KR with E85
09-06-2012, 07:35 PM
#1
KR with E85 I got my tune setup pretty good so i converted it over for e85. Before i had no KR on premium fuel. With the same spark table I am now getting 3 degree's of KR. Do you think this is a bad batch of e85, false knock, or maybe just too lean?
what is the optimum a/f i should be tuning for? I only get kr at wide open throttle. A/f ratio on a gas scale is around 12.3:1. I'm guessing i need to richen it up a bit as it seems v8's like to run on the rich side. (on our motorcycle engines max power with e84 is 12.7:1)
thanks for the help
what is the optimum a/f i should be tuning for? I only get kr at wide open throttle. A/f ratio on a gas scale is around 12.3:1. I'm guessing i need to richen it up a bit as it seems v8's like to run on the rich side. (on our motorcycle engines max power with e84 is 12.7:1)
thanks for the help
09-07-2012, 02:26 AM
#2
Too lean if based on true gasoline stoich, but I think 12.3 for E85 on a gas scale wouldn't even run. Which wideband are you using?
E85 has a stoich point of 9.7
Set your WB to read in Lambda and target for 0.85 lambda at WOT and 1.0 at cruise
E85 has a stoich point of 9.7
Set your WB to read in Lambda and target for 0.85 lambda at WOT and 1.0 at cruise
09-08-2012, 05:38 AM
#4
Um I'm a little confused, you tell me I'm way to lean and should shoot for .85 lambda. However 12.3 on a gas scale is .84 lambda, thus I'm already richer than you suggest.
I guess what i wanted to see was if anyone one out there has tuned a car to run e85 on a dyno, and what a/f ratio did they end up using to make max power?
I guess what i wanted to see was if anyone one out there has tuned a car to run e85 on a dyno, and what a/f ratio did they end up using to make max power?
09-08-2012, 06:19 AM
#5
Um I'm a little confused, you tell me I'm way to lean and should shoot for .85 lambda. However 12.3 on a gas scale is .84 lambda, thus I'm already richer than you suggest.
I guess what i wanted to see was if anyone one out there has tuned a car to run e85 on a dyno, and what a/f ratio did they end up using to make max power?
I guess what i wanted to see was if anyone one out there has tuned a car to run e85 on a dyno, and what a/f ratio did they end up using to make max power?
Lambda is the same for any fuel you use. 1.0 Lambda is stoich, it doesn't matter if it's regular gas or 100% methanol.
AFR depends on fuel and wideband settings, so it may give you incorrect readings.
Use Lambda 1.0 for cruise, 0.85 for WOT and you'll be 100% sure you aren't rich nor lean. A little more o less but you got the idea.
You need to learn how to think in lambda and forget about AFR for a while. It's like learning HEX, you need to forget about decimal to understand it.
09-08-2012, 11:26 AM
#6
09-09-2012, 01:03 PM
#7
You guys are killing me. You can read E85 just fine on a gas scale wideband and targeting a low-mid 12 a/f on the gas scale for E85 is correct. All widebands read in lambda and convert based on the fuel scalar but not all can be switched to give E85 A/F ratios, etc.
Trending Topics
09-09-2012, 08:37 PM
#10
interesting, mine runs perfect all the way up to 12.9-13:1, and I normally run at 12.4 or so. then again I cruise at 16:1 and some say 14:1 max and get terrible milage, guess none of us know what we are doing you better teach us all how wrong we are....
09-10-2012, 10:35 AM
#11
It's very obvious you are not understanding what is being said here. He is talking about reading on the gas scale for the air fuel ratio, it equates to around a .84 lambda reading which is just about what he should be targeting for E85 in an N/A application. This is a pretty simple concept for somebody who has "on the dyno tuning in MD" in their location...
09-10-2012, 11:35 AM
#12
9 Second Club
iTrader: (2)
Join Date: Jul 2002
Location: on the dyno tuning in MD
Posts: 2,583
Likes: 0
Received 1 Like
on
1 Post
I understand the concept just fine... You can misrepresent the data like that if you want to, but you better do it consistently throughout or it will bite you in the ***. AFR=stoich*lambda - so, if you were using the correct stoich value for the fuel you are running (which all of you guys obviously are not) then mid 12's on E85 would be lean... This, along with blended fuels, is exactly why experienced tuners use lambda to tune instead of AFR...
09-10-2012, 11:48 AM
#13
I understand the concept just fine... You can misrepresent the data like that if you want to, but you better do it consistently throughout or it will bite you in the ***. AFR=stoich*lambda - so, if you were using the correct stoich value for the fuel you are running (which all of you guys obviously are not) then mid 12's on E85 would be lean... This, along with blended fuels, is exactly why experienced tuners use lambda to tune instead of AFR...
09-10-2012, 12:22 PM
#14
9 Second Club
iTrader: (2)
Join Date: Jul 2002
Location: on the dyno tuning in MD
Posts: 2,583
Likes: 0
Received 1 Like
on
1 Post
I'm not sure what is so hard to understand about saying GAS SCALE in regards to AFR since a lot of wide bands do NOT have an E85 scalar option and not everybody is changing over to Lambda (like that matters when the math is so simple). The OP clearly stated above that he understands it's the gas scale AFR on the wideband and it gives the same information. It's also pretty obvious you misunderstood what was being said originally by the OP and are now backpedaling.
And by the way, my 2nd job of "on the dyno tuning" has taken a back seat to the reason I'm not getting enough sleep - one little one at home and a second one due in 6 weeks... haven't been on the dyno much in the last couple years...
Last edited by BLK02WS6; 09-10-2012 at 12:28 PM.
09-10-2012, 02:24 PM
#15
BLK02WS6, I appreciate the help and advice but i have to agree with NicD. I put my a/f ratio out there on a gas scale because that is what i am familiar with. I am actually tuning and logging the data with lambda. It is running .83-.84 lambda and I convert it to air fuel ratio of a gas scale cause that is what i have used for years and years tuning other engines on e85.
It doesn't matter if you use lambda or a/f on gas scale because they will be both the same as the gas scale is calculated based on lambda. Also my Innovative DB gauge will only read on a gas scale. so when i watch the gauge it shows in air fuel ratio, when i read the logs it is in lambda.
anyway enough arguing about that. i'm 100% sure i am not running lean. Mods on the car is it is a stock 2002 camaro. I have 1 7/8 kooks headers into dual 2.5" exhaust. stock coils with msd wires, and i can't remember what plugs. I think they are a tr6, but they are whatever NGK has listed as a stock replacement plug.
The engine does have a cam in it, but i don't know the specs as the car came that way. Everything else is stock.
Originally I was thinking I was getting false knock (as i have seen that before when the ls1 sensors get rusted and corroded out) but looking back at my gas logs they don't show any signs of detonation.
It doesn't matter if you use lambda or a/f on gas scale because they will be both the same as the gas scale is calculated based on lambda. Also my Innovative DB gauge will only read on a gas scale. so when i watch the gauge it shows in air fuel ratio, when i read the logs it is in lambda.
anyway enough arguing about that. i'm 100% sure i am not running lean. Mods on the car is it is a stock 2002 camaro. I have 1 7/8 kooks headers into dual 2.5" exhaust. stock coils with msd wires, and i can't remember what plugs. I think they are a tr6, but they are whatever NGK has listed as a stock replacement plug.
The engine does have a cam in it, but i don't know the specs as the car came that way. Everything else is stock.
Originally I was thinking I was getting false knock (as i have seen that before when the ls1 sensors get rusted and corroded out) but looking back at my gas logs they don't show any signs of detonation.
09-10-2012, 10:08 PM
#16
TECH Senior Member
gpr,
you're measuring lambda 0.83 and you see KR...?
are you sure the wideband is still working ok...?
can you hear it knock (listen with knock phones)...?
what is the shape of the KR waveform...?
when you go richer does it still show KR...?
you're measuring lambda 0.83 and you see KR...?
are you sure the wideband is still working ok...?
can you hear it knock (listen with knock phones)...?
what is the shape of the KR waveform...?
when you go richer does it still show KR...?
09-11-2012, 12:41 PM
#18
I'm not sure if i can simply cut a portion of the log and save just that portion, this way i don't have to put a 20 minute log as an attachment??? But here is a screen shot of some KR i got this morning. This is typically what i am seeing. About 3 degree's of kr when I punch it, then slowly tapers down as the computer backs off timing. However i am running stock 2002 camaro spark tables.
BTW, how do you setup a car to cruise at a leaner a/f mixture? Instead of setting it up to cruise at 14.7 or lambda of 1, how would i make it leaner to try and get a little better fuel mileage?
BTW, how do you setup a car to cruise at a leaner a/f mixture? Instead of setting it up to cruise at 14.7 or lambda of 1, how would i make it leaner to try and get a little better fuel mileage?
09-11-2012, 01:10 PM
#19
9 Second Club
iTrader: (2)
Join Date: Jul 2002
Location: on the dyno tuning in MD
Posts: 2,583
Likes: 0
Received 1 Like
on
1 Post
What is your timing there? Also, how rich is it going at the very beginning of the pull (right before the knock) - I can see a dip in lambda there, but can't tell how much - that might be the cause...
09-11-2012, 03:34 PM
#20
TECH Fanatic
iTrader: (6)
Join Date: Jan 2002
Location: Springfield, IL
Posts: 1,194
Likes: 0
Received 0 Likes
on
0 Posts
You're sure the only thing you changed was your fueling for E85? Based on my experiences with E85, it's HARD to make an N/A motor knock with it. Several years ago a friend of mine wanted to do some experimenting with it, and we couldn't get his heads/cam car to knock on E85. We didn't lean it out excessively, but we threw all sorts of other stuff at it that should've made it knock and it didn't.