Air/Fuel Ratios

[87gtNOS]

That's ok Iceman, that's twice I am wrong! Keep up the good work.

Glad you tune your Apex like an LS7.

 

[Iceman57]

Better then tuning it like a 2 stroke.

And by the way the info in my quote below, isn't from the internet

You don’t have to get your panties all up in a knot I was just posting information about air/fuel mixtures. That same information is posted all over the internet and is very accurate info and I never claimed to be the author. What is written in that article is referring to 4 strokes and is very accurate information according to my resources at the GM Milford Proving Grounds here in Michigan. I was directed to that article from someone that works in the powetrain division. My experience is with auto engines but what we are talking about here is a naturally aspirated 4 stroke engine and not 2 strokes, or big bores or turbo. You may need more fuel for cooling in certain circumstances for what we are talking about here is a near stock apex engine. 1badattack ran his sled at 18:1 at WOT until he installed a wideband and I am pretty sure he would still be running that ratio if he hadn’t. That 18:1 is way lean and I would bet that a lean condition is pretty common on our sleds and you don’t see Apex engines failing often. In most circumstances running too rich will hurt performance. Allens dyno results show that a rich 12.1:1 mixture reduces HP over the 12.6:1 mixture. With the Genesis 150 in the naturally aspirated state you don’t need to use piston wash for your air fuel settings, that is over kill, nothing more then an o2 sensor is needed. The 2009 GM LS7 puts out 505 HP and is set to run at 14.7:1 air fuel mixture at the factory settings don’t tell me that the Genesis 150 is a more high performance engine then the LS7.

 

[DoktorC]

The 2009 GM LS7 puts out 505 HP and is set to run at 14.7:1 air fuel mixture at the factory settings don’t tell me that the Genesis 150 is a more high performance engine then the LS7.

Be careful on your assumptions of high performance. The LS7 is what a 7.0L making 505hp at like what...6000rpm. That's a mear 72hp/liter...which is less then half of the power/liter AND rpm that the apex engine operates at. I don't have a horse in this race but I know for a fact that this motor likes fuel...

 

[Iceman57]

The 2009 GM LS7 puts out 505 HP and is set to run at 14.7:1 air fuel mixture at the factory settings don’t tell me that the Genesis 150 is a more high performance engine then the LS7.

Be careful on your assumptions of high performance. The LS7 is what a 7.0L making 505hp at like what...6000rpm. That's a mear 72hp/liter...which is less then half of the power/liter AND rpm that the apex engine operates at. I don't have a horse in this race but I know for a fact that this motor likes fuel...

I have a koso a/f gauge on my attak, I found at idle it was around 11 and as lean as 18 at wot.

I have a boondocker and adjusted the fuel between 12.5 to 13 throughout the rpm now. That is with the stock airbox, no mods.

How do you explain the 18:1. And im not saying that 14.7:1 is the ideal ratio for power its set that way for emissions. 12.6:1 is better for power with the LS7.

 

[DoktorC]

The 2009 GM LS7 puts out 505 HP and is set to run at 14.7:1 air fuel mixture at the factory settings don’t tell me that the Genesis 150 is a more high performance engine then the LS7.

Be careful on your assumptions of high performance. The LS7 is what a 7.0L making 505hp at like what...6000rpm. That's a mear 72hp/liter...which is less then half of the power/liter AND rpm that the apex engine operates at. I don't have a horse in this race but I know for a fact that this motor likes fuel...

I have a koso a/f gauge on my attak, I found at idle it was around 11 and as lean as 18 at wot.

I have a boondocker and adjusted the fuel between 12.5 to 13 throughout the rpm now. That is with the stock airbox, no mods.

How do you explain the 18:1. And im not saying that 14.7:1 is the ideal ratio for power its set that way for emissions. 12.6:1 is better for power with the LS7.

How do I explain the 18:1? I dunno...does it need explaining? I honestly didn't think the motor would actually run that lean. Maybe the gauge was having a bad day.

If you like testing just run a rich map back to back with your 12.6 map. See if you pick up rpm.

 

[Iceman57]

I have received many PCIII maps that were set up with a o2. All of them are set at WOT from 12.5:1 to 12.8:1, even Allen sets his between that very range.

There is not much difference between 12.0 to 13.0 on the Apex.

B (Green in color) 12.1

F (Red in color) 12.6

G (Blue in color) 13.1

I try to shoot for 12.5 to 12.8 usually.

 

[DoktorC]

I have received many PCIII maps that were set up with a o2. All of them are set at WOT from 12.5:1 to 12.8:1, even Allen sets his between that very range.

There is not much difference between 12.0 to 13.0 on the Apex.

B (Green in color) 12.1

F (Red in color) 12.6

G (Blue in color) 13.1

I try to shoot for 12.5 to 12.8 usually.

I'm not disputing your or Allen's mapping...I was commenting on your assumption that a GM push rod motor is somehow superior to what's under my hood.

But I still like rich .

 

[Iceman57]

In no way am I saying that the LS7 is superior, I was just talking about high performance engines. My whole point; and it has been all along; is that for the most part a 12.5:1 fuel mixture is a good ratio, thats it.

 

[rehm70]

.

[quote="Iceman57
How do you explain the 18:1. And im not saying that 14.7:1 is the ideal ratio for power its set that way for emissions. 12.6:1 is better for power with the LS7.[/quote]

I have a Dynojet Wideband Commander, and the stock Apex Map is WAY lean right off idle/throttle snap.
My warning light goes off at 15.0, and the needle flies past that for a millisecond.....maybe that will explain the 18.1??

 

[justin gallant]

I have a koso a/f gauge on my attak, I found at idle it was around 11 and as lean as 18 at wot.

I have a boondocker and adjusted the fuel between 12.5 to 13 throughout the rpm now. That is with the stock airbox, no mods.

Did you find a difference in response?

 

[Pete_man26]

Going to bring a old post back to life here.

So I have question for you all, I'm running a PC3, I have a AEM Wideband AFR gauge on the sled, its been dialed in to the 12.6-12.8 range. I left it like that when it was parked last spring. I just went for ride this past Saturday night and the gauge is reading one full point leaner from last spring.(13.6-14.0) I have made zero changes. I put Shell premium in the tank when I filled up right before the ride.

So I heard a rumor, that apparently in Canada now 91 Octane premium could have up to 10% ethanol in it. Based on my knowledge of jetting, since we are now replacing the 100% gasoline fuel to 90% gasoline and 10% ethanol which displaces the amount of fuel this in fact would lean out the AFR.

I even pulled the map last night to make sure the map didn't somehow get deleted and it was still in the PC3.

Can anyone confirm my theory about the leaner AFR?
Has anyone heard the same rumor about 10% ethanol in premium fuel?

 

[Stubbs]

Really depends on the source of the fuel, but unless something has changed, Shell V Power has no ethanol in it at all.

 

[sideshowBob]

I used to run a Bender exhaust on my Attak and it eventually developed a crack. My first clue of an issue was that the AFR started showing lean especially at lower RPM.
Check your exhaust donuts and headers and muffler for leaks/cracks.