So I put a supercharger on this 2002 Ranger

[Bad Idea]

Eaton M90 oval style 89-93 rebuilt
2002 FX4 Ranger 4.0 232k miles (lol)
Used a Modd Box install kit with a 3.4 inch/3.5 psi pulley

I know I'm late to the party with this, but I got beat by a Prius in a race to the exit just so they could cut me off and then slow down 30 mph. So... Supercharger! (I'd buy a new whatever but for reasons nobody cares about I'm not going to, so I waste my money on this)

Install went good; Cut to what matters: ONLY 1.5 psi BOOST!? Well, it's 2 psi about 5000 rpm but, man, 232k miles... (lol) I'm ASE certified so I kinda know stuff, but I'm not the worlds greatest service tech by any means and I'm not immune to stupid mistakes or over looking something. That being said, the engine runs better than expected and the supercharger appears in good working order (I have no experience with these superchargers or custom boost builds)

So if anyone has any experience with these setups (not holding my breath) I'd like to know if 1 - 2 psi boost is normal in this situation. Nothing appears wrong with the install: Midwest location - 600ft elevation. The boost measurement is accurate, the bypass appears to be working (I could be wrong here, but it closes/opens when the throttle is snapped at idle. I have not checked but I could video record the operation during WOT pull), the belt is not slipping, there are no vacuum leaks, no misfires, no codes, no warning lights, no noises (rattles/knocks/pings) It actually runs great, its just I was expecting closer to 3.5 psi boost since 3.5 psi pulley.

I figure this is either a normal outcome for the setup, the supercharger is just not moving air like it should and get a different one, or I'm over looking something stupid.

 

[PetroleumJunkie412]

Define rebuilt.

Also, iat relocation?

 

[Bad Idea]

M90 was purchased from ebay and listed as 'rebuilt'. In my professional opinion it looks rebuilt (no slop in pulley, rotors were shiny with no nicks or obvious wear coating, shiny paint even, new oil) and sounds healthy, but I have never taken one apart myself. I wanted the 94-95 supercharger, but the few listings for those were twice as much money, covered in dirt, corroded, old gasket material and junk hanging off them... This one seemed the better buy.

IAT relocate is not done but I am pulling everything back off and doing that tomorrow. This lower than expected boost problem might be as simple as belt slipping as there is belt dust on the alternator after beating the hell of it this morning - I had to shove the intake further forward than I liked due to interference with the fuel rail, so the belt is misaligned about 1/8 inch; but with about 60% wrap on the super pulley and only 30% on the alternator pulley I kind of expect the alternator to slip some - I have my doubts the belt is actually slipping on the super, but maybe. I honestly kinda slammed this together a little too fast - A few things were 'Aww WTF? I'll just, ehh. Good enough... Maybe.' Tomorrow I won't have the time constraint.

I plan to push this to 8 psi on a rebuilt engine, but I gotta get past 2 psi first.

 

[Jim Oaks]

Getting a bigger bumper seems like an easier solution.

Just kidding. Carry on...

 

[Roert42]

The rated psi is at 6000 rpm, I think.


I never logged it, but I don’t think you really see any boost on the gauge until after 3k.


These types of super chargers build more boost as the rpm increases.
Bell superchargers are more linear across the rpm range.