Turbo Boost after mod peaking at 36psi

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BreakingPar67

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2017 F150 Raptor 50K miles - aFe Super Raptor CAI, 73mm TB, Mishimoto intercooler, Turbosmart BOV, SPD Turbo Adapters, 170 deg Therm. MPT Tuned 93PRX. Just got the new tune from MPT to adjust for the new thermostat. I also just had the intercooler and BOV installed. Seems to be a problem with boost pressure peaking very soon (early midrange) and spiking to 36psi at 75% throttle. The BOV is an EM (electro mechanical) likely controlled by the PCM. I have Forscan and wondering if i can control the BOV to open sooner and lower the boost. All help appreciated. HI Y'ALL, new member. Go Bills!
 

TwizzleStix

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The problem is in the tune. The BOV has nothing to do with any boost value. It opens when you lift throttle to release any pressure in the tubes against the closed throttle plate. Talk to your tuner ASAP.

I’ve been thinking as to WHY people think the BOV controls boost. Maybe it was the Indy cars of old. The CART rules limited the max boost, so they all had a pop-off valve installed right on top of the intake manifold that indeed would release any pressure above the set limit.

Mazda also had a clever recirculating BOV that also had a boost input on both sides of the valve against the internal spring such that it limited max boost to 20psi. You couldn’t get it above 20 no matter what the max boost and WGDC were set to. If you replaced it with aftermarket, it automatically canceled the engine internals warranty.
 
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thatJeepguy

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Yes, but it isn’t “useful” boost and will destroy the turbo(s) very quickly.
Oh that i know , the smaller units would be overclocked and detonate. None the less thats pretty impressive celling for turbos that can basically fit in your hand.
 

GooseTuned

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My guess is you’re looking at absolute pressure.

The boost sensor on these trucks are 3bar sensors.

14.5x3 = 43.5

But now take into consideration atmospheric pressure; I’m guessing you’re at sea leave so 43.5 -14.5 ~29psi

That’s as high as the boost gauge will read, 29psi.

If you’re looking at psia which doesn’t take into consideration atmosphere, then it’s (relative) boost + 14.5.

So likely you’re actually only making 22psi.

36psi - 14.5 (atmospheric pressure) = 21.5-22psi

Sorry for the long post :D
 
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