Mazda SPEED6 Bedienungsanleitung PDF herunterladen (Seite 30)

01 ENGINE

Fuel Octane

The MZR 2.3L L3T engine has a high compression ratio for a turbocharged vehicle

of 9.5:1. Typically turbocharged engine compression ratios are in the range of 7.5:1

to 8.5:1. This engine also has high boost pressure from the turbocharger 15.6 psi.

Typical turbochargers boost from 5 to 12 psi . When you combine a high compression

ratio and high boost, the result is a higher compression engine, somewhere in the

range of 11:1. Higher compression engines require higher octane fuel.

Using lower than 91 octane fuel is not recommended. Lower octane fuel must be

injected and ignited earlier. Less timing advance results in lower power and more heat.

This engine should be run with 91 to 93 octane, 93 is ideal for its compression ratio.

There are several disadvantages to lower octane fuels, less power, more heat, lower

fuel economy, more carbon deposits. 89 octane should only be used in an emergency

if 91 octane is not available.

The engine management system is able to seemlessly modify the ignition timing and

fuel delivery for the entire range of fuel octane from 89 to 93 without detonation. It is

also designed to protect the engine from damage due to lower octane fuel. When low

octane fuel is used, the fuel delivery and ignition timing are retarded and power output

is reduced. Continued operation with low octane fuel can result in increased engine

intake air temperatures, when temperatures exceed safe levels, the PCM commands

the turbochargers waste gate regulator solenoid off at 4200 rpm. With the wastegate

regulator solenoid off, the wastegate opens earlier to reduce heat. A customer using

low octane fuel in hot climates may describe this as a loss of power over 4000 rpm.

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Mazda SPEED6 Bedienungsanleitung Seite 30