View single post by Chris E
 Posted: 01-28-2009 06:43 am
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Chris E


Joined: 11-23-2006
Location: Fremont, California USA
Posts: 12
 I originally had plans to build a couple of sidedraft throttle bodies which would look cool & bolt right on, However after looking into it a little more there are a couple of issues that are hard to get around. As Joachim mentioned the speed/density changes will make it difficult to get a consistant mixture with a constant stream of fuel. But it gets worse than that. GM TBI works with pulse width modulation with one pulse every OTHER ignition event. Therefore it is possible for most of the fuel to go to #2 while #1 gets almost none. see pic. For it to work, the injectors would need to be timed to the intake events. 

 I believe that for a TBI to work correctly on a 4 cylinder both injectors need to fire into a single plenum. (this is what they're designed to do) otherwise we need to go to a port injection system. This is what prompted my quick & dirty design.

 That's my opinion anyway. I'll post further as my experiment gets further along.



Attachment: TBI Timing.jpg (Downloaded 53 times)