Now up to 57.3 mpg at 60 mph in my 97 Saturn SC1

[cheapybob]

Gettin up there! Maybe I'll make it to 60 mpg when I finish aero mods and get my preheated fuel gizmo I built working. I wish I had lighter rims and tires, and a 98+ trans, but just too much money to change those things. Once the mods are stable, I'll make one try with gas additives just to see if they help or not.

This is a 97 SC1 5 spd 1.9L with AC and PS on normal 87 octane Mobil gas, no additives, driving at about 60 mph on the same 22 mi test loop I've been using with small hills and turnaround cloverleaf, etc, avg speed 57 mph, max speed 62 mph, outside temp about 60f, no wind, slight drizzle, no drafting trucks, no coasting, had to hit brakes 1 extra time due to traffic. All readings from my Scangage with error max about 1%. I also have a constant Air/Fuel LED readout and its not running lean. I had about 35 lbs of groceries in the car, but have the spare removed to reduce weight

Aero mods
- no antenna (I have a CD changer, who cares)
- no wipers (using RainX like my race car)
- Taped front end for lower drag with holes sized for optimal cooling (like my race car)

Engine/Trans
-hotter thermostat Napa 268
-105 ohm resistor on a switch instead of IAT sensor for 242-247f signal
-all synthetic fluids + Valvoline Synthetic Oil Treatment
-insulated hot air intake (actual temp about 150f) look in my pics at Saturnfans.com
-Champion copper plugs gapped .040
-Bosch plug wires

Other
-45 psi tire pressures

[JanGeo]

Somebody needs to check the shift points in an automatic with a vacuum gauge to see if it is being controlled by engine vacuum. I think it is pump pressure in the automatic and that requires tapping into the transmission with a pressure gauge to figure out when the shifting occurs. Either way you guys over 50mpg are doing great. Wish my Geo was road worthy to test some acetone and aero mods with.

[mikefxu]

Are you using a wideband O2 or just checking your cars narrowband?

[SVOboy]

Why no o2?

[mikefxu]

Originally Posted by cheapybob

I also have a constant Air/Fuel LED readout and its not running lean.

Originally Posted by maxc

No O2 being used. Custom fuel system. Exhaust temps only 325 to 350F after 3 min of run time at 1200 to 1600rpms.

this was directed to cheapybob, dunno why u responded?

I am trying to figure out how fooling the ecu that the intake temp is hot helps, does it lean out the mixture?

[cheapybob]

Originally Posted by mikefxu

this was directed to cheapybob, dunno why u responded?

I am trying to figure out how fooling the ecu that the intake temp is hot helps, does it lean out the mixture?

I have an A/F meter. It doesn't run too lean. I heat the air up to about 200. Anything over that is bad. Same with water temp up to about 205, over that is bad. Once its warmed up, I cheat the computer with a resistor network on a switch and tell it the air is 247, but its really only 200. I need to rig a cold air intake to sense when the air is over 200 and mix in some cold air and keep the temp at or under 200. It might be nice if it activated under heavy throttle conditions, too. Ignition retards if the actual air gets over 200, killing mpg gains.

Found out my scangage was off. So when I thought I got 59 mpg it was really on 56.

[diamondlarry]

I am trying to figure out how fooling the ecu that the intake temp is hot helps, does it lean out the mixture?

On a Saturn anyhow, the ECU leans out the mixture as the air temp increases.

[mikefxu]

I don't know how accurate your narrowband read out is. Most the forced induction community calls them a light show. http://www.honda-tech.com/zerothread?id=1001592

Originally Posted by diamondlarry

On a Saturn anyhow, the ECU leans out the mixture as the air temp increases.

How bout on a Honda?

Originally Posted by cheapybob

Same with water temp up to about 205

How do you keep the fan from kicking on? Mine kicks on at 195 I though about getting high thermostat but I am at 185 now and I could go to 190 if I go to 195 it might make my fan kick on all the time.

[mamalujo2003]

Originally Posted by cheapybob

Gettin up there! Maybe I'll make it to 60 mpg when I finish aero mods and get my preheated fuel gizmo I built working. I wish I had lighter rims and tires, and a 98+ trans, but just too much money to change those things. Once the mods are stable, I'll make one try with gas additives just to see if they help or not.

This is a 97 SC1 5 spd 1.9L with AC and PS on normal 87 octane Mobil gas, no additives, driving at about 60 mph on the same 22 mi test loop I've been using with small hills and turnaround cloverleaf, etc, avg speed 57 mph, max speed 62 mph, outside temp about 60f, no wind, slight drizzle, no drafting trucks, no coasting, had to hit brakes 1 extra time due to traffic. All readings from my Scangage with error max about 1%. I also have a constant Air/Fuel LED readout and its not running lean. I had about 35 lbs of groceries in the car, but have the spare removed to reduce weight

Aero mods
- no antenna (I have a CD changer, who cares)
- no wipers (using RainX like my race car)
- Taped front end for lower drag with holes sized for optimal cooling (like my race car)

Engine/Trans
-hotter thermostat Napa 268
-105 ohm resistor on a switch instead of IAT sensor for 242-247f signal
-all synthetic fluids + Valvoline Synthetic Oil Treatment
-insulated hot air intake (actual temp about 150f) look in my pics at Saturnfans.com
-Champion copper plugs gapped .040
-Bosch plug wires

Other
-45 psi tire pressures

Hi Bob, What is a hot air intake and is the resistor you cite 105 ohms or 150? I have a '96 sc2 w/ dohc and i'm trying to improve the mileage. Thanks.

[cheapybob]

This is a real old thread. My plugs said i was running too lean, and i found out that the scangage doesn't actually monitor fuel used, but rather the fuel it thinks should be used, so I stopped using the resistor cheat. The fact that it ran TOO lean says it really did affect the mixture, but I didn't want it running TOO lean.

I recently cobbled a 2 sensors in parallel + resistor setup as suggested by froggy and it allows me to feed the computer a reading about 10% higher than actual, which I think will give me a mixture thats a little lean, but not to the point of being a problem, and that's what i was looking for. I haven't driven with it long enough to make any comment on whether it solves everything though.