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Discussion Starter · #1 ·
What gives better performance? lean or rich?
 

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p10driver said:
What gives better performance? lean or rich?

Neither, just right makes better performance but for all purposes richer is better.

You should be asking what is a safe or ideal A/F ratio, by they way all performance engines run the rich side stoich 14.7-10.0.

I'll give some general A/F ratios for turbo and non-turbo

Turbo = 12.6 A/F ratio or richer

Non-turbo = 13.6 A/F ratio or leaner/richer

Again this is just a very general estimate other things need to be taken into account.
 

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Discussion Starter · #5 ·
I know that lean is going to smoke up the engine. And I know that EFI cars have enrichment fields for accelereation, my carb has a acceleration pump witch fogs some extra fuel into the carb when I floor it. But most people told me that lean gives better power?? so I'am a little confused.
 

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p10driver said:
I know that lean is going to smoke up the engine. And I know that EFI cars have enrichment fields for accelereation, my carb has a acceleration pump witch fogs some extra fuel into the carb when I floor it. But most people told me that lean gives better power?? so I'am a little confused.
Bro its a much bigger picture than LEAN or RICH. Here I'll draw you an A/F ratio scale:

RICH***************STOICH*******************LEAN
10___11___12___13___14.7___15__16__17__18__19__20


RICH = 10.1 - 14.6 this is the range you need to be in when driving in open loop, WOT. (see prev. post)

STOICH = 14.7 = closed loop, cruising, non-WOT although some newer cars now run closed loop during idle for better emission.

LEAN = 14.8 - 20.1 The only time you can be on this side of scale would be at idle or no load such as coast down.

So the question that should be asked is how LEAN can I run RICH or whats the leanest I can run on the rich side of stoich or better yeat talk A/F ratios or O2 senor voltage because asking whats better lean or rich will get your engine blown up. So if someone tells you one or the other, rich or lean hows that gonna help you?
 

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Doesn't running a little lean(less than 15 though) provide a more complete combustion? Isn't that good for something(I know running too lean isn't good for the internals)?
 

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Discussion Starter · #8 · (Edited)
Shure!
I know that there is not only lean or rich. the think I am asking for is going more rich or more lean than stock? and my car is always in open loop becouse is a carb engine :) ( so there are no loops at all)

So does give more rich better performance?

Barnout if lean gives better performance, why to have enrichment fields and acceleration pumps then?
 

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bitter old man
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Stoichiometry is for chemists. What works in the real world is totally different.

Idle mixture will be rich because of very low airflow and problems igniting a stoichiometric ratio at that low flow. Steady-state cruise will be lean to get get good mileage. Full power requires very rich mixture at tip-in then a gradual leaning out, though full-throttle will still be on the rich side to protect against detonation.

Carbs are typically richer in all regimes compared to more precisely-controlled fuel injection.
 

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Should we bring up the topic of a/f mix and catalytic converters just to add some confusion?
 

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Discussion Starter · #11 ·
no thanx. who needs catalytic converters.

I know that some people(general not anly nissans) play with their MAF's they lower the spring force so the flap opens faster and the ECU thinks that more air is sucked into the engine. This would result in a richer A/F mixture?
A guy told that he improved his performace by 20km/h (he measured the max speed on a hill) an lowered his fuel consuption by 0,5-1l/100km(this would mean that he is going leaner) by reducing the spring force. Is he talking hot air???
 

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bitter old man
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No. He is indeed fooling the ECU into thinking the engine is drawing more air than is actually the case. This will enrichen the mixture and could very well increase power slightly. It will NOT improve his fuel mileage, it should instead decrease it slightly while commuting but will make no difference at steady cruise.

Just so everyone is on the same page, GA16 and SR20 uses hot-wire MAF, not flapper valve. Thank you, Nissan, for not placing toilet plumbing under my hood!
 

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Discussion Starter · #13 ·
yes thanx to nissan and thanx to god that my car has a carb!

But the guy comes up with a theory that the engine runs leaner?? I
 

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bitter old man
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Monkeys come in all shapes and sizes, and they are allowed to purchase any vehicle.
 

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okay........running leaner, produces more unnecessary heat, inside and out, more heat, more Nox, an efficient engine runs at cooler temperatures, forced induction or not, but runnning too rich will not make it run colder, so it all goes back to ecu mapping, but for carb engines, runnning richer will provide more upside than running leaner........
 

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sorry, i know this has nothing to do with A/F ratio, but I'm hearing this light, barely noticeable squeaking from the front of my car and just wondering what it was? Someone said it might be a loose fan belt? Does that sound right? any help back would be great. thanks.
 

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akk51 said:
sorry, i know this has nothing to do with A/F ratio, but I'm hearing this light, barely noticeable squeaking from the front of my car and just wondering what it was? Someone said it might be a loose fan belt? Does that sound right? any help back would be great. thanks.
Make a new thread bro, it's not that hard;)
 

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This doesn't really HAVE to do with A/F ratio's, but check this out and tell me if you've ever had this happen or something is just plain wrong. Earlier this week I had 1/4 tank of gas and my car was running great. Purrin like a kitten. Then I filled up, and my car seems to drop RPM's really fast now, almost like I have my AC on. It feels like it bogs a lot and is running super rich. It almost feels like my car is under some sort of strain. This is the first time it's happened, and the more gas I burn, the better it starts running. Anyone have ANY idea?
 
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