STG 3 Bar Ultimate Display chip with readout.
Update - technical information

 What’s a 3 bar chip and why is it better than a 2 bar chip?

  To answer this question you must understand the ECM (your engine’s computer). Late model GM vehicles use one of 2 methods to determine the engine’s fueling needs: mass air flow or speed density. Mass air flow uses a sensor that actually measures the amount of air going into the engine, and from other data (engine speed, throttle position etc) can calculate the exact fueling needs. Speed density measures the manifold pressure, and its changes (along with engine speed and other related data) to meter fueling needs. On a naturally aspirated car (non supercharger/turbocharger) a 1 bar map sensor is needed, as the engine only operates in vacuum. The 1 bar map sensor can read from about 14.7psi vacuum (or negative pressure) to atmospheric pressure (0 psi). A 2 bar map sensor can read from 14.7psi vacuum to 14.7psi positive pressure (one bar vacuum, one bar pressure greater than atmospheric). In the same respect, a 3 bar map sensor reads from 14.7psi vacuum to 29.4psi positive pressure (one bar vacuum, two bar of boost pressure).

What are the disadvantages and advantages of each?

  A mass air flow system can take into account different modifications (cam/heads etc) that are done to increase power, as the sensor can ‘see’ the additional air going into the engine and will add fuel as necessary. This is as long as the sensor is not maxed out, as mass air flow sensors have a limit to their readings. The speed density system is not as forgiving in its calibrations, as the calibration is usually set for a stock system. When major changes are performed on the engine, the computer reads the same manifold pressure levels as a stock engine, and the same amount of fuel is delivered, when more or less is really needed. So in this respect, a mass air flow system is better. It also does not use a restrictive sensor to meter air, as the mass air flow systems do. As I mentioned before, however, the mass air flow systems can be maxed out, so in a higher performance system, the speed density is the winner (and this is the main reason speed density is used on aftermarket ECM systems). In the syty application, however, this benefit did not exist.....

What does all this have to do with Syclones/Typhoons?

  The SyTy’s use a speed density system, BUT the stock setup uses a 2 bar map sensor. So the ECM can only read up to 14.7psi of boost. So if the boost is raised above this amount, the ECM will not know the actual pressure, as the sensor is maxed out. Anything over 14.7psi would be read as 14.7psi by the computer. So fueling cannot be changed at higher boost, timing cannot be altered at higher boost levels, and boost control will not function efficiently (as the SyTy’s ECM controls boost also). So basically, for a person on a budget who wants a bit more performance out of their truck, it was a risky venture, as fueling wasn’t being compensated as the boost was turned up, timing would not be changed at higher boost levels, and the factory boost control was not operating as well as it could, all very dangerous situations, especially on vehicles so prone to detonate.

  What’s the solution?

  A chip calibrated for a 3 bar map sensor, to take advantage of the extended range of that sensor.


  FUELING  A 3 bar chip now has the potential to add fueling at boost levels greater than 14.7psi. However, the stock setup is limited as the stock injectors are nearly maxed out (100% duty cycle). On the STG 3 bar chip,. the fueling is slightly leaner than stock, so a higher base fuel pressure can be run to deliver a bit more fuel at higher boost levels.

  TIMING  The timing can be modified on a 3 bar chip at higher boost levels, for either safety or performance. On the STG Display chip, there are 3 levels of timing, for different performance levels (to be used with higher octane gas also). The levels are designated T1,T2,T3 (T3 most aggressive timing, T1 mild timing, stock like). Also, on each program, the timing is MUCH lower above the set boost level, in case of a boost spike or creep, the timing will drop significantly, hopefully enough that no damage would have been done.

  BOOST CONTROL The boost control on the 3 bar chips has the potential to control boost up to 30psi, BUT the stock wastegate is very undersized. If the stock wastegate is ported or if an upgraded integral is used on a larger turbo, boost control will be solid, with fine adjustments possible on the multi chip. So with this chip, there is no need for an aftermarket boost controller. No boost controller will work well with an improperly sized wastegate.

  Special Features in the STG 3 bar chips:

  Performance Features:

  Additional Ultimate Chip Features:


  The program selection will be displayed on the Ultimate Display chip, showing what timing level (T1,T2,T3), and what boost level (in PSI).

  As was mentioned above, speed density ECM’s usually need chip updates/reprogramming for every little modification. Our programs seem to work well on trucks with mild modifications (intercooler modifications, turbo upgrades). Trucks with wild modifications (high lift cams/ported heads/significantly larger turbos) will not run as well as a lightly modded truck using these programs. In the future, I hope we can offer programs for trucks with serious upgrades, and perhaps design some buildup plans that can utilize our programs, as the alternative (aftermarket ECM) is the only real solution right now, and is an expensive one.

From: Todd.A.Austinson (

  Brian Green and I are finally ready to make the STG 3 bar multichips available. The chip will be available in two forms, unless you have purchased a 2 bar chip previously, then you have a third option which will be described below.

  The first option is simply called the STG 3 Bar Multichip. It has 4 programs that can be selected with a small pushwheel microswitch, similar to the Todd A. 4-1 2 bar chip. This unit's first program is a reduced power program, with all stock limits in tact, reduced timing, and no intercooler pump operation. This could be thought of as a "valet" setting.

  The second is a "street" program designed for 93 octane fuel, and will run 16 psi of boost if ecm boost control is used. The third is a "street/strip" program, running 18 psi of ecm controlled boost, and requiring greater than 93 octane. The fourth is a "strip" program runs 20 psi of ecm controlled boost, disables EGR function, and also requiring greater than 93 octane. The actual octane requirements will vary from truck to truck, and it is best to use a scan tool to determine safe levels.

  As a rough rule of thumb, the "street/strip" should have at least 95 octane, and the "strip" 104 octane. All three performance programs will turn the intercooler pump on at a 60 degree engine coolant temperature, 5400 rpm limit, and no mph limit. Only the "valet" and "street" settings have programmed boost limits, both occurring at 18 psi. This allows the user to use an external boost controller without hitting any pre-programmed limits while operating the #3-4 settings. Price for this chip will be $200.

  The second option is the most interesting. It is unofficially called the STG Ultimate Chip for now and is actually a timing/boost controller in one chip. It has a digital display/control unit that will indicate the selected timing and boost level, as well as a key operated lock-out to prevent setting changes when the key is removed. A pushbutton is used to select the programs when the unit is enabled by the key switch. There are 3 levels of timing and 6 levels of boost, from 16 -24 psi, that can be selected. In addition there is a valet and security setting which is nearly impossible to defeat due to the lock-out function of the display/control unit. There is really no way to defeat the lock out by any means other than breaking open the display/controller and re-wiring the internal circuits, requiring a good working knowledge of the system. Simply cutting the cable and getting "lucky" by shorting the correct wires together will only result in blowing the ECM B fuse, disabling the truck even further. In other words, it's a pretty good security system, minus a blaring alarm. Similar precautions will be needed as expressed above in determining safe octane levels for use with this chip. The high timing level can be run with 24 psi of boost, necessitating 107+ octane. I want to add that the higher boost settings (20+) might not be very usable with stock turbos due to their limited capacities. The 12.17 @ 112.1 that I ran last fall with my Typhoon was accomplished using the high timing program level with 22 psi of boost. I have been running a prototype version of this chip since last October. The high level timing selections also have the EGR disabled. Price for this chip will be $350.

  The last option applies to those who already have one of the 2 bar multichips. These can be upgraded to a 3 bar chip by several methods. The first is to simply send the original back to me for reprogramming. You will get your chip returned with 4, 8, or 10 3 bar programs loaded, depending on what type of chip you have. The cost for this will be $50 for the new programs. The 4-1's will have the same programs as described for the STG Multichip. The 8-1's will get security, valet, 16 psi and 17 psi street, 18 and 20 psi street/strip, and 18 and 20 psi strip settings. The 10-1's will get an 18 psi street and 22 psi strip in addition to the 8-1 programs listed. The other option is to upgrade to the "Ultimate Chip" by returning your original to me plus $150.

  All these new 3 bar chips will be easily upgradable due to hardware changes if and when software improvements are made. We will keep this cost at minimum to the 3 bar users. We are shooting for something in the ballpark of $25 for these upgrades.

  The STG Multichip is avalable now and can be ordered through Brian Green. The "Ultimate" will be available in about 3-4 weeks, but if you want one of these I'd like you to contact Brian (or me if this will be an upgrade) now so that he can relay to me how many I need to make. I'm sure Brian will have something to add to this so stay tuned.

Todd Austinson
'92 Ty #1548
12.17 @ 112.1

From: Brian Green

  To upgrade to a 3 bar chip, we will need a 3 bar map sensor right?

  Yes. GM/ AC Delco part number 1604-0749 - sensor assembly.

  All these new 3 bar chips will be easily upgradable due to hardware changes if and when software improvements are made. We will keep this cost at minimum to the 3 bar users. We are shooting for something in the ballpark of $25 for these upgrades.

  If you have questions, concerns, or want to order one of the chips, email me with "STG 3 bar chips" in the subject.

  For those of you interested in the display, I don't have much information on it yet, as Todd is still working on it and changing it. When we have it ready, we'll probably have a webpage with pics and description of it.

Brian Green
syclone 160
STG Racing

From: Todd.A.Austinson (

  Some things I inadvertently omitted while writing the initial message. That's what you get when you try to write a lengthy note while holding 2-3 instant message conversations.

  First of all, it has been pointed out that I should have mentioned that a GM 3 bar MAP sensor is needed (replacing the stock 2 bar) to run these chips.

  The display/control unit will be shown shortly on a web site, but this hasn't been completed yet. The display will indicate which particular program is being executed, e.g., security, valet, timing, and boost level. As you toggle through the selections the display will update. The best way I can describe the size and appearance of the display/controller is that it will look like a G-tech performance meter or small radar detector.