Transmission options.

[Mista Bone]

Does everyone here understand that MOST Honda's are not acurate with the speedo and odometer?

While 92-95 DX/LX came with 175/70/13 or 185/60/14 neither are tall enough to give accurate readings. 185/65/14 on my 1995 LX sedan as well as on my 1994 DX Sedan gave the correct info.

FACT: I've been doing these number calcs for 15 years, before ECM was born.

[Ecky]

Can't speak for others, but my odometer was accurate within 0.1% stock, comparing displayed miles to highway markers and GPS. I've increased the tire size by 1.1% and my odometer reads ~1.1% slow now. The speedometer is within ~1.5MPH but I've pulled the needle off so I can't expect it to read any more accurately than I stuck it back on the peg.

[California98Civic]

I have a whole thread devoted to the calibration of my odometer against the transmission and tires sizes. In my current set up and my previous I repeatedly measured significant undercounts in miles on the odo. My current arrangement with a 1993 transmission, 1998 gauge cluster, and 175/70-r13 tires I have repeatedly measured an average approximate 2.9% odo undercount. That's my finding.

[bkuehl]

Originally Posted by Mista Bone

You will likely find out that your mileage is LOWER from lugging the car in too tall of a gear, keeping the engine out of the range it is most efficient in.

The 16 valve DX motor likes a higher cruising rpm, say 2800-3200 rpm, over the lower rpms the HF/CX or VX/HX on low cam to keep intake port velocities up. This helps with even fuel atomization and dispersion in the cylinder.Just look at the throttle body diameter.

Now with better aero than I had 10 years ago it might be possible to lower the cruising rpm without lugging the motor.

While I have no scientific proof to back it up, I'm going to side with bone here. I get noticeably better fuel economy on my 16v when I shift at higher RPM's.

[some_other_dave]

So a Fit doesn't compare to the DX?

CleanMPG Forums - View Single Post - Steady state speed vs fuel economy results

I have a question for Bone and bkuehl: Have you checked a fuel consumption gauge (MPGuino, built-in iFCD, or ScanGauge or equivalent) driving the same stretch of road at the same speed in two different gears?

-soD

[bkuehl]

Originally Posted by some_other_dave

So a Fit doesn't compare to the DX?

CleanMPG Forums - View Single Post - Steady state speed vs fuel economy results[/url]

I have a question for Bone and bkuehl: Have you checked a fuel consumption gauge (MPGuino, built-in iFCD, or ScanGauge or equivalent) driving the same stretch of road at the same speed in two different gears?

-soD

I wouldn't compare the two simply because they are two entirely different engines, with many years of development between them. Having daily driven a 07 Fit for a few years before switching to older D-series hondas, I'd agree that the L15 returns better economy when short shifted. I have not found the same to be true with the 16v D series engines. But comparing a D15/16 and L15 is an apples to oranges deal.

Mr. Dave, I've actually got a MPGuino sitting on my desk at home(been there for months! ). Just have to find the time to build a box for it and wire it in. Whenever that happens, I will make sure to report back with my findings.

[California98Civic]

Originally Posted by bkuehl

While I have no scientific proof to back it up, I'm going to side with bone here. I get noticeably better fuel economy on my 16v when I shift at higher RPM's.

Originally Posted by some_other_dave

.... Have you checked a fuel consumption gauge (MPGuino, built-in iFCD, or ScanGauge or equivalent) driving the same stretch of road at the same speed in two different gears? ...

I have done this comparison in my car: http://ecomodder.com/forum/showthrea...tml#post414423

james

[Mista Bone]

Originally Posted by some_other_dave

So a Fit doesn't compare to the DX?

CleanMPG Forums - View Single Post - Steady state speed vs fuel economy results

I have a question for Bone and bkuehl: Have you checked a fuel consumption gauge (MPGuino, built-in iFCD, or ScanGauge or equivalent) driving the same stretch of road at the same speed in two different gears?

-soD

None of those gizmo's were around 9-13 years ago. You had to drive a few tanks, note the mileage driven and gas used to get a true consistent AVERAGE number. Real seat of the pants driving.

Different FD + 5th ratios I have driven in my old Civic

4.250 * .702
4.250 * .750
4.250 * .771
4.250 * .878
4.058 * .702 (best mpg in my drives, stock 92-95 DX gearing)
4.058 * .771
3.722 * .878
3.250 * .702
3.250 * .771
3.250 * .878

Current combo in the CRX is DOHC ZC, 3.89 * .878 which got 49 mpg last fall. I will be switching to 4.437 * .694 in the performance build with long 5th combo. I should drop cruising rpm by 250-300.

Right now 3000 rpm = 60.34 mph using the calc. With new gearing 3000 rpm = 66.89 mph.

So 67 mph is my target speed for safe Interstate travels. Speed limit was 65 mph, now 70 mph in most places.
Current 3.89 * .878 = 3331 rpm
Planned 4.437 * .694 = 3005 rpm

Note: I don't change the tire diameter in the calc as it closely reflects the speedo reading from Honda, even though the OEM tire size is 3-5% smaller in cases. GPS or 5th wheel needed for TRUE mileage driven.

Now if I could find a state highway with a 60 mph limit that was flat and no traffic for best mpg....right at 2700 rpm cruising, at the lower edge of my preffered rpm window.

[some_other_dave]

Originally Posted by bkuehl

Mr. Dave, I've actually got a MPGuino sitting on my desk at home(been there for months! ).

I hear you on that! I think I still have the MPGuino (built, but no enclosure) that I bought to put in my CRX. And I haven't owned the CRX in over 2 years...

Bone, I'm saying your research was OK for the time but is not accurate enough. I personally went from under 30 MPG per tank in the CRX to over 50 MPG, just by changing the way I drove. Unless you know the conditions were identical, and the way you drove were completely identical, your comparisons have a very significant margin of error.

If you'd like I can mail you my MPGuino, once I find the thing. Installation would be up to you, of course.

"Target speed" for maximum efficiency is pretty much always "as slow as you can stand to go in your top gear". Lower RPM may be more efficient per squirt of fuel, but with taller gears you are traveling farther for every RPM--for every squirt of fuel. You have to be a lot more efficient per RPM to make up for turning less RPM. And I don't think that's the case for most reasonable situations.

-soD

[Mista Bone]

"I'm a good driver"

Funny, since the movie was partly filmed where I live, but it is the truth. I learned through MANY miles of driving what MY car liked by reading analog gauges before the MPGuino was ever thought of. If one was to dig through the posts on DSO you'd find the gauge I wanted, using info from ECU, with minor calculation, is all the MPGuino does. Which is why I want one! As good as I think my driving is, it likely could be better.

I drove a buddies 95 Civic CX HB several times on our Detroit trips. He was getting 38-40 mpg in 5th gear at 65-70 mph. I was getting 45-46 doing the same trip due to my better driving style. He wouldn't look far enough ahead and would have to get off the gas and hit the brakes due to traffic. If you have ever seen me post about a cattle prod, it was because I wanted to use it on Ryan to better his driving.

Now for the fun fact. I made the trip in 4th gear, driving my style and the car topped 50 mpg. Ryan never got better than 42 mpg on same trip.

I'm already getting close to 50 mpg in the CRX, only real mod for MPG so far is LRR Ecopia EP100's. I really wanna play with some pipe insulation that someone started using here.

The big key is my old car is I was able to take the rpm it was happy at and refine it further. Aero drag being what it is, I'm sure better MPG could have been had....if I had the time then to drive slower. Now I have that time.

I also know with the motors I'm working with it is VERY easy to do engine damage from detonation by lugging the engine at too low of rpm even before my tweaking.

Some of the mods being done here, in the name of better MPG, IMHO are causing possible damage. Esp. in older cars (like mine) that don't have a reliable knock sensor.

A) I will NOT give up any performance capabilities of the CRX in the name of better MPG, period.
B) Combined with what I have done in the past, with what others are doing here now, I really think merging the info I can get some insanely good mpg numbers.

Also factor in I've driven close if not more than one million miles so far. Honestly, I cannot wait to create new data points, I know there is more possible.