Am I making the boost I should?

[t14mhall]

Hey guys,

Looking for some advice here...

2018 Mustang GT w/ a stage 1 Procharger HO kit. My stock pulley was a 4.38" and it was rated for 6.5lbs ( I constantly saw 6.2 lbs). I've since changed to a 4.10" pulley and was told by Procharger that I should make 9 PSI with this. Since installing the new pulley the max I've seen is 7.6 lbs. My question is, should I be seeing more boost or is 7.6lbs correct for a 4.10" pulley?

• I'm reading boost through a mechanical gauge
• The belt is tight/ no slipping
• PBD tuned- Shoemaker says he expected to see more boost
• The power from the stock pulley to the new one isn't really noticeable ( maybe a boost leak somewhere?)

Thanks in advance!

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[SheepDog]

a 1.5ish psi increase sounds about right for a pulley that is 3/10ths of an inch smaller. There are many factors that effect measured boost pressure. What is your crank damper diameter? What engine RPM are you seeing your 7.6 PSI?

 

[t14mhall]

a 1.5ish psi increase sounds about right for a pulley that is 3/10ths of an inch smaller. There are many factors that effect measured boost pressure. What is your crank damper diameter? What engine RPM are you seeing your 7.6 PSI?

I have no idea on the crank diameter- I didn't touch that when doing the install as it's only the stage 1 kit ( so I'm assuming w/e the stock size is). Both logs for 6.2 and 7.6 were at about 7500 RPM.

 

[SheepDog]

I think you are seeing pretty much exactly the boost you should with that size pulley and the OEM damper. Max blower speed is achieved with a 3.2 inch pulley and a 6.78" diameter balancer on the HO kit at around 7500 rpm. (I think the 18+ cars have a slightly larger diameter balancer than the 2015-2017 cars, which would mean a slightly larger blower pulley)

 

[t14mhall]

I think you are seeing pretty much exactly the boost you should with that size pulley and the OEM damper. Max blower speed is achieved with a 3.2 inch pulley and a 6.78" diameter balancer on the HO kit at around 7500 rpm. (I think the 18+ cars have a slightly larger diameter balancer than the 2015-2017 cars, which would mean a slightly larger blower pulley)

Well, that sucks if that's the case. I would have gone with a smaller pulley like a 3.90 or so if I knew a 4.10 would have only made 7-8 lbs.

 

[SheepDog]

same thing happened to me. I live at 5,000 feet above sea level and originally ordered my kit to make 12psi. They sent it with a 3.5" pulley and I was only seeing around 9 psi. Like I said though, there are many factors that effect the measured boost pressure in the manifold. Procharger's "estimates" on boost pressure are just that, estimates. Power under the curve is far more important than max effort in regards to a street car. As long as your fuel system can support it, pulley down. How often is the engine actually at 7600RPM's?- pretty much never unless your at the track.

 

[t14mhall]

same thing happened to me. I live at 5,000 feet above sea level and originally ordered my kit to make 12psi. They sent it with a 3.5" pulley and I was only seeing around 9 psi. Like I said though, there are many factors that effect the measured boost pressure in the manifold. Procharger's "estimates" on boost pressure are just that, estimates. Power under the curve is far more important than max effort in regards to a street car. As long as your fuel system can support it, pulley down. How often is the engine actually at 7600RPM's?- pretty much never unless your at the track.

Agree with you. Do you have the stage 1 or stage 2 kit? I have ID1000's and a JMS boost max at the moment and just wish I would have gone smaller w/ the pulley from the beginning. If I pulley down again, this will be my 3rd belt/pulley lol. I'm also all stock besides the blower, so I don't want to push it over 10lbs. Decisions decisions.....

 

[SheepDog]

I have the HO kit with the stage 2 intercooler and Big Red valve. I also have headers and a fuel system though, and corn blood. Go with a 3.8"

 

[t14mhall]

I have the HO kit with the stage 2 intercooler and Big Red valve. I also have headers and a fuel system though, and corn blood. Go with a 3.8"

How much power are you putting down with that setup? I'm up in the air with doing another pulley- I don't feel like pushing the limits on the car ( I'm sure it can handle a 3.8 assuming I'm staying under 7500 RPM)

 

[SheepDog]

Honestly I don't know, never had it on a dyno. I really just concern myself with how it "feels" and data log info. I will tell you that having E85 and tune makes a world of difference especially in the midrange because of the ability to crank up the timing. I see around 11-12 psi at redline but I'm using a 3.25" pulley. At sea level this would be somewhere in the neighborhood of 15 psi. I almost never take the motor to 7600 RPM, I want the power down lower where it is usable.

 

[ahl395]

Alot of factors can go into boost numbers. Altitude, tune, exhaust setup, rpm.

If you rev higher you'll see the boost your looking for without changing the pulley again. Or change the pulley again

 

[turnswrench]

I just switched from HO to stage 2. I have a 3.7 pulley for your setup I don't need. Let me know if you're interested. I saw 10 psi. Good luck either way.

 

[t14mhall]

I just switched from HO to stage 2. I have a 3.7 pulley for your setup I don't need. Let me know if you're interested. I saw 10 psi. Good luck either way.

10 PSI on a 3.7?!? Man, procharger told me 8-9 with the 4.10 lol. I just checked one of my logs and the boost is kind of jumping throughout the rpms. First attempt is to tighten the belt some more then step two is to talk to you more about getting that pulley off your hands lol. Do you have a belt too?

 

[t14mhall]

This is how the belt was after about a turn and a half of tightening. I couldn’t tighten it anymore because I was running out of light but it’s not maxed out either. It sure looks like it needs a few more cranks to tighten it more?

 

[turnswrench]

10 PSI on a 3.7?!? Man, procharger told me 8-9 with the 4.10 lol. I just checked one of my logs and the boost is kind of jumping throughout the rpms. First attempt is to tighten the belt some more then step two is to talk to you more about getting that pulley off your hands lol. Do you have a belt too?

I have a procharger belt and a brand new green belt for ya

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