how much boost should i run with a 5.4 that has 75mm edelbrock throttle body, ATI FMU, ATI Fuel Pump, Bosch 4 plugs, electric fans, and a diablo sport chip? i have a powerdyne supercharger kit. thanks. ohyeah, it's a 2002.

 

well i'm guessing you should stay with 8psi or less. Maybe the powerdyne guys can chime in.

 

I am running 10# of boost on my 4.6 with a powerdyne, I do have a vortech air/water aftercooler, If I can find a larger crank pulley I believe I am going to try for 12# My air/fuels are very safe and there is very little knock sensor activity as long as I use good fuel so i feel it can stand a little more. I have 2.5 supercharger pulley and although I see that 928 motorsports does make a smaller pulley i think that it will have too much belt slipage. I believe the 2.5 pulley would make a little more if you can keep the belt tight enough, but belt slipage is a problem when you get to such small diameter pulleys. This supercharger is very quite it does have the newer SKF ceramic bearings and so far has been holding up well.

 

I am running a somewhat similiar setup.

98 Navigator 5.4L 2v powerdyne BS-11A
3 inch true dual exhaust, K&n

Anyway, I talked to the guys over at dugan racing here in GA and he told me not to expect much more than 5 lbs of boost since the intake ports are so big. And I had heard that several times before, just never believed it but now I give it a little credit.

 

I guess you mean on the supplied pully? I think the question is how much boost can he run safely on a stock N/A setup?

 

Its got the 9psi pulley on it.

From all that I have asked, and I have asked aplenty, they all say for the nav/expy to not run more than 6-8, and they tell me that 8 is kinda pushin it. I have a diablosport chip on order to try and get everything to "communicate" with one another better, and to cure a rich condition, and we'll see what I have then. But, based on it all, I don't expect to get more than 6 out of a 9 pulley

One other thing I might add, is that the general consensus was that copper or iridium plugs are best and make sure they are gapped between .035 and .038. Mine are .036, and its really hard to gap iridium, they have the tiniest littlle electrode that will break, and they are $12 each.

 

I don't think that anyone will tell you what is safe when it comes to boost. There are too many factors. I will tell you that I see between 13 and 14 psi depending on ambiant temps and conditions with stock internals and stock heads. Yes it is tuned and I have done all the fuel upgrades and my tune is on the safe side with very little timing advance and on the rich side.

I have seen people blow engines with 6 to 8 psi turbo setups (I know we are not talking apples to apples discussing turbos and blowers) where like I said above I see nearly twice that and for nearly 20,000 miles at that boost and 60,000 miles being blown. A lot comes down to how you control temperature and fuel not just pressure.

I have a Procharger P1SC kit and I assume that you are refering to the life of the engine and not the life of the Powerdyne at that boost.

 

Yeah, I read that the powerdyne will at high PSI pop that belt mechanism, but if it does it doens't eat itself apart, the car just functions normally as if it weren't supercharged. And the rebuild kit for powerdyne has a Kevlar belt and ceramic bearings which are supposed to be less restrictive resistance wise and provide another pound of boost. I don't reallly believe that, or I would have already ordered the rebuild kit/.

 

On my setup Mike T. told me that 8lbs of boost on the 5.4L is the best setup, anything over that and it becomes exponentially detrimental to your engine life. I have to get a larger pulley.

 

I agree, like I said no reputable person is going to tell you to push the limits in the same sentance as being safe. I am sure I am killing my engine, that is not my intent it is just the side effect of the obsession.

 

there are many guys running 12psi on stock blocks..I am one of them...I ran 11.5 with my ATI setup and now running 12psi with my L setup...it has to be tuned perfect to make this happen and there are L tuners will get you there

 

I agree 12 psi is achievable but you must be dead on, or very safe. 8 psi allows more "error" in tune, gas, etc.... I don't know but i'm willing to bet some of the lower end blowers are out of their efficency range at much above 8psi.

 

I'm running 12psi on an intercooled Eaton setup (lightning conversion) on the stock block.
I'm also using a conservative program.

 

I'm running a 5.4 with Kenne Bell Pushing 12PSI and a 100 SHot of NOS. But then again, I had a shop do the engine work. All I can do is change the oil, small repairs and drive it. I know I'm bored, blown, cam'd, Gas'd and BROKE! LOL

 

There really isn't an absolute set max boost pressure. It all depends on tuning. I've seen these engines blow at 4psi, I've seen them take enormous punishment and keep ticking (not like a Hemi...). Mark ran what.....500 to the wheels before something broke? I'm running about 14 psi and I'm going for 400 whp once I get my truck tuned for methanol injection.