Notices
C7 Z06 Discussion General Z06 Corvette Discussion, LT4 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Sponsored by:
Sponsored by:

What is AFR on a stock C7 Z06 LT4

 
Old 07-01-2019, 04:16 AM
  #1  
ettan47
Junior Member
Thread Starter
 
Member Since: Jan 2009
Posts: 22
Received 2 Likes on 1 Post
Default What is AFR on a stock C7 Z06 LT4

Hi, i need your help regarding AFR on a C7 Z06 LT4. What is the Air fuel ratio on a stock C7 Z06?
I canít find what AFR is on the direct injection LT4.
I am planning to some mods on my car so I need that information. I know that direct injection has much leaner AFR then port injection but what is AFR on a LT4? Thanks in advance for all help / information I can get from members on this forum.
ettan47 is offline  
Old 07-01-2019, 06:39 AM
  #2  
Higgs Boson
CF Senior Member
 
Higgs Boson's Avatar
 
Member Since: Jul 2007
Location: Texas Hill Country
Posts: 9,659
Received 1,065 Likes on 679 Posts
Default

at full throttle 12.4-12.5 (assuming 14.68 stoich) except for when it injects extra fuel to keep the cats cool, which is almost always, pushing it into the 11s or in some cases even 10s.

at part throttle it runs at stoichiometry in closed loop like all other mass produced vehicles. That is 14.1 on E10, 14.7 on E0, or if you fill it up with something else, whatever stoich is for that particular fuel.
Higgs Boson is offline  
The following 2 users liked this post by Higgs Boson:
C5-VERT (07-01-2019), ettan47 (07-02-2019)
Old 07-01-2019, 02:24 PM
  #3  
8850
CF Senior Member
 
Member Since: Feb 2004
Location: Sugar Land TX
Posts: 2,976
Received 103 Likes on 85 Posts
Default

My 2017 commanded is 11.85 at 6400 rpm in PE. Stoich = 14.1(E10) with an EQ Ratio of 1.90. Leaner as I come down in rpm. Never checked it with my wideband before I started modifying so don't really know actual.
8850 is offline  
The following users liked this post:
ettan47 (07-02-2019)
Old 07-02-2019, 07:20 AM
  #4  
ettan47
Junior Member
Thread Starter
 
Member Since: Jan 2009
Posts: 22
Received 2 Likes on 1 Post
Default

Thanks 8850 and Higgs Boson for your answer. I havenít planned to do any complicated mods for the moment. Itís just a CAI, Katech ported OEM throttle body and Borla X-pipe (that removes the secondary passive cats).

I was hoping that original factory tune is sufficient to manage these minor mods.

But I am also planning to attach a wideband sensor before one monitored primary cat, so i can see what the AFR is after these minor mods. Thatís why I need what OEM AFR is for the LT4 so itís not to lean AFR after my minor mods.

Last edited by ettan47; 07-02-2019 at 07:24 AM.
ettan47 is offline  
Old 07-02-2019, 07:25 AM
  #5  
ettan47
Junior Member
Thread Starter
 
Member Since: Jan 2009
Posts: 22
Received 2 Likes on 1 Post
Default

Originally Posted by Higgs Boson View Post
at full throttle 12.4-12.5 (assuming 14.68 stoich) except for when it injects extra fuel to keep the cats cool, which is almost always, pushing it into the 11s or in some cases even 10s.

at part throttle it runs at stoichiometry in closed loop like all other mass produced vehicles. That is 14.1 on E10, 14.7 on E0, or if you fill it up with something else, whatever stoich is for that particular fuel.
Thanks for your answer. I havenít planned to do any complicated mods for the moment. Itís just a CAI, Katech ported OEM throttle body and Borla X-pipe (that removes the secondary passive cats).

I was hoping that original factory tune is sufficient to manage these minor mods.

But I am also planning to attach a wideband sensor before one monitored primary cat, so i can see what the AFR is after these minor mods. Thatís why I need what OEM AFR is for the LT4 so itís not to lean AFR after my minor mods.
ettan47 is offline  
Old 07-02-2019, 07:26 AM
  #6  
ettan47
Junior Member
Thread Starter
 
Member Since: Jan 2009
Posts: 22
Received 2 Likes on 1 Post
Default

Originally Posted by 8850 View Post
My 2017 commanded is 11.85 at 6400 rpm in PE. Stoich = 14.1(E10) with an EQ Ratio of 1.90. Leaner as I come down in rpm. Never checked it with my wideband before I started modifying so don't really know actual.
Thanks for your answer. I havenít planned to do any complicated mods for the moment. Itís just a CAI, Katech ported OEM throttle body and Borla X-pipe (that removes the secondary passive cats).

I was hoping that original factory tune is sufficient to manage these minor mods.

But I am also planning to attach a wideband sensor before one monitored primary cat, so i can see what the AFR is after these minor mods. Thatís why I need what OEM AFR is for the LT4 so itís not to lean AFR after my minor mods.
ettan47 is offline  
Old 07-02-2019, 11:28 AM
  #7  
C7/Z06 Man
CF Senior Member
 
C7/Z06 Man's Avatar
 
Member Since: Apr 2010
Location: Maryland
Posts: 3,879
Received 324 Likes on 259 Posts
Default If WOT fuel ratio is 12.4-12.5 on E0, what's it at on E10?

For the members running E10 what would the stock full throttle AFR be?

Last edited by C7/Z06 Man; 07-02-2019 at 11:35 AM.
C7/Z06 Man is offline  
Old 07-02-2019, 11:33 AM
  #8  
Internets_Ninja
CF Senior Member
 
Internets_Ninja's Avatar
 
Member Since: Mar 2004
Location: South Florida
Posts: 1,741
Received 216 Likes on 154 Posts
Default

Originally Posted by C7/Z06 Man View Post
For the members running E10 what would the full throttle AFR be?

We should all really be speaking in Lambda when it comes to any Ethanol content. E0 has a stoich value of 14.7 but E10 has a stoich value of 14.1. You can determine AFR from Lambda based on the stoich value if the given fuel.
Internets_Ninja is offline  
The following users liked this post:
ettan47 (07-08-2019)
Old 07-02-2019, 11:37 AM
  #9  
C7/Z06 Man
CF Senior Member
 
C7/Z06 Man's Avatar
 
Member Since: Apr 2010
Location: Maryland
Posts: 3,879
Received 324 Likes on 259 Posts
Default

Originally Posted by Internets_Ninja View Post
We should all really be speaking in Lambda when it comes to any Ethanol content. E0 has a stoich value of 14.7 but E10 has a stoich value of 14.1. You can determine AFR from Lambda based on the stoich value if the given fuel.
Well for those who do not have a chart what would it be? Thanks
C7/Z06 Man is offline  
Old 07-02-2019, 11:46 AM
  #10  
Higgs Boson
CF Senior Member
 
Higgs Boson's Avatar
 
Member Since: Jul 2007
Location: Texas Hill Country
Posts: 9,659
Received 1,065 Likes on 679 Posts
Default

Originally Posted by C7/Z06 Man View Post
Well for those who do not have a chart what would it be? Thanks
lambda doesn't need a chart.

all fuel is lambda 1.0 for stoich
PE is .75 - .9 depending on the fuel and what you're doing with it, engine combo, etc.

on the LT4 PE lambda in the .8 - .85 range will work best, but you need to pinpoint that yourself at the track or dyno, etc.
Higgs Boson is offline  
The following users liked this post:
ettan47 (07-08-2019)
Old 07-02-2019, 12:47 PM
  #11  
C7/Z06 Man
CF Senior Member
 
C7/Z06 Man's Avatar
 
Member Since: Apr 2010
Location: Maryland
Posts: 3,879
Received 324 Likes on 259 Posts
Default Looking at my notes from the forum.

* 14.7 Lambda (E0)

* E10 correction factor = .959

* 12.4 X .959 = 11.89 AFR

So a 14.7 lambda at 12.4 afr comes out to 11.89 afr running E10 gas.
C7/Z06 Man is offline  
The following users liked this post:
ettan47 (07-08-2019)
Old 07-02-2019, 01:05 PM
  #12  
Higgs Boson
CF Senior Member
 
Higgs Boson's Avatar
 
Member Since: Jul 2007
Location: Texas Hill Country
Posts: 9,659
Received 1,065 Likes on 679 Posts
Default

Originally Posted by C7/Z06 Man View Post
* 14.7 Lambda (E0)

* E10 correction factor = .959

* 12.4 X .959 = 11.89 AFR

So a 14.7 lambda at 12.4 afr comes out to 11.89 afr running E10 gas.
or

12.4 / 14.7 = .84 lambda

.84 * 14.1 = 11.84 AFR

when your fuel can be between 14.08 and 14.7 AFR but your wideband interprets Lambda 1.0 Stoich at 14.5 and another one interprets it at 14.68 and the dyno itself something else.....who really knows what "AFR" you're running or tuning to......

but if you make it easy and PE is a 20% enrichment from stoich then it's 20%. then you start tuning your car based on your own car rather than just comparing arbitrary AFRs on the internet.
Higgs Boson is offline  
The following 2 users liked this post by Higgs Boson:
C7/Z06 Man (07-02-2019), ettan47 (07-08-2019)
Old 07-02-2019, 01:09 PM
  #13  
dar02081961
CF Senior Member
 
Member Since: Oct 2007
Posts: 1,790
Received 427 Likes on 270 Posts
Default

My rule of thumb for the LT4 is basically .5 less AFR for E10 as opposed to E0.
Thats what the numbers work out to anyway.
However E10 "can contain up to 10% Ethanol" so it varies in the real world and can be anywhere in between the two for any given fill up.
dar02081961 is online now  
The following 2 users liked this post by dar02081961:
C7/Z06 Man (07-02-2019), ettan47 (07-08-2019)
Old 07-02-2019, 01:32 PM
  #14  
rflow306
CF Senior Member
 
Member Since: Sep 2007
Posts: 352
Received 94 Likes on 76 Posts
Default

Originally Posted by Internets_Ninja View Post
We should all really be speaking in Lambda when it comes to any Ethanol content. E0 has a stoich value of 14.7 but E10 has a stoich value of 14.1. You can determine AFR from Lambda based on the stoich value if the given fuel.

If you have a wideband sensor you set it for regular gas regardless of the e-content. The wideband sensor reads it in Lambda and converts it to your selected display fuel, so you can keep the reading to what you are most familiar with regardless of the fuel. Wideband sensor= lambda sensor.


Last edited by rflow306; 07-02-2019 at 01:34 PM.
rflow306 is offline  
The following users liked this post:
ettan47 (07-10-2019)
Old 07-08-2019, 02:22 AM
  #15  
ettan47
Junior Member
Thread Starter
 
Member Since: Jan 2009
Posts: 22
Received 2 Likes on 1 Post
Default

Originally Posted by Internets_Ninja View Post
We should all really be speaking in Lambda when it comes to any Ethanol content. E0 has a stoich value of 14.7 but E10 has a stoich value of 14.1. You can determine AFR from Lambda based on the stoich value if the given fuel.
Thanks for your input!
ettan47 is offline  
Old 07-08-2019, 11:41 AM
  #16  
Internets_Ninja
CF Senior Member
 
Internets_Ninja's Avatar
 
Member Since: Mar 2004
Location: South Florida
Posts: 1,741
Received 216 Likes on 154 Posts
Default

Originally Posted by rflow306 View Post
If you have a wideband sensor you set it for regular gas regardless of the e-content. The wideband sensor reads it in Lambda and converts it to your selected display fuel, so you can keep the reading to what you are most familiar with regardless of the fuel. Wideband sensor= lambda sensor.
I appreciate the review but that was not my purpose of the comment. Gen V ECU's use a sliding stoich scale based on ethanol content so my comment was geared towards the assumption of tuning the Air Fuel Ratio which is easier done if you work in Lambda.
Internets_Ninja is offline  
The following users liked this post:
ettan47 (07-10-2019)
Old 07-10-2019, 07:25 AM
  #17  
ettan47
Junior Member
Thread Starter
 
Member Since: Jan 2009
Posts: 22
Received 2 Likes on 1 Post
Default

Originally Posted by rflow306 View Post
If you have a wideband sensor you set it for regular gas regardless of the e-content. The wideband sensor reads it in Lambda and converts it to your selected display fuel, so you can keep the reading to what you are most familiar with regardless of the fuel. Wideband sensor= lambda sensor.
Thanks for your input!
ettan47 is offline  
Old 07-10-2019, 07:39 AM
  #18  
CamOnlyJabroni
CF Senior Member
 
Member Since: Sep 2018
Posts: 200
Received 25 Likes on 21 Posts
Default

Originally Posted by Internets_Ninja View Post
I appreciate the review but that was not my purpose of the comment. Gen V ECU's use a sliding stoich scale based on ethanol content so my comment was geared towards the assumption of tuning the Air Fuel Ratio which is easier done if you work in Lambda.
Its less confusing going off Lambda if you over think it. Itís easier to use AFR if you only have that type of wide band already installed in the car. I have used both AFR/Lambda running E85 in my Camaro and Neon. The Gen V ECUís use AFR so itís still easier IMO to view your commanded AFR in the ecm and see if it is matching the AFR gauge that you most likely have anyway when tuning. The flex fuel table in the ecm also uses stoich values in AFR for any given e content.

-Point being, both will get the job done.
CamOnlyJabroni is offline  
Old 07-10-2019, 10:29 AM
  #19  
Internets_Ninja
CF Senior Member
 
Internets_Ninja's Avatar
 
Member Since: Mar 2004
Location: South Florida
Posts: 1,741
Received 216 Likes on 154 Posts
Default

Originally Posted by CamOnlyJabroni View Post
Its less confusing going off Lambda if you over think it. It’s easier to use AFR if you only have that type of wide band already installed in the car. I have used both AFR/Lambda running E85 in my Camaro and Neon. The Gen V ECU’s use AFR so it’s still easier IMO to view your commanded AFR in the ecm and see if it is matching the AFR gauge that you most likely have anyway when tuning. The flex fuel table in the ecm also uses stoich values in AFR for any given e content.

-Point being, both will get the job done.
I guess we just see a little differently. I find it much easier to work in Lambda when tuning E85 or any non E0 fuel.

Last edited by Internets_Ninja; 07-10-2019 at 10:30 AM.
Internets_Ninja is offline  
The following users liked this post:
ettan47 (07-13-2019)
Old 07-10-2019, 11:24 AM
  #20  
Higgs Boson
CF Senior Member
 
Higgs Boson's Avatar
 
Member Since: Jul 2007
Location: Texas Hill Country
Posts: 9,659
Received 1,065 Likes on 679 Posts
Default

Originally Posted by CamOnlyJabroni View Post
Its less confusing going off Lambda if you over think it. Itís easier to use AFR if you only have that type of wide band already installed in the car. I have used both AFR/Lambda running E85 in my Camaro and Neon. The Gen V ECUís use AFR so itís still easier IMO to view your commanded AFR in the ecm and see if it is matching the AFR gauge that you most likely have anyway when tuning. The flex fuel table in the ecm also uses stoich values in AFR for any given e content.

-Point being, both will get the job done.
This illustrates the problem exactly. A wideband AFR will show a preprogrammed stoich value so if you are running E85 with a 9.8 stoich value and the wideband shows 14.7 at stoich, wouldn't you rather it display Lambda 1.0 for stoich at all times?

AFR is a conversion, Lambda is a raw value. A wideband, an ECM, a dyno, etc will all show a different value for AFR stoich but will all show 1.0 for Lambda stoich.
Higgs Boson is offline  
The following users liked this post:
ettan47 (07-13-2019)

Thread Tools
Search this Thread
Quick Reply: What is AFR on a stock C7 Z06 LT4


Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: