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SUVs Acura RDX Acura RDX Real World MPG
189 messages, Last post on Nov 08, 2009 at 3:44 PM
You are in the Acura RDX Forum. Your Hosts are steve_ & tidester
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Replying to: blufz1 (May 07, 2007 1:56 pm) I don't know what lofty engine specs are normal for you, but most shoppers see a big difference between the RDX and CR-V in terms of power and general sport feel. I know I did. The RDX is certainly not super fast and it's not a sports car despite what some people may think, but it's no slouch either. It's one of the best handling SUVs I have driven, and the powertrain is decent. 0-60 times in the 6 second range are still pretty good for a realistic SUV nowadays.
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Replying to: c_hunter (May 07, 2007 6:40 pm) |
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This may have been covered already, I just didn't feel like reading the next 100+ posts. People on here keep saying "well my other car didn't do this bad and I drive them both the same". Is your other car TURBO'D? If you have a firm foot off the line, doesn't have to be heavy, just firm til you hit second or third. On a turbo'd vehicle, you are engaging the turbo that much more which uses more gas. The whole idea for the reduced lag is to get the turbo goin sooner so you dont have to dip into the throttle that much. If you don't change your style of driving, you will get crappy mileage if you drive the way I explained. One more thing on the turbo. It is ALWAYS spinning which means you will use a bit more gas, even at low throttle or cruise. If Acura was REEEEALLY serious about addressing this problem they would do well to do one of a few things. One, put a better variable geometry turbo in. They make models that vary intake across all driving conditions and dont open and close one valve when a certain parameter is reached. This one has vanes that turn to allow the ideal flow for just about any driving condition. Another idea, one mentioned, is to adjust the tuning or have a knob that adjusts it for you, maybe even allow a lower octane or just tune for 89 instead of 91. The reason 86 or 87 doesn't work is because the ECU can't accomodate that degree of a difference and running for extended periods on this will hurt the engine. 89 on and off from 93 won't hurt anything. All the time, maybe it'll do some damage. One last thought that might help not with mpg, but range, is a bigger tank. Just a few more gallons as weight will become eventually become a concern. I don't own one but am seriously looking. What is the break-in instructions for the car? I see people who have to drive other cars a set amount of miles UNDER a certain speed in order to properly break the engine in. I'm curious if this has any bearing on what some people are doing. People are saying they do several hundred mile trips on a BRAND NEW car. That doesn't sound like a great idea to me. Any thoughts?
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Replying to: oncrank (May 09, 2007 6:59 am) There have been numerous variable nozzle / variable vane turbo designs over the years, but none have proven reliability or longevity -- they have too many delicate moving parts in a hot exhaust gas stream. One of Honda's stated goals was to make the RDX turbo simple and reliable, something that should last a long time. They just would not be able to achieve that goal with the more exotic variable geometry turbo designs. I believe that's why you never see those in production automobiles nowadays. In fact the last application I remember was one of Shelby's turbo Dodges back in the late 80s or early 90s. I actually appreciate that the RDX has a couple more gallons in the tank than my last similarly sized vehicle. It means I can realistically go past 400 miles on a highway trip, something I could not do before. The RDX has a 600 mile break-in period. They give the usual guidelines: no hard stops, moderate acceleration, no constant speeds for long periods of time, etc. There would be nothing wrong with short highway trips as long as you make an effort to vary speed once and a while.
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Replying to: oncrank (May 09, 2007 6:59 am) |
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Replying to: c_hunter (May 09, 2007 8:07 am) 1989 Shelby CSX-VNT BorgWarner makes one built for the 2006 Porsche 911 Turbo.(last paragraph) About the only time the turbo would be "free-wheeling" would be at idle. With any throttle input the turbo provides some form of boost as the exhaust side impeller would be spun. From what I understand the blow-off valve on a turbo doesn't work like the by-pass valve on a blower allowing a no boost condition under cruise. It just protects from an over-boost condition. I might be wrong, my knowledge of turbo's isn't as good as on blowers. I didn't mean to say that it is ALWAYS under boost, I meant under lighter throttle conditions, it is still providing some form of boost which uses more fuel. Even only a few pounds of boost still uses a noticeable bit.
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Replying to: oncrank (May 09, 2007 10:16 am) There's no way I would be getting 25mpg in this vehicle on the highway if it was boosting significantly all the time.
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Replying to: c_hunter (May 09, 2007 4:11 pm) Amount of boost requested is directly controlled by the amount of throttle opening. Ability of the turbo to generate the desired boost is directly related to engine RPM - higher RPM = better ability to generate high boost. This is why many turbo engines have lag at low RPM - high boost is requested, but the turbo can't spool up enough to provide it until the engine revs up. Newer engines usually have very good low-RPM torque characteristics to offset the initial turbo lag.
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Replying to: samiam_68 (May 09, 2007 6:14 pm) I guess what I'm driving at is if this is a large four cylinder, shouldn't this thing be getting a little more than 21-23mpg(as opposed to your 25 which apparently is NOT the norm, I think you're experience with previous turbod vehicles gives you an advantage on how to drive for mpg(note: this is just an opinion))? I'm just trying to see where this drain on mpg is on the highway. If you're getting 25 fairly consistently I'm assuming, what are other people doing that they aren't? Not feathering the throttle enough during cruise? After a little more thought, the biggest thing might just be weight. Compare it to the RAV4 which is aerodynamically similar, 4 cylinder engine, the most glaring difference appears to be weight. The Rav is 400lbs LIGHTER and it's rated at 27mpg highway. Seems to me that may be the biggest reason. All said and done, the biggest culprits in my opinion, are a heavier suv and less skilled drivers or less mpg road conditions(ie alot of hills). As I said, if someone here can consistently get 25, where's the problem? Doesn't seem to be completely the cars problem if the turbo isn't as involved as we've discussed. Just seems to be a HEAVY turbod car with people that aren't as consistent on the throttle as they think or live in slightly hillier areas.
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Replying to: oncrank (May 10, 2007 3:22 am) Also, the RDX 4-cyl spins a lot faster on the highway than the Rav4 V6. A slower spinning engine results in more complete combustion of the air-fuel mix, in turn resulting in better fuel efficiency. Plus, the Toyota/Lexus 3.5L V6 is an absolute gem when it comes to power and efficiency, whereas the RDX 2.3L Turbo is a new and unproven engine. I'm sure Honda will make it more efficient over time. Add all of this up, and there's the MPG gap. |
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