20.19 lbs per minute.......wtf is wrong with my logger?

[lowridin2g]

ive been tuning with a logger for a good amount of time now and ive never logged lbs/minute. so last night i decided i would. i logged timing, 02's, rpm, and lbs/min. welp i had an average of 18-19lbs/minute and by redline it was 20.19 lbs/minute. this is way wrong, this is at 22 psi. not to mention i ran 3 consistent 12.8's @ 108 mph last time at the track. this is on a big16g turbo. maybe my logger is inaccurate? maybe it cant handle logging more than 3 items at a time? it is a palm m100 and only takes 5 samples per second. wtf is going on here? ill post my mods below.

big16g turbo, ss tubular o2 housing, greddy 24r fmic, ported evo3 exhaust manifold, apexi gt 3in. dp, 3in. apexi n1 catback (no cat), cool blue intake filter, 3in. extreme turbo intake pipe, matrix short throw shifter, greddy profec B2 ebc, 1G TB , port matched intake manifold, greddy uicp, greddy type s bov, RRE throttle body elbow, RRE licp, act 2100 clutch, walbro 255lph, 650cc injectors, apexi safc-2, datalogger, autometer boost/vac, egt, a/f guage, B&M fuel press gauge, bpr7es ngk plugs/ma-gnecore 8.5mm wires, aeromotive afpr

 

[KPWSerpiente]

You have the safc pulling fuel out. It does this by intercepting the airflow signal and telling it that you are flowing less air. That is why you are logging low airflow numbers.

-T

 

[lowridin2g]

yes, that is what i was thinking, but at the same time i doubted myself cause all these other guys are logging 30lbs per minute plus with their loggers. guess they are not tuning with a safc. i also have my high settings at the lowest right now, -43. so i would say that i am after all pulling normal lbs/minute numbers thank you for clarifying this for me

 

[myblack98gst]

my fuel is set around -35% on the top end and at 23 psi on a cool night it will hold 22.xx lbs/min from 6k to redline. so I supposed if I add 35% back in that is 29.7 lbs/min. then need to account for the MAF being hacked I would think about -15%, so yeah 33 lbs/min sounds about right

cant wait for a good 65 lb/min turbo

 

[lowridin2g]

tell me why u doubt 30 lbs/minute with a big 16g???? if i do recall shape gsx is seeing 44lbs/minute with the evo316g. which does not flow much more than a big16g. i would say 30-32 lbs/min should be aquireable with not much of a problem on a big16g

 

[Violater101]

tell me why u doubt 30 lbs/minute with a big 16g???? if i do recall shape gsx is seeing 44lbs/minute with the evo316g. which does not flow much more than a big16g. i would say 30-32 lbs/min should be aquireable with not much of a problem on a big16g

You can't compare every EVO16g to shape's. I seriously doubt most of those are flowing that much air..alot of it has to do with the rest of the car's setup. That would have to be at 100% efficiency almost I would guess. I'm not sure how much that turbo is rated at, but a green or even an fp3052 isn't rated that much higher than that. As for a Big16g flowing 30 to 32, I would agree that should be np. I was flowing 30lbs with my big28 with only 18lbs of boost. Just my 2 cents.

 

[myblack98gst]

well since you read it before I finished editing you can see it is changed now.. I forget about the MAF being hacked and that can cause it to be lower. and I am still running stock cams. but my manifold/turbo/o2 have had SERIOUS port work done to them .

so no i dont doubt its ability to see 30+ but 40+ is truely hard to see, when a fp3052 is flowing 40 at 18 psi.

 

[kpt4321]

tell me why u doubt 30 lbs/minute with a big 16g???? if i do recall shape gsx is seeing 44lbs/minute with the evo316g. which does not flow much more than a big16g. i would say 30-32 lbs/min should be aquireable with not much of a problem on a big16g

A small 16g is capable of 34-36 lb/min, and the big is capable of a little bit more. 30 is like, not very exciting, that's about the max of a 14b.

 

[kpt4321]

You can't compare every EVO16g to shape's.

Why not? Every EvoIII16g is the exact same thing.

That would have to be at 100% efficiency almost I would guess.

Huh? Compressor efficiency? Turbine efficiency? Volumetric efficiency? Fuel efficiency?

I'm not sure how much that turbo is rated at, but a green or even an fp3052 isn't rated that much higher than that.

So, since a Green (50 trim T4) doesn't flow a lot more than an EvoIII 16g, that means the EvoIII must not be able to flow as much as people are saying?

Isn't it possible that the EvoIII is just closer in size to a Green than you originally though?

A Green is rated at about ~48 lb/min maximum flow.

 

[tstkl]

engine demand is different per car, so the turbo will flow a different lbs/min,... but fp has the evo3 quoted at 42 lbs/min, so im assuming that would be 100%

 

[spyderturbo007]

For the sake of this post I will assume that the -43% correction factor on the SAFC-II corresponds to the rpm where the peak airflow of 20.19 occurs.


You are actually pushing 38.09 lbs/min

 

[Lionel Hutz]

For the sake of this post I will assume that the -43% correction factor on the SAFC-II corresponds to the rpm where the peak airflow of 20.19 occurs.


You are actually pushing 38.09 lbs/min

Can you elaborate?

 

[spyderturbo007]

Can you elaborate?

Sure, that's what I'm here for.

The SAFC-II intercepts the airflow signal, in the form of Hz, before it reaches the ECU. Then, based on your correction factor, pulls the user defined amount of air from the signal, which in turn, modifies the mass of air as seen by the ECU. Because the ECU does not know that you have larger injectors it will open them for the same amount of time that it would the stock 450's (IDC). Because larger injectors flow more in a given period of time, you will end up injecting too much fuel. Without some type of compensation, this will result in a lean condition. By modifying the airflow signal to the ECU, less air is seen and the ECU lowers the IDC.

At peak airflow the ECU is seeing 43% less airflow than is actually entering the combustion chamber. This drops you onto a lower timing map than you would be on if the ECU saw the actual airflow. Which, in turn, leads to higher than normal timing.

The 20.19 lbs/min you are seeing at the logger is the mass of air that is seen by the ECU, which has already been corrected by the SAFC-II. This means that you need to back calculate the mass to find the actual unmolested airflow.

Ignore the post where I told you that you were flowing 38.09 lbs/min, for some stupid reason I used -47% in my calculation instead of the -43% that I wrote in my post. I'm such an idiot

You are actually flowing, now that my brain is functioning 35.42 lbs/min.

You will need a couple of things for the calculation

1. Peak airflow displayed by the logger
2. Correction factor of SAFC-II, corresponding to the rpm where peak airflow occurs

Anyway,

Here is the calculation:

Peak airflow (lbs/min) / (1 - SAFC-II correction factor in decimal form) = actual airflow

In your case:

20.19 / (1 - 0.43) = 35.42 lbs/min

Wow, that was fun Enjoy!