Hey everyone I was wondering something about the PowerFC.

People always say "the stock MAP sensor is good to 17 PSI with the PowerFC", which I'm sure is probably true.... The stock sensor probably stops being accurate at 17.

BUT...

According to the PowerFC instructions, it says:

"If the press. value is [20000], it is equal to 2.0 kg/cm^2 of absolute pressure. Atmospheric press is about [10000] of pressure value"

The values for P1-P20 are 1000-20000 in steps of 1000.

So at cell P20, you have 2.0 kg/cm^2 or 28.4 PSI absolute pressure. (13.7 PSI boost).

So what's the deal here? Can you REALLY do 17 PSI on the nose with a stock PowerFC and stock MAP sensor or is it really that you can do it only if you remap your P-values?

Thanks!

Brian

 

Brian,

P20 is 1.37 - 1.5bar for my v7.07 default map.

Map reference setting, as default, is:
20: 24000 (under Settings 3, Datalogit)
19: 22000
18: 20000
17: 18000
16: 16000
15: 15000
.
.
.

I thought there was a change in the default maps awhile ago, where 20 was upped to 24000 from 20000. In searching through all my "default" maps, I cannot find it.

Does that help?

 

The most boost, as measured from the PFC on a stock 1.5 sensor, is 16.8psi (I could have rounded wrong during the conversion, but I doubt it)

 

Hmm I'll go home and double check my Datalogit files/PowerFC and see for SURE what my P20 is.

But my question/comment is the same... if my P20 = 20000 then my max boost is 13.7 PSI right?

If my P20 were = 24000 as you suggest, then I would imagine I could go up to about 16.5 or so.

 

You can go "off the chart" so to speak. For instance, you ever rev'ed higher than 8000rpm? What is your N20 set to? Higher or lower than you've ever hit in terms of RPM?

I believe the PFC will use the "last settings available" when allowing you to do that.

 

Yeah I know you can go off the chart, but my question is that if you have P20 = 20000, you can't go over 13.7 PSI with accurate mapings right? You will hit 20000 (or 13.7), and then after that, it just keeps thinking you are at 13.7 no matter how high you go.

 

Brian,

When you rev over 8000rpm the PFC still has an accurate data log of the actual RPMs. Why do you suspect this is different for boost? It will still see the actual boost, and use the last setting(s) for that boost. If you can set the boost to over the target, I think you'll go over the target.

Not to be confused with the adage about the guy with the broken hand going to ER and having it looked at. The Doctor treats the hand and says: "You're good as new"
Patient says "But Doctor, will I be able to play the piano?"
Doctor says "Only if you could before!"

 

My stock MAP sensor peaks at 1.15 kg/cm^2 or 16.3 psi or so. I think they are supposed to peak at 1.2, but mine doesn't read that high (manufacturing tolerances, I guess). You can see a flat line across the top of the boost graph at 1.15 when you go over that amount.

I am not sure what P cells map to what pressures. I just wanted to share my observations of the MAP sensor behavior.

-Max

 

From memory I believe at 1.15kg/cm^2 (16.36psi)the PFC will read only read to row 19 (22000kg/m2). I don't think it is possible to get to map 20 because 1.15kg/cm^2 is equal to 21500kg/m2 on the map, so therefore it stops at row 19. 24000kg/m2 is actually eual to 20.14psi or 1.42 kg/cm2.

I hope I made this clear. I tried. All numbers hae been rounded up to the nearest hundreth.
John

 

When I was running 20 pounds on the stock turbos with the stock map sensor I had to richen up row 19 so I wouldn't run lean. Obviously because of the said explanation above row 20 didn't change anything.

John

 

To answer your question, yes. In your case it will use the settings for 13.7 no matter how high you go, assuming your map is only setup for 13.7. Haven't heard whether you verified that yet or not.

k