Roush Supercharger real world PSI at altitude?

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Dane

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I had a Roush supercharger installed around May of 2016. The dealer didn't get my gauge until sometime later and then had to replace it due to an issue. What I found strange was a change in boost readings afterwards (replacement was just due to LED colors, not boost function). It seemed like my max boost went down, but I get to my max boost (reading 6 psi) pretty quickly.

I have the smaller pulley, larger throttle body, injectors, plugs, and tune by JDM.

Couple questions.
How do you identify that upgraded/smaller pulley versus what comes normally and what belt goes with it (mine reads 6K2085-8620-AA)?
What realistic max boost should I be seeing in Denver (~5,600 feet)?

What should it take to achieve max boost (whatever max is)? I realize this question is a bit open ended, but I figure I'll get a couple good descriptions to compare against.

I didn't notice any change in how the truck ran between the two gauges (and shouldn't), so I think one gauge wasn't right - but which one?
 

biturbomg

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I'm at 5500ft give or take and with a 69mm pulley made 8# and with a custom 10% IW lower my Roush setup made 10# on 91 pump gas. I have seen all my SC cars and trucks lose about 2# vs sea level numbers.

Hope that helps.
 
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Dane

Dane

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I'm at 5500ft give or take and with a 69mm pulley made 8# and with a custom 10% IW lower my Roush setup made 10# on 91 pump gas. I have seen all my SC cars and trucks lose about 2# vs sea level numbers.

Hope that helps.

It does.

The IW you reference is the lower pulley, right? Basically gearing the whole system just like changing the pulley size? What'd that set you back if I might ask?

I'm getting myself confused. What size is the stock Roush pulley?
 
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biturbomg

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Roush I think is 75mm and smallest pulley I have seen you can drop to is 69mm. Yes the IW is the lower pulley and mine is an 10% OD size to spin the blower faster.
 
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Dane

Dane

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Roush I think is 75mm and smallest pulley I have seen you can drop to is 69mm. Yes the IW is the lower pulley and mine is an 10% OD size to spin the blower faster.

Also meaning new tune and new belt with any change to these I assume?
 

biturbomg

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Yes anytime you change a pulley I would look at tune and data log and new belt.
 
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Just to be clear, Phase I = standard = 75mm. So there are three options? What it comes with, 72, or 69? In addition you can change the lower pulley?

Wow you quoted me fast! I updated my post almost immediately after I posted it. I mistyped the phase II is a 75mm, this is what is quoted at the 590 hp and 590 tq from Roush. Should be around 8-9 psi on the phase II, obviously varies by elevation etc. If your SC was installed recently I would bet it is the phase II. It doesn't take long to make the measurement on the pulley though.

72mm and 69mm pulleys are usually put on aftermarket, VMP has them and think there are a few others.
 
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Steps

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I agree. I typically see a 2# loss here in Denver (blown Mustangs, etc.). If I end up installing a blower on my Raptor I will plan for +2# here and have a "safe" tune for when I get to a lower elevation.
 

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