Reply With Quotelook at the numbers in the gray blocks across the top, race map has gas at different rpm levels, then the stock maps
I'm trying to understand why the RACE Map is superior to my stock map. I see some inconsistencies, but what is so great about it?
I have a 2006 xb9sx:
K&N
Breather Reroute
White Wire mod (haha)
wrapped & painted headers
Jardine RT ONE
Stock Map is highlighted (both for FRONT only)
Race Map
look at the numbers in the gray blocks across the top, race map has gas at different rpm levels, then the stock maps
A factory race eeprom has more than just modified fuel tables. There's also spark timing tables.
Whether or not it would be considered superior depends on your goals. The factory race ECMs are intended for track use and are tuned for that environment, in combination with a specific muffler and air filter!
I understand the orientation of how it is laid out. But wanted to know what levers there are that feed into performance. Fuel map, timing, etc
Tuning is all about volumetric efficiency and finding maximum brake torque (mbt). You make power by optimizing timing advance throughout the rpm range. Finding mbt can simply be stated as the point at which your engine makes the most power and any further timing advance results in little or no change in power output. Timing advance is also directly related to preignition and detonation. Where too much timing advance causes the fuel mixture to combust before it has reached top dead center, typically causing an audible ping or knock. On most engines running 91 pump gas, MBT is reached well before the threshold of engine pinging or knocking. High performance engines require race fuels to allow for more timing advance to be applied before it reaches MBT without pinging. Okay, a little basics on timing advance and MBT. So where does fuel come in? The volumetric efficiency is how much air and fuel the engine can ingest. Of course the most efficient is 100% cylinder fill. Now, where air fuel ratios come into play is how efficient that air/fuel mixture is burned. 14.7:1 for gasoline engines or what is called stoichiometry has been determined where you get maximum combustion with maximum efficiency. And of course the leaner the AFR is the most fuel economy you get but at the cost of power. Now for maximum power it has been determined that between 13.0 and 13.4:1 AFR creates the most power in a gasoline engine. Running a richer AFR than that really isn't beneficial. Okay...So how does this all play in? With EFI you can tell the computer how much fuel you want, when you want it. For fuel economy there is no need to exceed 14.7:1 AFR. at part throttle cruising and low load this is where you want to be to get the most MPG's. Now as you put a load on the engine and open the throttle up because you want that power, well you tune the fuel to transition between throttle ranges until you get at wide open throttle, this is where you tune the engine to have 13-13.4:1 AFR. With optimal timing, this will give you the most power. Also it is important to note, that along with the combustion properties of gasoline, it also acts as a thermal management. In essence, less fuel equals more heat and that also contributes to preignition. But too much fuel and it too has adverse effects on the engine.
Sorry, for the long explanation, but it's important to understand these principles when discussing tuning and fuel mapping. As pertaining to race vs stock tunes. The simple answer is the tuning was done to meet EPA regs on a stock bike and that is why most people have problems with heat, especially after exhaust/intake upgrades. The race map was tuned to perform in a certain range with the race exhaust it was tuned for. The race tune actually has less aggressive timing in some areas and more aggressive timing in others, and the fuel maps will show that also. Typically the more advanced you run the ignition, the more fuel it requires to obtain the desired AFR. Does any of this makes sense?...
Awesome Melvster. Pretty much exactly what i was looking for. I appreciate the detailed write up.
So how do i gauge AFR using ECMSpy? Do I have to datalog to capture that?
spy wont give you afr
youll need a wideband o2 sensor
I would assume then you need a wideband 02 sensor to properly tune then?
Is the assumption on the race map that it is optimized AFR across the powerband for max power?
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