Joined
·
594 Posts
Below is a air/fuel vs RPM chart two pieces of information worth noting. The spikes going down are simply my tach pick up not being consistent, just smooth those over.
1. Air/fuel ratio. Notice it is very lean to a point then drops below 13. What is happening is the stock system with the stock O2 sensors manages fuel to a certain point thru what is called closed loop then it drops off and then fuel is done by a fuel map that has been manually programmed into the ECU. Point I am making is the stock system does not compensate for fuel after this point, it is what is called a narrow band system and will only change fuel in a very narrow range for cruising just like your car does and it will NOT compensate for some mod you do past this point and probably not under this point if it changes fuel much.
Note thepoint where it drops off is below 13 where I would run it at WOT so it appears we might be able to squeeze out a few more ponies by simply manipulating the fuel curve with a fuel controller and I have one coming, the Dobeck Gen 4. I will install it before I put the pipe on to see what good a fuel controller does.
2. RPM note how it ramps up toward 7900 then backs down then back up. This is NOT what we want to see, actually time test have proven this engine is quickest at 7650 in stock form so we are going to install the Dalton clutch kit to hold RPM at that point during the shifting phase then speed on up as shift out finishes. You can also notice between this graph and the HP graph how the rpm drop coincides with the HP drop off too.

1. Air/fuel ratio. Notice it is very lean to a point then drops below 13. What is happening is the stock system with the stock O2 sensors manages fuel to a certain point thru what is called closed loop then it drops off and then fuel is done by a fuel map that has been manually programmed into the ECU. Point I am making is the stock system does not compensate for fuel after this point, it is what is called a narrow band system and will only change fuel in a very narrow range for cruising just like your car does and it will NOT compensate for some mod you do past this point and probably not under this point if it changes fuel much.
Note thepoint where it drops off is below 13 where I would run it at WOT so it appears we might be able to squeeze out a few more ponies by simply manipulating the fuel curve with a fuel controller and I have one coming, the Dobeck Gen 4. I will install it before I put the pipe on to see what good a fuel controller does.
2. RPM note how it ramps up toward 7900 then backs down then back up. This is NOT what we want to see, actually time test have proven this engine is quickest at 7650 in stock form so we are going to install the Dalton clutch kit to hold RPM at that point during the shifting phase then speed on up as shift out finishes. You can also notice between this graph and the HP graph how the rpm drop coincides with the HP drop off too.
