Overclocked ECU

ECU overclocking to increase the engine rev limiter is a relatively new idea (to my knowledge) that was created (or at least made known) by TurboBob on 3SI.org. I'm not a computer or electronics expert, but based on what I've read, overclocking the ECU causes the computer to speed up the perception of time, thus interpreting the engine RPM signal more slowly, allowing the engine to go to a higher RPM before reaching the rev limiter.

I decided to have my ECU overclocked because the engine seems to make good power all the way to redline, and it seemed like there was more available at the top end.

The percent changes that were available for my car (1993) were 0%, 10.5%, and 15%. This correlates to rev limits of 7300 rpm, 8030 rpm, and 8400 rpm. All available crystal options are included when the modification is performed and they can be swapped. I chose to go with the 10.5% (8,030 rpm) for initial testing. If the car still appears to have more top end available, I may consider moving to the 15% overclock.

This change in perception in time also affects all other ECU inputs and outputs. Therefore, the signal being sent to the fuel injectors is modified by the same percentage as the rev limit. I compensated for this by increasing the settings on my S-AFC by 10% on all settings (high and low throttle, all rpms).

The following pictures show the sticker placed on the ECU case, the new crystal in the ECU (blue, rev limit of 8030 rpm), and the other crystals that were included (green, 7,300 rpm which is stock; and red, 8,400 rpm). The instructions are available here.

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