Air Fuel Ratios
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Advanced
Joined: Jan 2007
Posts: 74
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From: Costa Mesa CA
Air Fuel Ratios
This is going to sound strange, but what is the best air fuel ratio for the LS1 motor that has a modified intake system, Diablo programmer and Corsa exhausts?
I read in the latest issue of Vette or Corvette magazine, do not recall exactly which one, that someone has hopped up a C-5 with moderate changes to get 60 added ponies at the rears. One of the changes being made is they reduced the air fuel mixture by 5% which allegedly gave them 12 added ponies at the rear. They also spoke of replacing the rocker arms, going to another cam and replacing the cam followers in the article, worth a read.
Back in the days when we had 3-2's it was simple, tweak the center carb to max rpms then back it down 100 rpms and you were good to go. Had a 67 427 solids motor, wish I still had it, only mine for 3 weeks before a beautiful theft stole it in Dallas.
Thanks Guys.
grandpa bear
I read in the latest issue of Vette or Corvette magazine, do not recall exactly which one, that someone has hopped up a C-5 with moderate changes to get 60 added ponies at the rears. One of the changes being made is they reduced the air fuel mixture by 5% which allegedly gave them 12 added ponies at the rear. They also spoke of replacing the rocker arms, going to another cam and replacing the cam followers in the article, worth a read.
Back in the days when we had 3-2's it was simple, tweak the center carb to max rpms then back it down 100 rpms and you were good to go. Had a 67 427 solids motor, wish I still had it, only mine for 3 weeks before a beautiful theft stole it in Dallas.
Thanks Guys.
grandpa bear
Pro
Joined: Jan 2005
Posts: 612
Likes: 0
From: Simi Valley CA.
I'm sorry I can't give you exact figure re: air/fuel ratios, but I can confirm a considerable increase in HP by merely adjusting the factory setting.
My 1999 A4 coupe is pretty much bone stock (BlackWing & FlowMasters) and the RWHP went from 299.2 to 312.1 by doing nothing more than leaning out the air/fuel mixture from the factory setting which, according to the tuner, is purposely set "rich" from the factory to protect the motor.
My 1999 A4 coupe is pretty much bone stock (BlackWing & FlowMasters) and the RWHP went from 299.2 to 312.1 by doing nothing more than leaning out the air/fuel mixture from the factory setting which, according to the tuner, is purposely set "rich" from the factory to protect the motor.
Last edited by Red903L; Feb 18, 2007 at 03:25 AM.
Melting Slicks
Joined: Sep 2006
Posts: 2,041
Likes: 4
From: Rockford Illinois
This is going to sound strange, but what is the best air fuel ratio for the LS1 motor that has a modified intake system, Diablo programmer and Corsa exhausts?
I read in the latest issue of Vette or Corvette magazine, do not recall exactly which one, that someone has hopped up a C-5 with moderate changes to get 60 added ponies at the rears. One of the changes being made is they reduced the air fuel mixture by 5% which allegedly gave them 12 added ponies at the rear. They also spoke of replacing the rocker arms, going to another cam and replacing the cam followers in the article, worth a read.
Back in the days when we had 3-2's it was simple, tweak the center carb to max rpms then back it down 100 rpms and you were good to go. Had a 67 427 solids motor, wish I still had it, only mine for 3 weeks before a beautiful theft stole it in Dallas.
Thanks Guys.
grandpa bear
I read in the latest issue of Vette or Corvette magazine, do not recall exactly which one, that someone has hopped up a C-5 with moderate changes to get 60 added ponies at the rears. One of the changes being made is they reduced the air fuel mixture by 5% which allegedly gave them 12 added ponies at the rear. They also spoke of replacing the rocker arms, going to another cam and replacing the cam followers in the article, worth a read.
Back in the days when we had 3-2's it was simple, tweak the center carb to max rpms then back it down 100 rpms and you were good to go. Had a 67 427 solids motor, wish I still had it, only mine for 3 weeks before a beautiful theft stole it in Dallas.
Thanks Guys.
grandpa bear
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
The tuner I use (supporting tuner on CF) showed me that moving the AFR from a safe value to 13:1 on the dyno netted about 5 hp and wasn't worth the risk. Timing plays a role as well as fuel, and with the number of people who have lost the #7 piston I would rather keep the fuel a little richer myself.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
IMO, I wouldn't go any leaner than 12.9 on the dyno for a N/A engine... and 12.5 on the dyno for a blower setup.
and keep in mind that this dyno 13.10 will be more like 13.20 to 13.25 on the street.
Experienced dyno operators (those that have knowledge beyond the dynos owners manual) know that the street AFR will be leaner than whats measured on the dyno.
Experienced dyno operators (those that have knowledge beyond the dynos owners manual) know that the street AFR will be leaner than whats measured on the dyno.
Drifting
Joined: Sep 2005
Posts: 1,258
Likes: 0
From: Home Southern Maine
St. Jude Donor '08
Here is my 99 Stock LS1 w/ Blackwing and Borla Quad Tip Catbacks.
The Stock tune (1) and AFR of 11's VS other run from a Diablo Sport tune using a Predator w/ AFR @ 13 Gained about 8 HP and about 10 Ft/lbs torque.
Beer
The Stock tune (1) and AFR of 11's VS other run from a Diablo Sport tune using a Predator w/ AFR @ 13 Gained about 8 HP and about 10 Ft/lbs torque.
Beer
Burning Brakes
Joined: Jan 2006
Posts: 1,170
Likes: 27
From: Magnolia Greens NC
My tuner won't put any more than 11.8 "Dyno AFR" on my blown stock LS1, for that very reason. I sleep nights...
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