*The official what works to improve miles per gallon thread*

[JanGeo]

Generally speaking there is only a certain amount of energy in the coil so if you gap the plug smaller you will be able to spark at higher pressure maybe for a longer time - not sure how that discharge time constant works out - this only helps if you have misfire at full throttle. What I did was to install a CDI ignition in the Rambler - Capacitive Discharge Ignition. The oscilator circuit steps the 12 volts up to 300 volts and an SCR discharges the charged 300 volt cap into the regular ignition coil and WHAM big precise high energy short duration spark and to take advantage of the higher energy and voltage you have to open up the spark cap. Energy (watts) is volts times amps - the bigger the voltage the more watts the bigger the amps the more watts but also the faster you burn up the electrodes so the bigger the gap the bigger the spark and better to ignite the fuel with.

[GasSavers_DaX]

Originally Posted by JanGeo

a CDI ignition in the Rambler - Capacitive Discharge Ignition.

"capacitive discharge ignition ignition" Kind of like and ATM Machine. //end grammar nazi

Yes, though, I am a big fan of MSD's CDI setup, especially on high revving vehicles [inductive ignitions just can't keep up].

[JanGeo]

Ran my 12 mile test loop route yesterday with high winds and rain with warm temps and got 44.0 mpg when I usually get 42mpg

[cheapybob]

Originally Posted by Compaq888

Can we make this a sticky??
It might help the new people out more.

Here is all the things that work and it will be in the 1st post. It will be updated if members have any more ideas.

-Overinflating tires

-Getting a credit card with cash back on gas purchases.

-Airdonamic mods

-Engine block heater(allows the motor to go into closed loops faster to save fuel)

-Pulse and glide technique

-Low Rolling Resistance tires

-Less weight in the car (especially rotating weight).

-Hotter Thermostat

From experimentation on my Saturn...

1. Aero mods had negligible effect
2. Hotter thermostat had negligible effect (did better, but attribute gain to 70 degree hotter air, 2 mods at once)
3. Didn't try different tires, but think that overinflating and switching to synthetics helped me get 40.4 mpg vs 37 EPA highway
4. I just try to keep a steady foot on the accelerator and press the accelerator a bit early before going up a grade. Pulse and glide type stuff is not for daily driving
5. I have a 5% rebate credit card, LOL
6. I think using a block heater would be a waste of electricity unless you needed it anyway
7. Reducing weight had negligible effect (removed spare and child)
8. The vast majority of my MPG improvement has been from building/installing an insulated hot air intake and IAT sensor override setup. That was worth the difference between 40.4 mpg and 51.4 mpg under the same conditions (60 mph using cruise). If I don't use cruise control I can get about 2 mpg more from it, and I drive slower, MPG rises, but here in Chicago it isn't safe to drive at 60 let alone under 60.

[SVOboy]

Why did you trick the iat and have a warm air intake?

What aero mods were done?

Many of our users have kicked total *** with aero mods.

Also, it seems like saturns love hot air.

[cheapybob]

I blocked off all the holes on the nose except for an area about 10" x 5" under the license plate bracket with a smooth surface of race tape. No effect on MPG on 60 mph test trip, or maybe just not enough to offset any other variables. Same thing with hotter thermostat. I really expected to get a MPG or 2 out of each of these.

WHY did I build a hot air intake?
I'm a racer. We use cold air intakes to get more power. The PCM senses colder, denser air and injects more fuel to match it. Reverse the whole thing with a hot air intake and get less power but use less fuel to get it. To roll along at 60 mph I must not have needed the amount of power the motor was putting out, I guess.

WHY did I trick the IAT? Because it improved the MPG over and above what the hot air intake got me. I built a 3 way switch setup. I can use IAT sensor value, IAT sensor value + 4700 ohms, or value from Potentiometer set at 110 ohms currently. I use sensor for cold starts, sensor + 4700 for warm starts, and 110 ohm when warmed up on the highway.

[SVOboy]

I was just wondering why you did both of them. I know for a fact that hondas will not pull any fuel after like 140 degrees so I only need the HAI, I didn't know that saturns were different. Good to know though.

[cheapybob]

Originally Posted by SVOboy

I was just wondering why you did both of them. I know for a fact that hondas will not pull any fuel after like 140 degrees so I only need the HAI, I didn't know that saturns were different. Good to know though.

The temp in my airbox has gotten up as high as 232f. Today it was about 180f. I have an Utraflow III A/F stochieometric LED display so I can monitor A/F ratio. It doesn't run lean. My suspicion is that it attempts to use the value from the IAT but corrects from the O2 readings, or its just designed to run rich. It definitely gets another 3 MPG from having the 110 ohm option out on the road as compared to just hot air. IIRC I got 48.6 MPG before I added the 110 option. The sensor + 4700 option was added because I was having problems starting it when it was already warmed up.

[SVOboy]

Do you have a wideband o2 sensor monitoring your afrs?

It should not be technically running lean unless the iat mod is doing most of the work and the warm air isn't, which doesn't seem to be the case.

[cheapybob]

Originally Posted by SVOboy

Do you have a wideband o2 sensor monitoring your afrs?

It should not be technically running lean unless the iat mod is doing most of the work and the warm air isn't, which doesn't seem to be the case.

Exactly. I'm USING GM's system for the most part instead of trying to cheat it completely. That's helping me avoid problems, I think.

I don't think the sensor is a wideband one. Its a single wire O2 sensor and the LED A/F meter is just teed off the lead.