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Aircooled bettle AFR
Posted: Mon May 01, 2006 12:07 pm
by Mario
I have a air cooled bettle and I just finished the MS conversion. I've heard that aircooled motors run better tuned at around 13:1 is this true? Or should I tune to 14.7:1?
Posted: Mon May 01, 2006 2:16 pm
by Minami Kotaro
You need to set for ~12.5:1 at WOT for best power. I set mine at 12.5:1 under all condtions because it runs well and I don't have to worry about acceleration enrichment.
It still gets about two mpg better than carbureted.
If you want to run it leaner under cruise, you might find better fuel economy but your acceleration enrichments will have to be spot-on to prevent ping.
Re: Aircooled bettle AFR
Posted: Mon May 01, 2006 3:34 pm
by PSIG
Mario wrote:...I've heard that aircooled motors run better tuned at around 13:1 is this true? Or should I tune to 14.7:1?
That sounds like a general statement about a particular engine combo and installation. Most of my air-cooled experience is with 2-strokes, but in the 4-strokers I would tune for best economy (~15 to 16.5:1) up to about 80kpa and straight to 12.5-13.2 above that. If cooling was an issue I might go to 12:1 but if it needed more it's time to rectify the base cooling issue. It sometimes helps to use a vacuum gauge for tuning idle and the leaner ranges unless you have a dedicated WB o2 that will read reliably at light loads. Hope that helps.
Posted: Mon May 01, 2006 4:01 pm
by Mario
Thanks for your input guys, i'm going out right now to try it out ;)
Posted: Wed May 03, 2006 7:06 pm
by Perry
I'm just getting started but my beetle is running pretty well at about 15.5 at cruise, around 14.5 at idle, and 13 at WOT (no boost). I go richer under boost but haven't worked out what is best there yet. I put the coasting mixture about 19 to save gas.
Boost is loads of fun in my baja....
Perry
Posted: Wed May 03, 2006 10:12 pm
by Mario
What are your specs on engine and such. I gave it a go on the 1600.
Very fun...
Posted: Thu May 04, 2006 3:05 am
by Minami Kotaro
Let me contradict my previous post.
Now that I have my EDIS working properly, I can run 14-15:1 AFR at cruise and still have plenty of power with the same head temps.
Very enlightening.
Posted: Thu May 04, 2006 3:48 pm
by Perry
I too am EDIS.
To the best of my knowledge, I have a 1600 with a "110" cam in it. it may be one of the slightly larger bolt on displacements, since it was rebuilt before I bought the car and the previous owner didn't seem all that knowledgable about it. I am just starting into adding boost to it, but so far it's loads of fun at 5 psi. I think it's basically stock other than the cam, they didn't even add an oil filter to it when they rebuilt it.
Perry