both ends. Take the project Vortec TPI built for the something old, something new article.

It peaked in BSFC between 3,300 and 5,000 rpm and was relatively flat between .4 and .43 lb/hr/hp, which is a stellar number for an old 5.7

http://www.gmhightechperformance.com...ck/page_3.html

[Hog]

This statement is false. While European fuel is labeled at the pump with RON numbers US fuel is labeled with octane numbers reflecting the formula RON+MON/2. Here is a link to an article explaining just that.

http://motocrossactionmag.com/mobile...-MO-10984.aspx

Besides that, octane numbers are not a real good measure of fuel quality. Things like the distillation curve and specific gravity have more to do with how a fuel preforms than a simple octane rating.

Agreed, the article makes it sound as if higher octane fuel is available in Europe than in North AMerica, the opposite is true. Sunoco's conventional street blend 94 octane (R+M)/2 is markedly higher in octane than European 95 octane (RON) when compared properly on their ability to resist detonation/pre-ignition.

peace
Hog