[Aerotest]

Hello,

This is my first post here. I have enjoyed reading the forum for about two years but until recently, my car was stock and I had nothing really to contribute.

I am currently running the OFT Stage 1 OTS maps on 93 octane. Data logs look really good which have been confirmed by Shiv (thanks). I have been wading through all the conjecture over acceptable pressure levels of boost and decided to map my car against the TD03-10TK3 compressor map to see the actuals.

To start, I built a calculator that applies all the theory regarding the affects of turbo machinery and reciprocating engines. Additionally, I was able to reinforce the theory with empirical data collected via the OFT data log function. Attached are the results of my calculations in tabular format. Also attached is the RPM points plotted against the compressor map. It is importance to consider theory is just that and while I worked hard to account for all of the influences, nothing is perfect.

Limitations:
First, I had to fix VE at .95 across the RPM range which I know not to be the case. This shouldn't have a huge affect on plotted points but having VE for the engine across the RPM range would be better. Second, the map is referenced against 20C (68F) and my data was taken at 73F with considerable humidity. I couldn't re-reference my data to match the map because I don't have the air density of the map data. Also, IC efficiency tends to shift across the RPM band which would be expected as the car gains speed. You can see where I backed out the correct IC eff. across the top of the data plot based on IC intake charge temps actually collected. Efficiency improves with road speed as expected but takes a dive on the back end of the run. Not sure if that is an aerodynamic effect (flow through IC) or heat soak of the IC. More experimentation to follow......

The conditions for this data were 73F @ 84% humidity. Pressure altitude was 754 ft. Pressure ratio plotted is adjusted for altitude accordingly. Car is completely stock with fresh plugs and drop in AFE filter.

A couple of things I see on the compressor map are:

1. I would like to be running much higher boost in the mid range (PR=2.5) to take more advantage of the 72% efficiency island. This would give me much higher flow volume for approx. the same adiabatic penalty. This would mean targeting 21.3 PSI for my pressure altitude.

2. I am a little concerned about running off the back of the map (choke line) at the 6K and 6.5K points. I didn't log data to the 7K point which would have been grossly off the map. I am thinking a more aggressive ramp down from a mid range PR=2.5 is called for to keep the turbo out of choke.

I don't have enough experience to say how the turbo reacts to running in choke but I suspect it is damaging to the long term longevity of the turbo. I am sure Mitsubishi did not design the bearings for the thrust and vibratory loads out in this region. Keeping in mind my runs were in a relatively high density altitude environment, they might stay on the map better given a cooler, less humid environment.

I am just starting to learn how the tables affect tuning. Using the compare function in Tuner Pro, I did notice that the base WGDC table seems to have an even 80% scale applied across the entire table, as compared to the stock table. I believe I can achieve the map adjustments desired by scaling the WGDC and load tables in a non-linear fashion that represents where I want to be on the map. My only issue is Shiv made changes to several other WGDC related tables that I don't even begin to understand. These changes make me realize my approach is likely oversimplified.

Any input on my research from the resident experts is much appreciated.

Tks,

[AMERICUS]

Como what? Interested to learn, but never understood compressor maps.

[135Pats]

Well thought out. You could certainly ramp down boost targets north of say 5K. Experiment!

[Aerotest]

Thanks for the response guys.

Christooher02,

Good feedback. I am not familiar with the proceed maps but agree that Shiv had probably played with all this before. I think the dilemma is that aggressively ramping down boost with RPM doesn't make well for the dyno horsepower comparison with other products. I don't really care about that.......I am after nice broad torque curves which make for fast street cars IMO.

As you point out the risk is having the car fall flat after 5.5K. I plan to make the changes and do a butt dyno comparison. If all goes well maybe get dyno pulls of the torque curves for comparison.

I am trying to figure out what needs to be changed in the maps by conducting a comparison audit of the Stock BIN and Stage 1 BIN. Once I understand the differences, my hopes are someone can help me understand what each factor in the WGDC tables considers and how much weight it holds. Would be nice if I had the BMW diff equation for load control then I could figure all this out on my own.

[808AWD325xi]

Great info OP, subscribed.

Noticed the compressor map is from dmetune.com... What ever happened to those guys? They vaporized like "Shark Edit."

[Aerotest]

Originally Posted by 808AWD325xi

Great info OP, subscribed.

Noticed the compressor map is from dmetune.com... What ever happened to those guys? They vaporized like "Shark Edit."

Dont know. I found the plot on Google so tell them thanks.

[E90Company]

What are you looking to understand here? If your boost curve is safe/can be altered for more power within the turbo's efficiency? You need to take into account boost pressure loss within the FMIC as well as exhaust backpressure to get an accurate picture (which will vary from car to car noticeably with our size turbos)

[Aerotest]

Originally Posted by Christopher02

I'll send you a PM once I'm on my computer (and not my iPhone). There's plenty of good info out there, albeit spread across a few different websites/forums.

I would appreciate it.

[Aerotest]

Originally Posted by E90Company

What are you looking to understand here? If your boost curve is safe/can be altered for more power within the turbo's efficiency? You need to take into account boost pressure loss within the FMIC as well as exhaust backpressure to get an accurate picture (which will vary from car to car noticeably with our size turbos)

IC pressure loss is not a factor b/c I used the actual TMAP reading at the throttle.

[Joshboody]

Nice calcs. VE is reduced a bunch in the top... prob could estimate from torque curve. The turbine is undersized relative to compressor. Even though you are taking tmap psi, pre-IC will change all your calcs mass flow, PR, compressor eff, etc.

AFAIK, flash is somewhat limited in max boost without getting a little "creative"... piggy you can add whatever curve you want.

[Aerotest]

Originally Posted by Joshboody

Nice calcs. VE is reduced a bunch in the top... prob could estimate from torque curve. The turbine is undersized relative to compressor. Even though you are taking tmap psi, pre-IC will change all your calcs mass flow, PR, compressor eff, etc.

AFAIK, flash is somewhat limited in max boost without getting a little "creative"... piggy you can add whatever curve you want.

Good info. My formulas are set up to account for compressor output and effeciency, IC effects, air density, etc. All this is represented by the density ratio computed and ploted for each point. The DR is then multiplied by the N/A volumetric flow of the engine to determine the real impact of the turbo charger, considering all these factors.

I was thinking the same thing about est. VE via a torue curve. I really woukd like to have a MAF to measure actual air flow, but rigging that up even for a dyno is much more complicated thsn it seems. Not sure i could get a laminar section of flow in any of that charge pipe mess under the hood?

[Aerotest]

Originally Posted by Joshboody

AFAIK, flash is somewhat limited in max boost without getting a little "creative"... piggy you can add whatever curve you want.

I am starting to see that. I noticed last night that load is caped at 220 and Shiv has it set to 190 across most of the range already. I am starting to think boost is a second order to load. The nice thing about a load based system is it will respond identically in all environmental conditions until it is mechanically limited. Using a boost curve, you get X psi wether younare at SL or 5k feet which is not always safe fornthe engine.

[Ilma]

Originally Posted by Aerotest

I am starting to see that. I noticed last night that load is caped at 220 and Shiv has it set to 190 across most of the range already. I am starting to think boost is a second order to load. The nice thing about a load based system is it will respond identically in all environmental conditions until it is mechanically limited. Using a boost curve, you get X psi wether younare at SL or 5k feet which is not always safe fornthe engine.

That is a limitation/annoyance when you are seeking maximum performance.

In colder ambients, the DME will actually reduce boost to maintain a constant power level.

Nice management system for stock as BMW intended, but in cooler temperatures I don't want my boost to be reduced.......the greater air density in colder ambients is free power....

[Aerotest]

Originally Posted by Ilma

That is a limitation/annoyance when you are seeking maximum performance.

In colder ambients, the DME will actually reduce boost to maintain a constant power level.

Nice management system for stock as BMW intended, but in cooler temperatures I don't want my boost to be reduced.......the greater air density in colder ambients is free power....

I agree 100%.

[Aerotest]

Would be nice if someone could crack the RTOS and give us the ability to run modified programs and change I/Os. Other platforms are already there.