derekmd07

Is Rx350 Engine The Same As Toyota Highlander?

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Hi,

I have looked up some specs and found that Toyota Highlander and Rx350 engines have the same displacement, very similar output (favoring Lexus), and compression ratio. I wonder if they are in fact identical but Lexus has modified the software to squeeze out 5 more hp with premium fuel requirement.

Thoughts?

Given the compression ratio is modest and that the engine is identical to that of Toyota Highlander, I am starting to think that the Rx can accept regular fuel with little compromise with regards to reliability and performance. Ok, I give Lexus that 5hp lol

Comments are welcome.

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Hi,

I have looked up some specs and found that Toyota Highlander and Rx350 engines have the same displacement, very similar output (favoring Lexus), and compression ratio. I wonder if they are in fact identical but Lexus has modified the software to squeeze out 5 more hp with premium fuel requirement.

Thoughts?

Given the compression ratio is modest and that the engine is identical to that of Toyota Highlander, I am starting to think that the Rx can accept regular fuel with little compromise with regards to reliability and performance. Ok, I give Lexus that 5hp lol

Comments are welcome.

You've provided some very good information here (i.e., that the Highlander engine is a doppelganger for the RX engine). You'll hear from some that you are doing horrible things to your engine running 87 octane; why would you risk expensive damage just to save 20 cents a gallon?; etc. etc. yada yada yada.

Your logic is correct; virtually the same powerplant tuned to make slightly more power output if you run higher octane fuel. Who wants to spend thousands more for a Lexus and have it reported that it is only as powerful as it's Toyota brethren?

I've run 87 octane in three RXs now for well more than 100k miles (some miles at wide open throttle right up to redline) and never heard a ping, a knock, a bang, etc.; every owners manual recommended 91 octane or better (but how much better? - I can get my hands on 112 - should I run this instead?) And I've always been pretty impressed at the power output - never a sign of compromise from my vantage point. The 2010 engine is very impressive.

My opinion: high octane and 5 horsepower is just marketing BS. The owner's manual does not "prohibit" you from running 87 octane; only recommends high octane to obtain best performance.

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I agree with everything said. I've had many cars before, including 335xi and M3. Those cars, without doubt, stipulate premium fuels because of their high compression ratios and turbo. Having said that, Lexus 3.5L engine is essentially the same as Highlander. It's marketing gimmick to make people believe they've purchased a Lexus and it "deserves" to be fed premium fuel. I consider myself a car aficionado. I will never cheap out on gas to risk damaging the engine. But I firmly believe the Rx can and will take regular fuel with little to no decline in performance.

I've read an older post, which is now locked, regarding the prospect of using regular fuel. The person who broached this topic got flamed. Although a few bucks saved for every fill up seems inconsequential, this amount sure beats the interest you garner from the bank nowadays. Food for thought :)

Hi,

I have looked up some specs and found that Toyota Highlander and Rx350 engines have the same displacement, very similar output (favoring Lexus), and compression ratio. I wonder if they are in fact identical but Lexus has modified the software to squeeze out 5 more hp with premium fuel requirement.

Thoughts?

Given the compression ratio is modest and that the engine is identical to that of Toyota Highlander, I am starting to think that the Rx can accept regular fuel with little compromise with regards to reliability and performance. Ok, I give Lexus that 5hp lol

Comments are welcome.

You've provided some very good information here (i.e., that the Highlander engine is a doppelganger for the RX engine). You'll hear from some that you are doing horrible things to your engine running 87 octane; why would you risk expensive damage just to save 20 cents a gallon?; etc. etc. yada yada yada.

Your logic is correct; virtually the same powerplant tuned to make slightly more power output if you run higher octane fuel. Who wants to spend thousands more for a Lexus and have it reported that it is only as powerful as it's Toyota brethren?

I've run 87 octane in three RXs now for well more than 100k miles (some miles at wide open throttle right up to redline) and never heard a ping, a knock, a bang, etc.; every owners manual recommended 91 octane or better (but how much better? - I can get my hands on 112 - should I run this instead?) And I've always been pretty impressed at the power output - never a sign of compromise from my vantage point. The 2010 engine is very impressive.

My opinion: high octane and 5 horsepower is just marketing BS. The owner's manual does not "prohibit" you from running 87 octane; only recommends high octane to obtain best performance.

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My 2003 RX300 uses 87 octane with no problems. Like most, I stared using the premium stuff as recommended, until gas hit $4.15/gal in 2005. Out of necessity I switched to 87 octane regular (at Krogers no less)and have had no regrets. Just changed the spark plugs at 110,000 miles and they looked fine. Engine runs like a clock. Why waste your money on highly branched hydrocarbon chains if you don't need to? I'd invest in more frequent oil and transmission fluid changes. For me that is 5000 and 50,000 miles respectively.

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From an engineering point of view, the only thing that higher octane ratings give is reduced "pinging" with a given compression/timing setup. Modern automobiles have computer control of the timing that makes up very nicely for the lower octane--perhaps at some loss of power. I have run my RX-350 and my wife's ES-350 on 87 octane since we got them and never had a problem. We may have lost a little mpg, but we sure paid a lot less $pg.

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Hi,

I have looked up some specs and found that Toyota Highlander and Rx350 engines have the same displacement, very similar output (favoring Lexus), and compression ratio. I wonder if they are in fact identical but Lexus has modified the software to squeeze out 5 more hp with premium fuel requirement.

Thoughts?

Given the compression ratio is modest and that the engine is identical to that of Toyota Highlander, I am starting to think that the Rx can accept regular fuel with little compromise with regards to reliability and performance. Ok, I give Lexus that 5hp lol

Comments are welcome.

Is the compression ratio on the RX350 and the Highlander the same?

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For peak performance and MPGs stay with the recommended premium.

I just checked at Motor Trend specs. for the 2009 Highlander and the 2009 RX350

Same motor designation 2GR-FE

Same compression ratio: 10.8

3,456 cc

Toyota: Power: 201 kW , 270 HP SAE @ 6,200 rpm; 248 ft lb , 336 Nm @ 4,700 rpm

Lexus: Power: 201 kW , 270 HP SAE @ 6,200 rpm; 251 ft lb , 340 Nm @ 4,700 rpm

It may be that the Lexus has a slightly more aggressive timing or camshaft (or not) but the specs are so similar (max. power and torque at same RPMs) that I don't see that there really is a need for premium fuel for the one and not for the other.

As a first step, I will try using 89 octane fuel (mid-grade here in Miami) instead of premium 93.

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A close friend of mine has made his career in fuels development for BP and Amoco. He clearly states that for an engine where premium is recommended, you will get better MPG and performance with premium, but that most modern engines can run just fine on regular. So, you will get better slightly MPG and performance on premium but it will likely cost more per mile because you perform improvement is less than the 8-10% cost difference of the fuel. Use premium because you want the performance, not because you engine 'needs' it.

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From an engineering point of view, the only thing that higher octane ratings give is reduced "pinging" with a given compression/timing setup. Modern automobiles have computer control of the timing that makes up very nicely for the lower octane--perhaps at some loss of power. I have run my RX-350 and my wife's ES-350 on 87 octane since we got them and never had a problem. We may have lost a little mpg, but we sure paid a lot less $pg.

Actually its the ECU control of the A/F mixture via EFI that allows use of regular gas in high compression engines in the "power band". Knock/ping as a result of "detonation" (fuel ignition due to "dieseling", ignition BEFORE the spark) is "cured" by slightly enriching the mixture.

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How about another variable....Ethanol vs Non Ethanol? I get better economy with non Ethanol regular than with Premium Ethanol. Premium non Ethanol provides slightly better economy but is now 25-35 cents a gallon more and I can't tell any difference in power over regular non Ethanol. I'm lucky enough to still have a choice of fuel and will pay a little more for non Ethanol. I'd buy Premium if it made a significant difference in power or economy. Maybe some can discern 5 HP but I sure can't.

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How about another variable....Ethanol vs Non Ethanol? I get better economy with non Ethanol regular than with Premium Ethanol. Premium non Ethanol provides slightly better economy but is now 25-35 cents a gallon more and I can't tell any difference in power over regular non Ethanol. I'm lucky enough to still have a choice of fuel and will pay a little more for non Ethanol. I'd buy Premium if it made a significant difference in power or economy. Maybe some can discern 5 HP but I sure can't.

Ethanol provides about 25-30% less energy (per unit of volume) than does gasoline. If you use 10% ethanol fuel (and if the fuel is really only 10% ethanol), you are losing some 3% vs. gasoline without ethanol.

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I have been using 87 octane for the last 3 months. I see no difference. After my third tank my mileage combined is the same 28mpg.

I did lots of checking before I did it. The lexus mechanics told me "luxury" cars always suggest premium fuel to act like they are in the league with Mercedes or BMW. (My experiences tell me Lexus is not in that class, however they market that way.)

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I have been using 87 octane for the last 3 months. I see no difference. After my third tank my mileage combined is the same 28mpg.

I did lots of checking before I did it. The lexus mechanics told me "luxury" cars always suggest premium fuel to act like they are in the league with Mercedes or BMW. (My experiences tell me Lexus is not in that class, however they market that way.)

You are correct, Lexus is not in the "league" with Mercedes or BMW, Lexus is more than a few notches above...!

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Hi,

I have looked up some specs and found that Toyota Highlander and Rx350 engines have the same displacement, very similar output (favoring Lexus), and compression ratio. I wonder if they are in fact identical but Lexus has modified the software to squeeze out 5 more hp with premium fuel requirement.

Thoughts?

Given the compression ratio is modest and that the engine is identical to that of Toyota Highlander, I am starting to think that the Rx can accept regular fuel with little compromise with regards to reliability and performance. Ok, I give Lexus that 5hp lol

Comments are welcome.

I have a 2010 RX. Have used premium for 2 months and Regular for 2 months. Observed no difference in MPG and no ping at all. Since then have been using Regular and all well.

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I have been using 87 octane for the last 3 months. I see no difference. After my third tank my mileage combined is the same 28mpg.

I did lots of checking before I did it. The lexus mechanics told me "luxury" cars always suggest premium fuel to act like they are in the league with Mercedes or BMW. (My experiences tell me Lexus is not in that class, however they market that way.)

You are correct, Lexus is not in the "league" with Mercedes or BMW, Lexus is more than a few notches above...!
Your right. That's why for several years now, Lexus has been the number one selling luxury car in America. Could be because while your driving your Lexus your friend is waiting to get his BMW out of the repair shop. LOL

Paul

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