Those who are running a MAF and multiple boost settings.....how are you making up the difference in fuel between high and low boost?

I have been trying to decide on the best and most consistent way to proceed. Looking to run 11lbs low and 15lbs high...here are what I see as some options:

1)Thinking that having a different program for high and low. This would appear to be a bit of a PITA to flash thepcm to switch back and forth for settings and that I would also have to maintain/tweak two sets of tunes if I changes/add things down the road.

2)I was also thinking that I could tune for high boost and then run a rich low boost setting and pull back on the alky. Probably the most practicle and safest but I am not sure whether it would be too rich at the low setting

3)Use the roadrunner pcm/EFI live real time tuning but it just does not seem like many have tried this approach yet...I did not see where anyone tried this on this forum yet but who knows

4) Run SD but at the moment constant tweaking is not desireable. But I would be willing to go this route once I become more versed in tuning.

Thanks for your input!

 

This is exactly what I do, although I usually just run my low boost setting pig rich as it still makes gobs of power.

 

This is the option i would choose. I have tuned my one time (took a few hours) and have never touched it since...working great. I am sure it will need some changes in the long run, but you are talking maybe once every few months...maybe

 

Where does that leave your A/F at low boost?

 

Once I become more versed in tuning, I will probably go down this route to keep myself busy and try something new. I would really like to see if anyone gets the road runner pcm running realtime with EFI live as this would make adjustments to the tables based on real-time wideband readings...I would not think you could get more acurate than that.

 

I have seen some here, i think with one of the twin turbo set ups move the ECU to the battery compartment(location). If this is done then buying a second ECU for 200 buck with a second tune would allow a 15 second swap if needed without the risk of frying the ECU. Just use a battery quick disconnect as well.???

 

LPE set mine up such that I flash the ECM with a custom tune for each of my two boost settings. 10 psi and 13 psi, with fuel and spark optimized for each. Their usual way is to be too rich at low boost and retarded timing on high boost with a single tune which compromises both settings somewhat. The SD solution is best, but I'm very happy with my two tune set up!

 

A few psi of boost is not really that much in the grand scheme of things, and other than the power output difference I doubt most of us could tell the difference between a car running at 12:1 vs. running at 10.5:1. You want two boost settings to have a "kill" mode and a normal mode, with normal mode having a reduction in power, right? I would tune for kill mode, and then dial back your boost pressure for normal mode until you've found the sweet spot where power output is about where you want it. Your car doesn't have to be running a perfect 11.5:1 or 12:1 to run well at WOT.

 

This is probably what will be done

 

Help me understand the tuning issues involved here. Does the difference between high and low boost tune requirements have to do with the relationship between boost and throttle position and rpms? Why are the tuning requirements for an engine tuned for say 15 lbs of boost but only seeing 10 lbs at part throttle or full throttle at a lower engine speed different than an engine that is being limited to 10 lbs by a second setting on the boost controller?

 

100%

i agree with tony, your AR dont have to be perfect.
tony is right, ive my car pig rich 10.0 high 9s @ 18psi and there is no way your going to complain about lack of power.

 

YOU have run your car and made nine second passes?

 

I run on the wastegate spring. Some call that kill mode..

 

10 psi on a 408 is kill tire mode.. that is for sure.

These turbos kill on a big cube motor.

 

Tires are something I have to keep in stock. I already have a set of 335's sitting in the garage waiting for me to get home....

 

ahhhh u read wrong...i was trying to say that my car runs strong on AR of 10 and even high 9s

 

Thanks Nick....Sounds like dialing high for the kill is the way....just was not sure about how loaw boost would turn out. Sounds like it will NOT be a problem.

 

I just ordered my spare set today At my new power levels, I am sure I will be needing another set in a couple of months