What upper pulley to run with 4# lower plus bolt ons.

[Sweet35th]

So after years of running the same combination, I want to turn the wick up a little bit. Here is what my truck has been running
basically since new.

-#4 johnny lightning lower pulley (only saw about 2.5psi gain)
-Stock air box with k&n
-Bassani high flow cats and cat-back
-Custom tuned by me
Made 401rwhp 502rwtq with these mods seeing 11.5psi and went 12.7 @ 108.9mph

I am going to make the fallowing changes.
-upgrade injectors
-fuel pump upgrade
-Long tube headers (got a sweet deal, couldn't pass up)
-Aux idlers
-JLT cold air intake (mainly just to dress up engine bay a little)

My question is, what upper do you think is the best choice to run with the 4# lower? As I said I am currently seeing about 11.5psi boost. I have no plans on doing a ported blower unless one fell in my lap.. Also should I run 90 or 100mm idlers.

Thanks
Casey

 

[Jroc]

Upper pulley changes FTL on a L. Do you enjoy belt slip?(which results in less boost) If you don't want to do a #6 lower than none at all.

Port the blower.

 

[gmtech]

Been runnng a 4lb lower/2.81 upper for 6 years now. About 40K miles (daily driver), and never have had a problem. Have all the usual bolt- ons and still running a canned tune!

 

[WhiTriCobra]

Go with the 6lb lower.

 

[mystickb1996]

coming from the guy with a stock L. you will not have belt slip with a 2.80 upper which is a 2lb pulley. i ran that for a long time with 4lb lower and had no belt slip, that was without aux idlers also. i just replaced the stock idlers with metco ones more for looks. also you should really consider pulling the blower if you haven't and clean the intercooler up as it will have alot of oil on it and port the blower while its off..porting eatons is not to difficult if you take your time, and as long as you look up with others have done to make them more efficient and follow that you will be happy with the gains.

Upper pulley changes FTL on a L. Do you enjoy belt slip?(which results in less boost) If you don't want to do a #6 lower than none at all.

Port the blower.

 

[Jroc]

coming from the guy with a stock L. you will not have belt slip with a 2.80 upper which is a 2lb pulley. i ran that for a long time with 4lb lower and had no belt slip, that was without aux idlers also. i just replaced the stock idlers with metco ones more for looks. also you should really consider pulling the blower if you haven't and clean the intercooler up as it will have alot of oil on it and port the blower while its off..porting eatons is not to difficult if you take your time, and as long as you look up with others have done to make them more efficient and follow that you will be happy with the gains.

And this is coming from a guy who doesn't even own a factory boosted Ford anymore. But yes my DD L with 140K that see's 60 miles a day is running stock boost as factory L motors are weak, and I'm not trying to vent a block right now as it's my only vehicle.

I'm just giving the guy some common L owner knowledge. Go one some other more populated L forums and see which of us most agree with. I was running a 2.93 on my Terminator and didn't have belt slip problems without a aux idler. Many do though. The lower pulley is the better swap on a L. The smarter thing to do is to buy a lower with a removable ring from the get go.

 

[mystickb1996]

lol your right i just currently own a KB cobra and a 2014 5.0 with a lightning in my past on top of other factory f/i cars and blower added cobras with build engines What the hell do i know! im still learning just like anyone else!!....all i was getting at is i have swapped upper pulleys and lowers of alot of my f/i cars and unless you really are wanting to upp the boost a ton then i suggest an upper because the ease of install and i believe ford put a caged lower on these Factory blower cars for a reason which some have found out the hard way... j roc i do agree with you if your wanting anything more then a 2lb boost increase then lower pulley is the way to go, i also suggest putting a 2.80 on your dd just so those 60 miles a day are a little more exciting!!

And this is coming from a guy who doesn't even own a factory boosted Ford anymore. But yes my DD L with 140K that see's 60 miles a day is running stock boost as factory L motors are weak, and I'm not trying to vent a block right now as it's my only vehicle.

I'm just giving the guy some common L owner knowledge. Go one some other more populated L forums and see which of us most agree with. I was running a 2.93 on my Terminator and didn't have belt slip problems without a aux idler. Many do though. The lower pulley is the better swap on a L. The smarter thing to do is to buy a lower with a removable ring from the get go.

 

[WhiTriCobra]

03-04 Cobra is worth taking off that huge pulley and go lower. I had a 2.8/6lb lower on my Cobra. But with the L stock with a 2.93, honestly, that's good enough. Stock upper with 6lb lower is a good combo.