Tuning Tip: Methanol Issues

[Rich Z]

Tuning Tip: Methanol Issues

When tuning a methanol engine, make sure the engine is warmed up before you switch on the wideband system. (The short operation without heater power will not damage the sensor.) Here's the reason:

Many methanol engines run very rich, not only because of the low stoich AFR of methanol (6.4), but also because methanol has a very high latent heat value compared to gasoline. On a cold engine only part of the inducted or injected methanol even vaporizes and takes part in the combustion. The rest runs out of the exh. ports still in liquid droplet form. This can be seen on the exhaust ports that show traces of liquid methanol running out. This liquid methanol can kill the sensor by heat shock (high latent heat, as said), just as water can.

In addition the EGTs of methanol are typically much lower than on a gasoline engine, while the exhaust gas volume is higher. This causes the sensor heater to not be able to keep the sensor at operating temperature and it will error out. Even higher supply voltage will not help because the sensor heater has a limit to how much wattage can be supplied to it. After all, these sensors are designed for production cars with much lower power than a methanol fueled dragster. Using a double height bung so the sensor is out of the direct exhaust stream will help the sensor heater to keep the sensor in its operating temperature range.

-Innovate Motorsports

Source: http://www.innovatemotorsports.com/resources/news15.php