AV8R_BOB

But again, how is the RX taking avantage of higher octane, when the HP is the same for both Toyota and the RX?

AM1

iTrader: (6)

thats why when people say it feels like, or "seat of the pants" feel, might have some psychological benefit, but theres no uniform data to back it up. even those in car units like the gtech unit i think it is still isnt 100 perecent accurate. even using a dyno could depend on type of dyno, ambeint temperature, octane rating, load in car, etc etc.....so many variables at "play" so to speak, bob has got it right on though.

good way to explain the weight to power issue. as just about any racer will tell you that adding more weight slows it down. or could be weight distrubution also, i dont know for fact since i havent checked the rx might have less weight over its front wheels which would also give it a quicker accleration, just like how it would be reveresed in a RWD car, well kinda anyways.
well you know what they say people who drive luxury cars many times expect big engines or lots of HP, even though most cars used for street purposes really dont need that much power. the same could theoretically be said for "feeling" the need to put the perceived "better" gas (premium) in their cars whether or not it truly needs it. **disclaimer** im not knocking what anyone does with their cars. i do understand why cars that run high compression, are using forced induction (turbo, super) need higher octane, same with cars using N20 better known as nitrous oxide.

you might be right on that one. i just think that bob has a valid point and a valid case for putting or not putting in higher octane gas in the RX. it would be cool if people can try and see his point rather then jump to conculsions based on evidence and data that at best is "shaky", Lexmex for example has tried out some experiments to see what works, his case is different then most since his car is modified, proably beyond what most people do to their own RX.

The G Man

The RX has 3 more ft-lb of torque.

lexus114

I understand where you are coming from,(so to speak) with this.And you are correct with what you mentioned,(same route,no ethonol etc.)But we are never going to get an answer from Lexus,at least not a correct one re:this.because their are too many different people involved(on their end)that simply put DONT KNOW the answer.I only mentioned to you an average Joe way of finding out the differences.It`s not rocket science here,it`s simply how you like your vehicle to perform.
Ryan

AV8R_BOB

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?

The G Man

I got a feeling either the HP or the rpm have been round off here somewhere. I have been saying for years that the 3.5 L engine in the RX does not require premium fuel, the compression ratio is not high enough. For people who tow or drives in a hilly terrain, they should use premium for the added performance. I have tested 91 vs 87 octance for MPG, there was virtually no diff. in gas mileage and a slight diff. in performance.

sup_lexio

All RX'S HAVE THE Knocking PROBLEM WHEN USE 87 octane.

biff44

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.

Benny49

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............

The G Man

Mid grade is a waste of time IMO, its only 10 cents cheaper.

howdybob22

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.

ecount00

Then what would there be to bicker about? What's fun about that?

sup_lexio

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

Boognish

The engines could have identical peak horsepower but different peak torque if there is more area under the torque curve in the engine tuned for premium.

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.

oarnura

"The 2GR-FE is a 3.5 L (3456 cc) version. Bore remains at 94 mm but stroke is reduced to 83 mm. Reported output varies depending on the vehicle application, but is approximately 268 hp (200 kW) at 6200 rpm with 248 lb·ft (336 N·m) of torque at 4700 rpm on 87 octane (R+M/2) or 280hp and 260ft of torque using premium 91 octane.".
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.