ATACC - Auto Temp & Altitude Carb Compensator

Take almost any carbureted sled and install the contents of this box. When you’re done, the system will compensate for temperature and altitude changes. Automatically.

The system is called ATACC, for Automatic Temperature and Altitude Carburetor Compensator. This compensator automatically adjusts your carburetor jetting through a wide range of temperature and elevation changes; from -40F to +50F and elevation changes of over 10,000 feet. It makes carburetion perform more like fuel injection in that it automatically adjusts the fuel flow for changes in atmospheric conditions (temperature and altitude changes), thereby improving performance while reducing fuel consumption and emissions.

The new ATACC decreases the fuel flow by applying a regulated vacuum to the carb float bowls. It uses the same (patented) temperature compensation technology used in the Holtzman Tempa Flow, but the ATACC replaces the manual altitude adjustment (of the Tempa Flow) with an automatic altitude adjustment; a diaphragm and patent pending control chamber (sealed gas chamber) perform this function. The unique design of the control chamber allows the ATACC to easily be set up to work with any minimum altitude, or “baseline” calibration. In other words, the ATACC’s construction allows it to work with sea level jetting, or if a rider has a minimum altitude of 5000 feet, the carbs can be jetted for 5000 feet and the ATACC will work with that jetting also.

When you open up the little white box the ATACC looks like some fittings, some tubing, an air filter and a diaphragm. You’ll also find detailed instructions. The instruction sheets may look a bit intimidating at first glance; just take time to read them completely and it should all make sense. You’re basically re-routing your carb vent lines to a device that changes the pressure in the float bowls, thus the jetting compensation. Just slow down and figure out where you’re going to be making the connections before you start tearing things apart.

Installation requires about an hour and is similar to the Tempa Flow and Vari Flow products (which in most cases can be easily replaced by the ATACC). Typically both units (the compensator and control chamber) are installed inside the air box, being mounted to the air box wall. There is a vacuum source required which on most late model sleds - with flat slide carbs, a small fitting installed in one of the slide cover plates. After that there are just tube connections to make. On a Polaris EDGE, for instance, an experienced installer can complete the installation in about 20 minutes.

This kit is ideal for most every bone-stock machine. You jet your sled for the coldest temps and lowest elevation you ride at, which is what stock jetting is on many machines. Most installations will jet their sled for –20 or –40 and the lowest elevation they ride at. The ATACC does the rest.

Field testing of the ATACC was performed by several competent tuners during this past season. Dale Fett of Fett Brothers Performance tested the ATACC in Idaho to elevations of 9600 feet and temperatures as high as +40F on a 2001 Arctic Cat ZR 800. The sled was jetted one size leaner than stock with needles in the stock position – basically set for Minnesota riding at low elevation. Dale reported that the sled ran as well if not better than the same sled when it was jetted for 8000 feet but did not have the ATACC.

Rick Sorken of Snowwest Distributing, Inc. (Edmonton, Alberta) was also very helpful in arranging testing of the ATACC on several sleds. It was tested on a 2002 800 Polaris, a 2002 800 Cat, a 900 Cat, and a 700 Mountain Max with a Union Bay 944 big bore kit. All testers either were dealers or owned performance shops. These sleds were run at elevations from 2000 feet to as high as 9000 feet with no jetting changes. The 800 Polaris and the 800 Cat with the ATACC were run simultaneously against identical sleds jetted for an intermediate altitude but without ATACC. These tests indicated improved performance with the ATACC and significantly better fuel economy. The Mountain Max tester was running a Race Pak Pro Tune and reported consistent EGT readings from 2000 feet to 8000 feet.

Snowmobilers aren’t the only ones who benefit from this technology. Brothers Gary and Greg Trachy installed ATACC systems into their two-stroke dirt bikes and took first and second place in the coveted Pike’s Peak International Hill Climb. Gary used an ATACC in his modified Honda CR250 fitted with a PSI Big Air carb, and brother Greg mounted his ATACC to a modified Honda CR500, also using a PSI Big Air carb. The race was run from 9,000 to 14,000 feet, and the addition of ATACC was said to provide spot-on performance for the duration of the race. According to Gary, “The bikes ran well at all altitudes and never missed a lick”.

A limited number of these kits will be available this season for $210. Both of these field testers were so impressed with the performance of the ATACC that they’ve added the ATACC to their own catalogs, stocking them and are recommending them to their customers. The demand for this product is expected to be huge. In the U.S. contact Holtzman Engineering (715-479-8727) or Fett Brothers Performance (218-334-3388). In Canada contact Snowwest Distributing, Inc. (780-436-8888).