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Last week I learned that a lot of fuel pumps have a built-in bypass that limits a fuel pump to a maximum of 63psi no matter how much is commanded - basically 20psi of boost is the limit.
I reviewed some of my log files and sure enough I'm commanding 75psi of fuel pressure (32psi boost) but it's limited at 63psi in the log files...aarrgg.
The discussion then went into what pumps don't limit the output and what pumps should I get that can flow enough for 1200-1300 crank HP (1000 RWHP) and the 450lph pumps were brought up. There are three from TI Automotive (Walbro) but one is not made for boosted applications due to the 63psi limit while the other two can produce over 100psi of fuel pressure. Something else I learned from my dyno tuner (Chad) is that not all 450's have built-in check valves so they cannot be used with more than one pump otherwise the fuel can back-feed into the other pump thus loosing pressure/volume.
Chad told me that their "Hellcat" pump does have the internal check valve and that's what he uses for multiple pump setups.
I had ordered what I thought was the correct pumps for my application the 450 "high Pressure" (p/n F90000274) but Chad wasn't familiar with this p/n so he told me to get the Hellcat Pump (F90000285) b/c he knew this had the internal check valve so I also ordered these pumps. I tried calling TI Automotive to get the real answer from them but the phone number listed on their site was a dead number.
Yesterday I received both 450lph pumps from Summit: the 450 "high Pressure" (p/n F90000274) and the Hellcat Pump F90000285.
Looking down inside the pumps through the inlet tube the construction of both pumps look 100% identical. There "looks" to be a check ball type feature way down inside of both pumps but unless I dissect them I still can't be 100% sure enough in that is what I am seeing. Based on what some people have said the (p/n F90000274) does have a check valve. If they both have check valves in them I don't know what the difference in design is between these two pumps and why TI Automotive offers the same type of pump unless the internal motors are designed differently.
Side Note:
If anyone is using an On3 Triple Fuel Pump Hat made for their 320/340 pumps these 450lph pumps DO NOT work with their hat, the pumps are located too close to fit. I spent well over an hour fabricating/milling the locating plate that holds all three pumps in order to get the 450 pumps to fit side-by-side and I had to mill off the plate .40" to make it thinner. The same issue may happen with other brand pump hangers, so keep this in mind. The issue stems from the bottom portion of these 450 pumps are larger than the body of the pump and the pumps would hit each other and not fit down far enough and not fit into the machined hole in the hat. So do your research on pump hats before buying.
The car now has three 450lph Hellcat pumps so the fuel system should be ready for another dyno session in March.
ks
I reviewed some of my log files and sure enough I'm commanding 75psi of fuel pressure (32psi boost) but it's limited at 63psi in the log files...aarrgg.
The discussion then went into what pumps don't limit the output and what pumps should I get that can flow enough for 1200-1300 crank HP (1000 RWHP) and the 450lph pumps were brought up. There are three from TI Automotive (Walbro) but one is not made for boosted applications due to the 63psi limit while the other two can produce over 100psi of fuel pressure. Something else I learned from my dyno tuner (Chad) is that not all 450's have built-in check valves so they cannot be used with more than one pump otherwise the fuel can back-feed into the other pump thus loosing pressure/volume.
Chad told me that their "Hellcat" pump does have the internal check valve and that's what he uses for multiple pump setups.
I had ordered what I thought was the correct pumps for my application the 450 "high Pressure" (p/n F90000274) but Chad wasn't familiar with this p/n so he told me to get the Hellcat Pump (F90000285) b/c he knew this had the internal check valve so I also ordered these pumps. I tried calling TI Automotive to get the real answer from them but the phone number listed on their site was a dead number.
Yesterday I received both 450lph pumps from Summit: the 450 "high Pressure" (p/n F90000274) and the Hellcat Pump F90000285.
Looking down inside the pumps through the inlet tube the construction of both pumps look 100% identical. There "looks" to be a check ball type feature way down inside of both pumps but unless I dissect them I still can't be 100% sure enough in that is what I am seeing. Based on what some people have said the (p/n F90000274) does have a check valve. If they both have check valves in them I don't know what the difference in design is between these two pumps and why TI Automotive offers the same type of pump unless the internal motors are designed differently.
Side Note:
If anyone is using an On3 Triple Fuel Pump Hat made for their 320/340 pumps these 450lph pumps DO NOT work with their hat, the pumps are located too close to fit. I spent well over an hour fabricating/milling the locating plate that holds all three pumps in order to get the 450 pumps to fit side-by-side and I had to mill off the plate .40" to make it thinner. The same issue may happen with other brand pump hangers, so keep this in mind. The issue stems from the bottom portion of these 450 pumps are larger than the body of the pump and the pumps would hit each other and not fit down far enough and not fit into the machined hole in the hat. So do your research on pump hats before buying.
The car now has three 450lph Hellcat pumps so the fuel system should be ready for another dyno session in March.
ks
