Q1. Is the Hobbs pressure switch included with the DP system?
A1. A 15PSI Hobbs pressure switch and interface harness are included with the system as standard equipment. 15PSI is the best pressure at which to activate the secondary fuel pump in most Turbo Buicks. Ideally the secondary pump should be activated approximately 100HP shy of the primary pump running out of fuel to prevent pressure spikes or lean conditions. Some customers have computers which can control both pumps via the jumpers (shown in our picture) on our dual harness. Some customers have upgraded return lines and chose to run both pumps all the time. We recommend using either your computer or our Hobbs switch to control the secondary pump. This reduces the electrical load, fuel heating and wear on the secondary pump. The primary and secondary pump may be easily switched by swapping the control jumpers if you wish to balance out the run-time on the pumps. The DP harness comes with both control jumpers plugged in as shown in our ad. In addition to this the DP harness comes with a Weather-Pack connector so you can interface the secondary pump control to your aftermarket computer or any pull-to-ground signal. Q2. Can other pumps be used in the DP sender as an option?
A2. We offer the RXP255 255LPH and RXP340M 340LPH pumps in our DP systems. Only pumps with a 22mm center inlet will fit our hangers and will fit through the tank opening side-by-side. It is a VERY tight fit. NOTE: WE DO NOT ACCEPT CUSTOMER-SUPPLIED PUMPS TO BE INCORPORATED INTO OUR DP SYSTEM. Q3. Is the DP system E85 compatible?
A3. True E85 certified systems have their electrical connections fully isolated from the fuel and the internal pump components that come in contact with the fuel are made of special plastics and nickel. Current production hangers use Racetronix RXP pumps which have E85 handling capability. E85 is like a sponge for moisture and since the Buick fuel system was never designed for E85, pump life expectancy will vary from vehicle to vehicle. Fuel system condition and vehicle location are the two key factors impacting this. Q4. I have your D-I-Y DP kit on a factory sender and I would like to upgrade / replace the sender. Can I buy the sender with the required parts?
A4. We no longer offer piece parts for DIY applications anymore. Q5. Can the single Racetronix Hotwire Harness be used to power the new DP system?
A5. No it cannot. The harness for the DP system is very different in almost all aspects. Q6. Can I buy the entire DP system in a D-I-Y format?
A6. We no longer offer the DP G7 D-I-Y kit. Q7. I already have some other pumps. Can I use them with your system?
A7. NOTE: DUE TO PROBLEMS WITH CUSTOMER SUPPLIED PUMPS AND PRODUCTION FLOW ISSUES WE ARE NO LONGER ACCEPTING CUSTOMER-SUPPLIED PUMPS TO BE INCORPORATED INTO OUR DP SYSTEM NOR DO WE OFFER IT LESS PUMPS. ALL DP SYSTEMS ARE SOLD AS COMPLETE TESTED SYSTEMS. Q8. I have heard some bad things about Walbro pumps on this forum. Are there other options?
A8. This is old news. The pump in question was the F20000169. Racetronix never sold this with any of our Buick-specific kits. Racetronix has always bundled the GSS340M and GSS294M pumps with our kits so our customers did not have the multitude of problems people had to deal with YEARS ago. Racetronix is currently bundling RXP340M pumps the with its 680LPH dual systems. These pumps have improved flow, reduced noise and enhanced E85 handling. Q9. I have a digital dash car. Do you have a sender for me?
A9. Yes, please specify the digital dash level sender option when ordering your system. Q10. What size of fuel lines do you recommend with this system?
A10. We recommend conductive Teflon braided -8 feed and a -6 return line. We do not recommend any type of rubber (braided or not) for use with modern-day fuels. These Teflon lines will be more than able to support the full performance of our DP systems. Please view our G7 PnP fuel line kits by clicking > HERE < Q11. Where is the biggest restriction in the fuel system?
A11. The factory steel lines running up the front of the motor. Q12. Is the factory filter able to flow enough for the DP 680LPH system.
A12. A clean factory filter is adequate for two 340LPH pumps however minor contamination at this flow level will have a great impact on performance. We do not recommend most aftermarket cartridge paper filters or SS mesh filters. The idea here is to protect the motor, limit restriction and provide reasonable service life. We offer a fuel line kits with E85 compatible filter assemblies> HERE <. Q13. Can I use a volt-booster with your system?
A13. Yes, we recommend a voltage booster for increased system voltage which benefits pump performance. Q14. What brand of fuel pressure regulator do you recommend?
A14. Accufab (factory location / best option) or Weldon / Accel aftermarket fuel rail configurations. Q15. Where do I get support and installation information?
A15. All technical and warranty support is now provided by your Racetronix dealer ONLY! Q16. Do you offer a -10 / -8 outlet version of this sender?
A16. We do not offer a -10 / -8 outlet version. The -8 / -6 version is more than large enough to support the fuel volume two pumps provide. You can see the outlet comparisons click > HERE < for a comparison.
The outlet tubes will not easily accept larger fittings. If your motor 7-second race motor really needs -10 / -8 lines to support the HP it produces then perhaps a dedicated external fuel system is worth considering. We offer in-line Weldon gear and Walbro screw pumps in our web store. Q-SPEC. What are the performance specs of the DP system?
A-SPEC. These are the typical specs with 2 x 340LPH pumps:
680LPH @ 43.5psi @ 13.5v @ 22.5A
820LPH @ 43.5psi @ 16.0v @ 27.5A
635LPH @ 58.0psi @ 13.5v @ 24.5A
790LPH @ 58.0psi @ 16.0v @ 29.5A
550LPH @ 80.0psi @ 13.5v @ 28.0A
710LPH @ 80.0psi @ 16.0v @ 32.5A Q17. How much HP will this system support in a Turbo Buick? (Will it support my HP requirements?)
A17. Multiply your HP by 0.42 which will give you the required fuel in LPH with a 20% safety margin. You must consider the flow at your maximum boost pressure. For example, if you base fuel pressure is 43.5PSI and your your regulator increases 1LB of fuel pressure for every 1LB of boost and you run 20PSI of boost your maximum fuel pressure would be 63.5PSI. Using the flow data above, confirm that the DP system is able to provide the required flow at your maximum fuel pressure and voltage. This calculation does not factor restrictions in the fuel lines. Since the condition of each system tends to vary it is best to run a return flow test at max fuel pressure once the DP is installed to determine if upgrading the fuel lines is required. Note that some Racetronix customers have run mid 8-second 1/4 mile times at 160MPH+ using our 680LPH dual system, deluxe Teflon line kit on race gas.
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