Fuel/ignition settings for best gas mileage??, up to 42° advance crazy?? |
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Fuel/ignition settings for best gas mileage??, up to 42° advance crazy?? |
Mueller |
Aug 15 2005, 05:10 PM
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#1
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
I "borrowed" the quote below from aircooled.net
With the fuel prices going up and up, I figured that was the kick in the @ss I need to get my 914 up and running as a daily driver....since my fuel and ignition can be set however I want with my laptop, I figure I should optimize my little 1.8 for being as frugal with the petrol as it could be right now (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)
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mightyohm |
Aug 15 2005, 05:14 PM
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Advanced Member Group: Benefactors Posts: 2,277 Joined: 16-January 03 From: Seattle, WA Member No.: 162 Region Association: Pacific Northwest |
gas mileage, engine life... gas mileage, engine life... hmm, which do i choose. (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)
just kidding mike. at least you will get rid of those pesky carbon deposits (and valve seats too) |
Dr. Roger |
Aug 15 2005, 05:16 PM
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A bat out of hell. Group: Members Posts: 3,944 Joined: 31-January 05 From: Hercules, California Member No.: 3,533 Region Association: Northern California |
absolutely true.
my dream car will have whatcha' got on yer ride, mike. have fun. there is a fine line with that advance thing though. i experimented in high school auto shop with my parents van.... removed the engine cover so it was basically right next to me while driving it around. had a buddy playing with the timing and was driving at the same time. lots of learnin' and fun. i still say people can go max advance under a particular circumstance as long as there is no ping. nice to read your posting.... (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) |
bd1308 |
Aug 15 2005, 05:17 PM
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#4
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Sir Post-a-lot Group: Members Posts: 8,020 Joined: 24-January 05 From: Louisville,KY Member No.: 3,501 |
42 deg....is that even possible???
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Cap'n Krusty |
Aug 15 2005, 05:23 PM
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#5
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
You DO realize that the vacuum advance on a bone stock 914 does, under certain conditions, go to 42 degrees, right? The mechanical advance goes to 28, or so, and the vacuum goes on from there. The Cap'n |
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Mueller |
Aug 15 2005, 05:29 PM
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#6
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
I "thought" you mentioned that once John, I guess I was not too crazy afterall (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)
My wife starts working at the HD near your house in a few weeks, give me a good reason to come on over and check out your progress (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif) |
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Dr. Roger |
Aug 15 2005, 05:47 PM
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#7
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A bat out of hell. Group: Members Posts: 3,944 Joined: 31-January 05 From: Hercules, California Member No.: 3,533 Region Association: Northern California |
she's working at the HD? Harley Davidson? =-))) i didn't know you were hitched to a biker chick.... (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/aktion035.gif) |
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bd1308 |
Aug 15 2005, 05:56 PM
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#8
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Sir Post-a-lot Group: Members Posts: 8,020 Joined: 24-January 05 From: Louisville,KY Member No.: 3,501 |
yeah but after 73, the vac advance port wasn't, in most cases, even available...... at least from my pelican reading.... |
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lapuwali |
Aug 15 2005, 05:58 PM
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#9
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Not another one! Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743 |
There's a point at every engine speed and every load point where the spark happens at exactly the right time. That point is going to vary depending on the exact engine, which is why your Link will allow you to alter ignition advance with engine speed and manifold pressure. Anything away from that point will give less power and use more gas.
If you feel you can detect knock well enough by ear, then go ahead a fool with lots of advance in certain areas. Experimentation of this kind is easy with a fully programmable setup, so EXPERIMENT! Overadvanced or overretarded engines can run hot, so I'd rig up a CHT if you haven't already. Use ping and CHT to find the safest operating range. For best economy, you really only need to tune the fairly narrow range of MAP/rpm where cruising takes place. |
lapuwali |
Aug 15 2005, 06:00 PM
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#10
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Not another one! Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743 |
Huh? All stock 914s had vacuum distributors. Some used manifold pressure to alter BOTH advance and retard. |
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bd1308 |
Aug 15 2005, 06:01 PM
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#11
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Sir Post-a-lot Group: Members Posts: 8,020 Joined: 24-January 05 From: Louisville,KY Member No.: 3,501 |
i was talking about vaccuum advance only.....
i realize the retard was used in all years. |
rhodyguy |
Aug 15 2005, 06:54 PM
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#12
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,072 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
for great fuel cost savings per week use public transportation. mileage smileage. so If you get that much better on the mpg you're saving what on an average tankful. 3 or 4 bucks? i didn't check, but my guess is i got in at least the very high 20's on the way home from the cruise last weekend. steady throttle, no highjinxs.
k |
cnavarro |
Aug 15 2005, 07:02 PM
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#13
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Cylinder Guru Group: Members Posts: 472 Joined: 30-December 02 From: Chicagoland! Member No.: 49 Region Association: None |
Total advance aside, what target a/f ratio are you aiming for? I've set up more than one Nickies engine with 13.8-14 without any ill effects of heat. But I wouldn't experiment with leaning it out and upping the advance- one at a time please :-)
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Dr. Roger |
Aug 15 2005, 07:33 PM
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#14
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A bat out of hell. Group: Members Posts: 3,944 Joined: 31-January 05 From: Hercules, California Member No.: 3,533 Region Association: Northern California |
13.8 to 14.2 to 1......... air to fuel ratio........
there is a effect of an explosion vs. a controlled burn. case in point. when i fire my potatoe cannon, if i use too much starter fluid it just pops out the end. barely.... when i give it just the smallest of squirts of starter fluid and fire it, it blows that spud so far, it goes out of sight! engines need that controlled burn effect. any more lean and power detiorates very quickly. (IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif) |
Mueller |
Aug 15 2005, 07:53 PM
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#15
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
it would take me about 4 hours each way with public transit (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) |
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Jake Raby |
Aug 15 2005, 07:56 PM
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#16
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
I could write for days on this one- I won't even try.
There are no standards for this- EVERY engine is different and ITS ALL DEPENDANT UPON THE COMBO and your climate/elevation... Don't attempt any of this until you have EGT, CHT, AFR gauges in your car- you can't make any observations until you are able to monitor/log the changes that adjustments make. Every change has an equal reaction and you HAVE to remember that first and foremost. |
Andyrew |
Aug 15 2005, 08:53 PM
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#17
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Spooling.... Please wait Group: Members Posts: 13,376 Joined: 20-January 03 From: Riverbank, Ca Member No.: 172 Region Association: Northern California |
So what could you do to a sbc with an electronic dizzy, and FI (holley pro jet..)
Just learning great stuff with this new toy!!! GL mike... YOu know you need it (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) |
scotty914 |
Aug 16 2005, 12:16 AM
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#18
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suby torque rules Group: Members Posts: 1,525 Joined: 20-July 03 From: maryland, the land of 25 year Member No.: 924 |
28 + mpg at 80 + mph (IMG:http://www.914world.com/bbs2/html/emoticons/lol2.gif)
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Jake Raby |
Aug 16 2005, 12:25 AM
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#19
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
I beat that in my 912E..... (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) TIV powered..
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airsix |
Aug 16 2005, 10:21 AM
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#20
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I have bees in my epiglotis Group: Members Posts: 2,196 Joined: 7-February 03 From: Kennewick Man (E. WA State) Member No.: 266 |
As always, the Cap'n is correct.
On my PEFI I have an rpm-based (ie. mechanical equivalent) max of 27 degrees. I have a vacuum-based table that is independent of the rpm-based table. The vacuum-based curve is set for a max of 12 degrees. These two tables combine to give a total max advance of 39 degrees under high-rpm/high-vacuum conditions (highway cruise for example). This is very similar to the stock advance curve (ok, a hair more conservative). I think what aircooled.net is trying to say is that if you don't have any vacuum advance you are always going to have sucky gas mileage. I'll add that you'll also always have a big flat spot from 2,400- 2,700rpm. While we're on the subject... I played with seemingly infinite ignition advance settings since it's so easy to type them into the laptop. After extensive testing I found that there is a real sweet spot that works better than anything else I tried -- The stock advance curve. (note: I have stock cam and compression. YMMV) -Ben M. |
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