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  #1  
Old 05-02-2011, 08:37 AM
cropdusterdave cropdusterdave is offline
 
Join Date: Mar 2005
Location: Fargo, ND
Posts: 146
Default Better boost pump location?

I'm trying to rig my carbeurated setup to better deal with vapor lock issues. If I were building an injected setup...I know that the pumps in the wing roots would be the way to go. But how about for a boost pump? The location on the drawing has a very sharp 90 bend right at the firewall that I'm not at all excited about. I'm thinking about mounting the pump on the floor aft of the firewall and running teflon braided fuel lines everywhere to eliminate sharp bends. My other idea is to mound a pump at each wing root and run two switches (less desirable to me...but eliminates most of the suction)

Any suggestions?
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  #2  
Old 05-02-2011, 08:54 AM
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rv9av8tr rv9av8tr is offline
 
Join Date: Dec 2006
Location: Portland, OR
Posts: 827
Default Why mess with success...

Van's fuel system is simple and straight forward. Changing a known and established fuel system is a common way to create unforeseen problems.
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  #3  
Old 05-02-2011, 09:17 AM
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Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,668
Default

Vapor Lock in Fargo, ND, does it even get above freezing there??

Van's fuel system is a proven design, so why not go with it.

To deal with the heat here in TX (especially when doing a "quick turnaround") I added a "Purge" system. It basically consisted of a 'T' at the carb inlet fitting (all steel fittings) with a return line back to the fuel tank, it was controlled by an electric primer valve.

When I switched to AFP FI I installed their purge valve.

Both systems worked great and give you the ability to flush the fuel system with cool fuel prior to start.
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  #4  
Old 05-02-2011, 11:21 AM
cropdusterdave cropdusterdave is offline
 
Join Date: Mar 2005
Location: Fargo, ND
Posts: 146
Default

Well I'm giving consideration to using mogas and auto gas. Generally it Is a 1good idea to eliminate sharp radius bends in the fuel line and make the BP function the way it was meant to by pushing the fuel as opposed to sucking it uphill. That pump can suck on an air bubble against gravity all day long and accomplish nothing. A pump located at the low point near the fuel source will always be able to push cool gas to the mech pump. At least that's the. Way i see it. A lot of FI guys are preaching this....I want to see what the equivalent is for us carbd guys
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Last edited by cropdusterdave : 05-02-2011 at 11:42 AM.
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  #5  
Old 05-02-2011, 12:43 PM
RV8R999 RV8R999 is offline
 
Join Date: Dec 2008
Location: na
Posts: 1,457
Default

suction fuel systems are far more survivable post mishap than pressure systems. After a crash and fuel system rupture occurs the suction system sucks air while the pressure system sprays fuel all over the place.
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