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Twin SU -> EFI conversion


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Hi everyone

I'm new to this forum but thought I should share this with you as with fuel prices going as they are (at least in our banana republic) it makes sense to squeeze every bit of economy out of a 3.5 V8 by converting from the twin SU setup to EFI.

Briefly, I used the EFI hw from a 3.9 Disco with a Megasquirt-2 ECU to do the conversion with. The ECU now also controls timing although "basic" timing is still being provided by the dissy. The ECU can add/substract timing from whatever advance is received from the dissy.

Before I did the conversion, I first measured air-fuel ratios of the carbs. The leanest I saw was 13.5 (that is seriously rich under partial throttle conditions) and under full throttle it would easily go below 11 (that is almost "liquid fuel" coming out the tail pipe - exagerating but that is over-the-top rich). Idle gave about 12.5 which is good for idle, so one can not argue that the carbs were way out of adjustment.

Its too early to comment on fuel consumption improvements but already it is clear that its not worse but there is a tangible amount of power increase at full and partial throttle.

You can read more here if interested : http://www.msruns.com/viewtopic.php?f=92&t=22645

post-9531-1211885334_thumb.jpg

Best regards

Philip

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