Today I am spending the day on the stand testing some db2 ideas I’ve had, and wanted to share what I have going on. Today’s pump is a late model db2 case with a torque screw, no leaf spring, locked advance set at 6*, no transfer pump blades or regulator, and a 4500 governor spring.
I am experimenting with running no transfer pump so that I can externally control the transfer pressure to be able to dial fuel back without adjusting the ip itself, and to build a stronger pump that can handle more ccs and rpm. Once we start pushing these db2s to their limit we run the risk of transfer pressure spikes with the internal pump and regulator, which is what will seize a head and rotor in the case and grenade a pump. By externally supplying the transfer pressure we can more steadily control the transfer pressure to alleviate the spiking issue. I will update as we play with this pump more throughout the day, and possibly start another thread dedicated to the db4 we are running next, assuming all goes well with this pump.
First run we were just feeling things out, found that 65 psi inlet pressure produces the most fuel for 1500 rpms, with 110ccs there and over 20 psi housing pressure. We found the higher housing pressure to be limiting our fuel up top as the housing pressure pushes against the plungers not allowing them to travel out fully. We gutted the return and are gonna run it again, more to come.
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I am experimenting with running no transfer pump so that I can externally control the transfer pressure to be able to dial fuel back without adjusting the ip itself, and to build a stronger pump that can handle more ccs and rpm. Once we start pushing these db2s to their limit we run the risk of transfer pressure spikes with the internal pump and regulator, which is what will seize a head and rotor in the case and grenade a pump. By externally supplying the transfer pressure we can more steadily control the transfer pressure to alleviate the spiking issue. I will update as we play with this pump more throughout the day, and possibly start another thread dedicated to the db4 we are running next, assuming all goes well with this pump.
First run we were just feeling things out, found that 65 psi inlet pressure produces the most fuel for 1500 rpms, with 110ccs there and over 20 psi housing pressure. We found the higher housing pressure to be limiting our fuel up top as the housing pressure pushes against the plungers not allowing them to travel out fully. We gutted the return and are gonna run it again, more to come.