Finding The My Target Afr With Gas/ethanol 90/10 Mix

[gbradley]

I was using 100 octane race fuel and my target afr was 12.5:1, but this particular brand isn't available in my area any more. Now I use Sunoco gt plus 260 104 octane with 10% ethanol. I'm trying to find the afr that's equivalent to my original target afr with 100% gasoline. I know the stoich of gas with 10% ethanol is 14.13:1, but I'm not sure if that means I can run leaner or need to run richer. Any input would be greatly appreciated.

 

[Bud92gsx]

I'm running 70/30 gas/ ethanol. I noticed she wants to pull alot harder when in boost.. But have the boost set on wastgate pressure, because you can't run too high of boost on ethanol I'm told..

 

[greengoblin]

You were told wrong. You run Ethonal so you can run high boost with good timing. You however need to have the proper tuning tools and fuel system to do this.

 

[greengoblin]

I would use the same A/F if you where not seeing knock. Ethonal is much less prone to detonation. However 10% is not much at all and may have some effect but very little.

 

[gbradley]

I'm not having any knock issues but since I'm not I would like to try to lean the afr more to see if I can eek out a little more power without melting pistons. I'm just not sure if I can go lean or I need to richen with a stoich of 14.13:1. Thanks.

 

[greengoblin]

I'm not having any knock issues but since I'm not I would like to try to lean the afr more to see if I can eek out a little more power without melting pistons. I'm just not sure if I can go lean or I need to richen with a stoich of 14.13:1. Thanks.

Not sure what you mean. 14.13:1 would be WAY lean at WOT. That is clost to what you would want at idle and criuse.

Truly I would not go any leaner. You could try I guess but if you don't net anymore or little hp it not worth the risk.

Depending on what timing your running maybe increase it and make more power. Again though to much can kill the engine even if you are not seeing knock. I don't like to go over 20 degrees(ecmlink) of timing.

Big boost and really high timig really increase the cylinder pressures and can do lots of bad stuff.

Kevin

 

[gbradley]

I not saying my afr is 14.13:1, I saying the stoich for gasoline with 10% ethanol is. My afr is 12.5:1 on 100% gasoline race fuel which has a stoich of 14.7:1. Since the stoich for the fuel I'm using now is different from 100% gasoline I was using before I'm trying to find the equivalent afr. Thanks.

 

[Bud92gsx]

Put on a 2g mas if you want to lean it out a bit...I think i'm doing this today, If i get off of my fat ass and get going..

 

[matthewdesigns]

I not saying my afr is 14.13:1, I saying the stoich for gasoline with 10% ethanol is. My afr is 12.5:1 on 100% gasoline race fuel which has a stoich of 14.7:1. Since the stoich for the fuel I'm using now is different from 100% gasoline I was using before I'm trying to find the equivalent afr. Thanks.

Your wideband doesn't care what fuel is being burned...stoich is always displayed as 14.7:1. I run straight e85/e70 (depending on the season) and stoich doesn't change. When I go back to pump91, still 14.7:1. When I'm blended, it's still 14.7:1.

If you are WOT tuning for 12.5:1 on race gas, then you could probably bump that a little leaner, maybe a couple of tenths, but 10% e85 isn't going to give you a lot of room. My pump gas tune targets 10.5:1, whereas my e85 tune targets 11.5:1 given it's knock suppression qualities. I'm on a blend right now of 2gal pump91/14gal e70 (for cold start help), and I shoot for 11.2:1 since the mix is a little gas heavy. You are already going to a higher grade fuel in the 104 from the 100 octane, so you'll be able to run a little leaner theoretically on just that (or are you saying that the fuel is already blended?). Either way, your best bet is to do what you normally do...find the place you don't make any more power and then come back a little for safety.

 

[greengoblin]

Put on a 2g mas if you want to lean it out a bit...I think i'm doing this today, If i get off of my fat ass and get going..

You are aware that by just dumping E85 into your car will make it run leaner all by itself right. I really not sure what you are tuning with but after your first post on this topic thn your vague and questionable second post, I don't thnk you know what you are talking about.

gbradley

I pretty sure your ecu will be able to handle the 10% blend while in closed loop all by itself . Also your wideband is going to read 14:7.1 even on straight e85 for stoich. Mine does and everyone else I know does too.

Kevin

 

[Bud92gsx]

You are aware that by just dumping E85 into your car will make it run leaner all by itself right. I really not sure what you are tuning with but after your first post on this topic thn your vague and questionable second post, I don't thnk you know what you are talking about.
Kevin

I really don't sir. I'm still learning just like everyone else...
I tried the 2g mas and I did something wrong so I put the 1g mas back on.. But shes running like a champ I have to say...