A/F ratio adjustment

[Bradley G]

Hey MM'ers,
After my 1st baseline on the dyno a few weeks ago.The A/F was a little lean I think it was 13.6 or 13.8.I am curious to know if I can back that down to a safer range?I have an SCT tuner and a JLT air kit.I would like to have it dynotuned but that will be a while. Is thier anything I can do myself, with the new SCT software to get the A/F down a little?can I pull the A/F without a dyno test?Am I at risk at the ratio I am currently at? I am(way) into the pedal almost every time I get in the Big Black Brick:burnout:
Bradley G

[BillyGman]

Hey MM'ers,
After my 1st baseline on the dyno a few weeks ago.The A/F was a little lean I think it was 13.6 or 13.8.I am curious to know if I can back that down to a safer range?I have an SCT tuner and a JLT air kit.I would like to have it dynotuned but that will be a while. Is thier anything I can do myself, with the new SCT software to get the A/F down a little?can I pull the A/F without a dyno test?Am I at risk at the ratio I am currently at? I am(way) into the pedal almost every time I get in the Big Black Brick:burnout:
Bradley GBrad, a 13.6 to 13.8 AFR would only be too "lean" for a Supercharged engine, but NOT for an N/A engine like you have in your Marauder. 14.7:1 ratio is normal, and considered optimal. However, what is "optimal" is also dependent upon what the ignition timing advance curve is set at.

The terms "rich" and "lean" are both relative since having a 13.8:1 AFR would be too "Lean" for a S/Ced engine, however what that really means is that 13.8:1 AFR is NOT "rich" enough, because anything lower than 14.7:1 is considered "rich" and not "Lean". But again, that standard of 14.7:1 ratio is for N/A engines. There's more power to be had with a lean AFR, but the more lean you go with the AFR, then along with the extra power, you also get an increased tendency for detonation("pinging","knocking") which can destroy an engine quickly, and thefore the fuel octane requirement is increased (higher octane is needed) to prevent that.

[Bradley G]

Hey Billy,

Thanks for the reply!
I thought optimum was 13 A/F. I may stand corrected, Mine may have been in the lower 13's(I wish that was my 1/4 mi. ET's;) )How far away from an optimum 14.7 is acceptable for a N/A motor before it would be advantagous to correct/adjust this?My car makes good power 250 to the wheels.I don't hear any ping.But I do hear a rattleing on WOT that doesnt sound like the engine.Is this anything I should concern myself with?
Bradley G

[BillyGman]

Hey Billy,

Thanks for the reply!
I thought optimum was 13 A/F. I may stand corrected, Mine may have been in the lower 13's(I wish that was my 1/4 mi. ET's;) )How far away from an optimum 14.7 is acceptable for a N/A motor before it would be advantagous to correct/adjust this?My car makes good power 250 to the wheels.I don't hear any ping.But I do hear a rattleing on WOT that doesnt sound like the engine.Is this anything I should concern myself with?
Bradley GAn engine tuner I'm not, so I cannot say how far you can go with the AFR, but I don't think that even an engine tuner would be able to give a blanket statement about what's acceptable that would be responsible unless he also knows what your ignition timing advance curve looks like on a graph. They're both related. I'd recommend you talk to Lidio. He's the expert, and has been tuning many engines of various cars for a number of years now.

"Rattling" noises at WOT doesn't sound good to me, but any diagnosis over the internet cannot be taken too seriously. My brother's Roadmaster emits a rattling noise, but it's something coming from a part of the exhaust pipe. BTW, like I've previously stated, the "13 to 1" AFR that you always hear as being optimal for Marauders is NOT for N/A Marauders, but for Supercharged ones. The S/Ced engine would be much more prone to pinging if the AFR was set at the normal 14.7:1 since the S/Ced engine creates more heat in the combustion chambers than the engines of Naturally Aspirated ("N/A") Marauders do. That's why all S/Ced engines have to be tuned with an AFR which is on the rich side, in order to prevent pinging (detonation). And that's the case with all means of forced induction (Nitrous, turbo, & S/Cing). The ignition timing advance also has to be more conservative, and therefore pushed back(for the engines using forced induction I mean).

[Bradley G]

Thanks Billy,I am going to contact Lidio,and quiz him on any suggestions.

Bradley G


An engine tuner I'm not, so I cannot say how far you can go with the AFR, but I don't think that even an engine tuner would be able to give a blanket statement about what's acceptable that would be responsible unless he also knows what your ignition timing advance curve looks like on a graph. They're both related. I'd recommend you talk to Lidio. He's the expert, and has been tuning many engines of various cars for a number of years now.

"Rattling" noises at WOT doesn't sound good to me, but any diagnosis over the internet cannot be taken too seriously. My brother's Roadmaster emits a rattling noise, but it's something coming from a part of the exhaust pipe. BTW, like I've previously stated, the "13 to 1" AFR that you always hear as being optimal for Marauders is NOT for N/A Marauders, but for Supercharged ones. The S/Ced engine would be much more prone to pinging if the AFR was set at the normal 14.7:1 since the S/Ced engine creates more heat in the combustion chambers than the engines of Naturally Aspirated ("N/A") Marauders do. That's why all S/Ced engines have to be tuned with an AFR which is on the rich side, in order to prevent pinging (detonation). And that's the case with all means of forced induction (Nitrous, turbo, & S/Cing). The ignition timing advance also has to be more conservative, and therefore pushed back(for the engines using forced induction I mean).

[maraudernkc]

BillyGman, I thought that 11.8 to 1 A/F Ratio on a S/C motor is where you want to be at aroung 3000 RPM and above. A engine tuner I am not. Looked at the SCT software one time to buy but you better have a year to study it.

It makes you appreaciate those tuners that do what they do so well and make it look easy.



An engine tuner I'm not, so I cannot say how far you can go with the AFR, but I don't think that even an engine tuner would be able to give a blanket statement about what's acceptable that would be responsible unless he also knows what your ignition timing advance curve looks like on a graph. They're both related. I'd recommend you talk to Lidio. He's the expert, and has been tuning many engines of various cars for a number of years now.

"Rattling" noises at WOT doesn't sound good to me, but any diagnosis over the internet cannot be taken too seriously. My brother's Roadmaster emits a rattling noise, but it's something coming from a part of the exhaust pipe. BTW, like I've previously stated, the "13 to 1" AFR that you always hear as being optimal for Marauders is NOT for N/A Marauders, but for Supercharged ones. The S/Ced engine would be much more prone to pinging if the AFR was set at the normal 14.7:1 since the S/Ced engine creates more heat in the combustion chambers than the engines of Naturally Aspirated ("N/A") Marauders do. That's why all S/Ced engines have to be tuned with an AFR which is on the rich side, in order to prevent pinging (detonation). And that's the case with all means of forced induction (Nitrous, turbo, & S/Cing). The ignition timing advance also has to be more conservative, and therefore pushed back(for the engines using forced induction I mean).

[BillyGman]

BillyGman, I thought that 11.8 to 1 A/F Ratio on a S/C motor is where you want to be at aroung 3000 RPM and above. Like I've previously stated here in this thread, it depends on what the ignition timing advance curve is tailored like. Some engine tuners don't even realize that. I know that from speaking to a few different ones. That's why I'd never have my S/ced Marauder dyno tuned by just anyone. having it dyno TESTED is no biggie, but Dyno TUNING is a whole other ball game, because you're placing the durability and longevity of your engine in the hands of the tuner in question.

Ofcourse a good S/Cer kit comes complete with the required tune included right in the chip that you plug in, and doesn't make any Dyno TUNING neccessary. but I guess that's another topic for another thread.

[Smokie]

Bradley, if your current A/F ratio is for a WOT condition across an rpm range it may be considered a little lean by a tuner, not dangerous by any means. Your A/F ratio is not supposed to remains constant under all throttle conditions because your timing advance is not constant either.

To get the best fuel economy you want to be around 14.5 to 1 under light throttle for common everyday driving. Check inside of tailpipe or pull some plugs and you will get a very accurate story of your fuel ratio, spark plugs do talk if you know the language.

Tell me more details about the noise.

[Bradley G]

Thanks for your comments.I was told that the slightly lean condition was not a big concern By CJ @ Dyno-pro(vendor here)I was curious to know if a dynotune would always be required to make minor adjustments or is there any other way.I am not going to do any thing foolish or rash,I am not that braizen.I would'nt let anyone including myself change any settings until I knew for sure that it was OK.

Smokie; the sound is more like a non metal rattle (dull sounding) but it only appears under WOT when the engine starts to enjoy it's power Band
Bradley G

Bradley, if your current A/F ratio is for a WOT condition across an rpm range it may be considered a little lean by a tuner, not dangerous by any means. Your A/F ratio is not supposed to remains constant under all throttle conditions because your timing advance is not constant either.

To get the best fuel economy you want to be around 14.5 to 1 under light throttle for common everyday driving. Check inside of tailpipe or pull some plugs and you will get a very accurate story of your fuel ratio, spark plugs do talk if you know the language.

Tell me more details about the noise.

[BillyGman]

Smokie has a good point about the AFR that Brad listed since it's only at one stage of the RPM spectrum. the entire RPM range must be viewed. Antoher thing too is that AFR's measured at the tailpipe aren't very accurate. Any engine tuner that measures them at the tailpipe wouldn't even be allowed to go near my car when it comes to tuning it. The good engine tuners will take AFR readings from the header collector, or not too far away rfom that by drilling a whole in the pipe, and installing a threaded bung to accomadate the AFR sensor. that's the way it's supposed to be done.

using a tailpipe sensor is fine for state emissions tests, but for an accurate and reliable performance engine tune, the sensor should be placed more upstream in the exhaust system closer to the engine. Before the catalytic converters is preffered.

[MitchB]

You have to get you A/F correct first, then you tune for spark. In a normally apirated engine, I would shoot for 13.2 to 13.4:1. This will give good engine and cat cooling. Best to tune for spark on a load bearing dyno that will impose engine loads similar to those the car will actually see while in service. Remember, A/F first, then spark.

Mitch

[BillyGman]

You have to get you A/F correct first, then you tune for spark. In a normally apirated engine, I would shoot for 13.2 to 13.4:1. This will give good engine and cat cooling. Best to tune for spark on a load bearing dyno that will impose engine loads similar to those the car will actually see while in service. Remember, A/F first, then spark.

Mitch I'm sure that's true for stock tuning in general, but when it comes to tuning for optimal performance for the street, I've been told by one of the best performance engine tuners in the country that ignition timing advance settings are MORE important, and more critical than AFR settings are (atleast with S/Ced engines anyway) when it comes to pushing the envelope in peformance tuning. That's why I mentioned the ignition timing advance. ;) Just because you have to set the AFR "first" doesn't mean that what it's set at isn't dictated by or atleast relavent to, what you'll be setting the ignition timing advance at for a performance tune.

But since none of us here are professional engine tuners, I don't think it's advantagous for us to get into a big debate about engine tuning here. The bottom line is, that you better know that you can trust the guy who burned your chip, or put the settings into that handheld tuner that you bought, or who is performing a dyno TUNE on your car. Otherwise, you're gambling with the longevity of your engine.

[Smokie]

Back to your question about adjustment, I notice that your tuning originates from Lidio, what is possible with SCT is to make a correction to base program and add for example a 2-3% correction for fuel at WOT and the file can be e-mailed to you and if you have the SCT program and cable, it can be loaded from computer to tuner to car. Talking to Lidio would be best, it can be done.

[BillyGman]

Back to your question about adjustment, Talking to Lidio would be best. Agreed. Lidio is DA MAN. :2thumbs:

[FordNut]

My car is N/A and has been dyno tuned numerous times. No tuner that has ever worked on my car has suggested setting the AFR leaner than 13:1 or so. I would never let anyone set mine up in the 14's, although 14.7:1 is in fact the theoretical optimum. And I do recall most commonly the supercharced cars are setup in the high 11's or low 12's (AFR, not necessarily ET).

[maraudernkc]

BillyGman, Why is it that you have to make everything into a Trilogy vs. everyone else.

Have I ever said anything bad about your s/c kit? No, I have not.

Sorry, I did not mean to highjack the thread.

My apologies




Ofcourse a good S/Cer kit comes complete with the required tune included right in the chip that you plug in, and doesn't make any Dyno TUNING neccessary. but I guess that's another topic for another thread.

[BillyGman]

FordNut,You need to keep in mind what smokie stated earlier......you cannot simply look at one RPM point, and state what the AFR is at that point. Because the AFR will fluctuate up and down throughout the RPM scale. So you have to view what range the AFR stays in. my S/ced marauder goes from 11.8:1 up to 13.1:1, and my car is run very hard, and has been for the last 12,000 miles since I've installed the S/Cer. And it runs just fine. but w/out paying attention to the timing advance settings, all of this is just hot air anyway.

[BillyGman]

BillyGman, Why is it that you have to make everything into a Trilogy vs. everyone else.

Have I ever said anything bad about your s/c kit? No, I have not.

Sorry, I did mean to highjack the thread.

My apologiesget real Dude..you're being defensive for some reason. but let it be known that I wasn't starting any S/cer war. So what's up w/you? Where did I mention any comparisant of S/cers in this thread? you show me that, and then you would have a point that's valid.But you're simply spitting out false accusations here. This thread is about AFR's, and because my car is S/ced, and because AFR requirements for S/ced cars are different than that of N/A engines, then I wanted to make it clear that forced induction engines need to be run at a richer AFR than N/A engines need to be. that's all. you're reading into things that aren't there.

[Tallboy]

BillyGman, Why is it that you have to make everything into a Trilogy vs. everyone else.

Have I ever said anything bad about your s/c kit? No, I have not.

Sorry, I did mean to highjack the thread.

My apologiesBilly hasn't mentioned anything like what you're describing.

Get your facts straight and lighten up.

[maraudernkc]

BillGman, we do agree on one thing that a good tune is important and you guys are very lucky to have Lidio. He is a great tuner.

We will drive my car to Paul's HP if that is what it takes to get a proper tune.



get real Dude..you're being defensive for some reason. but let it be known that I wasn't starting any S/cer war. So what's up w/you? Where did I mention any comparisant of S/cers in this thread? you show me that, and then you would have a point that's valid.But you're simply spitting out false accusations here. This thread is about AFR's, and because my car is S/ced, and because AFR requirements for S/ced cars are different than that of N/A engines, then I wanted to make it clear that forced induction engines need to be run at a richer AFR than N/A engines need to be. that's all. you're reading into things that aren't there.

[BillyGman]

BillGman, we do agree on one thing that a good tune is important and you guys are very lucky to have Lidio. He is a great tuner.

We will drive my car to Paul's HP if that is what it takes to get a proper tune.Greg, I haven't been paying attention to any of the threads you've started about this S/Cer project of yours since I posted a question for you about the Cobra fuel pumps, which was back a few weeks ago when you came out with some dyno numbers. So whatever is going on with your project good or bad is unknown to me, and therefore there's no way that my comments in this thread could've been directed at you. i was speaking about AFR's concerning S/ced marauder engines, as compard to AFR's required for N/A Marauder engines, and that's all.

[MitchB]

I'm sure that's true for stock tuning in general, but when it comes to tuning for optimal performance for the street, I've been told by one of the best performance engine tuners in the country that ignition timing advance settings are MORE important, and more critical than AFR settings are (atleast with S/Ced engines anyway) when it comes to pushing the envelope in peformance tuning. That's why I mentioned the ignition timing advance. ;) Just because you have to set the AFR "first" doesn't mean that what it's set at isn't dictated by or atleast relavent to, what you'll be setting the ignition timing advance at for a performance tune.

But since none of us here are professional engine tuners, I don't think it's advantagous for us to get into a big debate about engine tuning here. The bottom line is, that you better know that you can trust the guy who burned your chip, or put the settings into that handheld tuner that you bought, or who is performing a dyno TUNE on your car. Otherwise, you're gambling with the longevity of your engine.

In so far as a 'tuner' is concerned, I have seen more engines blown-up on a tune by a 'tuner' (so called professional I guess) than I can recall. What this guy is trying to tell you is that detonation will get you in trouble faster than a lean A/F. Once again, and I have been through this many, many times: first you tune A/F, then spark. This is how the so called real professionals do it. Especially with a forced induction app. In fact, the way to tune a SC'd app is to back way off on timing and dial-in A/F. Then you dial-in spark. You cannot tune spark if your A/F is off.

Mitch

[maraudernkc]

Mitch, I agree with you 100%.




In so far as a 'tuner' is concerned, I have seen more engines blown-up on a tune by a 'tuner' (so called professional I guess) than I can recall. What this guy is trying to tell you is that detonation will get you in trouble faster than a lean A/F. Once again, and I have been through this many, many times: first you tune A/F, then spark. This is how the so called real professionals do it. Especially with a forced induction app. In fact, the way to tune a SC'd app is to back way off on timing and dial-in A/F. Then you dial-in spark. You cannot tune spark if your A/F is off.

Mitch

[BillyGman]

What this guy is trying to tell you is that detonation will get you in trouble faster than a lean A/F.

MitchWe're both talking about staying away from detonation here. And that's avoided with having the proper AFR, as well as the proper ignition timing. Both of those parameters are important, however ignition timing is of greater importance according to what I've been told by someone who has tuned more performance engines SUCCESSFULLY than you or I ever will. You want to argue with that, then go ahead. But my car has 12,000 very hard supercharged miles on it, and w/out even so much as a hiccup. And my SUPERCHARGED MARAUDER was tuned by that same tuner via his chip. Which tuner tuned YOUR SUPERCHRGED MARAUDER? Or do you even have a supercharged Marauder? If not, then what Supercharged cars have you had? And what PSI were they running at? And who was it that tuned them? And did they have a 4.6L 32 valve engine under the hood like the Marauder does?

BTW, the engine tuner who I get my advice from, and who tuned my SUPERCHARGED MARAUDER has tuned 60+ SUPERCHARGED MARAUDERS successfully, and even more 4.6L engined SUPERCHARGED Mustangs. And he tunes cars with the roots type S/Cers as well as the centrifugal type ones. He isn't by any means the only good tuner around, but he's one of the best. How about your engine tuner? As for me, I'll stay with the advice of my engine tuner for my 4.6L engined Marauder thankyou. To each his own.

[Pat]

FWIW - I had my MM on the dyno a couple of weeks ago, no AF instrumentation (broke), and after a base line run, the operator increased the fuel in small increments @ WOT until power peaked. It didn't take much of an enrichment adjustment. The ignition timing was optimum from the Diablesport predator tuner. Any change there up or down resulted in lower power.
The predator allows one to change the fuel enrichment by as much as 40% from stock setting.

Like others stated, A Wide band AF instrument connected before the CATS would be ideal. I'm saving for that now. Two sensors, one meter, one switch.

[Smokie]

FWIW - I had my MM on the dyno a couple of weeks ago, no AF instrumentation (broke), and after a base line run, the operator increased the fuel in small increments @ WOT until power peaked. Increasing fuel was the safest way to go, my experience after replacing stock air box was rich results, when tuner leaned mixture I gained power.....:dunno:

[MitchB]

We're both talking about staying away from detonation here. And that's avoided with having the proper AFR, as well as the proper ignition timing. Both of those parameters are important, however ignition timing is of greater importance according to what I've been told by someone who has tuned more performance engines SUCCESSFULLY than you or I ever will. You want to argue with that, then go ahead. But my car has 12,000 very hard supercharged miles on it, and w/out even so much as a hiccup. And my SUPERCHARGED MARAUDER was tuned by that same tuner via his chip. Which tuner tuned YOUR SUPERCHRGED MARAUDER? Or do you even have a supercharged Marauder? If not, then what Supercharged cars have you had? And what PSI were they running at? And who was it that tuned them? And did they have a 4.6L 32 valve engine under the hood like the Marauder does?

BTW, the engine tuner who I get my advice from, and who tuned my SUPERCHARGED MARAUDER has tuned 60+ SUPERCHARGED MARAUDERS successfully, and even more 4.6L engined SUPERCHARGED Mustangs. And he tunes cars with the roots type S/Cers as well as the centrifugal type ones. He isn't by any means the only good tuner around, but he's one of the best. How about your engine tuner? As for me, I'll stay with the advice of my engine tuner for my 4.6L engined Marauder thankyou. To each his own.

Oh please, a pissing contest. Well, for the cars I have had/have: a 1969 Boss 429 Mustang, a 1993 Powerdyne'd 5.0 Thunderbird which is now becoming twin turbo'd. Your car runs fine? Good. I am telling you how Liingenfelder tunes his supercharged/turbo'd cars/engines. Is that good enough? Mike Wesley tunes this way. So does Jerry Wroblewski. You do things the way you want, accept the explanaitions you feel comfortable with. Good, good, good.

Mitch

Oh yeah, we do have an 03 Marauder in the family.

[Bradley G]

Guess this explaines why you can tune a car,! but you can't tuna- fish!....Hey , .. Wait this is My thread:confused: :Offtopic:

Thanks for your comments and enthusieasm!
Bradley G

[BillyGman]

. You do things the way you want, No Mitch, actually, I have them done by someone else when it comes to tuning computer controlled fuel injected engines, and my guess is that you do also. That's why I originally didn't want to get into all of these details with you, since neither one of us are aware of all the details I'm sure. But you came across as though you were challenging me on this, so that's why I kinda took the low road there. However, perhaps it was just the way that I perceived your posts. But I guess we both spoke our minds, and hopefully something in our posts were of help to someone here. That would be best.

[tmac1337]

Guess this explaines why you can tune a car,! but you can't tuna- fish!....Hey , .. Wait this is My thread:confused: :Offtopic:

Thanks for your comments and enthusieasm!
Bradley G

Good joke dude!

[Bradley G]

Hey Greg, No Pickin on my pal Billy cause he is the Guru of burnouts.Good luck on your project with the first air to air Supercharger developed and offered.I have been following your progress!I hope you are able to find a tuner to dail in your set-up!your kit appears to be first rate! Thank you for your efforts!:bows:

Bradley G


BillyGman, Why is it that you have to make everything into a Trilogy vs. everyone else.

Have I ever said anything bad about your s/c kit? No, I have not.

Sorry, I did not mean to highjack the thread.

My apologies

[BillyGman]

Hey Greg, No Pickin on my pal Billy cause he is the Guru of burnouts.Good luck on your project with the first air to air Supercharger developed and offered.I have been following your progress!I hope you are able to find a tuner to dail in your set-up!your kit appears to be first rate! Thank you for your efforts!:bows:

Bradley GLOL.....Brad the diplomat. :D I guess I can learn a few things from you pal. :2thumbs:

[Bradley G]

Thanks Billy,

I can't begin to describe how much I have learned over the last ten months.
The members here are quick to offer help toward virtually every topic!There are even topics I would not have guessed that I would patisipate in.:o I have sparked controversey with a couple of my inquiries(threads)at first, I was feeling a little queasy that members got thier dander ruffeled a bit.Now , I am thinking,the topics are/were probing enough to motivate such responses.Thier are different philosophys on these topics,I enjoy all points of view.Bottom Line :


You Guys And :rock: Girls! Rock!!!


Bradley G