Stock boost numbers
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Mountain Pass
Joined: Feb 2021
Posts: 200
Likes: 36
From: NorCal
Stock boost numbers
Researching various forums, seems like plenty of PSD 7.3L owners see boost in the high teens and twenties. Highest I have seen on my nearly stock '97 F350 is 12psi, stomping on it on an uphill freeway onramp. No performance mods on the truck that I'm aware of. Is peak boost of ~12psi weak? If so, what are typical causes other than boost leaks? And when cruising around 65mph on level ground in overdrive, what boost psi should I see, not accelerating?
Logistics Pro
Joined: Mar 2007
Posts: 4,577
Likes: 837
From: knoxville, tn
Were you empty or towing? If empty, that is not bad, but you may have a few small leaks which are hurting you a little. May want to look around the up pipes for any soot. Soot is a sign of exhaust leaks, which hurt boost performance.
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Mountain Pass
Joined: Feb 2021
Posts: 200
Likes: 36
From: NorCal
I was empty. Taking the snake cam under the hood for the first time today. I also have RiffRaff's bellowed up pipes in my shopping cart, with safety off on the Buy Now button. Tempting, based on many reports that it's only a matter of time for the OEMs, and the strong endorsement of the RiffRaff bellowed.
Mountain Pass
Joined: Dec 2019
Posts: 220
Likes: 13
From: VA
If you feel you might have some boost leaks, you can use a boost leak detector. You can make one, or DieselSite makes a nice one but you pay about $70 for it if I remember correctly. Solid numbers for a truck with that kind of mileage. I’m sure there area few boots you can tighten up/replace and probably could replace up-pipes. But your numbers aren’t too bad.
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Mountain Pass
Joined: Feb 2021
Posts: 200
Likes: 36
From: NorCal
Thanks Conner. See my new thread posted moments ago on exhaust leek detection. For boost leaks, obviously, the pressurized air + soapy water method will be employed. I DIY'd a PVC-based rig for boost leaks on my 911 Turbo. Pretty straightforward to repeat for the 4" beast. Agree there probably aren't any major boost leaks if I can get ~12psi punching it without trailer in tow. Still, when I see guys reporting 20+psi, I get boost envy. 
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Lead Driver
Joined: Sep 2002
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From: North Texas
Is your truck still equipped with the stock downpipe?
12psi...was that shifting at where ever the E4OD does at WOT? Say 3300.
12psi...was that shifting at where ever the E4OD does at WOT? Say 3300.
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Laughing Gas
Joined: May 2007
Posts: 793
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Don't.
More boost is more heat. More heat is less power.
FWIW, on my SOB v8 diesel, OE was ~17 psi at max power. Folks thought mods which got 20 - 25 psi were awesome. For the same reported power, I got 14 psi and the enjoyment of a less stressed engine. Even put that vehicle on a dyno to back-up the numbers.
Point is, the whole thing is a balancing act and boost is just a number in the larger scheme.
More boost is more heat. More heat is less power.
FWIW, on my SOB v8 diesel, OE was ~17 psi at max power. Folks thought mods which got 20 - 25 psi were awesome. For the same reported power, I got 14 psi and the enjoyment of a less stressed engine. Even put that vehicle on a dyno to back-up the numbers.
Point is, the whole thing is a balancing act and boost is just a number in the larger scheme.
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Mountain Pass
Joined: Feb 2021
Posts: 200
Likes: 36
From: NorCal
Re shifting, yes, pedal to the metal starting at about 5mph on a highway rump sloping uphill for the duration of the pull. So shifting whenever the PCM/E4OD decided it was time. I can log with Torque Pro if details are of interest.
Don't.
More boost is more heat. More heat is less power.
FWIW, on my SOB v8 diesel, OE was ~17 psi at max power. Folks thought mods which got 20 - 25 psi were awesome. For the same reported power, I got 14 psi and the enjoyment of a less stressed engine. Even put that vehicle on a dyno to back-up the numbers.
Point is, the whole thing is a balancing act and boost is just a number in the larger scheme.
More boost is more heat. More heat is less power.
FWIW, on my SOB v8 diesel, OE was ~17 psi at max power. Folks thought mods which got 20 - 25 psi were awesome. For the same reported power, I got 14 psi and the enjoyment of a less stressed engine. Even put that vehicle on a dyno to back-up the numbers.
Point is, the whole thing is a balancing act and boost is just a number in the larger scheme.
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