2008 RX-350 Fuel Octane Rating
#106
Driver School Candidate
Join Date: Sep 2008
Location: WI
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
Just because its the same engine, that doesnt mean everything else is the same. There is a lot of other components and electronics that might differ between the 2 powertrain. The bottom line is, we know the RX can take advantage of the higher octane and the verdict is still out as far as if Toyota can.
#107
Lexus Champion
iTrader: (6)
As an engineer I don't accept subjective comparisons, or objective comparisons that are not well measured.
Things like "smells", and "noticing a performance difference", and even most mpg checks are not valid.
Mpg checks must be over the same route under the same conditions in order to be valid. Especially when the mpg differences are small. Also both reg and premium must have either ethonol or no ethonol. That's hard to find around here since reg has it and premium doesn't. Pure gas with no ethonol will get higher mpg due to more BTU's per gallon.
Performance should be measured on a dyno. Too many variables with a timed 0-60 run for example. Humans driving the car, working the stopwatch, etc.
Things like "smells", and "noticing a performance difference", and even most mpg checks are not valid.
Mpg checks must be over the same route under the same conditions in order to be valid. Especially when the mpg differences are small. Also both reg and premium must have either ethonol or no ethonol. That's hard to find around here since reg has it and premium doesn't. Pure gas with no ethonol will get higher mpg due to more BTU's per gallon.
Performance should be measured on a dyno. Too many variables with a timed 0-60 run for example. Humans driving the car, working the stopwatch, etc.
Why use Consumer Guide data? Here's the manufacturer data:
Toyota Highlander AWD Limited is 4321 lbs
http://www.toyota.com/highlander/specs.html
Lexus RX350 AWD is 4090 lbs
http://www.lexus.com/models/RX/detai...fications.html
Given that by Lexus' admission both vehicles have identical engines, it is not unexpected that the lighter vehicle would accelerate faster. That's due to a higher power to weight ratio, not premium gas.
Also when comparing acceleration you need to consider the transmissions (gear ratios, shifting points, etc) . I don't know if both vehicles have the same transmission or not.
Toyota Highlander AWD Limited is 4321 lbs
http://www.toyota.com/highlander/specs.html
Lexus RX350 AWD is 4090 lbs
http://www.lexus.com/models/RX/detai...fications.html
Given that by Lexus' admission both vehicles have identical engines, it is not unexpected that the lighter vehicle would accelerate faster. That's due to a higher power to weight ratio, not premium gas.
Also when comparing acceleration you need to consider the transmissions (gear ratios, shifting points, etc) . I don't know if both vehicles have the same transmission or not.
Just because its the same engine, that doesnt mean everything else is the same. There is a lot of other components and electronics that might differ between the 2 powertrain. The bottom line is, we know the RX can take advantage of the higher octane and the verdict is still out as far as if Toyota can.
#108
Lexus Test Driver
#109
Lexus Champion
As an engineer I don't accept subjective comparisons, or objective comparisons that are not well measured.
Things like "smells", and "noticing a performance difference", and even most mpg checks are not valid.
Mpg checks must be over the same route under the same conditions in order to be valid. Especially when the mpg differences are small. Also both reg and premium must have either ethonol or no ethonol. That's hard to find around here since reg has it and premium doesn't. Pure gas with no ethonol will get higher mpg due to more BTU's per gallon.
Performance should be measured on a dyno. Too many variables with a timed 0-60 run for example. Humans driving the car, working the stopwatch, etc.
Things like "smells", and "noticing a performance difference", and even most mpg checks are not valid.
Mpg checks must be over the same route under the same conditions in order to be valid. Especially when the mpg differences are small. Also both reg and premium must have either ethonol or no ethonol. That's hard to find around here since reg has it and premium doesn't. Pure gas with no ethonol will get higher mpg due to more BTU's per gallon.
Performance should be measured on a dyno. Too many variables with a timed 0-60 run for example. Humans driving the car, working the stopwatch, etc.
Ryan
#110
Driver School Candidate
Join Date: Sep 2008
Location: WI
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
248 vs 251.
I'm aware of that but assumed it's an error of some type since HP is identical (270) at the same rpm. Since HP is a function of torque and rpm, it's impossible by definition to have two engines with identical hp and rpm, but different torque.
Besides that, even if you did get 1% higher torque, is it worth paying 10% more for gas to get it?
I'm aware of that but assumed it's an error of some type since HP is identical (270) at the same rpm. Since HP is a function of torque and rpm, it's impossible by definition to have two engines with identical hp and rpm, but different torque.
Besides that, even if you did get 1% higher torque, is it worth paying 10% more for gas to get it?
#111
Lexus Test Driver
248 vs 251.
I'm aware of that but assumed it's an error of some type since HP is identical (270) at the same rpm. Since HP is a function of torque and rpm, it's impossible by definition to have two engines with identical hp and rpm, but different torque.
Besides that, even if you did get 1% higher torque, is it worth paying 10% more for gas to get it?
I'm aware of that but assumed it's an error of some type since HP is identical (270) at the same rpm. Since HP is a function of torque and rpm, it's impossible by definition to have two engines with identical hp and rpm, but different torque.
Besides that, even if you did get 1% higher torque, is it worth paying 10% more for gas to get it?
#113
When gas was skyrocketing, I tried a few tankfulls of 87, and I could definitely hear the knocking when hard accelerating. It would knock a lot until you backed way off on the accelerator. Now this was basically at sea level, spring/summer temps. I pretty much settled on 89 for a while, and then back up to premium now that the price is down again.
I have asked this before, but got no answer: is there any sort of compilation of engine knocking performance/spark retard setting that you could read with an OBD II reader? If so, we could do some actual scientific testing as a group, and settle this once and for all.
I have asked this before, but got no answer: is there any sort of compilation of engine knocking performance/spark retard setting that you could read with an OBD II reader? If so, we could do some actual scientific testing as a group, and settle this once and for all.
#114
Driver School Candidate
Join Date: Nov 2008
Location: IN
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
When I was complaining to the mechanic about the '08 RX 350 needing to use premium gas (when it was over $4/gal.), he said I could occasionally use mid-grade if I wanted. However, I'd notice not as much pick-up and lower mpg............
#116
Ultimately, if your engine doesn't knock and you prefer to use to regular (87 octane) fuel by all means do so. For the rest who goes by manufacturer recommendation and/or engine knock on regular fuel, use premium. Just enjoy the car for the reason we bought it and not worry about these little things that comes up. What would Lexus gain for recommending their customers to use premium. They don't get any kick back from the oil company, or at least any I heard about.
#118
Driver School Candidate
Join Date: Nov 2008
Location: New york
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
Just get the higher octane gas>>>verify gas stations<<< some of them like to((( mix gas))) meaning premium with regular if you still hear the knocking stay away from those ....im telling because my friend use to deliver gas i know
#119
248 vs 251.
I'm aware of that but assumed it's an error of some type since HP is identical (270) at the same rpm. Since HP is a function of torque and rpm, it's impossible by definition to have two engines with identical hp and rpm, but different torque.
Besides that, even if you did get 1% higher torque, is it worth paying 10% more for gas to get it?
I'm aware of that but assumed it's an error of some type since HP is identical (270) at the same rpm. Since HP is a function of torque and rpm, it's impossible by definition to have two engines with identical hp and rpm, but different torque.
Besides that, even if you did get 1% higher torque, is it worth paying 10% more for gas to get it?
Like you, I don't think the price tag is worth the premium price and wish I could have my ECU flashed for the lower octane tune. The RX350 has more power than the brakes or chasis can handle and a mild detune would not affect my driving experience (or lack thereof) in the least. The RX line is more about the riding experience than the driving experience. I'm not knocking it - the same thing could be said for *most* Mercedes and Acura's.
#120
Driver School Candidate
Join Date: Sep 2008
Location: CA
Posts: 25
Likes: 0
Received 0 Likes
on
0 Posts
Why use Consumer Guide data? Here's the manufacturer data:
Toyota Highlander AWD Limited is 4321 lbs
http://www.toyota.com/highlander/specs.html
Lexus RX350 AWD is 4090 lbs
http://www.lexus.com/models/RX/detai...fications.html
Given that by Lexus' admission both vehicles have identical engines, it is not unexpected that the lighter vehicle would accelerate faster. That's due to a higher power to weight ratio, not premium gas.
Also when comparing acceleration you need to consider the transmissions (gear ratios, shifting points, etc) . I don't know if both vehicles have the same transmission or not.
Toyota Highlander AWD Limited is 4321 lbs
http://www.toyota.com/highlander/specs.html
Lexus RX350 AWD is 4090 lbs
http://www.lexus.com/models/RX/detai...fications.html
Given that by Lexus' admission both vehicles have identical engines, it is not unexpected that the lighter vehicle would accelerate faster. That's due to a higher power to weight ratio, not premium gas.
Also when comparing acceleration you need to consider the transmissions (gear ratios, shifting points, etc) . I don't know if both vehicles have the same transmission or not.
http://en.wikipedia.org/wiki/Toyota_GR_engine#2GR-FE
As an engineer, get a Highlander and a RX350 and put them on a dyno. Put 87 in one and 91 in one or both and measure it.
No real engineer argues solely on spec sheets. Manufacturers are in the habit of being conservative with HP ratings due to litigation. The Nissan GT-R is rated at ~470HP but production units often measure 500+.
The same engine in different applications produces very different numbers:
http://rav4world.com/forums/viewtopi...e298a98f35da83
"The 2GR-FE in the RAV4 is rated at 269hp and 246ft lb of torque on regular gas
The 2GR-FE in the Camry is rated at 268hp and 248 ft lb of torque on regular gas
The 2GR-FE in the Highlander is rated at 270hp and 248 ft lb of torque on regular gas
The 2GR-FE in the RX350 is rated at 270hp and 251 ft lb of torque on premium
All ratings are for 6200 rpm for HP and 4700 rpm for Torque "
In the Lotus evora the same engine produces 276HP@6400 and 252 lb-ft@4700.
So your argument that it is the same engine so must be the same no matter which car it is in holds no water. Lexus tuned the 2GR-FE to produce the numbers with 91 octane for RX. Acura does the same with the Pilot and MDX.
Last edited by oarnura; 11-23-08 at 12:33 PM.
Thread
Thread Starter
Forum
Replies
Last Post
amf1932
ES - 5th Gen (2007-2012)
2
06-20-06 07:06 AM