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Increasing Boost

brettzo007

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Hey All,

Excited to get back in to the season in a month or so and planning some additional mods. I'm currently running a Procharger Stage 2 P1SC kit on my 2015 with a 4.63 pulley (still only getting around 7psi boost) and looking to add some boost. I was having quite a few issues with the tune last season (false knock, high gear load drop). Got to the bottom of most of the false knock, though now going to up boost a bit and get it on a dyno for tuning to get it dialed in.

Anyway know what the smallest size pulley I should be looking at for use with the stock fuel system, Boost A Bump and 52# injectors would be (also stock internals, drive shaft, etc.)? If I go with a larger injector to try to get to around 11psi out of the Procharger, would I be OK on the stock fuel system + BAP? If I get it to 10psi, will I still be OK with the MU52's? I spoke with Procharger and they said that I am OK to spin the P1 at 11psi, but wouldn't recommend any more. I'm only getting about 530whp on a Mustang Dyno out of the kit right now and load dropping off in the higher RPM is still an issue in 3rd/4th. It's Lund tuned and though they've been responsive in trying to help with issues, it's certainly been a painstaking process. I've seen people at the 650whp+ mark on stock internals, but would rather be safe than sorry. Hoping to up boost a bit and get this thing on the rollers in April and get it running smoother and with more power.
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foff667

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what is your injector duty cycle at currently?
 

whatsup62

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Well I am at 10psi on a P1SC-1 now and plan on 12psi this spring. I ran 10psi on 93 with BAP and ID1000s, switched to a fuel system when I went E85. On your setup injectors will be your limiting factor for big numbers. Lund won't let you hurt your engine so talk to him. I'm all stock internals and my numbers are in sig.
 

SolarFlare

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For what is worth I was only seeing 8psi on my Stage 2 P1sc-1 at 7500-7600. I put on a Gates belt and swapped the Pro-flo BOV to a Turbosmart raceport and see 11psi at that same RPM.
 

ahl395

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With ID 1050x and a BAP I was able to do 11-12psi. You'll definitely feel a difference over only 7psi.
 

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Dominant1

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Davepurp

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I currently have the same 4.63 stock pulley on a stage 2 system and I am running about 9.5-10psi max( Stock Headers/Cats W/ Proflow Valve) House of Boost sold me on a 4.38 pulley to up the boost close to 12 psi while still only yielding 55,000 RPM @ 7300 Red Line.

With your headers you might have to pulley down again since you are running more efficiently

I was planning to reach out to MY tuner about this just to be safe, but I have heard mixed info. Do pulleys require re tune? Some say yes others say no the tune should be able to adjust fueling as needed.
 

Tommy V

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I have dropped down one pulley size without needing a tune revision,but 2 sizes would probably need some tweaks.
 

foff667

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I have dropped down one pulley size without needing a tune revision,but 2 sizes would probably need some tweaks.
The major problem with dropping down in pulley size, particularly on the stock style fuel system, is that with every psi you go UP that boost pressure is working AGAINST your fuel system by that same psi so 1psi in boost = 1 less psi of rail pressure essentially. So if you go from say a 4.5 pulley to a 4.25 pulley you might grab 3lb of boost but instead of, lets say 51lb of rail pressure you might only have 48lb of rail pressure feeding your injectors. If the OP is at 85% IDC on his current setup maybe 1psi won't be enough to get to a point where he's going lean but maybe 2psi+ is. If he's at 90+DC I would say he needs to AT LEAST upgrade injectors before switching pulleys and for that he'd need a retune anyway.
 

Tommy V

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The major problem with dropping down in pulley size, particularly on the stock style fuel system, is that with every psi you go UP that boost pressure is working AGAINST your fuel system by that same psi so 1psi in boost = 1 less psi of rail pressure essentially. So if you go from say a 4.5 pulley to a 4.25 pulley you might grab 3lb of boost but instead of, lets say 51lb of rail pressure you might only have 48lb of rail pressure feeding your injectors. If the OP is at 85% IDC on his current setup maybe 1psi won't be enough to get to a point where he's going lean but maybe 2psi+ is. If he's at 90+DC I would say he needs to AT LEAST upgrade injectors before switching pulleys and for that he'd need a retune anyway.
Yes i.agree if we're to jump from a 4.5 to 4.2 that is a big jump and why I said if he were to just one size he probably be ok,as long as he fuel.system is not maxed out already,which I doubt running 7psi of boost.But more then one size down aand yes changes will probably have to be done.
 

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Davepurp

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I imagine Fuel Trims be off in addition to running lean in peak boost with Injector maxed out?

im running a 1000cc Injector on 93 Octane with a BAP so I cant imagine a scenario ill max out but I would like to know what to look for before I have my tune adjusted, but I can see the concern with a set of 52# injectors
 

Dominant1

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Procharger D1x with standard 4.88 pulley makes 13lbs of boost on pump and a bap with no fuel starving issue. at redline the blower spins 42,000 rpm..the max on this blower is rpm 62,000. Its all about the efficiency of the head unit itself. unlike roots blowers centrifugal head units can be interchanged most of the time using the same brackets. So instead of pulleying down your blowers to the point that they over spin to their demise. look into trading in your head unit for a more efficient unit. im pretty certain both paxton and procharger offer trade ins so long as your current head unit is in good shape. I know some will say that its more money and yes it is but more power and longevity will cost you less in the long run...
 

Davepurp

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Procharger D1x with standard 4.88 pulley makes 13lbs of boost on pump and a bap with no fuel starving issue. at redline the blower spins 42,000 rpm..the max on this blower is rpm 62,000. Its all about the efficiency of the head unit itself. unlike roots blowers centrifugal head units can be interchanged most of the time using the same brackets. So instead of pulleying down your blowers to the point that they over spin to their demise. look into trading in your head unit for a more efficient unit. im pretty certain both paxton and procharger offer trade ins so long as your current head unit is in good shape. I know some will say that its more money and yes it is but more power and longevity will cost you less in the long run...
This was actually my original thought over the winter, but when I only tack on 3k miles a year and im not going balls out all the time the $100 bucks for the pulley made more sense than the $2k to swap out the blower. but who knows if usage goes up and I wanna rip around more the head unit could always be swapped out later on.
 

foff667

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One guy on this forum has been 9 seconds on the P1sc. I don't think you need to switch blowers.
I agree, the p1sc is more than capable on these cars, If you are striving for big boy numbers ie 850+ to the wheels you'll want to step up to like a d1x or an fseries blower but IMO under 850 or so its almost pointless.
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