jstev4610

Working on logging my 2015 5.3 with tvs 1900 long tubes and catback. Added some calculations to track, hp and boost. I can't tell if boost is really tracking correctly. HP seems to close by checking manually off delivered torque. Want to dial in boost before I try to add my wideband. Crank HP was just added to see it output.

1 - Does 3.9psi seem like the correct number for boost at wot, considering I have a magnuson hearbeat, stock pulley, and long tubes? At idle boost is -9.8, which could be a product of the math -14 something, although I would think it would be constant at a close psi.

2 - The injector duty, is that really 125.3% duty cycle? So it's not going to show xxx.x, just xx.x? They're stock injectors and I realize they might need to be upgraded. Want to see accurate data before making that decision though.

FFDP

iTrader: (2)

The 1 BAR map sensor stops reading at like 3.9psi. You need to remove that channel and replace it with the 2 BAR channel to see PSI above that. Thus also requiring you to install a 2 bar or 3 BAR MAP sensor.


I've never bothered to log an actual boost channel or tried to set one up, I just take the map KPA and do the math instead.

Duty cycle isn't like older vehicles, you do not really have to concern yourself with that as far as I know. The pulse width in the main concern, I forget where you run out of fuel but I thought it was somewhere around 6ish.

jstev4610

I was pretty sure my magnuson came with a 3 bar, and might have pulled the wrong variable in, I'll try to redo it. Glad to confirm it's incorrectly reading. Do you mind sharing the MAP kpa to boost math with me?

FFDP

iTrader: (2)

You can double check what MAP sensor the tune it set for. Just look at the linear and offset settings for the MAP under the airflow tabs. Stock one bar is like 128 and -0.31 or something close to that. A 3 BAR sensor if using a newer GM sensor is 312.50 and -11.25.

I just use the tools function and unit converter for boost. So above 100kpa is boost and if you had 140kpa that's 5.8psi. I mainly said that because I don't like the negative boost numbers that get shown when running a boost channel. I prefer MAP kpa or logging the MAP in/hgs in some scanners.

jstev4610

confirmed linear is 312.5kpa and offset is -11.25. Looking at the kpa logged, the boost is correct

readings:
kpa=126.7
boost=3.9

122 kPa = 3.2 psi
129 kPa = 4.2 psi

FFDP

iTrader: (2)

Yeah it's correct to the log. Check to see what channel you logged and if it's the 1 BAR channel then it won't show the real psi like the 2 or 3 bar channels will.

Most of those TVS1900 kits should run 6-7psi right out of the box.

jstev4610

I logged:
[50030.98]-14.5
Manifold Absolute Pressure = 50030

So looks like I'm reading the right 3 bar. I think the heartbeat is supposed to run around 5.5 out of the box, and I thought I would lose some boost with the headers but not down to 3.9psi.

jstev4610

looking at that again, and looking at the log, the log is reading the map at 18.3psi, which with my math gets me around 3.9 with rounding, so got the math variable right and didn't do my due diligence before asking.

Last Call

iTrader: (4)

What is your MAP reading with the key on and engine off?

smokeshow

iTrader: (16)

The HP calculation will only be as accurate as your torque model. I've never seen anyone with an aftermarket calibration adjust it, mostly due to the difficulty in doing so.