How does this target AFR table look?, VE table results after autotune Options

[rwilner]

I'm going to use the autotune feature of Microsquirt to set my fuel map (VE table). This system will automatically adjust the VE to achieve the mixture as defined by the target AFR table.

This is a 12x12 table. The Y axis is MAP reading (load), and the X axis is RPM. This table was auto-generated by this microsquirt calculator.

What do you guys think? Is this a solid target AFR table or are adjustments needed?

[gothspeed]

Are you looking for max power or max economy? For basic all around use that is just about where you want it. (IMG:style_emoticons/default/smile.gif)

If the o2 sensor is responsible for most/all of the A/F measurements ....... make sure there are absolutely zero exhaust leaks before the o2 sensor.

[aircooledtechguy]

Disclaimer: I can barely program my cell phone. (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/biggrin.gif) I had someone much younger and MS savvy help me program my MS powered car. . .

If you're going for max power, then you will need an AFR in the high 11s low 12s where you are on the gas during hard WOT acceleration. My car leans out on cruise to 14-16 around 65-75 mph in high gear. Once I blip the gas it goes back into the 12s for power.

I've got more tuning to do on mine. Now that I have a CHT gauge installed I will be better able to lean out the mixture to go after better fuel economy w/o worrying about cooking the heads.

That table will get you started, but richening will give you power.

[rwilner]

Are you looking for max power

Yes

or max economy?

Yes!

For basic all around use that is just about where you want it. (IMG:style_emoticons/default/smile.gif)

This is really my goal. I might buy some dyno time at some point to squeeze a little more power out.

If the o2 sensor is responsible for most/all of the A/F measurements ....... make sure there are absolutely zero exhaust leaks before the o2 sensor.

Hm...I believe I have no exhaust leaks...is there a way to check besides listening? Whenever i've heard exhaust leaks they have been obvious to me. If I put my foot over my tailpipe while the car is idling, the engine loads up and I don't hear any obvious leaks.

I'll make sure to warm up the engine/exhaust before doing the tuning to get everything expanded.

[Andyrew]

You need to be low 12's high 11's for power. Especially with air cooled. Running lean will also create more heat...

[mrbubblehead]

You need to be low 12's high 11's for power. Especially with air cooled. Running lean will also create more heat...

how do you figure?
(IMG:http://www.914world.com/bbs2/uploads_offsite/i722.photobucket.com-12492-1332948731.1.jpg)

[904svo]

Air cooled engines use the AFR to help cool the engine thats why the like to run rich.

[mrbubblehead]

Air cooled engines use the AFR to help cool the engine thats why the like to run rich.

looks like rich of peak is the hottest to me. how do you know this?

[Mark Henry]

Air cooled engines use the AFR to help cool the engine thats why the like to run rich.

Exactly!

My head temps would go up 75+ degrees when I tried similar AFR's and pulling long hills it was totally getting into the danger zone.

[JamesM]

I'm going to use the autotune feature of Microsquirt to set my fuel map (VE table). This system will automatically adjust the VE to achieve the mixture as defined by the target AFR table.

This is a 12x12 table. The Y axis is MAP reading (load), and the X axis is RPM. This table was auto-generated by this microsquirt calculator.

What do you guys think? Is this a solid target AFR table or are adjustments needed?

I have mine set closer to 12-12.5 in the WOT range. I would guess you may get some pops on overrun where you have it leaned out to 15+

[Mark Henry]

The 13.5:1 AFR is fine, running stoich or higher is when temps start getting too high. One nice thing nice about SDS is the lean/rich mixture control knob. I've seen this first hand and have played with the AFR. Head temps increases were almost immediate when you leaned out the mix.
Seat of the pants best power was 12-12.5:1 AFR

[underthetire]

IMO your lean all the way through, except maybe decel. I tried 14.5-1 at cruise, engine not happy. 13.5 was ok for hwy, 12 for hard accel.

[gothspeed]

good chart mrbubblehead ............ that chart shows temps at ideal ignition timing ........ (IMG:style_emoticons/default/smile.gif)

if one's temps vary much beyond what the chart shows ......... it means the timing is not ideal for that given A/F ratio.


A/F ratio changes affect 'flame front speed', here;

http://www.innovatemotorsports.com/resources/myths.php


Here is a simple explanation on the rich vs lean heat issue;

http://www.newton.dep.anl.gov/askasci/eng99/eng99611.htm


Also:

http://www.innovatemotorsports.com/resources/rich.php

[rwilner]

I'm finding this table from the megamanual quite helpful.

[mrbubblehead]

good chart mrbubblehead ............ that chart shows temps at ideal ignition timing ........ (IMG:style_emoticons/default/smile.gif)

if one's temps vary much beyond what the chart shows ......... it means the timing is not ideal for that given A/F ratio.


A/F ratio changes affect 'flame front speed', here;

http://www.innovatemotorsports.com/resources/myths.php


Here is a simple explanation on the rich vs lean heat issue;

http://www.newton.dep.anl.gov/askasci/eng99/eng99611.htm


Also:

http://www.innovatemotorsports.com/resources/rich.php

(IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif)

there arnt many people that realize the relationship between a/f ratio and timing.... most just set the timing and tune to it.

[McMark]

(IMG:style_emoticons/default/agree.gif) You're probably going to want something around the 12.5-13 in a lot of those bins. Gaining fuel economy can come from keeping your foot out of it and tuning the cruize mixture a little leaner. But I would play with that after the fact. Get it running strong and cool first.

[Mark Henry]

You're probably going to want something around the 12.5-13 in a lot of those bins. Gaining fuel economy can come from keeping your foot out of it and tuning the cruize mixture a little leaner. But I would play with that after the fact. Get it running strong and cool first.

This is a good plan, the deceleration values can be left alone because in reality the number is meaningless. Most likely you have to enter a value just to keep the program happy, you will find your O2 meter will lean out off the chart. This is normal on deceleration since there is no load and you cut the fuel.
You will not hurt anything (except MPG) by running a little rich. Run lean and you can fuch things up PDQ.

As to timing I have programmable crankfire and I also played with this extensively. Important yes, but it's not rocket science.

As to all the articles linked they apply to watercooled engines not so much to aircooled. As 904svo stated the aircooled engines use the fuel charge to help cool the engine. This one of the main reasons aircooled engines couldn't meet later emission standards.

I've learned by doing, BTDT.

[gothspeed]

904 engines are carbureted

[Mark Henry]

904 engines are carbureted

Hoe...kay (IMG:style_emoticons/default/rolleyes.gif)

Members name "904svo" post #7.

[polo classic]

it is also better to start tuning from slightly rich

Lean -> hole in pistons
Rich -> bore wash

Hole in pistons happens faster than bore wash (IMG:style_emoticons/default/wink.gif)