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

[rwilner]

Lean -> hole in pistons

Won't holes in my pistons make my car lighter and therefore faster?

(IMG:style_emoticons/default/wink.gif)

[McMark]

And your main bearings will last longer.

[gothspeed]

904 engines are carbureted

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

Members name "904svo" post #7.

ok, misread your post (IMG:style_emoticons/default/shades.gif) ........ however the points still stand.

[mrbubblehead]

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)

hmmmm? my car is as lean as i can get it. 16-17 at cruise......no holes yet. i drive 500 miles a week into las vegas and back. how can that be?

look at the chart. lean is cooler. less fuel less heat. fuel is not a coolent. now at wot or 1/3 throttle and above (or load) i swing rich to 12.7

running rich under light load is a waste of fuel. you get no benefit....

BTDT

[Andyrew]

Bubble, do you monitor your head temps or exhaust temps?

Do you dyno your vehicles? do you do comparison tunes between different A/F rations? What you are claiming, 16+ cruise is OK if its properly tuned (this includes timing like you mentioned). But the OP is looking for baseline to get things going, for that purpose its better to be SAFE. In that instance 14.5 is the target for cruise +/- 1 and 12.5 is the target for WOT. This is for your TYPICAL engine. Aircooled engines, being aircooled, need to have their a/f ratio a bit more conservative than watercooled engines to prevent potential overheating. Granted high 11's might be rich in your eyes, but I like to keep my engines cool when running WOT.

All that being said I havent tuned an aircooled engine in a long time and primarily spend my time with big v8's and turbo 4's and typically shoot for 12 flat under WOT.

[Mark Henry]

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)

hmmmm? my car is as lean as i can get it. 16-17 at cruise......no holes yet. i drive 500 miles a week into las vegas and back. how can that be?

look at the chart. lean is cooler. less fuel less heat. fuel is not a coolent. now at wot or 1/3 throttle and above (or load) i swing rich to 12.7

running rich under light load is a waste of fuel. you get no benefit....

BTDT

And is this a aircooled or watercooled car?

[mrbubblehead]

aircooled type 4.... no egt. cylinder head temp, oil temp, and a/f gauges.
actually 14.7 is the death zone. that is where your cyl head temps and pressures are the highest. you never want to be there, light load or heavy WOT. the chart is from piston powered aircooled aircraft engines. im not guessing. aircraft guys have known this for 70 years... we in the automotive world are just catching up... their engines are a little more costly to rebuild than ours.

your right, i did stray. yes for a base line, i would try to hit 12.7-13.5.

[rwilner]

All
Thanks for your responses! I revised my AFR table...goal is to be "strong and cool" per mark's suggestion, I can always optimize for fuel economy later. What do you guys think?


Also, for reference, here's my spark advance table...how does that look?

[Valy]

Retard the spark a bit at idle with no load. Helps with emissions and heat.

[FourBlades]

Remember that Gasoline with 10% ethanol will be stoich at something like 14.1 and not 14.7...

John

[Andyrew]

All
Thanks for your responses! I revised my AFR table...goal is to be "strong and cool" per mark's suggestion, I can always optimize for fuel economy later. What do you guys think?

Great baseline. Thats where you should start.

[JamesM]

aircooled type 4.... no egt. cylinder head temp, oil temp, and a/f gauges.
actually 14.7 is the death zone. that is where your cyl head temps and pressures are the highest. you never want to be there, light load or heavy WOT. the chart is from piston powered aircooled aircraft engines. im not guessing. aircraft guys have known this for 70 years... we in the automotive world are just catching up... their engines are a little more costly to rebuild than ours.

your right, i did stray. yes for a base line, i would try to hit 12.7-13.5.

Is this a stock engine? 1.7, 1.8, or 2.0? What sort of timing are you running when you are at 16-17:1? What sort of head & oil temps are you seeing? Are you missfiring at all?

[McMark]

You might get a little power benefit from adding 'vacuum advance' in this area.

[rwilner]

You might get a little power benefit from adding 'vacuum advance' in this area.

Mark, I thought the same thing. What do you think, another 2 or 3 degrees in that area?

[914werke]

Im digging this thread! (IMG:style_emoticons/default/smile.gif)

[McMark]

You should do your own safe testing, because I haven't.

Here's what I see in the factory manuals...



Which I read to be:

+0° vac. adv. at 100 mmHg (33.8 kPa) and below
+11-14° vac. adv. at 200 mmHg (67.7 kPa) and above

What's your idling kPa?

I'm not proposing that adding 14° of vac. adv. is a good idea. Just suggesting that, based on my interpretation, the stock dist. adds that much. I wouldn't go over you max. adv. (28°), but bringing your 100kPa @ 1200rpm bin up to quite a bit and then linearly degrading with dropping kPa.

Something like the following, might be helpful. I distributed 14° between 45kPa and 100kPa, without going over 28° at any point.
8-22-26-28-28-28
8-20-24-27-28-28
8-18-22-25-28-28
8-16-20-23-26-28
8-14-18-21-24-28
8-12-16-19-22-26.5
8-10-14-17-20-24.5
8-8-12-15-18-22.5

And again, the above suggestion is based on speculation, not experience. Try it at your own risk and always listen for sounds of pinging or other problems. And only add as much advance as makes power. Watch your CHT & EGT.

[JamesM]

You should do your own safe testing, because I haven't.

Here's what I see in the factory manuals...



Which I read to be:

+0° vac. adv. at 100 mmHg (33.8 kPa) and below
+11-14° vac. adv. at 200 mmHg (67.7 kPa) and above

What's your idling kPa?

I'm not proposing that adding 14° of vac. adv. is a good idea. Just suggesting that, based on my interpretation, the stock dist. adds that much. I wouldn't go over you max. adv. (28°), but bringing your 100kPa @ 1200rpm bin up to quite a bit and then linearly degrading with dropping kPa.

Something like the following, might be helpful. I distributed 14° between 45kPa and 100kPa, without going over 28° at any point.
8-22-26-28-28-28
8-20-24-27-28-28
8-18-22-25-28-28
8-16-20-23-26-28
8-14-18-21-24-28
8-12-16-19-22-26.5
8-10-14-17-20-24.5
8-8-12-15-18-22.5

And again, the above suggestion is based on speculation, not experience. Try it at your own risk and always listen for sounds of pinging or other problems. And only add as much advance as makes power. Watch your CHT & EGT.

Mark, I had initially gone the same route and tried to translate the factory information into an advance table but then realized a couple things. One is that both vacuum advance and retard need to be taken into account and two is that the factory chart is listing the vacuum at the distributor ports which is not the actual manifold vacuum as these ports go to various locations on the throttle body so they dont translate directly into a table based on manifold vacuum. Also as far as the 2.0 motor goes, there was ZERO vac advance from 74 onward. even though the port was on the dizzy. I would say stick with the RPM only advance right now as that table appears to be close, if not exactly the same as specs I have seen Jakes RPM advance curve listed as and any adjustment beyond that should probably be done on a dyno.

I am not sure running near full advance at low RPM, WOT conditions is a good idea.

[McMark]

Good points James! Thanks for sharing actual experience. (IMG:style_emoticons/default/wink.gif)

[Richard Casto]

Fun thread!

(Hey, Rich, hope it's going well. It sounds like it is!)

Richard

[rwilner]

Fun thread!

(Hey, Rich, hope it's going well. It sounds like it is!)

Richard

Hey Richard! Make any progress on your resto lately? I checked your thread...been over a year since you updated it...

FYI, I'm going to try and run the autotune this weekend. I'll post before and after VE tables as well as driving impressions and my impression of the autotune in general. This is, of course, assuming we don't get any snow, which they are predicting..... (IMG:style_emoticons/default/WTF.gif)