air fuel ratio
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From: knoxville, tennessee, usa
air fuel ratio
what is an ideal air/fuel ratio for a comp4 car on itbs and off itbs i have heard 12.4 to 13.5 but i think factory gsr is like 14.8 so i am confused i would like to know so i can get my car out properly thanks
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From: Ben Lomond, Ca, USA
Re: air fuel ratio (allmtrdc4)
Air/fuel ratio is dependant on your engine and varies depending on enging speed and load. I am assuming the numbers people are throwing out are for WOT acceleration only. Normally, the air/fuel ratio at WOT will taper from a leaner ratio to a richer ratio. I'm not saying the engine is running leaner that stoich, I'm saying it may start off at 14:1 and end up at 12.5:1 at redline.
Tuning an unknown combination of parts that somebody has put together is a lot harder than tuning a known combination of engine parts that you already have maps that give you a rough start for. If you are building 5 identical engines you will only need to tune one engine and then transfer that tuning over to the other four - although you will always need to 'fine tune' all of them for best performance because of production tolerances. So each engines tuning will be slightly different.
And by 'identical', I mean identical. Header 'A' is not the same as header 'B' just because it's called a header.
You didn't list any specs on your engine so it is impossible to even guess at a WOT air/fuel spread although what people have said in the post is pretty close.
Tuning an unknown combination of parts that somebody has put together is a lot harder than tuning a known combination of engine parts that you already have maps that give you a rough start for. If you are building 5 identical engines you will only need to tune one engine and then transfer that tuning over to the other four - although you will always need to 'fine tune' all of them for best performance because of production tolerances. So each engines tuning will be slightly different.
And by 'identical', I mean identical. Header 'A' is not the same as header 'B' just because it's called a header.
You didn't list any specs on your engine so it is impossible to even guess at a WOT air/fuel spread although what people have said in the post is pretty close.
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From: Tuscaloosa, Al, usa
Re: air fuel ratio (SpeedDreamz.com)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SpeedDreamz.com »</TD></TR><TR><TD CLASS="quote">13-13.5 is usually good.</TD></TR></TABLE>
Yes that is wot.
Yes that is wot.
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From: Ben Lomond, Ca, USA
Re: air fuel ratio (Scott_Tucker)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Scott_Tucker »</TD></TR><TR><TD CLASS="quote">I am assuming the numbers people are throwing out are for WOT acceleration only. </TD></TR></TABLE>
Sorry, I thought I was in the Tech/Misc. forum. Hopefully you would be at WOT or you've got some serious traction issues!
Sorry, I thought I was in the Tech/Misc. forum. Hopefully you would be at WOT or you've got some serious traction issues!
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Thread Starter
Joined: May 2004
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From: knoxville, tennessee, usa
Re: air fuel ratio (Scott_Tucker)
hey scott_tucker i appreciate the advice i am just trying to get an idea as to where i need to be sitting i understand what you are saying about every motor is different i am just simply wanting a general idea and the engine specs are as fallow lsvtec 12.5to1 itr cams headertech header intake man wallbro 255 gsr injectors getting ready to swich to h22 so if you could give me a rough idea where i need to be standing i have heard from numerous people anywhere between 12.5 to 13.4 so i have a general idea
also i have not messed with the cam timing or the ignition timeing any sugestions on those would be nice just let me know
also i have not messed with the cam timing or the ignition timeing any sugestions on those would be nice just let me know
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From: Ben Lomond, Ca, USA
Re: air fuel ratio (allmtrdc4)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allmtrdc4 »</TD></TR><TR><TD CLASS="quote">hey scott_tucker i appreciate the advice i am just trying to get an idea as to where i need to be sitting i understand what you are saying about every motor is different i am just simply wanting a general idea and the engine specs are as fallow lsvtec 12.5to1 itr cams headertech header intake man wallbro 255 gsr injectors getting ready to swich to h22 so if you could give me a rough idea where i need to be standing i have heard from numerous people anywhere between 12.5 to 13.4 so i have a general idea
also i have not messed with the cam timing or the ignition timeing any sugestions on those would be nice just let me know </TD></TR></TABLE>
If you start at 1000 RPM and go up to redline you would 'roughly' graph a straight line starting at about 14:1 on your engine. A fine tuned engine that you can remap the ignition timing on could run istarting from 14.5:1 but since you are keeping timing stock, err on the rich side (but if it spews black smoke when you're done it is a problem and will hurt your engine). The line would go up to redline (8500 - 9000?) and would probably get as rich as 10.5:1 to 11.5:1.
What are you running for engine management? What you really want to know is, What is the fuel mixture required at each break-point? A break-point represents the rpm the engine is spinning at that point on the matrix. For example, if you had a main fuel map that was 10 x 10 bytes you would have 'headers' for each of the axis on the graph. These headers are the break-points. You need to shoot for a certain air fuel ratio at the RPM the header break-point represents. They are not normally broken into straightforward rpm breaks, it's more like 700 rpm, 1150 rpm, 1850 rpm, etc.
The basic procedure for tuning at WOT starts out by putting in in third gear (if you're doing this on the road with an air fuel meter). Start it off at about 500 rpm and then just open the throttle to WOT and run it a couple of hundred rpm past the breakpoint on the guage just before you see the tach sweep past the rpm break-point. Call it out and have a friend write down the reading on the gauge. repeat this for each break-point. You should be able to find out what the breakpoints are for whatever engine management system. Unless you are using stock, which is not the greatest idea.
also i have not messed with the cam timing or the ignition timeing any sugestions on those would be nice just let me know </TD></TR></TABLE>
If you start at 1000 RPM and go up to redline you would 'roughly' graph a straight line starting at about 14:1 on your engine. A fine tuned engine that you can remap the ignition timing on could run istarting from 14.5:1 but since you are keeping timing stock, err on the rich side (but if it spews black smoke when you're done it is a problem and will hurt your engine). The line would go up to redline (8500 - 9000?) and would probably get as rich as 10.5:1 to 11.5:1.
What are you running for engine management? What you really want to know is, What is the fuel mixture required at each break-point? A break-point represents the rpm the engine is spinning at that point on the matrix. For example, if you had a main fuel map that was 10 x 10 bytes you would have 'headers' for each of the axis on the graph. These headers are the break-points. You need to shoot for a certain air fuel ratio at the RPM the header break-point represents. They are not normally broken into straightforward rpm breaks, it's more like 700 rpm, 1150 rpm, 1850 rpm, etc.
The basic procedure for tuning at WOT starts out by putting in in third gear (if you're doing this on the road with an air fuel meter). Start it off at about 500 rpm and then just open the throttle to WOT and run it a couple of hundred rpm past the breakpoint on the guage just before you see the tach sweep past the rpm break-point. Call it out and have a friend write down the reading on the gauge. repeat this for each break-point. You should be able to find out what the breakpoints are for whatever engine management system. Unless you are using stock, which is not the greatest idea.
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Joined: May 2004
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From: knoxville, tennessee, usa
Re: air fuel ratio (Scott_Tucker)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Scott_Tucker »</TD></TR><TR><TD CLASS="quote">
If you start at 1000 RPM and go up to redline you would 'roughly' graph a straight line starting at about 14:1 on your engine. A fine tuned engine that you can remap the ignition timing on could run istarting from 14.5:1 but since you are keeping timing stock, err on the rich side (but if it spews black smoke when you're done it is a problem and will hurt your engine). The line would go up to redline (8500 - 9000?) and would probably get as rich as 10.5:1 to 11.5:1.
What are you running for engine management? What you really want to know is, What is the fuel mixture required at each break-point? A break-point represents the rpm the engine is spinning at that point on the matrix. For example, if you had a main fuel map that was 10 x 10 bytes you would have 'headers' for each of the axis on the graph. These headers are the break-points. You need to shoot for a certain air fuel ratio at the RPM the header break-point represents. They are not normally broken into straightforward rpm breaks, it's more like 700 rpm, 1150 rpm, 1850 rpm, etc.
The basic procedure for tuning at WOT starts out by putting in in third gear (if you're doing this on the road with an air fuel meter). Start it off at about 500 rpm and then just open the throttle to WOT and run it a couple of hundred rpm past the breakpoint on the guage just before you see the tach sweep past the rpm break-point. Call it out and have a friend write down the reading on the gauge. repeat this for each break-point. You should be able to find out what the breakpoints are for whatever engine management system. Unless you are using stock, which is not the greatest idea.</TD></TR></TABLE>
i am not leaving the timing stock or the cam timing stock i was just stating that they are stock right now and i order hondata s300 it will be here next week so i have engine management taken care of in two weeks i am getting the dyno for 2 days thanks to my sponsors and am tuning the **** out of my car
If you start at 1000 RPM and go up to redline you would 'roughly' graph a straight line starting at about 14:1 on your engine. A fine tuned engine that you can remap the ignition timing on could run istarting from 14.5:1 but since you are keeping timing stock, err on the rich side (but if it spews black smoke when you're done it is a problem and will hurt your engine). The line would go up to redline (8500 - 9000?) and would probably get as rich as 10.5:1 to 11.5:1.
What are you running for engine management? What you really want to know is, What is the fuel mixture required at each break-point? A break-point represents the rpm the engine is spinning at that point on the matrix. For example, if you had a main fuel map that was 10 x 10 bytes you would have 'headers' for each of the axis on the graph. These headers are the break-points. You need to shoot for a certain air fuel ratio at the RPM the header break-point represents. They are not normally broken into straightforward rpm breaks, it's more like 700 rpm, 1150 rpm, 1850 rpm, etc.
The basic procedure for tuning at WOT starts out by putting in in third gear (if you're doing this on the road with an air fuel meter). Start it off at about 500 rpm and then just open the throttle to WOT and run it a couple of hundred rpm past the breakpoint on the guage just before you see the tach sweep past the rpm break-point. Call it out and have a friend write down the reading on the gauge. repeat this for each break-point. You should be able to find out what the breakpoints are for whatever engine management system. Unless you are using stock, which is not the greatest idea.</TD></TR></TABLE>
i am not leaving the timing stock or the cam timing stock i was just stating that they are stock right now and i order hondata s300 it will be here next week so i have engine management taken care of in two weeks i am getting the dyno for 2 days thanks to my sponsors and am tuning the **** out of my car
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From: Ben Lomond, Ca, USA
Re: air fuel ratio (allmtrdc4)
OK, I just misread it. It is good you are using a good stand alone engine management system. You should have a much better running engine because of it.
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From: San Juan Capistrano, Ca, USA
Re: air fuel ratio (allmtrdc4)
In short, tune the a/f to what-ever is required to make max peak torque. That is just a general statement, but an engine can withstand a LEANER mixture above peak torque. An engine is most sensitive to a/f at peak torque. As such, the ignition curve is most sensitive below peak torque. Every PRO Stock engine retards timing to some degree after peak torque, and they lean the mixture out slightly also. There are other things to keep in mind during tuning, such as the acceleration rate the engine will see. The slower the acceleration rate 1.e. 600RPM/sec. the more important it is to have a safe tune rather than the tune up that makes max power....
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