Fundamental Question - Timing vs. A/F Ratio
Thread Starter
B*a*n*n*e*d
Joined: Mar 2002
Posts: 7,765
Likes: 1
Fundamental Question - Timing vs. A/F Ratio
Fundamental Question - Timing vs. A/F Ratio
What A/F ratio needs the least amount of timing?
Stated in a other fashion: at what A/F ratio does combustion occur the quickest.
Good luck to all (that are not dumbasses).
Top contenders should be (in no particular order)
Belbin
92TypeR
Constipation Contraption
LOL Hatch
Tony1
Cosworth FL (for life).
Modified by Don Lackey at 10:50 PM 1/12/2007
What A/F ratio needs the least amount of timing?
Stated in a other fashion: at what A/F ratio does combustion occur the quickest.
Good luck to all (that are not dumbasses).
Top contenders should be (in no particular order)
Belbin
92TypeR
Constipation Contraption
LOL Hatch
Tony1
Cosworth FL (for life).
Modified by Don Lackey at 10:50 PM 1/12/2007
Honda-Tech Member
Joined: Feb 2006
Posts: 3,789
Likes: 0
From: Single camshafting for now in, N.Y.
Re: Fundamental Question - Timing vs. A/F Ratio (Don Lackey)
if were talking about afr at wide open throttle then 13.7:1(gettin hot)
15.1+ would be closer to detonation meaning alot less timing is needed
(i bored at work
)
15.1+ would be closer to detonation meaning alot less timing is needed
(i bored at work
) 
Honda-Tech Member
Joined: Aug 2004
Posts: 4,680
Likes: 2
From: Carlisle, PA, USA
Re: Fundamental Question - Timing vs. A/F Ratio (alterdcreations)
I would think a leaner mixture would ignite the quickest, correct?
Less fuel to burn, therefore, quicker combustion?
I'm a noob.
Less fuel to burn, therefore, quicker combustion?
I'm a noob.
Honda-Tech Member
Joined: Oct 2002
Posts: 5,152
Likes: 24
From: chicago burbs, Il, USA
Re: Fundamental Question - Timing vs. A/F Ratio (Don Lackey)
I was always under the impression that less fuel burns slower, thus more timing is needed if you pull fuel from the cruising load/rpm range to keep EGTs down.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">at what A/F ratio does combustion occur the quickest.</TD></TR></TABLE>
wouldn't that depend on the temp/pressure of the incoming air, the temp of the engine, the compression ratio and about 10 other aspects?
or are you looking for the general term for it?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">at what A/F ratio does combustion occur the quickest.</TD></TR></TABLE>
wouldn't that depend on the temp/pressure of the incoming air, the temp of the engine, the compression ratio and about 10 other aspects?
or are you looking for the general term for it?
Trending Topics
Honda-Tech Member
Joined: Feb 2002
Posts: 3,970
Likes: 0
From: CA
Re: Fundamental Question - Timing vs. A/F Ratio (Relic1)
This may be totally wrong, but I will take a guess at it...
Generally, the AFR that requires the least timing will be whatever the AFR of your peak torque..???
Generally, the AFR that requires the least timing will be whatever the AFR of your peak torque..???
Re: (koczeka)
Combustion occurs quickest with A/F between 12 and 13 but mostly 13 for NA car.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by theyoungone »</TD></TR><TR><TD CLASS="quote">about 12.8-13:1 afr.</TD></TR></TABLE>
X2 agreed.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by theyoungone »</TD></TR><TR><TD CLASS="quote">about 12.8-13:1 afr.</TD></TR></TABLE>
X2 agreed.
Honda-Tech Member
Joined: Jun 2005
Posts: 791
Likes: 0
From: 209, USA
Re: (mar778c)
i have no idea. i'm on this thread to learn.
one thing i have read in the past is that stoich/14.7 is the most efficient combustion, but whether or not that means the quickest, I do not know.
one thing i have read in the past is that stoich/14.7 is the most efficient combustion, but whether or not that means the quickest, I do not know.
Honda-Tech Member
Joined: Jun 2004
Posts: 7,539
Likes: 5
From: Sherman Oaks, CA, United States
Re: Fundamental Question - Timing vs. A/F Ratio (Don Lackey)
I can only speak from personal experimentation.
Running really rich, my Spitfire needed a ton of timing to stay running and accelerate decently. After rejetting the carb to run leaner in all conditions, I had to pull a ton of timing to get it to run correctly.
Assuming that gas burns at a steady rate (it might not), regardless of the ratio of the mixture, then the leaner the ratio the faster you'll consume all available fuel. Which would back my limited experience of "more timing for more fuel".
So, I'm going to guess the leaner the mixture, the faster the burn.
Is anyone going to contribute the correct answer, as well as a nice explanation of why?
Running really rich, my Spitfire needed a ton of timing to stay running and accelerate decently. After rejetting the carb to run leaner in all conditions, I had to pull a ton of timing to get it to run correctly.
Assuming that gas burns at a steady rate (it might not), regardless of the ratio of the mixture, then the leaner the ratio the faster you'll consume all available fuel. Which would back my limited experience of "more timing for more fuel".
So, I'm going to guess the leaner the mixture, the faster the burn.
Is anyone going to contribute the correct answer, as well as a nice explanation of why?
Honda-Tech Member
Joined: Jan 2003
Posts: 2,841
Likes: 1
From: the backwoods, usa
Re: Fundamental Question - Timing vs. A/F Ratio (Don Lackey)
i guess i never really think of it in "timing for AFR", i think of it as timing for load/throttle position/air in engine
partial throttle, low load, lean mixture, low VE = timing advance
WOT, peak torque, max VE, highest cylinder pressure, mixture slightly rich = least timing
torque tailing off, less cylinder filling, less burn time = little more timing
just give them what they want. pretty good post rocket. gets members thinking
partial throttle, low load, lean mixture, low VE = timing advance
WOT, peak torque, max VE, highest cylinder pressure, mixture slightly rich = least timing
torque tailing off, less cylinder filling, less burn time = little more timing
just give them what they want. pretty good post rocket. gets members thinking
Honda-Tech Member
Joined: Mar 2004
Posts: 308
Likes: 0
From: Calgary, AB, CANADA
Re: Fundamental Question - Timing vs. A/F Ratio (alterdcreations)
Interesting question..
Take this scenario.. Pull a trailer in a "lean burn" car for example. At part throttle there will be lots of timing and high A/F but going up a hill when engine load changes more fuel and less timing is applied for reduce/prevent detonation. Quickest combustion may even occur during idle.
EDIT: ^^ damn nearly the same response haha
Take this scenario.. Pull a trailer in a "lean burn" car for example. At part throttle there will be lots of timing and high A/F but going up a hill when engine load changes more fuel and less timing is applied for reduce/prevent detonation. Quickest combustion may even occur during idle.
EDIT: ^^ damn nearly the same response haha
Honda-Tech Member
Joined: Feb 2006
Posts: 3,789
Likes: 0
From: Single camshafting for now in, N.Y.
Re: Fundamental Question - Timing vs. A/F Ratio (Don Lackey)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Don Lackey »</TD></TR><TR><TD CLASS="quote">
Good luck to all (that are not dumbasses).
</TD></TR></TABLE>
i guess some people in here are dumbasses
Good luck to all (that are not dumbasses).
</TD></TR></TABLE>
i guess some people in here are dumbasses
Honda-Tech Member
Joined: Jun 2005
Posts: 791
Likes: 0
From: 209, USA
Re: Fundamental Question - Timing vs. A/F Ratio (TunerN00b)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TunerN00b »</TD></TR><TR><TD CLASS="quote">I can only speak from personal experimentation.
Running really rich, my Spitfire needed a ton of timing to stay running and accelerate decently. After rejetting the carb to run leaner in all conditions, I had to pull a ton of timing to get it to run correctly.
Assuming that gas burns at a steady rate (it might not), regardless of the ratio of the mixture, then the leaner the ratio the faster you'll consume all available fuel. Which would back my limited experience of "more timing for more fuel".
So, I'm going to guess the leaner the mixture, the faster the burn.
Is anyone going to contribute the correct answer, as well as a nice explanation of why?</TD></TR></TABLE>
interesting
Running really rich, my Spitfire needed a ton of timing to stay running and accelerate decently. After rejetting the carb to run leaner in all conditions, I had to pull a ton of timing to get it to run correctly.
Assuming that gas burns at a steady rate (it might not), regardless of the ratio of the mixture, then the leaner the ratio the faster you'll consume all available fuel. Which would back my limited experience of "more timing for more fuel".
So, I'm going to guess the leaner the mixture, the faster the burn.
Is anyone going to contribute the correct answer, as well as a nice explanation of why?</TD></TR></TABLE>
interesting
