Best fuel mileage ever.... a conundrum

[claymore]

First the very good news the best ever for my car 34.5 mpg YAY:p

Now to try and figure out which condition made it happen the most???

A little background is in order. I recently made the loonnnggg trip from our house in Bangkok to the extreme eastern border where Thailand meets Laos and Cambodia. It's about 920KM (572miles) and normally I cruise at about 160KPH (100mph) and yes I drive like a Trooper .... I am one.;)

But this trip I had to drive slower because of one wheel being slightly out of balance so I had a shimmy starting at 140KPH (87 MPH). The wheel in question had a slight leak so I brought it to a local tire shop to find the leak in their water tank and found it to be the metal valve stem.

I was going to tell the guy just to break the bead so I could stick my hand inside to hold the valve and just tighten the nut a bit..... but before I could even open my mouth the dumbass dis-mounted the whole tire so it need to be balanced and he did a shitty job.

So there is one parameter that had changed driving at 140KPH vs my normal 160KPH would that help fuel mileage .....yes it would BUT read on.:p

Over here the Temperature is normally about 85-90 degrees all the time (even at night) so normal driving mode is A/C on set at blower speed number 2 and temp setting 1/2 way to cold. It's that way 99% of the time here with occasional made colder never warmer.

Driving around town in this normal mode my engine temp is 180 degrees even with a 160 degree thermostat and fan switch. Air temp at the TB with my hybrid Short Ram/CAI system runs about 90-100.

But on this trip leaving the house at 0330 in the morning it was a cold (for here) 66 degrees out because we are going into winter mode for the weather.

So on this trip the normal operating temps were much lower than normal with engine temp now right on 160 degrees and air at the TB at the coolest I have ever operated at a nice cold 66 degrees.

Also since it was cold out I could finally operate with the A/C turned off and just leave the vent open.

So there are the changed operating conditions:

1. Colder engine operating temp

2. Colder air going into the TB

3. No A/C running

4. Less electrical use (no a/c blower fan)

5. Finally lower engine and vehicle speed.

With all those changes mpg went from about 30 daily average to my best ever 34.5 YAY :)

Now let the discussion begin which change made the most difference in fuel mileage?


And an added thought..... cold air is MUCH BETTER than hot going into the TB. My intake system works sooo much better with cold air the car was much stronger passing was a breeze. It was soo strong it felt like elves had secretly installed a turbo while I was sleeping.:p

For you USA speed limited guys in this nice cold air I couldn't resist and took it up to 200 KPH again (124.3mph). This was with 3 adults up and in this cold air it got there much easier and could have went higher but that was enough as anyone that has gone that fast in a Jazz/Fit knows it's not a fun ride.

One thing that popped up was extremely high (in my opinion) oil pressure. Traveling at those high speeds (87mph) for 5 hours straight the oil pressure was an extreme 80 PSI. Some of you may remember that I couldn't get and 5-25w oil here anymore Honda had stopped selling it and so had everybody else here. So I was stuck using 10-30w.

In my opinion oil pressure that extreme makes spinning or washing a bearing much more possible and it takes mechanical power to turn the pump that fast at that pressure (resistance to turning) so you are wasting energy turning the pump that hard.:(

So there we have it a lot of ground to bring to a debate. We are doing pretty good here with members expressing their OPINIONS like adults so lets keep on that track and feel free to post your ideas but please keep any flaming to other sites.:p

[macbuddy]

Now let the discussion begin which change made the most difference in fuel mileage?



Ooh, I'm gonna go with number 5 (...the Scangauge told me so).

[claymore]

Yea that is probably my best guess also with no A/C second

[manxman]

Wow! Sorry to be late to the party- I just noticed this thread (too busy trying to drive ekonetics into bankruptcy). All of your conditions were ideal (other than the wheel being out of balance), but I would guess that #5 had the highest influence.

Why not do what some of the hypermilers do- dump the passengers, spare tire, back seats and windhshield wipers, maybe the radio antenna too to reduce wind drag. Oooh! Take off the side mirrors!

Never mind, I know why not. You are SANE.

[claymore]

;) Dave I don't do all that because mine is fast enough as it is you notice even with three up it will still crack 200KPH at will:rolleyes:

[claymore]

It looks like number 5 it is. I just filled up after the trip back home in daylight and the A/C on most of the way and the mileage was just slightly lower at 34 even.

[manxman]

;) Dave I don't do all that because mine is fast enough as it is you notice even with three up it will still crack 200KPH at will:rolleyes:
Fast enough. Ain't no such thing.

[cdninsw]

We have an '09 Fit Sport Auto. Drive from Pasadena, CA to Phoenix, AZ almost every weekend. Speeds vary between 70 and 80 MPH with occasional spurts above or below. A/C is usually on (wife likes combo of A/C with temp dial turned up, it does keep the windows from fogging). 400 miles one way. According to the MPG display on the dash, we get fairly consistant 38 to 39 MPG on the trip. Same display shows much lower during the week when commuting for work.

Pretty happy with that, but we'd both give up a few MPG for more ponies. :)

[manxman]

Hey, homie, (sorry, I hate that expression)

Colorado Blvd. was my main cruising ground back in the late 60's- I grew up in San Gabriel.

[cdninsw]

Hey, homie, (sorry, I hate that expression)

Colorado Blvd. was my main cruising ground back in the late 60's- I grew up in San Gabriel.

DUDE! (wow, I never actually say "dude", but I use it in emails frequently)

I'm a transplant from the snowy north. Enjoying CA and AZ the last 10 years now. Can't imagine moving back. :)

Yeah, can't beilieve we get almost 40 MPG hwy from our little Fit. It's really my wifes car, she wants to add NOS. :) I do so hate to argue with her at times like these. ;D

[manxman]

DUDE! (wow, I never actually say "dude", but I use it in emails frequently)

I'm a transplant from the snowy north. Enjoying CA and AZ the last 10 years now. Can't imagine moving back. :)

Yeah, can't beilieve we get almost 40 MPG hwy from our little Fit. It's really my wifes car, she wants to add NOS. :) I do so hate to argue with her at times like these. ;D
Funny coincidence- I have been considering adding NOS too. Seems fairly practical since it only comes into play at WOT, and I rarely drive in that condition. But in that condition, it sure would be nice to have another 20-30-40 (or whatever) whp!

But I am reluctant to sacrifice that amount of cargo room! I will keep thinking about it for a while (long while).

[claymore]

Wow that's a rare girl you got there. Can't imagine that at the speeds I drive that my wife would ever see the need to install NOS.

[macbuddy]

Wow that's a rare girl you got there. Can't imagine that at the speeds I drive that my wife would ever see the need to install NOS.

Maybe to use as a Euphoric sedative?

[manxman]

Maybe to use as a Euphoric sedative?
Ah, yes. An occasional hit on the bottled gas would tend to quiet the nerves. I might install the system for that purpose alone. Helping to put people back together after car crashes makes MY wife (the nurse) a complete basket case in my spirited driving.

[macbuddy]

See if this makes sense to any of you. Three tanks ago, I reduced the tire pressure from 35psi, down to the factory recommended 32psi, in hopes of regaining a "cushier" OEM ride. This adjustment was made because the high "pressure" has been getting to me... "pressure" from my wife that is.

I was typically getting ~33mpg, but now with the lower tire psi, I've been getting ~35mpg instead. I found a sudden increase of 1-2mpg! I was already prepared to accept a decrease in economy, in trade for increased comfort. What I discovered was totally unexpected!

This was a win-win situation, while ride did improve, the mpg did not drop. Finding no ill effects, I went a step further to improve the ride by dropping the psi to 31psi. To my surprise, that tank also yielded 35+mpg!
Recognizing a positive trend here, I decided to test the tires even lower, down to 30psi. Guess what? The mpg still continues to read on the high side. What gives?

All of this seems contrary what I have been told, and what I have read. I have come up with a theory. I agree that higher psi on most tires will give better mpg. However, lower psi may actually be the key to better mileage on lower aspect ratio tires! Here is what I am thinking. My 45 series Toyo T1Rs with lower pressure are now "floating" over the given road surfaces, while these same tires at higher pressure were previously "fighting" the given road irregularities, therefore actually causing more rolling resistance.
Also, while driving with the higher psi, over a given distance, I tended to average a slower over-all speed due to the "harsher" ride. Lately, with the smoother riding tire settings, I find myself inadvertently "speeding" over these same exact roadways!

I am thinking that the lower tire pressures may have increased my mpg because of one, or both of the following:
1) with lower aspect ratio tires, the lower tire psi promotes lower rolling resistance, therefore better mpg (at least on our aging California roadways).
2) the smoother ride allows me to maintain a speed more conducive to optimum cruising speed. My Fit seems to be more efficient running in the 2800 rpm range. It is too bad that the California speed limit isn't 75 mph (2800 rpm = ~75 mph on my GD3 5AT).

What do you think?
-macbuddy-

PS-Perhaps there may have been a recent change in the California fuel mixture. If so, what a coincidence. BTW, each fill up was done at 3 different fuel locations, Costco, Shell and Safeway. I use the least expensive, 87 octane fuel that I can get in the tank.

[MzFiT]

124 mph Wwwhat the ... how, what, I wanta, Fffast, cool, really claymore?
did it want to leave the ground? I have an old Dodge and it is floating @ 110-120 and it's 2 tons!
So what have ya done to the Fit that ya need a pilots license to drive it?

The A/C off & colder air to the T.B. and the engine getting and staying at operating temp.

I see bad MPG when I go back and forth to work/home (12 miles one way) but when we have gone on 300/400 mile trips 40-44 mpg have been recorded! 70 mph fall mid 70's high. And the gas mix for winter here in VA dropped my milage or something the Exxon took out of the mix. A fresh oil change I will net a 1-2 mpg increase too, Amsoil 5-20 and a Wix filter.

124 MPH I am impressed Claymore!:D

[claymore]

It's not something I would recommend for everybody. It does get "light" at those speeds. The good news is there is still more to go if I have the gumption to keep my foot in it.

What impressed me more was cruising at 90-95 for 5 hours straight with no problems at all.

[claymore]

Macbuddy how is the mileage doing now. It really goes against everything holy to have better mileage with lower tire pressure. I can't figure this one out unless the weather conditions and or different blend of gas from the stations was the cause.

[macbuddy]

Macbuddy how is the mileage doing now. It really goes against everything holy to have better mileage with lower tire pressure. I can't figure this one out unless the weather conditions and or different blend of gas from the stations was the cause.

Claymore,
I am still getting great mileage with that change in air pressure, i.e. going from 35psi down to 30psi. Mileage went up to ~35 mpg vs ~33 mpg! Keep in mind the sole intent of this adjustment was primarily done to find more ride comfort, the mileage part was just a surprise bonus! Anyway, that experiment is done, and I am going to leave the psi at 30 psi for now. I was toying with the idea of dropping the tire pressure down to 29 psi to see if the ride would get even better, and the to see if the mpg would still hold up. I feel 29 psi is the lowest that I feel comfortable dropping it to. FYI, I found a formula on line that brought me to that conclusion.

The "Tire Pressure Calculation Guide" kind of went like this:
On my Fit, the max load rating on my 215/45R15 Toyo T1Rs are 1102 lbs @ 44 psi. The Fit and I weigh about 2700lbs. Divide this load amongst 4 tires. Each tire needs to support ~675 lbs.
675lbs divided by 1102lbs = 61.25% 61.25% of 44 psi = ~27 psi. The formula went on to recommend adding 2 psi to the heavier end of the car. So, if I trust this formula, I could run 29 psi up front, and 27 psi in back (keeping in mind to add more psi for extra payload).

My Dilemma
Anyway Claymore, I've gone on to the next mod. This mod was originally inspired by you. Before I get started, let me first say that I intended to see how long my OEM plugs would last. I wanted to see if they would actually go the estimated 100,000 miles. Well, I was ready for a change, I've been waiting to do your "One Step Heat Range Lower Plug Mod" for quite a long time now. I couldn't wait any longer, so I decided to just do it!
(for the record, I went 92,500 miles on the OEM plugs, and they still look and work just fine. I'll keep the OEMs in the car in case I need them).

On With the Mod
Friday night, I installed the Denso IK22 plugs ($11.50 ea). I promptly took it out for a short ride just to make sure everything was running okay, and that I'd be able to get to work in the morning. During that short test run, my first, maybe biased impression was that the Fit was in fact running peppier! I was thinking perhaps I was just feeling the difference between a brand new set, and an old set of OEM plugs with 92.5K miles on them. Regardless, the throttle does feel a bit more lively. The best way to describe the sensation, would be to compare this to driving with a "tailwind."

The Maiden Run
This morning I kept the speed between 65-75mph. I am not the fastest driver on the road, but definitely not the slowest. I was hoping to see a Scangauge reading of at least ~35 mpg, the number that I have been seeing recently. About 40 miles into my 65 mile commute, I see the Scangauge display eventually climb into the 37+ mpg range! Whoa, I couldn't wait to get off work to see if I could duplicate that feat. Check this out, on the way back, I get the same 37+ mpg reading! I had to gas up tonight. I went 395 miles on 10.51 gallons. 395 mi / 10.51 gal = 37.58 mpg!...and this mod was only responsible for ~130 miles of that 395 mile tank of gas!

Conclusion
Claymore was right again! The "One Step Heat Range Lower Plug Mod" not only gave me peppier performance, it is also showing me a 1-2 mpg gain!

Claymore...what's next?...I'll do what ever you say!

Later,
-macbuddy-

PS-I am anxious to test the performance aspect next!

[claymore]

HHHUUUMMMM what kind of intake system are you running now?:rolleyes:

[macbuddy]

HHHUUUMMMM what kind of intake system are you running now?:rolleyes:

I am running an Injen CAI, PN: SP1511P. I had the choice of K&N or Amsoil filters. I chose the Amsoil, it is a dry type filter. The K&N requires a light coat of oil to filter correctly.

[claymore]

If you weren't so concerned about your mileage you could do my insulate the intake manifold trick but you would get more power but MAY get less mileage. :p

But it's another of those conundrums you cram more fuel in because it's denser BUT you make more power per power stroke you you need to provide less fuel to move the same mass ........but real world do they even out?

[macbuddy]

If you weren't so concerned about your mileage you could do my insulate the intake manifold trick but you would get more power but MAY get less mileage. :p

But it's another of those conundrums you cram more fuel in because it's denser BUT you make more power per power stroke you you need to provide less fuel to move the same mass ........but real world do they even out?

Okay, that's my next mod...I'll go shopping tomorrow!
Thanks,
-macbuddy-