Need Help- Fuel/Boost Questions

[kelleyperf]

hey guys i have an important question. i have a customer with a 2003 harley davidson f150 who wants more boost. he currenty has: custom magnaflow cat-back exhaust, airriad cold air intake, diablosport tuner, and he THINKS he has an upper pulley of unknown size. this is the main issue, he bought it used, and he bought an aftermarket upper pulley and the one on the car ended up being the same size. surprisingly the store had no idea what size the pulley they sold him was, and i honestly have no idea either. im unfamiliar with these trucks, i drive a supercharged ss silverado RWD epper: . so lets say it has a 2.8" upper, and i add a 4 lb lower, will i need to up the injectors?? how much boost would that total? what does the harley boost stock, lightning boost stock? any help appriciated!!! thanks

 

[EnglishAdam]

Just to clear the upper pulley size thing up

Standard Lightning upper pulley = 2.93" stock size
Harley Upper pulley = 3.25" stock size

You can get aftermarket 2.81" and 2.76" upper pullies but that increases the chance of belt slip so you then need aftermarket idler pullies to increase the belt wrap.

Under "normal" circumstances, the Harley makes 6lb boost as stock with the large upper and the L makes 8lb boost with the smaller upper
If it has the 2.93" upper already, adding a "4lb" pulley will up that to 10lb of boost.
At that level, you don't need to upgrade the fuel pumps or MAF but you should change the plugs to something like NGK TR6's (or equivalent) and gap them down to about 36 thou.
Also, adding the 4lb pulley makes a good tune mandatory. Get it on the dyno and the truck should be making somewhere around +/- 375 rwhp and capable of as high 13 - low 14 pass.

Good luck. :beer:

 

[kelleyperf]

Just to clear the upper pulley size thing up

Standard Lightning upper pulley = 2.93" stock size
Harley Upper pulley = 3.25" stock size

You can get aftermarket 2.81" and 2.76" upper pullies but that increases the chance of belt slip so you then need aftermarket idler pullies to increase the belt wrap.

Under "normal" circumstances, the Harley makes 6lb boost as stock with the large upper and the L makes 8lb boost with the smaller upper
If it has the 2.93" upper already, adding a "4lb" pulley will up that to 10lb of boost.
At that level, you don't need to upgrade the fuel pumps or MAF but you should change the plugs to something like NGK TR6's (or equivalent) and gap them down to about 36 thou.
Also, adding the 4lb pulley makes a good tune mandatory. Get it on the dyno and the truck should be making somewhere around +/- 375 rwhp and capable of as high 13 - low 14 pass.

Good luck. :beer:

ok man thanks alot for putting up with my ford noob questions lol. i believe he has the upper lightning pulley, he makes 8 lbs at WOT. so with L upper pulley, 4 lb lower, a suitable belt, i will have no fuel delivery issues? it has a diablosport, so if that doesnt work i will custom tune it. lucky i have a dyno on premisis :coolman: . thanks for your help. if you ever get a GM lemme kno man i can help you :lol1:

 

[EnglishAdam]

No problem mate but I don't see a GM in my near future oke:

The canned Diablo tunes are pretty fat so you'll be leaving free hp on the table unless you dyno it.
Shoot for an AF of 11.6 / 11.8 (no leaner) and you should be fine.