flar

In the "keeping things honest" department:

A couple of figures I've seen thrown about are that the RAV4 is 500 pounds lighter than the RDX and that a V6 engine would add 200 pounds to the RDX.

From the published specs I see that the RDX is only about 260 pounds heavier than the V6 RAV4, not 500 pounds. Also, the 3.5L V6 RAV4 is only about 160 pounds heavier than their normally aspirated 2.4L I4 version, so upgrading the RDX turbo 4 to a normally aspirated 6 might add under 160 pounds (less the weight of the turbo and its plumbing for an even closer weight), not 200 pounds - if the engine weight difference is comparable across manufacturers.

Some things to note - if you compare the weights of the base V6 and I4 RAV4 then the difference in weight is greater, but the V6 adds additional options which add more weight - comparing the higher end models with the two engines gives a figure that is closer to the difference in the engine weights since their higher trim levels have less options bundled with the V6. I also compared weights of the higher end RAV4 to the RDX, though all were less than 300 pounds lighter than the RDX - it seems fairer to measure vehicles with more comparable trim levels and the total variance is only about 20 pounds for all RAV4 models.

RDX Jockey

Lets do the math and hopefully end this discussion: I have noticed that I get ~2mpg better with premium 93 over 89. The tank size is 18 gallons (agree?). 18 gallons at $3.35 for 89oct (west of Chicago) = $60.3, 18 gallons at $3.45 for 93oct=$62.1. 18 gallons at 21mpg (93)=378miles, 18 gallons at 19mpg (89)=342miles (36 mile differnence = ~ 2 gallons). 378miles/19miles/gallon=19.9 gallons to go the same distance as putting in 93 oct. 19.9 gallons at $3.35=$66.6 vs $62.1 for the same distance if I would have put in premium to begin. When the margin between mid and premium is small there is absolutely no benefit to putting in mid grade. If one thought they could put in regular then go for it and you get what you deserve.

mav238

Exactly...

It's like a guy who buys a high performance Porsche 911 turbo, and asks if he could replace the brake rotors (which were originally ceramic composite) with lower grade metal alloy from manufacturers like Raybestos, Bendix, PBR etc... Go figure...

RDX Jockey

Someone might need to translate my math into Canadian liters. Thanks

Chas2

Where is the 50/50 from? It 57/49 according to Acura

http://www.hondanews.com/categories/762/releases/3464

Versus the X3 which is 51/49
Or the X5 which is 48/52 (yes, heavier in the rear)

Or the MDX 56/44
Or the RL 58/42
Or the TL 60/40
Or the TSX can't find it.

sasair

57/43

EKNE

Better performance with higher octane. Get the beast to work for you and enjoy the ride.
14-15 MPG (city), and I enjoy riding the beast.
It's only money and new ones are printed every day, live life.

mav238

I guess it is one of those things where you made a decision to go with a particular type of vehicle, and you simply stop complaining about the maintenance cost, since you should have already factored that in before the purchase.

One could be a somewhat conscientious driver and not excessively pollute the environment and waste unnecessary money, by not stomping the gas pedal every time one drives off from the traffic lights... and only boost the turbo up when required (passing a slow moving vehicle, climbing a steep hill).

Plus here, I have been raking up the airmiles by pumping premium at the Shell stations anyway... since I need to pump premium anyway, I went with Shell V-Power and earn the airmiles, great top-tier fuel + the added bonus...

sasair

I have been earning 5% cash back on my gas purchases so the $3.19 I am paying today for premium is really $3.03. Not too bad relatively speaking...

mav238

Me too... I use my Amex for fuel purchases, and get back 2% in cash savings.

PERDY

If premium fuel is such a question then do not buy an rdx period. It is way to precious of a vehicle to mess with something so small. PREMIUM PREMIUM PREMIUM PREMIUM PREMIUM Enough said!!!!!!!

1092

O.K. - I get your point. I'll buy another car.

dio

LOL.......You should if its that such a big a concern.
Seriously If you buy an Acura premium car, you should'nt sweat the extra cost of fuel.

gubby

Or use a credit card that offers gas price discounts! I have a Canadian Tire Gas Advantage card that accords me up to 10 cents per litre off if in the previous month I spent $1,000 or more on the card (not too hard to do), and you don't have to carry a balance. So, with 10 cents off per litre my premium costs the same as undiscounted regular. You get the best of all worlds - a premium vehicle that demands premium gas that you can buy at a regular price.

mav238

Which part of Canada are you in? Here in Vancouver, Canadiantire outlets do not have gas kiosks...

In any case, I have been planning my drive to work to optimally avoid as much heavy traffic as possible; the ride to work is fine (leave for work at 6:30am, no real congestion), but the ride back home is always congested. Most of my driving in 90% city traffic (lots of stop lights), and 10% highway. I also live on a mountain top community, so would have to drive up a somewhat steep hill road everyday.

Thus far, been getting about 11.3-11.5 L/100km; which i think is not bad for a full-time AWD system, plus the weight of being a CUV.
My old BMW 330i with it's 3.0L inline six was getting about 11.5L/100km, and that was only RWD. Granted the 330i was not a light car in itself...

I have to admit, I don't scoot the turbo too much, only hit the turbo when required to pass a vehicle... I also don't do jack-rabbit starts from traffic lights, definitely would waste a lot of gas doing that.

Thus far, been using only Shell V-power 91 and although the gas prices are crazy, I think the savings with using 87 octane does not outweigh the potential for engine trouble in the long run.

The same goes for the engine oil... Turbocharged engines run really really hot... so to prevent failure of the turbo, the oil must be heat stable, regular dino oil will not do... it has to be synthetic that provide the best protection...
synthetic oil is at least 2-3 times the cost of regular dino oil..

so if one would stinge on the price difference of 87 gas vs 91 gas, then why not stinge on the engine oil and use dino oil instead?

No...why... because the engine was designed to run reliably with synthetic oil...period...

gubby

Mav, you are out of luck if you don't live in Ontario. Apparently the gas advantage card is available ONLY in Ontario: http://www.ctfs.com/english/gasadvantage/index.html

mav238

Cool... Ontario does have a number of perks we British Columbians do not get, but hey, we have the gorgeous mountains!!!!!

But have you considered the possibility that your RDX turbo engine might suffer from deposit accumulation in the long run (within a year or so) with the use of gasolines with limited detergency?
From many reports (both from private and government agencies), only those gasolines with significant detergent agents in it keeps the engines running cleanly for a long time. That is one reason why I stay away from gasolines from supermart stores such as The RealCanadiansuperstore, Supersave, Saveon Gas. Over the past 10 years, running my various vehicles on the different gasolines, the non-branded ones definitely were not as good in keeping my engine running smoothly, even ESSO was inferior. The main one I found to be consistently great in keeping the engine running cleanly was chevron. But ever since Shell V-power was named top-tier gasoline as well, I switched to Shell V-power on my 2005 TSX and my 2007 RDX, and found it to be as consistent in it's overall clean performance (over a year now for the TSX).

Getting the engine overhauled, injectors cleaned out, and combustion chambers de-carbonized is not a cheap service...

Ledwinka

Wow. Thanks for the power of Google, I hit upon a VERY interesting read from USA Today, an article from FOUR years ago. Check it out.

http://www.usatoday.com/money/autos/...emiumgas_x.htm

And more interesting comments from engineers from car companies telling us that you do not REALLY have to use premium over regular.

[Quotes From the Article]
"I personally use regular even though my owner's manual says you'll get better performance with premium," says Lewis Gibbs, consulting engineer and 45-year veteran at Chevron oil company. He's chairman of Technical Committee 7 on Fuels, part of the Society of Automotive Engineers (SAE) Fuels & Lubricants Council. Gibbs knows gas. "My wife runs midgrade (89 octane) in her car, and it's a turbocharged engine" meant for 91-octane premium, he says.

"Generally, the more expensive the vehicle, the higher the expectation for performance and the more the customer is willing to pay for fuel," says Pete Haidos, head of product planning for Nissan in the USA.

The only modern engines that should really need premium are those with superchargers, which force-feed fuel into the cylinders. "You're driving along and just tramp the gas and the knock sensor cannot sense the knock fast enough in some cases," because the supercharger boosts pressure so fast, says Bob Furey, chemist and fuels specialist at General Motors.

All Porsche engines are designed for premium, too, but it's not available everywhere. "Our cars must be able to drive all over the world, and so we are able to run on regular," says Jakob Neusser, director of powertrain development at Porsche's research and development center in Weissach, Germany. "You don't have to feel that a mechanical problem or anything else will happen" using regular gas, even in the highest-performance, regular-production Porsches.

"There is no gain. You're wasting money," insists Jim Blenkarn, in charge of powertrains at Nissan in the USA.

...And the one for us Honda fans:
"I go back and forth, and I'm hard-pressed to notice" whether there's regular or premium in the tank, says Jeff Jetter, principal chemist at Honda Research and Development Americas. He drives an Acura designed for premium.

Ok, SAE, Nissan, GM, Porsche, and Honda engineers and scientists telling us that really, so-called premium gas cars need not be filled with premium and go with regular is a fact that is nice to know. So go with which ever you want: either way, it will satisfy your wallet or your sense of well being.

722ish

I think based on the knock sensor response itself is enough to use a mildly higher octane. Another big issue is the timing AND boost. It is important to know both to make judgements on what octane it needs. I do believe however that H/A used a premium fuel friendly calibration for the RDX based on timing and boost compensations. They assume people buying the RDX would enjoy the potential performance from the 2.3 turbo four, rather than just a bit of wooshy noises when they part throttle it from a traffic light.

I do also believe that at some point or another somewhere along the line, the RDX was designed solely as a 4 popper powerplant, and that a 6 or bigger would have required a revamp of the chassis, which for cost cutting is bad. Also, it was probably easier to produce the rdx with this motor for the epa, crash safety and im sure there are other potential reasons. It may have been to showcase honda's ability to try new stuff. The technologies in the car are good, why cant the underhood be!

take care
Mark

mav238

Interesting article... I am not so sure about the info regarding turbocharged engines... We are talking about high compression engines here... My old SAAB 9-3 sports sedan was a turbocharged 2.0L engine, and I tried running 87 octane on it, and the engine was not very happy... I fact, my gas mileage worsened with the use of 87 octane, so end up being about the same if I had used premium gas which it was designed for and what SAAB was stipulating as the required fuel grade.

We also need to talk about what kind of load conditions the cars are typically driven in... if the engine is always under significant load, such as driving in cities where the roads are hilly with steep grades, or the car is always towing something, then if the engine was designed to run on premium fuel, and you put in 87 gas, the engine will ping and knock constantly, which is not good for the engine in the long run...
On the other hand, if you drive constantly on perfectly flat roads, hardly boost the engine much at all, does not load up the trunk or tow anything regularly, then I guess 87 gas will do fine in your engine that was designed for 91 gas.

Ultimately the question lies in, why buy a car with an engine that was designed to give the peak performance and long-term durability with 91 gas, when you don't really care about the engine performance requirements or long-term durability. Then in the first place, you should have targeted cars with engines that do run on 87 gas.

As I posted previously, if someone buys a high performance Porsche, and his Ceramic composite brake pads and special rotors are worn out... he goes and buy Raybestos or some generic brand rotors and pads (assuming they do make them), and fit it to his Porsche, will it stop the car, sure it would... would it stop the Porsche as efficiently as it's special OEM parts, especially when coming to a stop from a fast run, say on the freeway? I bet you not...
If this person who bought the Porsche, drives it like an old grandmother, the generic brake components will probably be fine...

Performance = specially designed components and specific fuel grade requirements

Of course, there is absolutely nothing gained in a car that was designed for 87 gas, to run on 89 or 91 octane gas...

If running 91 octane gas is ludicrous or unimaginable, even if you car was designed to use it, then in the first place, don't go for cars like these, target cars like the Accord, CRV, Yaris, which are all great cars in their own respect...

loulinjai

Being a Canadian, for drivers in BC, SK and MB, Husky sells E10 90-octane grade fuel for the price of regular at other stations. Problem solved: high octane at a low price.
As for the ethanol discussion, many fail to know that ALL top-tier gas MUST contain at least 8% (to a max of 10%) of denatured ethanol across ALL grades of gasoline. (source toptiergasoline.com). Plus it's also a misconception that higher-octane gas makes ur engine run cleaner. According to top-tier requirements, all grades of gasoline at a top-tier gasoline recogized location must meet top-tier requirements, not just the premium grade.

Makolern

Where I live the octane ratings at the pump are 87, 89 & 93 - no 91 octane. I have been filling up as follows:
if I'm going to be taking a high speed trip or hot throttling around I fill it with the 93; for normal driving with a soft foot I alternate between filling up one time w/89 octane, next time with 93; I usually fill when it is barely below half full; when I forget what the last fill-up was or am not sure of the station I'm buying the gas at I may go for the 93 just to be safe.
My theory is that the gas will slop around as I drive and mix-up reaching an average of something near 91 octane. Anyone have toughts on this?
I could be screwing up the sensors or worse, I don't know. It really depends where I buy the gas I guess. Sometimes I'll pull into a station where prices are much higher than my usual neighborhood Mobil, so I'll put a little 89 octane in, not filling the tank, just enough to get home on and save a few pennies.

Fishbulb

I've been running 89 virtually exclusively since the 3rd fillup, and I'm at 45,000 kilometers now. No problems, no issues.

I did a test on 91 and 87 octanes to see how the mileage compared to the 89; the 91 provided no benefit from a performance or mileage standpoint, and the 87 provided worse mileage, and a bit of performance decline; the knock sensor probably came into play.

AcuraTLowner

Yeah..... 91 & 93 octane are virtually the same (same burn rate).... ratings are not a linear relationship.... What you are mixing up in your tank is something around 89.5-90 octane. If you want to save the money & hassel... just stick with 89..... If the difference is a dime per gallon or less, go with 93

mav238

I am sure you are being factual with your claim that using 89 octane caused "no tangible issues" with performance...

But if you are driving in a place with lots of hilly roads or ones with somewhat steep grades, then the difference with 89 and 91 octane gas can be quite significant...

I really don't get it... if the manufacturer indicates that premium gasoline is required (and only use 89 or lower gas when nothing else is available, temporarily), why try to "stinge" on the 0.05 cents per litre?

I can understand when it would be stupid to use 91 gas in a car that is designed specifically for 87 gas.
Say you use 200L of gas per month... you save 0.05 cents per litre using 89 gas...
That would be $100 a month, and $120.00 a year. I know that is not a little bit of money, but for $120.00 difference, why would you not put in what Honda says is necessary for optimium operation and durability of the engine?

XIS

I don't get it either. Why risk something so significant (engine) for such a low ($1.00 a tank) financial impact???

mav238

oops... me bad...

recalculating... saving $0.05 pre litre, equates to saving $10.00 a month for 200L of gas, and thus $120.00 a year.

anyway, to add to this point... if we are driving a GMC SUV, which requires only 87 gas, and we use 91 gas in it, assuming it is quite a gas guzzler, uses 400L per month, that would mean this person would be spending an extra $40.00 a month, or $480.00 a year. For some this is small change, but here, I think it is simply stupid to spend that extra $480.00, because there was actually no need to use 91 gas.

In the RDX, we all knew buying the RDX that Honda designed it as a turbocharged engine, which, if you check with all late model cars that has a turbo, specifically stipulates the use of 91 gas for proper operation and durability of the engine.

mav238

More threads on this issue of using premium fuel in turbocharged engines...


http://autos.yahoo.com/maintain/repa...ques071_5.html


http://action.publicbroadcasting.net...ist/45217.page

chipt911

Even the six cylinder, non-turbo Lexus RX350 required premium gas.

johnny99

Requires or recommends?

chipt911

Same wording as the RDX.

mav238

Think about this...

Why would a car manufacturer design an engine that runs on 91 octane gas and produce say 240 HP, and then put in a "smart" system such as anti-knocking software to alter engine timing, and allow the car to use 87 gas, and yet no detriment to performance...

The engineers who designed the above engine would be quite illogical and a little "off"... Actually to think of it, it is a stupid design effort...if 87 gas does the same as 91 gas, why even suggesting the use of 91 gas in the first place???...

If you read the manual again, it says that it recommends the use of gas with < 91 octane, only if you can't find any other available choice... but to move back to 91 gas when possible...

The engine will not "self-destruct" when 87 gas is used... but the anti-knock system can only adjust so much and for so long, until the engine will develop some issues over the period of ownership...
Well the above point is mute, if one is only leasing the vehicle and any repairs required after the lease period is not his/her problem...
But if you are intending to keep the vehicle for a bit of time... why stinge on the $120-150 a year on gas?

Trust me... if Honda wanted to have a RDX engine that runs on 87 or 89 gas specifically, it could very well put it in there... a de-tuned 3.2L iVTEC V6 would work...
But it specifically put a turbocharged engine in there... go figure...