How do I cure a lean condition?

[largeorangefont]

Originally Posted by camelll

Where did largeorangefont go? I would like him to explain some of this shiiiiit to me cause I really don't know. I understand about timing, advancing or retarding and when I am under boost the load is basically on 99 percent. I just don't understand how all of these tie together with rpm and manifold pressure.

Sorry, Had to do some actual work. I gotta head out to a customer, so here is a brief overview.

In reality \keeping an engine alive comes down to EGT (exhaust gas temperature) and knock.

You use a balance of AFR and timing to keep both factors in check. You can't crank up both and expect an engine to live.

Think of fuel as coolant for the combustion chamber. Think of ignition advance as how hot the fire burns. Obviously if the fire burns too hot, bad things happen. If it burns too cool, the car runs like crap and is slow. The temperature of that fire is EGT. You can control EGT by adding more coolant (fuel) or turning down the intensity of the flame (ignition retard).

OEM supercharged cars will (generally!!) run low timing and a high AFR to increase fuel economy and reduce emissions. My Cobra for example ran in the high 13 AFR range under load, but only had 10 degrees of ignition advance from the factory.

I now run the AFR and 11.3:1 AFR under load, and 21 degrees of ignition advance, and picked up 30 some odd HP and torque. It runs like a different car. The increased timing makes the car more responsive on tip in (passing etc.), and much more driveable. Power "under the curve" is increased as well as peak power.

EGTs in both scenarios were VERY similar, at around 1300F. From this example, you can see there are many ways to the same end. Some produce more power than others.

Knock is another factor to be wary of. Again, to get rid of knock you can add more fuel, or retard timing. Strategies can vary on how to get rid of knock, especially in turbo applications.

[eTiMaGo]

Originally Posted by largeorangefont

Sorry, Had to do some actual work. I gotta head out to a customer, so here is a brief overview.

In reality \keeping an engine alive comes down to EGT (exhaust gas temperature) and knock.

You use a balance of AFR and timing to keep both factors in check. You can't crank up both and expect an engine to live.

Think of fuel as coolant for the combustion chamber. Think of ignition advance as how hot the fire burns. Obviously if the fire burns too hot, bad things happen. If it burns too cool, the car runs like crap and is slow. The temperature of that fire is EGT. You can control EGT by adding more coolant (fuel) or turning down the intensity of the flame (ignition retard).

OEM supercharged cars will (generally!!) run low timing and a high AFR to increase fuel economy and reduce emissions. My Cobra for example ran in the high 13 AFR range under load, but only had 10 degrees of ignition advance from the factory.

I now run the AFR and 11.3:1 AFR under load, and 21 degrees of ignition advance, and picked up 30 some odd HP and torque. It runs like a different car. The increased timing makes the car more responsive on tip in (passing etc.), and much more driveable. Power "under the curve" is increased as well as peak power.

EGTs in both scenarios were VERY similar, at around 1300F. From this example, you can see there are many ways to the same end. Some produce more power than others.

Knock is another factor to be wary of. Again, to get rid of knock you can add more fuel, or retard timing. Strategies can vary on how to get rid of knock, especially in turbo applications.

A very delicate balancing act

[whooppee777]

so if we got the cam com we could adjust the cams to cope with the crazy a/f readings?

[largeorangefont]

Originally Posted by whooppee777

so if we got the cam com we could adjust the cams to cope with the crazy a/f readings?

No, the cam has nothing to do with it.

[kurokoma-kun]

Originally Posted by largeorangefont

You can control EGT by adding more coolant (fuel) or turning down the intensity of the flame (ignition retard).

Crap, I have got to get off my a$$ and install my gauges! Without knowing the AFR, seems like knowing the ignition timing means nothing

Currently I just gave a tach and scangauage on volt, ign, tps, and cycle through others (load, loop, temps). I have boost/vac and wideband a/f and oil press. still in their boxes

Cruising around at 2500-3500 rpm, the tps is ~25, load is say 50, ign timing is usually ~30. Under boost (load 99 and tps 25+) it quickly drops to half that... is that normal?

[LtNoogie]

Originally Posted by kurokoma-kun

Crap, I have got to get off my a$$ and install my gauges! Without knowing the AFR, seems like knowing the ignition timing means nothing

Currently I just gave a tach and scangauage on volt, ign, tps, and cycle through others (load, loop, temps). I have boost/vac and wideband a/f and oil press. still in their boxes

I cannot fault you for being slow. I started the thread about gauges for boosted applications at the end of October. It's now mid-March and I just got two of my three gauges working (boost/vac & wideband a/f). Oil pressure should be done next weekend...maybe.

As for the scangauge, I normally set it to trip MPG, instant MPG, RPM, & fWt

[largeorangefont]

Originally Posted by kurokoma-kun

Crap, I have got to get off my a$$ and install my gauges! Without knowing the AFR, seems like knowing the ignition timing means nothing

Currently I just gave a tach and scangauage on volt, ign, tps, and cycle through others (load, loop, temps). I have boost/vac and wideband a/f and oil press. still in their boxes

Cruising around at 2500-3500 rpm, the tps is ~25, load is say 50, ign timing is usually ~30. Under boost (load 99 and tps 25+) it quickly drops to half that... is that normal?

Yes that sounds correct.

[kurokoma-kun]

Originally Posted by LtNoogie

I cannot fault you for being slow.

thanks... this whole project has taken me forever though. I'm a terribly slow weekend mechanic and even slower electrician, plus it's taken me a long time to get a mental grip on the basics of boost--had a lot to learn and still do, but experience is the best teacher I guess

Originally Posted by largeorangefont

Yes that sounds correct.

thank you for the reassurance

[kurokoma-kun]

Originally Posted by camelll

These are pretty much the numbers I see as well jo.

Interesting! now I'm very curious to know what Long and others are getting, and how to interpret it all.

[largeorangefont]

Originally Posted by camelll

I am not seeing a lean condition, my wideband show's between 11 and 12 under wot and stoich at idle. my scangauge readings are on par with korokuma kun's. I was however experiencing pre ignition but that has been stopped with the lucas octane booster and 93 octane in the tank. Noogie however was seeing a lean condition when his car was on the dyno and is showing a condition now but does not have the sensor in the optimal spot.

I am gonna have to mess with the camera and check out its video settings or just break down and by a camcorder.

I could not tell you why the 2 of you are seeing differences. Is your black box hooked up properly? Noogie is stting stoich at idle and during cruise as well, so again, his wideband is close to accurate.

Noogie is seeing low timing, so I am assuming that the black box is offsetting timing under load. What kind of timing values do you see under boost?

[largeorangefont]

Originally Posted by camelll

I will say though that I have a different fuel controller than most, there are only 3 people that have the same fuel controller I do (that I am aware of). I was one of the first people to get this kit.

Well there you go. That probably explains some of the differences. If all of you were getting knock, they probably made some revisions to future kits.