Disclaimer:
First and foremost let me iterate what I belive is the current and most accurate advice of Mark Basch: Leave the tuning to him. A/F tuning (changing the ss fuel maps on a BBSC) can very easily result in a blown motor. I am not advocating that anyone do this on their own. However, if you do want to know methods on how to do it correctly - you may have some benefit of my own experiences.
I have cut and paste here from what I have written in the general discussion board. First, you should know that tuning for a/f requires special tools. Trying to tune using stock O2 sensors is TOTALLY useless... there is virtually nothing you will discern from a stock O2 sensor. You see a lot of these gauges and such for a/f and it is likely the biggest scam going. How a stock O2 sensors works is the following: when a/f is below 14.7:1 there is one voltage and when above 14.7:1 there is a higher voltage. Your stock ECU, similar to ECUs in other cars, simply uses the stock O2 to "hunt in" on the desired (ideal) a/f which is 14.7:1. In other words, there is really no way, for example, that these O2's can tell the difference between 10.0:1 and 14.0:1.
If you are trying to use the stock O2 for tuning forced induction motor, you likely want to target an ideal (under bosst) a/f of 12.5:1. If you are running under 11:1 you're too rich and if you get North of 13:1 you may be in trouble. The stock O2 or even the available aftermarket gauges CANNOT discern the difference. An a/f of 12.5:1 (under boost) is generally recognized as an ideal value for providing optimum power while being justa tad rich. A/F values over 13.5:1 are too lean and can cause detonation and ultimately holes in your pistons. A/F values between 11.0:1 and 12.0:1 are not bad but are on the rich side and will not provide you the optimum power. If you could achieve a flat line on 12.5:1... you, IMO, would have an ideal set-up. If you have known boost pressure (6psi in the current BBSC config) and you can achieve 12.5:1... then HP is just a by-product.
OK, so how do you do the tuning short of spending hours of time at a dyno... complicated by the necessity of doing a lot of analysis, planning and checking between runs as you modify fuel tables.
The good news (sort of) is that there is a solution. In fact it is a very good one, albeit expensive. I am using it now to tune my BBSC. The kit consists of a 5-wire O2 sensor and a black-box brain/controller. Once installed, it will let you display instantaneous a/f ratios (accurate to 1/100) and, more importantly, it will let you datalog for virtually any period of time. You can then playback the datalog or, using the supplied software, you can generate a/f graphs. There is a provision for a RPM-in (mandatory) and an auxilary in (0-5v) for a Map-in voltage, for example.
All values are datalogged.
My testing has consisted of modifying the fuel maps and then doing 4 or 5 2000-6000 full-throttle acceleration runs. (6K-8k can be tuned in after you get the hang of it.) I use 3rd gear and will use 4th gear for final tuning. It is almost essential to have a passenger with you. Have the passenger watch instantaneous a/f to make sure no values over 13:1... while datalogging the whole sequence. Next, return home and view the graphs. Make changes to the table and repeat the process.
If you are careful and methodical, I believe that this method with the right tools is the BEST way to tune a forced induction car like the BBSC. In my mind, many advantages over the Dyno.
I have made some pretty significant improvements to the tables in my car - but one size doesn't fit all - hence the need of MB to individually tune cars... or leave you with something known to be comfortable... i.e., conservative.
If there's enough interest from Forum members to go down the path I have gone, I'd certainly like to help. For example, the pre-requisite to a/f tuning is either a lot of dyno time, lesser dyno time with MB present with his experience, or purchasing the system I have and having the capability to tune without a dyno. (Another significant advantage to what I am doing is looking at 1-2 and 2-3 full throttle shifts and analayzing a/f ratios.) It's all in the details.
Chime in if you're interested. This is not limited to BBSC as it applies to all forced induction situations. This set of tools will give you very accurate data collection and analysis and the difference will be what tools you have available to modify the a/f numbers. For BBSC, this is the ss box. For Comptech this is the fuel pump voltage inverter and FMU, for many other FI cars this is only an FMU or potentially other sophisticated electronic boxes.
First and foremost let me iterate what I belive is the current and most accurate advice of Mark Basch: Leave the tuning to him. A/F tuning (changing the ss fuel maps on a BBSC) can very easily result in a blown motor. I am not advocating that anyone do this on their own. However, if you do want to know methods on how to do it correctly - you may have some benefit of my own experiences.
I have cut and paste here from what I have written in the general discussion board. First, you should know that tuning for a/f requires special tools. Trying to tune using stock O2 sensors is TOTALLY useless... there is virtually nothing you will discern from a stock O2 sensor. You see a lot of these gauges and such for a/f and it is likely the biggest scam going. How a stock O2 sensors works is the following: when a/f is below 14.7:1 there is one voltage and when above 14.7:1 there is a higher voltage. Your stock ECU, similar to ECUs in other cars, simply uses the stock O2 to "hunt in" on the desired (ideal) a/f which is 14.7:1. In other words, there is really no way, for example, that these O2's can tell the difference between 10.0:1 and 14.0:1.
If you are trying to use the stock O2 for tuning forced induction motor, you likely want to target an ideal (under bosst) a/f of 12.5:1. If you are running under 11:1 you're too rich and if you get North of 13:1 you may be in trouble. The stock O2 or even the available aftermarket gauges CANNOT discern the difference. An a/f of 12.5:1 (under boost) is generally recognized as an ideal value for providing optimum power while being justa tad rich. A/F values over 13.5:1 are too lean and can cause detonation and ultimately holes in your pistons. A/F values between 11.0:1 and 12.0:1 are not bad but are on the rich side and will not provide you the optimum power. If you could achieve a flat line on 12.5:1... you, IMO, would have an ideal set-up. If you have known boost pressure (6psi in the current BBSC config) and you can achieve 12.5:1... then HP is just a by-product.
OK, so how do you do the tuning short of spending hours of time at a dyno... complicated by the necessity of doing a lot of analysis, planning and checking between runs as you modify fuel tables.
The good news (sort of) is that there is a solution. In fact it is a very good one, albeit expensive. I am using it now to tune my BBSC. The kit consists of a 5-wire O2 sensor and a black-box brain/controller. Once installed, it will let you display instantaneous a/f ratios (accurate to 1/100) and, more importantly, it will let you datalog for virtually any period of time. You can then playback the datalog or, using the supplied software, you can generate a/f graphs. There is a provision for a RPM-in (mandatory) and an auxilary in (0-5v) for a Map-in voltage, for example.
All values are datalogged.
My testing has consisted of modifying the fuel maps and then doing 4 or 5 2000-6000 full-throttle acceleration runs. (6K-8k can be tuned in after you get the hang of it.) I use 3rd gear and will use 4th gear for final tuning. It is almost essential to have a passenger with you. Have the passenger watch instantaneous a/f to make sure no values over 13:1... while datalogging the whole sequence. Next, return home and view the graphs. Make changes to the table and repeat the process.
If you are careful and methodical, I believe that this method with the right tools is the BEST way to tune a forced induction car like the BBSC. In my mind, many advantages over the Dyno.
I have made some pretty significant improvements to the tables in my car - but one size doesn't fit all - hence the need of MB to individually tune cars... or leave you with something known to be comfortable... i.e., conservative.
If there's enough interest from Forum members to go down the path I have gone, I'd certainly like to help. For example, the pre-requisite to a/f tuning is either a lot of dyno time, lesser dyno time with MB present with his experience, or purchasing the system I have and having the capability to tune without a dyno. (Another significant advantage to what I am doing is looking at 1-2 and 2-3 full throttle shifts and analayzing a/f ratios.) It's all in the details.
Chime in if you're interested. This is not limited to BBSC as it applies to all forced induction situations. This set of tools will give you very accurate data collection and analysis and the difference will be what tools you have available to modify the a/f numbers. For BBSC, this is the ss box. For Comptech this is the fuel pump voltage inverter and FMU, for many other FI cars this is only an FMU or potentially other sophisticated electronic boxes.