EFI, Alpha-N vs Speed Density fueling Strategies

[pbp1]

Originally Posted by GUMP

These three sentences speak volumes.

I can have a new combination running well in Alpha-N within 3-4 dyno pulls. I have also found that it is pretty easy to dial a car from my log book once I have a couple of runs on it. I also don't have to worry about sudden changes in performance due to too much fuel correction.

You completely mis-read my statements, Speed Density does not make "sudden changes", unless the air suddenly changes, in which case you need corresponding changes in the fueling. This is a perfect example of the mis-information I hear over and over. What I have found when I discuss this with different racers and tuners is that if someone doesn't fully understand how speed density works, they don't trust it to calculate the changes in air density. The interesting thing is that it is using the exact same data that your weather station uses to predict performance.

[GUMP]

Take it easy. I am pretty sure that I don't have a learning disorder!

FYI. I am currently running two COPOs. One is running in Alpha-N. The other is running in speed density and closed loop. I believe that both tunes are pretty good. Both cars are extremely consistent. In the past I have had Stock computers, Accell Gen 6 and Gen 7, FAST, and Holley. I have always done my own tuning. I currently run the Holley HP system and find that it is far superior to anything that I have worked with in the past.

The reason for my previous comments was to make the point that Alpha-N with the corrections turned off is an extremely quick way to get a very consistent tune that will show good results.

The bottom line is that if you are going to run speed density, you need to know what you are doing. It takes much longer to define the cells to optimize the tune in all conditions. You corrections need to be spot on or the car will do dumb stuff. We are talking Stock Eliminator here. The MOV is normally very tight.

If it helps any, I drive Robin Lawrence at Holley nuts too!

[pbp1]

No worries, but now I understand why we are not on the same page. All of my information relates to VE based speed density only, not fuel flow based speed density (which is not speed density at all). As far as dialing in quickly, I think it is just a matter of what you are familiar with. I can dial in a speed density setup in 4-5 pulls, or 3-4 passes down track!

[GUMP]

Originally Posted by pbp1

No worries, but now I understand why we are not on the same page. All of my information relates to VE based speed density only, not fuel flow based speed density (which is not speed density at all). As far as dialing in quickly, I think it is just a matter of what you are familiar with. I can dial in a speed density setup in 4-5 pulls, or 3-4 passes down track!

Cool.

[Bobby Fazio]

Originally Posted by pbp1

No worries, but now I understand why we are not on the same page. All of my information relates to VE based speed density only, not fuel flow based speed density (which is not speed density at all). As far as dialing in quickly, I think it is just a matter of what you are familiar with. I can dial in a speed density setup in 4-5 pulls, or 3-4 passes down track!

I almost forgot, how about when you are on the two-step from an external ignition box? Do the TPS and map sensor think the engine is under load and start flooding the cylinders?

[Rick Schillereff]

Ed I bracket race an 01 ls1 camaro and how and where are you putting the ITS sensor in the intake manifold. Thanks just trying to get better.

[Ed Wright]

Originally Posted by Rick Schillereff

Ed I bracket race an 01 ls1 camaro and how and where are you putting the ITS sensor in the intake manifold. Thanks just trying to get better.

If I am the Ed you are talking to, I had a bung made & welded into the back of the plenum of my sheet metal Hogan Intake. Screwed the IAT sensor into that bung.
The older "TPI" cars used a threaded IAT sensor, screwed into the Intake. I just bought an IAT sensor for a '90 Vette.
I just remembered this:
I originally put my air temp sensor in the tray I had in front of my throttle body (no longer used)
And was seeing large temp variations from the water box to third gear. Looked too large to me.
Moving that sensor to the rear of my manifold took much of those large changes away. Also made my air/fuel ratio more stable during a pass, and made my car more consistent, easier to dial.