How much can the fuel pump handle?
Any idea how much power the pump can handle before it runs out of flow? I'm running 1000cc injectors and 17.5psi of boost. Is this thing gonna run out of capacity on the top end? Can I use a Boost A Pump on it despite the variable pressure? Or a bigger pump (which I would prefer to overdriving the stocker)? Does the OBD-2 have a PID that shows pump duty cycle? My DiabloSport Trinity does, but it never changes when I log it, so its either the wrong PID or the OBD-2 isn't reporting it.
Still looking for info on this.....
Tim, I'm not ignoring your PM. I tried to respond multiple times, but I keep getting the message "Tim@Lingenfelter has exceeded their stored private messages quota and cannot accept further messages until they clear some space."
Any further info?
2009-2013 Cadillac CTS-V Fuel Pump Flow Capabilites & Injector Size
Those are much bigger injectors than we use in any of the standard CTSV, ZL1 or ZR1 engine packages. A 1000 cc/min injector is a roughly 97 lbs/hr injector.
The stock twin pump system flows around 330 lph at 13.5 volts and 58 psi (400 kPa fuel pressure). At 14.8 volts it flows 390 lph. 330 lph is 5500 cc/min.
Eight (8) 1000 cc/min injectors could theoretically flow 8000 cc/min at 100% duty cycle or 7200 cc/min at 90% duty cycle if they were flowing into open atmosphere. We normally try to keep the duty cycles under 90%.
Assuming the 1000 cc/min injectors are flow rated at 43 psi (300 kPa fuel pressure), which is the common fuel pressure used when rating fuel injectors, then at 58 psi fuel pressure they flow 1154 cc/min.
If you are at 58 psi fuel pressure and 17.5 psi of boost then the differential pressure across the injector is actually 40.5 psi (58-17.5) so at that pressure the injectors flow 971 cc/min. For eight injectors at 100% duty cycle that would be 7760 cc/min and at 90% duty cycle that would be 6980 cc/min.
So you will have more fuel injector than what the pump can flow, so you will run out of fuel pump flow before you run out of injector.
What that means is that the fuel pressure should drop before you run out of injector duty cycle. As fuel pressure drops the fuel pump flow goes up (less load on the pump) so it might stabilize at a lower fuel pressure if he ends up using that much fuel.
On the other hand 330 lph fuel pump flow should be enough to support about 750-800 hp (at the crank). This doesn't account for voltage drop in the system to the fuel pump, hot fuel handling (mass flow drops as the fuel heats up), fuel flow lost to the transfer pump or pump to pump variation.
For this reason on our 700+ HP packages we voltage boost the fuel pump and fuel pump controller but we only do so to a fairly low voltage - just enough to make up for the voltage drop in the system and the other variables mentioned above. We normally voltage boost the CTSV twin pump system to 15 volts in these applications. You have to be careful about the added current load from doing so, especially on initial activation of the voltage boosting. Since you only need it in boost and at higher power levels we normally activate the voltage boosting only when in boost and above a certain RPM. That way the alternator is also at full output when the voltage boosting triggers.
Good info Tim, thanks.
Unfortunately, looks like I'm not gonna max out either one. Having neck surgery, so I have to sell the V and get a truck. Doing a partial demod, because I can't trust whoever buys it to keep tabs on what the motor is doing and make sure it doesn't blow up. Dropping the boost down to about 13psi and putting the stock injectors back in. :(