SpeedFactory Racing B-Series Mechanical Fuel Pump & Cam Trigger Combo Bracket

PUMP FLOW RATES

The larger pump in the drop down option menu is rated at 6.8gpm at 4000rpm (1850hp on methanol/3600hp on gasoline) by the manufacturer. This is PUMP rpm, not engine rpm. Since the pump is cam driven it spins at 1/2 engine speed. Flow rate increases with rpm - we've flow tested these pumps at 8.18gpm @ 145psi at 5000rpm (10,000 engine rpm) and spin them to 6000rpm (12,000 engine rpm) in our Outlaw car with zero issues. Flow rate at 6000rpm should be about 9.0-9.5gpm (2500+hp on methanol/4750+hp on gasoline) - all the fuel you will ever need!

95% of people DO NOT need this much fuel and we recommend the Waterman Sprint 500 fuel pump (Or Weldon 34704) pump as they are rated at 4.8gpm at 4000 pump rpm (1300hp on methanol/2500hp on gasoline) by the manufacturer. Flow rate on this pump at 10.5k rpm engine speed will be about 6gpm (1600+hp on methanol/3100+hp on gasoline) - plenty of fuel for most applications.

DO I NEED AN ELECTRIC LIFT PUMP?

On a race car with a 16V battery system the answer is NO! The pump will need to be primed before first use, and after that it will maintain prime. We have left the car sitting for months with the pump mounted above the fuel level and still had prime and instant fuel pressure. We have not used this on a 12V battery system but believe it will still have sufficient cranking rpm to build pressure and fire without a lift pump. TIP: Using an electric drill to prime the pump works great and eliminates prolonged cranking over of the engine to achieve prime.

USING A MECHANICAL PUMP AND METHANOL ON YOUR TURBO HONDA

Due to the massive volume of fuel flow required when running methanol, pumping losses and cavitation risk due to flow restrictions in the fuel lines, fittings, and filters needs to be given extra attention and these items need to be larger than the -8AN and -10AN lines that are typically used on a SFWD style turbo build that runs race gas or ethanol based fuels.

This is especially important on the inlet side of the pump. You must run at least a -12AN feed line and a large bodied pre-filter (we run a Weldon with 100 micron stainless steel element) to maximize filtering surface area without causing a restriction. If your fuel cell is not in the engine bay and has long feed lines to the pump (such as a rear mounted fuel cell), you will need an even larger feed line setup. Failure to do so will result in low and/or inconsistent fuel pressure issues and your setup will not be able to maintain a 1:1 rising rate ratio with manifold pressure.

The recommended Weldon and Waterman fuel pumps have -8AN inlet and outlet ports on them. We use a -12AN to -8AN adaptor fitting directly into the feed side of the pump body. If you notice that you still aren’t maintaining a 1:1 ratio, you may need to enlarge the ID of the fitting as much as possible and this will fix the issue.

Most of the common Honda fuel rails are only -8 or -10AN, if you choose to do this rather than run -12AN fuel rails and lines we will share our experience with that using a Waterman Sprint 700 Fuel Pump ( Or Weldon 34706 pump).

On the outlet (pressure) side of the pump to the fuel rails and regulator, you can run -10AN fuel lines and a -10AN in/out 10-12 micron post filter. In our experience this works fairly well but you will see a small amount of fuel pressure creep over the 1:1 ratio starting at 9400rpm and increasing with rpm if using a -10AN return line off the regulator back to the fuel cell. This is with the Waterman Sprint 700 / Weldon 34706 pump; if you use a Waterman Sprint 500 / Weldon 34704 pump you will be fine with -10AN lines.

That being said, the recommended Weldon A2047 regulator has -12AN inlets & outlet, and it is best to use -12AN line for return to the fuel cell to avoid fuel pressure climbing over a 1:1 ratio due to flow restriction on the return side. Again, if your fuel cell is located far away like at the rear of the car you may need an even larger return line.