blmcquig

iTrader: (15)

right, but it can only compensate so much. you need to watch your wideband, and fine tune everything, and make sure you have enough fuel in the mix.

icecreaman

afm isn't after the turbo, its before the turbo.

boost_its_what_for_dinner

so can you put it in the ic piping on the cold side???

edomund

No it maxes out rather easily sencing the turbo sucking air (before turbo) let alone pushing air (after turbo), there is no way. The AFM is made for a relatively stock setup not a perfoemance car or upgraded turbo.

BTW all this has been covered, please read my threads you will learn a lot. People have already blazed the trails you are heading down why not take advantage of the knowledge we already gained?

gxl90rx7

iTrader: (1)

a different turbo may have different flow at a set boost pressure, but the afm will pick up on the difference, i would think the airflow is the same before and after the turbo, the only difference is temperature and boost pressure

the ecu takes airflow, boost, rpm, temp all into account when determining fuel injection amount, the question is: does the stock map account for more airflow than expected at a certain rpm, boost, and temp

the best way to deal with the uncertainties would be to make it really rich, log do a few runs with a wb and/or egt, and back off the fuel until you are getting the a/f or power you want without risking pinging

edomund

The AFM will not accurately compensate for the difference in airflow because it gets maxed out. The AFM can only read so much air at a time and it's not a lot more than stock airflow. It sure as heck is not able to read boost, so it is not the same before and after the turbo. Thats why there is a map sensor after the turbo to read boost, the AFM only reads air rushing past it.

No, the ECU cannot account for the added air flow from a TO4 turbo and streetport because the AFM gets maxed out (can't keep up) as I said before. Henrik has also confirmed this in past threads by reading my data logs.
Think about it if the AFM could compensate for the added air from upgraded turbos you would not need to use the fuel slider to add additional fuel to the map. I have to add a bunch of fuel into my map. I have to keep the injector setting at 550 with 720's & 1000's.

I do agree with the last statement though. Thats a good rule of thumb for tuning.

turbo2ltr

iTrader: (1)

I just want to expand on something that edomund said... I dont know how we got on the subject of "blow through" airflow meters, but the stock AFM is designed to read *airflow*. With the AFM reading airflow, the Intake air temp sensor reading the temp, and the ATP sensor reading the atmospheric pressure, the ECU can calculate the AIR MASS. The AFM alone does not have the ability to calculate air *mass* so putting it after the turbo (AKA "blow through") will make it measure airflow at an increased pressure. The ECU doesn't know the pressure (well it does read the MAP sensor, but it's not using it to calculate air mass) so any reading from the airflow meter in a blow through application is totally useless.

gxl90rx7

iTrader: (1)

i will be sending my turbo off to bnr for stage3 at the end of this month. It makes that much of a difference? how much correction do you have with the 550/550 setting and what afr's are you getting?

I am running the about the same injectors as you (750/1000), and right now im using the 720/720 preset with 0% fuel correction across the board, and the afrs are in the 11's at full boost @10psi (with timing pulled back to 20 deg at 100% load and blended with stock map). I did notice i had to add 5% fuel at idle to get the same idle AFR i had with the stock injectors at -3% on the 550/720 preset.

boost_its_what_for_dinner

well guys i might be buying icecreaman's 2.0 maybe??

boost_its_what_for_dinner

well i bought his 2.0 and now ill be running his bnr stage 1 with 720cc/1000cc so ill be set up by the 1st week of may and be driving by the second week hopefully.
and i do apoligize to edo and turbo2ltr i didnt really know what i was getting into and now i have a broader imagine on this rtek progam and hope to have help from yall in the future

RotaryEvolution

iTrader: (30)

i will answer your question, a safe number for boost to run any turbo before getting it tuned proefessionaly is 0.

smartass reply or smart? only you can answer that.

edomund

+1 Agreed
Mind you this is coming from a professional rotary tuner.
Hopefully this will be the end of this thread.