HP Tuners MAP calculations

[16GoManGoHC2]

See 3 videos attached. Back when I was running a 3.8 Whipple I thought I was making 24-25 psi of boost. Forum member @fumanchu182 pointed out boost based on PR was more like 29-30 psi of boost so I hooked up a calibrated liquid filled gauge to the blower lid snd sure enough he was correct, see video of HP T verses actual boost gauge.
So now I’m testing a 2.7 IHI blower with my custom billet oil lubed front plate and same HP Tuners log channels file is telling me MAP is around 24 psi but PR of 2.75-2.80 is saying MAP is more like 25-26 psi at 14.5 Baro. I’m going to hook up same liquid filled gauge to the blower lid again and measure actual next run but how do I get HP T to calculate and display MAP correctly based on PR and Baro pressure?

3.8 Whipple

3.8 Whipple 60-130 log portion

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2.7 IHI 60-130 Log portion

Anyone know?

 

[fumanchu182]

Sensed map seems to be the most accurate. @Jon-MooredPerformanceLLC cam confirm.

 

[Speedy!]

On my 170 I log MAP, Sensed MAP, Pressure Ratio, Aircharge, and have a custom PID called "BOOST" in chart data. I also log Barometric pressure as it's needed to calculate actual pressure in most cases. They're all with in 1psi.

I think @fumanchu182 gave me a tip on setting up the "BOOST" PID since it's custom and actually reads one of the MAP sensors (from memory) and subtracts BARO from it.

Could it be something with the MAP sensor scale?

 

[Jon-MooredPerformanceLLC]

Problem is sae channels will not read over 37psi. Sensed map is not an sae thing parameter.

 

[16GoManGoHC2]

I’m going to try this somebody turned me onto on the other forum

 

[Speedy!]

That's what I did, only to get a little more accuracy I used the formula:

Pressure Ratio * Barometric pressure - Barometric pressure

 

[16GoManGoHC2]

That's what I did, only to get a little more accuracy I used the formula:

Pressure Ratio * Barometric pressure - Barometric pressure

@Speedy! What symbol do you use for Multiply the Asterix? * ?

Here’s it by IMAP

 

[Speedy!]

Yep asterisk

 

[zhc]

Where pressure is read from matters too. Pre-intercooler pressure will almost always read higher than post-intercooler pressure. The difference depends a lot on the temp delta, if you're using ice or a chiller, it's not uncommon to see a pressure difference of 1-2 psi between IMAP and bank 1 / bank 2 pressure readings.

 

[16GoManGoHC2]

Where pressure is read from matters too. Pre-intercooler pressure will almost always read higher than post-intercooler pressure. The difference depends a lot on the temp delta, if you're using ice or a chiller, it's not uncommon to see a pressure difference of 1-2 psi between IMAP and bank 1 / bank 2 pressure readings.

I log them all

So 25-26 psi is realistic number?

 

[16GoManGoHC2]

Yep asterisk

@Speedy! can you post a screen shot of your math page for boost based or PR? I can’t get mine to work that way.
See mine, look right or wrong PR channel?

 

[Speedy!]

 

[16GoManGoHC2]

View attachment 163782

Thank you!! I’ll see if I can find them. I use a much older version of HP Tuners with my 16 Hellcat yet, if I upgrade to something new none of my older tunes or logs I will be able to use or see.

 

[16GoManGoHC2]

View attachment 163782

@Speedy! I found the PR pid but I ca not find the Baro pid you used, I used sensor. Where did you find the Baro pid you used? I’d like to be comparing to a same calculation as others may be using to get an idea how this 2.7 is doing boost wise with my custom plate on it and hand ported snout with a 105 TB



Boost using above pids. 25 psi avg on the pull not bad for a +10 lower 2.74 clutched upper combo with a well used belt. From watching the boost pid I think there’s a hair of belt slip going on, may install a new belt before dyno visit.

Going to dyno the car soon to compare to previous blowers, ported 2.4, Whipple 3,0, and Whipple 3.8.
It did good on a 60-130 pull on the Mexican border crossing bridge Sunday am. Cold roads yet but the 305/35-20 half tread Conti’s did good yet.