Just got back from the dyno. Max rwhp: 347.3 @ 5400 Max rwtq: 453.4 @ 3800. So with a 11% drivetrain loss I have about 386/504 at the flywheel. Im kind of upset with the torque, it maxed so low and dropped off later on. The dyno operator said I was running rich then going lean, or the other way around I forget (I will scan the sheets later on) and that If I upgrade boost that should fix that problem. Im not too familiar with A/F ratios and such, but on the run it starts out at 14.9 then goes to 15.0 then drops to 13.1 and continues to drop till 12.1, it kind of plateaus (sp?) around 12.5 and drops every 2-300 RPMs. What does this all mean? And if its a problem how do I fix it?

 

With those A/F's you're really lean in the low rpms and also kind of lean on top. 12.5 A/F is pushing it. On a stock vehicle I usually saw 11.x:1 a/f's by the top of each gear. If you are stock I would check for unmetered air, vacuum leak or a clogged fuel filter. If you have mods you either need a chip or your chip reburned.

 

I hate to burst your bubble but according to Factory_Tech(our resident trans[Ford] expert), the drive train loss is only 11.2% in our trucks. Very efficient drive train !

Dan

 

if it was really that lean on a stock truck, shouldnt it register lean on banks 1&2 causing an ses light? ive seen dynos where their sniffer was registering a full point leaner than it should

 

I dynoed a stock '01 and got 348/448, so you're in the ballpark for a stock truck. The A/F will always start out lean while you're at part throttle (around 14.5/1) and drop down as the throttle is pinned. Your run sounds fine with the exception of the actual A/F numbers...post the graph and we'll check it out. The torque peak will also come early (2800-3000 rpm) and drop from there...that's what these trucks do. And it sounds as if you were running lean (although again, the truck will run at 14.5/1 or so at partial throttle and then will go richer with WOT) and then going rich...completely normal. Something about that crazy open vs. closed loop thing...

 

I believe that Greg said that the trans loss was 11%. You would have to add the rearend and driveshaft loss to it. 15% total sounds about right. Maybe I am wrong, Skip

 

I bet it takes round 50 ftlbs torque to turn our trannys ......