M1 0w20, 6900 miles, 2006 Civic
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Patman
Staff member
My average MPG has been the same with M1 0w20 as it was with Toyota 0w20, although the 53.3 was achieved with Toyota 0w20, I did that on a 70 mile highway run with the cruise set to 50 mph. I'm sure I could achieve that same number again with the same trip using M1 0w20 though.
This car is automatic, which is better for highway MPG because the manual's gearing has it revving about 500rpm higher at 60mph (mine revs at 2000 at 60)
I don't know the gas mileage when the car was new as I bought it last year with 80,000 miles on it.
This car is automatic, which is better for highway MPG because the manual's gearing has it revving about 500rpm higher at 60mph (mine revs at 2000 at 60)
I don't know the gas mileage when the car was new as I bought it last year with 80,000 miles on it.
You can not beat this oil for the $ IMO. 50% PAO based and in a 5qt jug at WM, the price can't be beat. It comes to $5.79qt.
This oil completely silenced the Honda 2.4L on cold starts, which can be a tad loud. Same with the 0w30 AFE. The AFE oils are a step above the regular M1 line. Not ultra long drain oils, but definitely a 10-15k mile oil in the right application.
MaxLife has also been great on cold starts so far. Running that now.
This oil completely silenced the Honda 2.4L on cold starts, which can be a tad loud. Same with the 0w30 AFE. The AFE oils are a step above the regular M1 line. Not ultra long drain oils, but definitely a 10-15k mile oil in the right application.
MaxLife has also been great on cold starts so far. Running that now.
Originally Posted By: Patman
My average MPG has been the same with M1 0w20 as it was with Toyota 0w20, although the 53.3 was achieved with Toyota 0w20, I did that on a 70 mile highway run with the cruise set to 50 mph. I'm sure I could achieve that same number again with the same trip using M1 0w20 though.
This car is automatic, which is better for highway MPG because the manual's gearing has it revving about 500rpm higher at 60mph (mine revs at 2000 at 60)
I don't know the gas mileage when the car was new as I bought it last year with 80,000 miles on it.
Perhaps in a flat steady speed comparison the AT could beat out the MT by a bit but in general the EPA numbers greatly understate what can be achieved in a MT while being much closer to the reality for the AT. For example, my Si, putting out twice the HP as an AT R18 Civic, with wider and stickier Max Performance summer tires, 5W-30 oil, more weight and shorter gearing than even the MT R18 Civic (I'm about 2650 RPM @ 60 MPH) will usually do 36-38 MPG on the highway at 65 MPH and well over 40 MPG if I were to cruise it at 50 MPH. EPA rating for my car is 21 city/29 hwy. My lifetime MPG is 35.1 which includes a fair amount of fun along the way. I generally can get 30-33 MPG in town. The ATs I've owned and driven (had a week in an AT R18 Civic and it was one of my favorite rentals) never seem to be able to do more than ~10% above the EPA ratings.
In real world driving I think the MT can do quite a bit better than the AT but it takes some manipulation.
My average MPG has been the same with M1 0w20 as it was with Toyota 0w20, although the 53.3 was achieved with Toyota 0w20, I did that on a 70 mile highway run with the cruise set to 50 mph. I'm sure I could achieve that same number again with the same trip using M1 0w20 though.
This car is automatic, which is better for highway MPG because the manual's gearing has it revving about 500rpm higher at 60mph (mine revs at 2000 at 60)
I don't know the gas mileage when the car was new as I bought it last year with 80,000 miles on it.
Perhaps in a flat steady speed comparison the AT could beat out the MT by a bit but in general the EPA numbers greatly understate what can be achieved in a MT while being much closer to the reality for the AT. For example, my Si, putting out twice the HP as an AT R18 Civic, with wider and stickier Max Performance summer tires, 5W-30 oil, more weight and shorter gearing than even the MT R18 Civic (I'm about 2650 RPM @ 60 MPH) will usually do 36-38 MPG on the highway at 65 MPH and well over 40 MPG if I were to cruise it at 50 MPH. EPA rating for my car is 21 city/29 hwy. My lifetime MPG is 35.1 which includes a fair amount of fun along the way. I generally can get 30-33 MPG in town. The ATs I've owned and driven (had a week in an AT R18 Civic and it was one of my favorite rentals) never seem to be able to do more than ~10% above the EPA ratings.
In real world driving I think the MT can do quite a bit better than the AT but it takes some manipulation.
Fram XG filter, was it the Xtended guard or the Ultra?
Patman
Staff member
Originally Posted By: LeakySeals
Fram XG filter, was it the Xtended guard or the Ultra?
It was the Extended Guard, although I do have an Ultra for my next OCI.
Fram XG filter, was it the Xtended guard or the Ultra?
It was the Extended Guard, although I do have an Ultra for my next OCI.
Originally Posted By: Patman
Originally Posted By: LeakySeals
Fram XG filter, was it the Xtended guard or the Ultra?
It was the Extended Guard, although I do have an Ultra for my next OCI.
Would you mind posting your opinion of the difference between the 2? I found the Ultra a vast improvement over the Xtended Guard as far as visible oil quality throughout an 8k OCI. Curious what you think.
Originally Posted By: LeakySeals
Fram XG filter, was it the Xtended guard or the Ultra?
It was the Extended Guard, although I do have an Ultra for my next OCI.
Would you mind posting your opinion of the difference between the 2? I found the Ultra a vast improvement over the Xtended Guard as far as visible oil quality throughout an 8k OCI. Curious what you think.
Patman
Staff member
Originally Posted By: LeakySeals
Would you mind posting your opinion of the difference between the 2? I found the Ultra a vast improvement over the Xtended Guard as far as visible oil quality throughout an 8k OCI. Curious what you think.
I'm not sure if I will really be able to tell a difference between the two once I start using the Ultra actually, I honestly think the two filters are close enough in performance that you won't be able to see a difference unless you were to do some sort of advanced testing with each of them and even then it would be splitting hairs. I don't think most people would see the kind of difference you saw in your car, it could have been something else accounting for the difference.
Would you mind posting your opinion of the difference between the 2? I found the Ultra a vast improvement over the Xtended Guard as far as visible oil quality throughout an 8k OCI. Curious what you think.
I'm not sure if I will really be able to tell a difference between the two once I start using the Ultra actually, I honestly think the two filters are close enough in performance that you won't be able to see a difference unless you were to do some sort of advanced testing with each of them and even then it would be splitting hairs. I don't think most people would see the kind of difference you saw in your car, it could have been something else accounting for the difference.
Originally Posted By: Patman
Originally Posted By: LeakySeals
Would you mind posting your opinion of the difference between the 2? I found the Ultra a vast improvement over the Xtended Guard as far as visible oil quality throughout an 8k OCI. Curious what you think.
I'm not sure if I will really be able to tell a difference between the two once I start using the Ultra actually, I honestly think the two filters are close enough in performance that you won't be able to see a difference unless you were to do some sort of advanced testing with each of them and even then it would be splitting hairs. I don't think most people would see the kind of difference you saw in your car, it could have been something else accounting for the difference.
+1. Unless all conditions (driving style, % City/Highway, Oil used, Air Filter cleanliness, etc. remained exact same on both occasions), it would really be hard to specifically wholly attribute a difference in an oil's visual cleanliness on just the oil filter.
Originally Posted By: LeakySeals
Would you mind posting your opinion of the difference between the 2? I found the Ultra a vast improvement over the Xtended Guard as far as visible oil quality throughout an 8k OCI. Curious what you think.
I'm not sure if I will really be able to tell a difference between the two once I start using the Ultra actually, I honestly think the two filters are close enough in performance that you won't be able to see a difference unless you were to do some sort of advanced testing with each of them and even then it would be splitting hairs. I don't think most people would see the kind of difference you saw in your car, it could have been something else accounting for the difference.
+1. Unless all conditions (driving style, % City/Highway, Oil used, Air Filter cleanliness, etc. remained exact same on both occasions), it would really be hard to specifically wholly attribute a difference in an oil's visual cleanliness on just the oil filter.
Originally Posted By: Patman
Originally Posted By: LeakySeals
Would you mind posting your opinion of the difference between the 2? I found the Ultra a vast improvement over the Xtended Guard as far as visible oil quality throughout an 8k OCI. Curious what you think.
I'm not sure if I will really be able to tell a difference between the two once I start using the Ultra actually, I honestly think the two filters are close enough in performance that you won't be able to see a difference unless you were to do some sort of advanced testing with each of them and even then it would be splitting hairs. I don't think most people would see the kind of difference you saw in your car, it could have been something else accounting for the difference.
I haven't changed my oil brand or driving conditions in 2 years. I thought difference between 97 @20 and 99 @20 + different media would be negligible too. No testing required, your eyes the dipstick and a paper towel is all you need. Wish I'd taken pics at milestones, but I didn't because I wasn't expecting what I saw. You have that opportunity, I'm not going back to prove it (aesthetic
)
Originally Posted By: LeakySeals
Would you mind posting your opinion of the difference between the 2? I found the Ultra a vast improvement over the Xtended Guard as far as visible oil quality throughout an 8k OCI. Curious what you think.
I'm not sure if I will really be able to tell a difference between the two once I start using the Ultra actually, I honestly think the two filters are close enough in performance that you won't be able to see a difference unless you were to do some sort of advanced testing with each of them and even then it would be splitting hairs. I don't think most people would see the kind of difference you saw in your car, it could have been something else accounting for the difference.
I haven't changed my oil brand or driving conditions in 2 years. I thought difference between 97 @20 and 99 @20 + different media would be negligible too. No testing required, your eyes the dipstick and a paper towel is all you need. Wish I'd taken pics at milestones, but I didn't because I wasn't expecting what I saw. You have that opportunity, I'm not going back to prove it (aesthetic
Originally Posted By: OrdnanceMarine
Originally Posted By: Patman
My average MPG has been the same with M1 0w20 as it was with Toyota 0w20, although the 53.3 was achieved with Toyota 0w20, I did that on a 70 mile highway run with the cruise set to 50 mph. I'm sure I could achieve that same number again with the same trip using M1 0w20 though.
This car is automatic, which is better for highway MPG because the manual's gearing has it revving about 500rpm higher at 60mph (mine revs at 2000 at 60)
I don't know the gas mileage when the car was new as I bought it last year with 80,000 miles on it.
Perhaps in a flat steady speed comparison the AT could beat out the MT by a bit but in general the EPA numbers greatly understate what can be achieved in a MT while being much closer to the reality for the AT. For example, my Si, putting out twice the HP as an AT R18 Civic, with wider and stickier Max Performance summer tires, 5W-30 oil, more weight and shorter gearing than even the MT R18 Civic (I'm about 2650 RPM @ 60 MPH) will usually do 36-38 MPG on the highway at 65 MPH and well over 40 MPG if I were to cruise it at 50 MPH. EPA rating for my car is 21 city/29 hwy. My lifetime MPG is 35.1 which includes a fair amount of fun along the way. I generally can get 30-33 MPG in town. The ATs I've owned and driven (had a week in an AT R18 Civic and it was one of my favorite rentals) never seem to be able to do more than ~10% above the EPA ratings.
In real world driving I think the MT can do quite a bit better than the AT but it takes some manipulation.
At the very least the car seems highly sensitive to speed and other factors. It's probably my driving style, but I've never broken 40mpg in my Civic 5-sp, the best I've done is 39mpg on a trip which included two lane roads at ~62 mph, four lane state highway (intermittent stoplights) at ~68 mph and interstate at ~72 mph. It was early spring this year so still pretty cold, call it 40*F. Daily driving is "extra urban" with lots of 55-65 mph highways, but with frequent stoplights. In that usage the car gets 34-36 mpg, usually with my wife at the wheel. I've even done a couple of things to improve mileage. My winter tires are narrower low-rolling resistance on 15" wheels (OEM are 16"), and I've installed the Civic Hybrid's undertray beneath the engine compartment.
Part of the problem with measuring highway mileage for me is the car never seems to get a full tank on the highway, it's got too much range. My best opportunity would be the round trip to my parent's place in Northern MN at ~360mi, but we've almost always got the hitch mounted bike rack on for that trip which hurts mileage, the 39 mpg trip is the only one I can recall without the rack. Hopefully I'll get a clean trip in this winter, though cold weather usually hurts my mileage.
My car is still quite new, so maybe more break-in of the engine will help. I'm pretty good at squeezing mileage out of my WRX having seen 29mpg on several occasions and even getting 27 with two kayaks on the roof earlier this summer, so I don't think my lower mileage in the Civic is just leadfootitus.
Maximizing use of the semi-Atkinson engine mode is likely key to mileage in an R18 Civic, and that's where speed and the auto tans may help. The Atkinson mode is not even available above 3,500 RPM IIRC.
Long and rambling post, I know, but I'm interested in other Civic owner's fuel economy thoughts.
Originally Posted By: Patman
My average MPG has been the same with M1 0w20 as it was with Toyota 0w20, although the 53.3 was achieved with Toyota 0w20, I did that on a 70 mile highway run with the cruise set to 50 mph. I'm sure I could achieve that same number again with the same trip using M1 0w20 though.
This car is automatic, which is better for highway MPG because the manual's gearing has it revving about 500rpm higher at 60mph (mine revs at 2000 at 60)
I don't know the gas mileage when the car was new as I bought it last year with 80,000 miles on it.
Perhaps in a flat steady speed comparison the AT could beat out the MT by a bit but in general the EPA numbers greatly understate what can be achieved in a MT while being much closer to the reality for the AT. For example, my Si, putting out twice the HP as an AT R18 Civic, with wider and stickier Max Performance summer tires, 5W-30 oil, more weight and shorter gearing than even the MT R18 Civic (I'm about 2650 RPM @ 60 MPH) will usually do 36-38 MPG on the highway at 65 MPH and well over 40 MPG if I were to cruise it at 50 MPH. EPA rating for my car is 21 city/29 hwy. My lifetime MPG is 35.1 which includes a fair amount of fun along the way. I generally can get 30-33 MPG in town. The ATs I've owned and driven (had a week in an AT R18 Civic and it was one of my favorite rentals) never seem to be able to do more than ~10% above the EPA ratings.
In real world driving I think the MT can do quite a bit better than the AT but it takes some manipulation.
At the very least the car seems highly sensitive to speed and other factors. It's probably my driving style, but I've never broken 40mpg in my Civic 5-sp, the best I've done is 39mpg on a trip which included two lane roads at ~62 mph, four lane state highway (intermittent stoplights) at ~68 mph and interstate at ~72 mph. It was early spring this year so still pretty cold, call it 40*F. Daily driving is "extra urban" with lots of 55-65 mph highways, but with frequent stoplights. In that usage the car gets 34-36 mpg, usually with my wife at the wheel. I've even done a couple of things to improve mileage. My winter tires are narrower low-rolling resistance on 15" wheels (OEM are 16"), and I've installed the Civic Hybrid's undertray beneath the engine compartment.
Part of the problem with measuring highway mileage for me is the car never seems to get a full tank on the highway, it's got too much range. My best opportunity would be the round trip to my parent's place in Northern MN at ~360mi, but we've almost always got the hitch mounted bike rack on for that trip which hurts mileage, the 39 mpg trip is the only one I can recall without the rack. Hopefully I'll get a clean trip in this winter, though cold weather usually hurts my mileage.
My car is still quite new, so maybe more break-in of the engine will help. I'm pretty good at squeezing mileage out of my WRX having seen 29mpg on several occasions and even getting 27 with two kayaks on the roof earlier this summer, so I don't think my lower mileage in the Civic is just leadfootitus.
Maximizing use of the semi-Atkinson engine mode is likely key to mileage in an R18 Civic, and that's where speed and the auto tans may help. The Atkinson mode is not even available above 3,500 RPM IIRC.
Long and rambling post, I know, but I'm interested in other Civic owner's fuel economy thoughts.
So are you running M1 0W-20 again for the winter?
That would provide more of an equal comparison to the TGMO in terms of fuel economy. That's where the lighter on start-up TGMO should make more of a difference.
All told TGMO has one clear advantage over M1 AFE in Canada being half the price.
That would provide more of an equal comparison to the TGMO in terms of fuel economy. That's where the lighter on start-up TGMO should make more of a difference.
All told TGMO has one clear advantage over M1 AFE in Canada being half the price.
Patman
Staff member
Originally Posted By: CATERHAM
So are you running M1 0W-20 again for the winter?
Yes, I do plan on sticking with M1 0w20 for a while. The Toyota 0w20 is definitely a lot cheaper up here, but I just wait for M1 to go on sale in order to reduce the cost a little more.
So are you running M1 0W-20 again for the winter?
Yes, I do plan on sticking with M1 0w20 for a while. The Toyota 0w20 is definitely a lot cheaper up here, but I just wait for M1 to go on sale in order to reduce the cost a little more.
Originally Posted By: gpshumway
[Maximizing use of the semi-Atkinson engine mode is likely key to mileage in an R18 Civic, and that's where speed and the auto tans may help. The Atkinson mode is not even available above 3,500 RPM IIRC.
semi-Atkinson engine mode? Can you school me on what this is?
[Maximizing use of the semi-Atkinson engine mode is likely key to mileage in an R18 Civic, and that's where speed and the auto tans may help. The Atkinson mode is not even available above 3,500 RPM IIRC.
semi-Atkinson engine mode? Can you school me on what this is?
Originally Posted By: Patman
Here are the latest results from my 2006 Civic, analysis done by Wearcheck Canada:
6,923 miles on oil
May 6 to Nov 3 (6 months)
97,354 miles on engine
Mobil 1 0w20 (SN)
Fram XG oil filter
4.0L oil capacity
no makeup oil (was down 0.75L)
MM was at 15%
..........................................................................
Viscosity at 100c - 7.4 cst
Starting vis is 8.7. so that is quite a bit of shearing, isn't it?
Here are the latest results from my 2006 Civic, analysis done by Wearcheck Canada:
6,923 miles on oil
May 6 to Nov 3 (6 months)
97,354 miles on engine
Mobil 1 0w20 (SN)
Fram XG oil filter
4.0L oil capacity
no makeup oil (was down 0.75L)
MM was at 15%
..........................................................................
Viscosity at 100c - 7.4 cst
Starting vis is 8.7. so that is quite a bit of shearing, isn't it?
It's a fair bit of viscosity loss but most of it is due to fuel dilution not the oil actually shearing.
Originally Posted By: OrdnanceMarine
Originally Posted By: gpshumway
[Maximizing use of the semi-Atkinson engine mode is likely key to mileage in an R18 Civic, and that's where speed and the auto tans may help. The Atkinson mode is not even available above 3,500 RPM IIRC.
semi-Atkinson engine mode? Can you school me on what this is?
The modern interpretation of an Atkinson cycle implementation is achieving higher efficiency and reducing pumping losses through the manipulation of the valve timing (through camshaft phasing).
http://en.wikipedia.org/wiki/Atkinson_cycle
Though gpshumway may also have been talking about the valvetrain's ability to either open both intake valves at the same or keep one nearly closed while it opens the other one fully.
Originally Posted By: gpshumway
[Maximizing use of the semi-Atkinson engine mode is likely key to mileage in an R18 Civic, and that's where speed and the auto tans may help. The Atkinson mode is not even available above 3,500 RPM IIRC.
semi-Atkinson engine mode? Can you school me on what this is?
The modern interpretation of an Atkinson cycle implementation is achieving higher efficiency and reducing pumping losses through the manipulation of the valve timing (through camshaft phasing).
http://en.wikipedia.org/wiki/Atkinson_cycle
Though gpshumway may also have been talking about the valvetrain's ability to either open both intake valves at the same or keep one nearly closed while it opens the other one fully.
Originally Posted By: Hokiefyd
Originally Posted By: OrdnanceMarine
Originally Posted By: gpshumway
[Maximizing use of the semi-Atkinson engine mode is likely key to mileage in an R18 Civic, and that's where speed and the auto tans may help. The Atkinson mode is not even available above 3,500 RPM IIRC.
semi-Atkinson engine mode? Can you school me on what this is?
The modern interpretation of an Atkinson cycle implementation is achieving higher efficiency and reducing pumping losses through the manipulation of the valve timing (through camshaft phasing).
http://en.wikipedia.org/wiki/Atkinson_cycle
Though gpshumway may also have been talking about the valvetrain's ability to either open both intake valves at the same or keep one nearly closed while it opens the other one fully.
I could be off but I'm not sure the R18 can take advantage of any change in cam phasing during operation. I'm pretty sure the R18 does not have VTC like certain variants of the K-series engines do (my Si's K20Z3 for example). If he's referring to the version of VTEC that the R18 has that does as you mention, lift one intake valve fully while barely cracking the other intake valve, that is indeed the version the R18 has. When VTEC engages, it ties both valves together so they follow the higher of the two cam profiles. The only real improvement I think that can be done is a lean burn by using Hondata's FlashPro to tune certain RPM and Load areas of the fuel and ignition maps to run lean of peak.
Originally Posted By: OrdnanceMarine
Originally Posted By: gpshumway
[Maximizing use of the semi-Atkinson engine mode is likely key to mileage in an R18 Civic, and that's where speed and the auto tans may help. The Atkinson mode is not even available above 3,500 RPM IIRC.
semi-Atkinson engine mode? Can you school me on what this is?
The modern interpretation of an Atkinson cycle implementation is achieving higher efficiency and reducing pumping losses through the manipulation of the valve timing (through camshaft phasing).
http://en.wikipedia.org/wiki/Atkinson_cycle
Though gpshumway may also have been talking about the valvetrain's ability to either open both intake valves at the same or keep one nearly closed while it opens the other one fully.
I could be off but I'm not sure the R18 can take advantage of any change in cam phasing during operation. I'm pretty sure the R18 does not have VTC like certain variants of the K-series engines do (my Si's K20Z3 for example). If he's referring to the version of VTEC that the R18 has that does as you mention, lift one intake valve fully while barely cracking the other intake valve, that is indeed the version the R18 has. When VTEC engages, it ties both valves together so they follow the higher of the two cam profiles. The only real improvement I think that can be done is a lean burn by using Hondata's FlashPro to tune certain RPM and Load areas of the fuel and ignition maps to run lean of peak.
Originally Posted By: OrdnanceMarine
Originally Posted By: Hokiefyd
Originally Posted By: OrdnanceMarine
semi-Atkinson engine mode? Can you school me on what this is?
The modern interpretation of an Atkinson cycle implementation is achieving higher efficiency and reducing pumping losses through the manipulation of the valve timing (through camshaft phasing).
http://en.wikipedia.org/wiki/Atkinson_cycle
Though gpshumway may also have been talking about the valvetrain's ability to either open both intake valves at the same or keep one nearly closed while it opens the other one fully.
I could be off but I'm not sure the R18 can take advantage of any change in cam phasing during operation. I'm pretty sure the R18 does not have VTC like certain variants of the K-series engines do (my Si's K20Z3 for example). If he's referring to the version of VTEC that the R18 has that does as you mention, lift one intake valve fully while barely cracking the other intake valve, that is indeed the version the R18 has. When VTEC engages, it ties both valves together so they follow the higher of the two cam profiles. The only real improvement I think that can be done is a lean burn by using Hondata's FlashPro to tune certain RPM and Load areas of the fuel and ignition maps to run lean of peak.
I don't believe the R18 does preferential valve opening like the D series, though it might to improve charge motion. It also doesn't change the phasing per-se, being SOHC, but it does change the duration dramatically. The i-VTEC system in the R18 works "backwards" from the traditional performance oriented VTEC implementations in the B and K series.
The "normal" cam profile is the "hot" profile and the VTEC profile is an "economy" profile. If you floor the pedal and wind an R18 to redline you never engage VTEC. VTEC only engages at light load and RPM under 3,500. When engaged it delays intake valve closure so long that some of the intake charge is pumped back out of the cylinder. Combined with the DBW throttle system holding the throttle open farther, the result is substantially reduced pumping losses. This is the semi-Atkinson mode I'm referring to. Mazda's new Skyactive engine does a similar trick, but with continuously variable phasing.
Most hybrids (Honda, Ford, Toyota) have semi-Atkinson engines which only operate like an R18 in economy mode, the result is low power output. Hybrids make up for poor engine torque by using the electric motor to supplement. A true Atkinson cycle engine requires a "double crankshaft" to achieve asymmetric compression and combustion strokes. Honda made a prototype for generator use. See this video.
Here's a not very well written, but very complete description of the way the R18's i-VTEC system works.
This description has better prose, but is shorter:
Originally Posted By: Hokiefyd
Originally Posted By: OrdnanceMarine
semi-Atkinson engine mode? Can you school me on what this is?
The modern interpretation of an Atkinson cycle implementation is achieving higher efficiency and reducing pumping losses through the manipulation of the valve timing (through camshaft phasing).
http://en.wikipedia.org/wiki/Atkinson_cycle
Though gpshumway may also have been talking about the valvetrain's ability to either open both intake valves at the same or keep one nearly closed while it opens the other one fully.
I could be off but I'm not sure the R18 can take advantage of any change in cam phasing during operation. I'm pretty sure the R18 does not have VTC like certain variants of the K-series engines do (my Si's K20Z3 for example). If he's referring to the version of VTEC that the R18 has that does as you mention, lift one intake valve fully while barely cracking the other intake valve, that is indeed the version the R18 has. When VTEC engages, it ties both valves together so they follow the higher of the two cam profiles. The only real improvement I think that can be done is a lean burn by using Hondata's FlashPro to tune certain RPM and Load areas of the fuel and ignition maps to run lean of peak.
I don't believe the R18 does preferential valve opening like the D series, though it might to improve charge motion. It also doesn't change the phasing per-se, being SOHC, but it does change the duration dramatically. The i-VTEC system in the R18 works "backwards" from the traditional performance oriented VTEC implementations in the B and K series.
The "normal" cam profile is the "hot" profile and the VTEC profile is an "economy" profile. If you floor the pedal and wind an R18 to redline you never engage VTEC. VTEC only engages at light load and RPM under 3,500. When engaged it delays intake valve closure so long that some of the intake charge is pumped back out of the cylinder. Combined with the DBW throttle system holding the throttle open farther, the result is substantially reduced pumping losses. This is the semi-Atkinson mode I'm referring to. Mazda's new Skyactive engine does a similar trick, but with continuously variable phasing.
Most hybrids (Honda, Ford, Toyota) have semi-Atkinson engines which only operate like an R18 in economy mode, the result is low power output. Hybrids make up for poor engine torque by using the electric motor to supplement. A true Atkinson cycle engine requires a "double crankshaft" to achieve asymmetric compression and combustion strokes. Honda made a prototype for generator use. See this video.
Here's a not very well written, but very complete description of the way the R18's i-VTEC system works.
This description has better prose, but is shorter:
Exactly how I understood the R18's economy-minded logic. I've always itched to see how well I could do with a MT R18 Civic considering in city driving I get about 150% of the EPA rating and highway driving I end up with about 125% of the EPA rating (I get about 33/37 with a lifetime MPG of 35.1 at ~42,000 mi). Considering I've got far stickier-than-stock Michelin Pilot Super Sport tires and I'm not always driving my car in "economy mode" I would think I could achieve something along the lines of 40 City/50 Highway with a combined average in the 43-46 MPG range if equiped with LRR tires, perhaps the underbody panels from the Civic Hybrid and maybe some tuning (though the cost of tuning would never be bought back with fuel savings until something past 100,000 miles).
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