Lean Burn for non-Civics? (custom???)

[Stan]

Originally Posted by steffen707

If you remap the fuel table in a modern EFI system and tell the injectors to flow less, then yes it will lean out in whatever manner you program it to.

Then you don't need smaller injectors, do you?

I thought I read that the VX will go to 20:1-25:1 AFR. This is a lot more than the 15:1 you were talking about.

Please reread my post. What I wrote was "Running an engine at peak egt (A/F ratio about 15:1...plus or minus)..." That is nothing like the leanest an engine can go. And then I wrote, "I don't know how lean they can go (anybody know?), but I wouldn't be surprised to learn that it's well over 16:1.". I didn't know it could go as lean as 25:1. That's very impressive.

[steffen707]

Originally Posted by Stan

Then you don't need smaller injectors, do you?

I don't think i said anything about smaller injectors, i said, "Try taking a stock d16z6 si engine and just lean the fuel injectors out to 20:1 air fuel ratio (edit: with a leaner fuel map) and you're going to destroy the engine. The engine has to be designed to go to lean burn in the first place."

Here is some good info, wiki says 22:1, http://en.wikipedia.org/wiki/Lean_bu...n_burn_systems
"One of the newest lean-burn technologies available in automobiles currently in production uses very precise control of fuel injection, a strong air-fuel swirl created in the combustion chamber, a new linear air-fuel sensor (LAF type O2 sensor) and a lean-burn NOx catalyst to further reduce the resulting NOx emissions that increase under "lean-burn" conditions and meet NOx emissions requirements.

This stratified-charge approach to lean-burn combustion means that the air-fuel ratio isn't equal throughout the cylinder. Instead, precise control over fuel injection and intake flow dynamics allows a greater concentration of fuel closer to the spark plug tip (richer), which is required for successful ignition and flame spread for complete combustion. The remainder of the cylinders' intake charge is progressively leaner with an overall average air:fuel ratio falling into the lean-burn category of up to 22:1.

The older Honda engines that used lean burn (not all did) accomplished this by having a parallel fuel and intake system that fed a pre-chamber the "ideal" ratio for initial combustion. This burning mixture was then opened to the main chamber where a much larger and leaner mix then ignited to provide sufficient power. During the time this design was in production this system (CVCC, Compound Vortex Controlled Combustion) primarily allowed lower emissions without the need for a catalytic converter. These were carbureted engines and the relative "imprecise" nature of such limited the MPG abilities of the concept that now under MPI (Multi-Port fuel Injection) allows for higher MPG too.

The newer Honda stratified charge (lean burn engines) operate on air-fuel ratios as high as 22:1. The amount of fuel drawn into the engine is much lower than a typical gasoline engine, which operates at 14.7:1—the chemical stoichiometric ideal for complete combustion when averaging gasoline to the petrochemical industries' accepted standard of C6H8.

This lean-burn ability by the necessity of the limits of physics, and the chemistry of combustion as it applies to a current gasoline engine must be limited to light load and lower RPM conditions. A "top" speed cut-off point is required since leaner gasoline fuel mixtures burn slower and for power to be produced combustion must be "complete" by the time the exhaust valve opens."

[Stan]

Originally Posted by steffen707

I don't think i said anything about smaller injectors, i said, "Try taking a stock d16z6 si engine and just lean the fuel injectors out to 20:1 air fuel ratio (edit: with a leaner fuel map) and you're going to destroy the engine. The engine has to be designed to go to lean burn in the first place."

The edit makes your point clear. Thanks.

[steffen707]

Originally Posted by guudasitgets

I should just go out and find a VX

If lean burn is what you want. I think the vx is the best, and cheapest. Remember that when in lean burn not a lot of fuel is being used, thus not a lot of power is being made. If you wanna drive fast you will be in constant battle of going in and out of lean burn.

While the engine gets awesome mpg in lean burn, it makes okay mpg out of lean burn. Like 55mpg in lean burn, then drops to 35mpg at highway speeds of 60-65mph in my car.

Some may find they like the cx better. More predictable.

[California98Civic]

Originally Posted by iveyjh

I have a 2000 Chevy Metro 1.0 3cyl. I use an Apexi Safc air fuel mixture adjuster that works with the map & TPS sensors. Google Safc/Vafc, I find mine on ebay or craigs list.
I get anywhere from 50 to 62 mpg according to how I drive. I get 52mpg at 60-65mph have got over 70 mpg on shorter legs.
You can adjust fuel ratio lean for only low load under 3000rpm or any range that you want.
I have been running this on 3 of my cars for 10 months, 2000 metro, 1998 hx 51-62mpg, 2002 Acura RSX 34-38 mpg. If you set it lean on low load it will not hurt the engine. It actually runs cooler.

I'm curious about the Apexi SAFC 2 idea for creating lean burn in non-lean-burn engines. But online there seems to be a conflict over what sensors it reads. Some say that it uses the MAP, which would mean it functions best in open loop or near WOT. These folks argue that under light load and partial throttle the ECU will regulate AFR in closed loop, using the O2 sensor, and therefore the Apexi will not help lean the mixture. Anyone with experience know what's true here? Does the Apexi SAFC 2 read both the MAP and the O2? Just the MAP?

[iveyjh]

The Safc just adjusts the Map sensor according to the throttle position sensor and rpm's. The ECU will compensate and change A/F ratio back to stoich. I run without O2 sensor in limp mode and then you can add or subtract fuel without the ecu interfering. It's best to check exhaust temp with EGT sensor. I adjust for light load cruising and there is not much risk at lean light load conditions.

[California98Civic]

Ah! You've hacked it! That makes better sense. I found owners manuals online for the SAFC and SAFC2 units and they don't list my my D16Y7 engine as compatible. But if you could hack it, that changes things. Did you instal an EGT sensor? I don't think your cars came with them (yet), did they?

[iveyjh]

Ah! You've hacked it! That makes better sense. I found owners manuals online for the SAFC and SAFC2 units and they don't list my my D16Y7 engine as compatible. But if you could hack it, that changes things. Did you instal an EGT sensor? I don't think your cars came with them (yet), did they?

No, they did not. I installed an EGT sensor and a wideband o2 sensor to monitor fuel ratio in the 2000 Metro 1.0 liter. I set it up to light cruise from 18 to 22-1 afr. at any other throttle position it is proportional. Wide open is about 12.5-1. I have never exceeded 600* C 1100* F. I was surprised that the Metro 3-cyl could run that lean. When running over 16-1 ratio I run between 400* to 500*C. Normal temp at stoich and under load (WOT) is much higher - 600* to 900*C.

None of my cars were listed as compatible either. All you need to do is find a schematic of the ECU pinouts and match them up.