LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Batch Fire vs Semi Sequential vs Sequential

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Old 03-13-2012, 10:10 PM
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Default Batch Fire vs Semi Sequential vs Sequential

Ok so heres the low-down
I've been looking at a Megasquirt setup for my procharged LT1, and my main worry is with the batch fire setup it runs. Since it fires each bank alternating, what happens with the extra fuel in the cylinders that are not used? I assume it would remain near the runner, or would accumulate in the intake manifold and evenly distribute ?

Next, is running semi sequential (firing 2 opposing injectors rather than the whole bank) much more efficient, or less efficient than full sequential injection?

Someone, help me understand this please!
Old 03-13-2012, 11:20 PM
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I saw your posts on the happy time forum.

All you need for triggers is the 24x crank and 1x cam, like the EFI connections guys run to go full sequential on fuel and ignition. The benefits are in part throttle responsiveness, fuel efficiency and emissions output on full sequential.

The example with an F body is the 93. It runs in batch fire and makes just as much power as the following years sequential. Semi-sequential is not really any better than batch in my experience. If you are firing the injector against a closed intake valve, you are basically just pooling fuel for when it opens. With most setups, you are firing against a closed valve at WOT no matter what system you are running, since the intake valve open time isn't sufficient to get all of the fuel injected unless you use really way too big injectors.
Old 03-14-2012, 12:11 AM
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So you figure that the fuel pooling in the runner or intake isnt really an issue, as it will make it into the chamber one way or another? I supose you just adjust for fuel based on what firing method you are using?
Old 03-14-2012, 12:33 AM
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My 93 is batch fire and it runs fine.
Old 03-14-2012, 12:46 AM
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I mean i know it will run fine, im just wondering if there is any drawback to batch fire, or any improvement for sefi?
Old 03-14-2012, 01:49 AM
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the fuel does not puddle, it partially vaporizes when it hits the (hot!) backside of the intake valve.



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