Fuel mileage update
- Thread starter erhayes
- Start date
singlemalt_18
My Way IS the Highway
- :
- 18Sig9/07GT7AWD
My wife & I bought our 2007 CX-7 AWD Touring in August 2006. Currently, we are at about 12,000 miles which are mostly highway, but they are "fully loaded" with luggage for the most part too. (It is not one of our day-beaters since we drive "used" Subaru Legacys for the daily grind.)
I have always used 91 octane, or a mix of 89 & 93, and we have averaged 18.7 mpg. I am not bashful with the boost.
We like it very much.
I have not run the standard deviation because I am a recovering analytic.(headbang)
I have always used 91 octane, or a mix of 89 & 93, and we have averaged 18.7 mpg. I am not bashful with the boost.
We like it very much.
I have not run the standard deviation because I am a recovering analytic.(headbang)
while i was stopping by, i saw this post..... how do "you" decide when you are going to use turbo power, absent a boost gauge....im not asking an idiot question, i guess what im asking is do u just not accelerate past 2k rpms or something, do u have a boost controller or something else?
seems crazy that you can tell, especially in the CX-7 where I found all turbo noise vacant from under the hood, how you could possibly know when u are using "turbo power". I find it impossible that you could know and or restrict the turbo from flaring other than when merging. Given that I have the active gauge in the RDX, turbo is spooling 90 % of the time in low boost, even when you would think ur not into boost range or under 2k rpms. so i guess the point of my post is...how can you can make a claim that u are not using boost unless you have proof otherwise (and if you do, sorry for my post!
)Well mickey, as we know the turbo is always spinning when the engine is running as it is part of the exhaust system. Boost is not an on or off situation but, rises and falls with exhaust gas velocity. We do know from Mazda engineering explanations that pressure boost does occur as low as ~1,500 rpm & climbs to a max at ~ 2500 RPM. The quoted figures are at WOT and we sometimes forget that part of the equation (@WOT). If one lets the engine come up to ~ 2500 and shift then one can assume that little boost is available since exhaust through-put is fairly low.. If one starts to demand more power then the wider throttle opening with produce more exhaust pressure and boost rises and you can feel the step function from the engine or at least most of my friends and I can. I have often wondered at what steady state cruising speed in 6th gear you start to get a boost of say 1/2 to 1.0 PSI. Since you do have a boost gauge, will you do a little experiment and try cruising at various highway speeds to determine where boost starts at steady state cruising speeds? Thanks for your input.
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all done on flat highway...baseline mph i kept at about 70 on more or less even highway
Steady Acceleration - turbo usually will just nudge off the resting needle & always stay in the lower 1/3 of the gauge..rpms highway cruising 60-80 are usually around 2k-2500k
acceleration - boost will shoot into 2/3rd section, sometimes going into the top 1/3rd of boost (depending on incline etc)
WOT - almost always will be full boost
Steady Acceleration - turbo usually will just nudge off the resting needle & always stay in the lower 1/3 of the gauge..rpms highway cruising 60-80 are usually around 2k-2500k
acceleration - boost will shoot into 2/3rd section, sometimes going into the top 1/3rd of boost (depending on incline etc)
WOT - almost always will be full boost
ok, so ........erhayes?
one thing i guess is missing from this, the instant u step on the gas to accelerate, whether you think u r just feathering the pedal or really getting on it, boost will spike in the mid/upper 2/3rds, no matter what speed/incline ur at...boost spikes greater on the highway than it does in the city...if u do a turtle acceleration from a stop, u can keep it in the lower 3rd, whatever that equals out to what psi the engine is pumping out i dunno, i know the psi is very similar in both the RDX & CX-7, coming on very strong than dying out in the 5k range, the RDX has much less if non-existent lag compared to the Mazda, whether thats a result of the psi at various points/increased boost who knows, maybe the vari-flow turbo is my guess....so generally, i guess my point is that its basically impossible in the RDX to keep the needle out of boost, keeping the boost low is one thing, but its much much harder than you think, even when you "think" ur accelerating slowly, going slow and all that...
ill also say its basically impossible to crack upper teens for city mpg in the RDX, and 22+ on the highway is a distant prayer, some people get it...but thats like a legit 90%+ highway
i added a K&N drop in air filter, improved my city mpg from 15's to 17's and highway from 20 to 22's
these vehicles are boost hungry its how they go....staying off the boost is possible on the highway, as long as you are seriously not depressing the gas pedal and keeping the car at such a steady speed ud rather be watching paint dry
one thing i guess is missing from this, the instant u step on the gas to accelerate, whether you think u r just feathering the pedal or really getting on it, boost will spike in the mid/upper 2/3rds, no matter what speed/incline ur at...boost spikes greater on the highway than it does in the city...if u do a turtle acceleration from a stop, u can keep it in the lower 3rd, whatever that equals out to what psi the engine is pumping out i dunno, i know the psi is very similar in both the RDX & CX-7, coming on very strong than dying out in the 5k range, the RDX has much less if non-existent lag compared to the Mazda, whether thats a result of the psi at various points/increased boost who knows, maybe the vari-flow turbo is my guess....so generally, i guess my point is that its basically impossible in the RDX to keep the needle out of boost, keeping the boost low is one thing, but its much much harder than you think, even when you "think" ur accelerating slowly, going slow and all that...
ill also say its basically impossible to crack upper teens for city mpg in the RDX, and 22+ on the highway is a distant prayer, some people get it...but thats like a legit 90%+ highway
i added a K&N drop in air filter, improved my city mpg from 15's to 17's and highway from 20 to 22's
these vehicles are boost hungry its how they go....staying off the boost is possible on the highway, as long as you are seriously not depressing the gas pedal and keeping the car at such a steady speed ud rather be watching paint dry
Interesting mikey1981. I am surprised at the sensitivity of the turbo response. Do you know if the boost gauge is linear? I am hoping to see where a one pound boost comes in at a given steady speed. Your first picture seems to indicate zero boost? at 70 mph? Am I seeing this correcly? Thanks again for all your effort-much appreciated mickey1981. Ed
you can keep it at zero boost, but u have to basically not move the gas pedal...any slight depression and the boost will float into the upper 1/3 or into 2/3rds of the gauge..the first pic was no boost - steady acceleration basically keeping my foot on top of the gas pedal...the 2nd pic was slight acceleration only to about 75mph and you can see the results
id say the gauge is close to linear because its almost immediate in response and given the power band in the RDX, seems to directly reflect...you will see a direct correspondance between rpms and boost, ex. at 5k and full boost, the needle will drop off when psi is cutoff by the comp
i guess the good thing in the RDX is that you can hear a direct correspondance of all systems working together - audible turbo, spool & blowoff, in relation to the gauge, speed, and rpms etc..so it all makes sense under the hood between noises = performance...from the needle you know when boost is kicking in
the Mazda, not really...I never heard anything to indicate to me when i was going to accelerate...i remember the waiting game at red lights and stop signs, and power was so abrupt i never felt comfortable behind the wheel...you try to use the tach as your guide but even then never had the feeling of security with power delivery, thus never knew when the turbo was spooling and boost would be delivered....which is why in my original post to you, had no idea how you could think you were controlling boost in relation to good mpg, i just never knew in the mazda...all i remember was going 75/80 netted me better mpg than going 60/65 (probably because it eliminated the horrible gear hunting from 5 to 6 6 to 5)
id say the gauge is close to linear because its almost immediate in response and given the power band in the RDX, seems to directly reflect...you will see a direct correspondance between rpms and boost, ex. at 5k and full boost, the needle will drop off when psi is cutoff by the comp
i guess the good thing in the RDX is that you can hear a direct correspondance of all systems working together - audible turbo, spool & blowoff, in relation to the gauge, speed, and rpms etc..so it all makes sense under the hood between noises = performance...from the needle you know when boost is kicking in
the Mazda, not really...I never heard anything to indicate to me when i was going to accelerate...i remember the waiting game at red lights and stop signs, and power was so abrupt i never felt comfortable behind the wheel...you try to use the tach as your guide but even then never had the feeling of security with power delivery, thus never knew when the turbo was spooling and boost would be delivered....which is why in my original post to you, had no idea how you could think you were controlling boost in relation to good mpg, i just never knew in the mazda...all i remember was going 75/80 netted me better mpg than going 60/65 (probably because it eliminated the horrible gear hunting from 5 to 6 6 to 5)
Thank you mickey. When you used the term steady acceleration did you really mean a constant or steady speed like in zero acceleration? If so then if one uses the cruse control on level ground and no wind that the boost will be zero or very low-true? at least up to 75 mph or so? You mentioned gear hunting between 5th & 6th. I had that issue until I had the dealer update the TCM. If you have not had this free software re-flash, I would do it. In fact I had both the EMC & TCM updated on my 2007 and it was a very worthwhile improvement for my type of driving. Thanks again mickey1981. Ed
i had all reflashes up to the point when they took the car back...i did not notice any significant improvement to be honest, the car did not like to be in 6th gear on the highway, and the second you would call for some acceleration, it would downshift no matter what....so, i left it in manual on the highway and kept it in 6th to eliminate the computer
70 no boost - im talking here about pure steady accerlation just as if cruise was on...no noticeable flux in rpms etc...but given that those conditions are likely never to be constant, theres always going to be a tad of boost whenever the cars speed changes, even if its 1mph etc - on the highway think of it this way, if u are depressing the pedal, the turbo will spool, whether that depression is barely noticeable or to actually speed up doesnt matter
70 no boost - im talking here about pure steady accerlation just as if cruise was on...no noticeable flux in rpms etc...but given that those conditions are likely never to be constant, theres always going to be a tad of boost whenever the cars speed changes, even if its 1mph etc - on the highway think of it this way, if u are depressing the pedal, the turbo will spool, whether that depression is barely noticeable or to actually speed up doesnt matter
TrueDelta conducts a real-world fuel economy survey that, unlike others, includes driving style and driving conditions. Results so far for the CX-7:
Real-world Mazda CX-7 gas mileage
More participants would help us sort out the impact of the various variables (need a fairly large sample size to break these out).
Real-world Mazda CX-7 gas mileage
More participants would help us sort out the impact of the various variables (need a fairly large sample size to break these out).
