Ummm rightttttt. You might save 0.001MPG with the radio off. As for the alternator being disengaged...lol.
The battery starts the car, the alternator runs the car, sending the power through the battery as a filter and to keep the battery full.
I have never EVER heard of an alternator "disengaging." There are different levels of operation, but it is always putting load on the engine. You save, about, 1MPG with the A/C compressor off. Everything else saves you almost nothing. A 2.4L engine running at a certain RPM is GOING to use a certain amount of fuel. You can't just turn load after load off and expect 43MPG, that isn't possible.

 

You can run a car for a while without an alternator. I drove over 100 miles on just the battery power in my Eclipse before it died. 60 miles of that was at night with the lights on.

The battery also smoothes out the voltage spikes/dips from the alternator. You used to be able to test an alternator by disconnecting the battery once the car was started. I wouldn't try it now, with everything computer-controlled.

 

you're wrong there, if you put all the accesories ON the alternator has to put put out more amps, that's how the voltage regulator works=>it controls the output of the alternator.

 

You are talking about the battery's reserve capacity. Has NOTHING to do with the charging/electrical system. The reserve capacity of the battery should never need to be used, provided the charging system is working properly.
As for disconnecting the battery cables, don't do that with any car. You will fry a 2004 alternator and you will fry a 1960 alternator doing that. The alternator starts running at "full throttle". The only thing you may have been able to do that with is a generator, but we haven't seen those since the 50s.
The alternator load DOES change, but not enough to really impact the MPG. The biggest user of power is the rear electric defrost, other things like heated seats, a high power stereo (1000watt range), constant use of electrical devices (power windows, seats if the car has power seats etc).
But yeah, the rear defrost hogs power, not enough to really gain much fuel mileage though.

 

plokivos: 43 mpg without boosting, is that really possible, because if it is, ill ****in buy an electonic boost controller and set the boost at like 5500 rpm or higher, that way i dont boost for ****, daily driving will just put too much damn mileage and cost too much, if anybody knows if this is true let me know, i would do it in a heartbeat. that way i will only use boost on weekends or something.

 

I thought an alternator's output was determined by engine speed (at least to a minor extent, it was more so in the days of generators). Then the voltage regulator restricts how much was let into the system based on demand.

 

to a very minor extent yes. As in when at 900rpm idle is not outputting as much but as soon as the engine is revved a bit its more or less running full output.

 

the alternator will turn ALL THE TIME.. it doesn't increase or decrease the load on the engine.. when the revs are really high and the output is higher than normal, the regulator kicks in and prevents a surge..

having all the electrical stuff off does not make you have more MPG.. you are possibliy looking at the side effects.. if the electrical system is strained (you have a 10000 watt stereo) then there isn't enough juice to light up a good spark, therefore the computer compensantes by pumping in more gas, which in turn means you use more gas..

but it's NOT because the alternator "disengages", it doesn't work the same way as the a/c compressor (which has an electric clutch to disengage)...

I brought the car knowing it's bad on gas, if you want a gas sipper, get a 1.3L 3 cylinder swift

-joe

 

That's some funny ****. This goes back to having a MIVEC controller similar to the VTEC controller (which some say can work w/ MIVEC), so we can control the MIVEC point........so if we want to cruise @ 80-85 like I do, we can move the MIVEC point higher in the RPM range .

 

does altitude affect mpg at all? just wondering... if the engine sucks in less dense air (higher altitude) wouldnt that result in the engine becoming more starved for air and less economy?

i am in CT... around 400 ft above sea level.. i dont think that matters though

 

i had two different brands of VTEC controllers on my accord (not at the same time, just in case the wise azz comments come up) and both of them didn't address the problem of VTEC mismatch.. the MIVEC controllers I saw had the same problem..

basically with a VTEC/MIVEC (from now on I will use VM to save me some typing) controller, you are intercepting the signal from the ecu that tells the engine to engage VM. When the ECU wants to engage VM, but the point has been moved, that signal is thrown away and the controller lies to the ECU and says "yep, VM has been engaged". The ECU will then run the VM high fuel map. This is where the "mismatch" comes in, since you are running the high fuel map on your low cam profile, which means you will run rich. When the VM controller gets to the new VM trigger point, then it will run the correct map because it will "match" the ECU's VM state. The reverse is also true, when the controller wants to run a higher VM engagement, the ECU might think that it's not in VM yet, therefore it will run the low fuel map when you are actually on the high cam profile, you will then be running lean

the Apexi V-AFC handles this better than the Field's Vtec/Mivec controller, it has a "mismatch" setting, but it's not perfect..

This is just the fuel part.. you can't adjust ignition maps on any VM controller.. so you will be sol on that end

a standalone (aem EMS) or semi-standalone (greddy emanage) will solve this problem by totally remapping all the fuel maps and ignition maps..

-joe

 

i did this same test about 2 months ago and got similar results. i think i was 23mpg /w the mivec ( but i kept it in ALL the time =) Still had a little over 27 /wout ever touching mivec. I also have the ECU and CAI. so, no, the ecu doesnt hurt mpg

 

Holy sh*t, I simply state that using the electrical components puts less load on the alternator and it turns into a flame fest.

 

the point is that it doesn't put less load on the alternator.. the alternator will put out the same load no matter what.. doesn't mean that because you are demanding more power it strains it.. the alternator will simply 'max out' and you will just run out of juice.. there is no magic "engagement" or "disengagement" just by you controlling the electrical accessories

-joe

 

That doesn't make the alternator run at "full throttle". If anything, it has LESS work to do, because it's not charging the battery after the start, while providing power for everything else.

On a carb'd car with an alternator, it was a perfectly safe test. No sensitive electronics to burn out. Didn't hurt the alternator one bit.

I don't know where you get your information, kid. Most of it's pretty good, but some of the stuff you take as gospel is total crap. Some of it is lack of experience, I guess.