Fuel Pump speed control
Discussion
Just waiting for a couple of components to land from the suppliers, then i will start testing for the best control strategy!
Found a few minor errors on the brds (both me labeling footprints in the wrong place, no errors in the actual "copper" ;-)
Need to get a flow turbine ordered and try the "controlled return" flow idea.
Found a few minor errors on the brds (both me labeling footprints in the wrong place, no errors in the actual "copper" ;-)
Need to get a flow turbine ordered and try the "controlled return" flow idea.
A very interesting thread, although for me, exactly the opposite.
I'm building a boat with a big block in. I definately do want a return feed to cool the fuel since the enclosed engine compartment can get a bit warm, whereas the tank sits on the hull and therefore makes a nice heat sink, but at the same time I don't want to be running a huge pump at full power the whole time.
I'm building a boat with a big block in. I definately do want a return feed to cool the fuel since the enclosed engine compartment can get a bit warm, whereas the tank sits on the hull and therefore makes a nice heat sink, but at the same time I don't want to be running a huge pump at full power the whole time.
Steve_D said:
I'm looking at this following a thread in the Ultima forum where some are experiencing fueling problems with temperature. The problem goes away for a while if you switch tanks (twin tank system) which leads me to think the fuel is getting hot in low demand situations. It is a return system so the tank of fuel is also heating up. As these engines are typically in the 600hp bracket with pump output at 200ish LPH a whole tank of fuel will pass through the fuel rail every 12 minutes.
Most, I believe, are running one pump probably the Bosch 044.
Most, I believe, are running one pump probably the Bosch 044.
MattYorke said:
A very interesting thread, although for me, exactly the opposite.
I'm building a boat with a big block in. I definately do want a return feed to cool the fuel since the enclosed engine compartment can get a bit warm, whereas the tank sits on the hull and therefore makes a nice heat sink, but at the same time I don't want to be running a huge pump at full power the whole time.
But what is the actual problem they claim to experience ? And at what fuel temperature ?I'm building a boat with a big block in. I definately do want a return feed to cool the fuel since the enclosed engine compartment can get a bit warm, whereas the tank sits on the hull and therefore makes a nice heat sink, but at the same time I don't want to be running a huge pump at full power the whole time.
Steve_D said:
I'm looking at this following a thread in the Ultima forum where some are experiencing fueling problems with temperature. The problem goes away for a while if you switch tanks (twin tank system) which leads me to think the fuel is getting hot in low demand situations. It is a return system so the tank of fuel is also heating up. As these engines are typically in the 600hp bracket with pump output at 200ish LPH a whole tank of fuel will pass through the fuel rail every 12 minutes.
Most, I believe, are running one pump probably the Bosch 044.
Most, I believe, are running one pump probably the Bosch 044.
Ive been running two 044's for several years. Ive driven non stop for 4+ hours with no problems ( yes, the pumps can get a little noisy, but they still perform, and fuel temperature during those conditions is never particularly warm.
Warmest Ive ever seen my fuel temps is about 50degC, but that was with it sitting stationary for a good while when queuing to race. Temp sensor mounted in a manifold in the engine compartment, that supplies fuel to the rails. Once the pumps are pumping, that soon drops, generally to around 20-35 degC, depending on ambient.
And that's at a fully tested miniumum flow level of 486 lph, but at 14v and idle fuel pressure that's probably a good bit over 500 litres per hour.
stevieturbo said:
MattYorke said:
A very interesting thread, although for me, exactly the opposite.
I'm building a boat with a big block in. I definately do want a return feed to cool the fuel since the enclosed engine compartment can get a bit warm, whereas the tank sits on the hull and therefore makes a nice heat sink, but at the same time I don't want to be running a huge pump at full power the whole time.
But what is the actual problem they claim to experience ? And at what fuel temperature ?I'm building a boat with a big block in. I definately do want a return feed to cool the fuel since the enclosed engine compartment can get a bit warm, whereas the tank sits on the hull and therefore makes a nice heat sink, but at the same time I don't want to be running a huge pump at full power the whole time.
Steve_D said:
I'm looking at this following a thread in the Ultima forum where some are experiencing fueling problems with temperature. The problem goes away for a while if you switch tanks (twin tank system) which leads me to think the fuel is getting hot in low demand situations. It is a return system so the tank of fuel is also heating up. As these engines are typically in the 600hp bracket with pump output at 200ish LPH a whole tank of fuel will pass through the fuel rail every 12 minutes.
Most, I believe, are running one pump probably the Bosch 044.
Most, I believe, are running one pump probably the Bosch 044.
Ive been running two 044's for several years. Ive driven non stop for 4+ hours with no problems ( yes, the pumps can get a little noisy, but they still perform, and fuel temperature during those conditions is never particularly warm.
Warmest Ive ever seen my fuel temps is about 50degC, but that was with it sitting stationary for a good while when queuing to race. Temp sensor mounted in a manifold in the engine compartment, that supplies fuel to the rails. Once the pumps are pumping, that soon drops, generally to around 20-35 degC, depending on ambient.
And that's at a fully tested miniumum flow level of 486 lph, but at 14v and idle fuel pressure that's probably a good bit over 500 litres per hour.
Steve
Steve_D said:
The instances of temp issues I was refering to were based on a car where everything is in the engine bay...tanks, pumps, engine, complete exhaust system. As you indicated the problem comes primarily whilst standing in traffic where the engine bay temp can climb alarmingly high.
Steve
No I didnt. I stated where the car was sat stationary, engine off. ie no fuel circulating, so heat soak will see temperatures within the engine compartment rise.Steve
Although I can see how such a setup could run warmer than my own
As soon as it starts to circulate though, that static temperature drops immediately.
And for all the claims of fuel temperature being called a problem. I've never once heard anyone state a temperature that is a problem. Which was the very reason I started monitoring temperatures a few years ago, just to see what they were actually like.
So, at what temperature does it become a problem ?
And of course the easiest solution, and actually the only solution to hot fuel. Is to fit a fuel cooler.
In the scenario you describe where all fuel related components are mounted in hot location. Then doesnt matter what speed the pump runs at, fuel is always going to be subject to heat ? Is that not correct ?
The thing that makes a big difference to fuel tank upheat is the velocity of the fuel in the fuel rail. On most engines the fuel rail is an metal tube bolted to the engine, and as such is an excellent conductor of heat. You engine metal temps will be close to ECT (say 80degC) with your fuel tank bulk temp of say 25degC, that gives a massive deltaT to driveheat flux into the fuel. As heat transfer is dependant on the shearing velocity across the heat transfer surface, having a high velocity in the rails effectively causes your fuel system to cool your engine!
OEM's now run with plastic fuel systems and returnless plumbing to prevent tank upheat, especially in modern cars where engine bay cooling is limited in the quest to reduce aero drag. (although the OEM's are doing it to try to minimise evaporative emissions)
Ultimately the fuel tank is your cooler, acting as a bulk cold source and a radiator.
The downside to limiting tank bulk heating, is that the smaller quantity of fuel in the rails is subject to a much higher temperature during hot soak events (peaking typically 12 to 18mins after keyoff). To avoid vapourisation and poor hot starting, all OEM returnless systems use an "scheduled Overpressure" strategy at key on after a hot soak, that increases fuel rail pressure well above the std setpoint, relying on this extra pressure to reassert the rail fuel volume back into its liquid phase
OEM's now run with plastic fuel systems and returnless plumbing to prevent tank upheat, especially in modern cars where engine bay cooling is limited in the quest to reduce aero drag. (although the OEM's are doing it to try to minimise evaporative emissions)
Ultimately the fuel tank is your cooler, acting as a bulk cold source and a radiator.
The downside to limiting tank bulk heating, is that the smaller quantity of fuel in the rails is subject to a much higher temperature during hot soak events (peaking typically 12 to 18mins after keyoff). To avoid vapourisation and poor hot starting, all OEM returnless systems use an "scheduled Overpressure" strategy at key on after a hot soak, that increases fuel rail pressure well above the std setpoint, relying on this extra pressure to reassert the rail fuel volume back into its liquid phase
Edited by anonymous-user on Thursday 3rd March 14:09
andygtt said:
Hi Max
Im doing the wiring for my fuel system at the moment.... Im having a relay for each of the 044's and another for the lifter pumps.
Anything else I need to do... putting engine in over weekend and its hard to get the area after engine is in.
Cheers
If using Max's controller, no relays are required.Im doing the wiring for my fuel system at the moment.... Im having a relay for each of the 044's and another for the lifter pumps.
Anything else I need to do... putting engine in over weekend and its hard to get the area after engine is in.
Cheers
If using a pair of 044's in parallel running all the time, say run one relay only and one fuse.
If really fails or fuse blows, both pumps stop.
I would never want a situation where one pump could stop without you knowing, until it is perhaps too late.
Sorry for the delay, been busy on other things....
I really just suggest, that whatever wiring you use, you insure that the power feed to the 3 pumps, and the main feed from the battery, ends up in some accessable location!
My control unit does not require any relays, although you could add a main power relay to disconnect it from the battery if you are really going belt and braces. You should however have a decent sized fuse or circuit breaker in the feed from the battery (say 50A)
At the moment i am struggling to find an affordable flow turbine that is ok to run with gasoline, they all seem to sit around the £200 mark which is a bit silly imo.
i might revert to the simple "follow fuel pulse width" control law.
I really just suggest, that whatever wiring you use, you insure that the power feed to the 3 pumps, and the main feed from the battery, ends up in some accessable location!
My control unit does not require any relays, although you could add a main power relay to disconnect it from the battery if you are really going belt and braces. You should however have a decent sized fuse or circuit breaker in the feed from the battery (say 50A)
At the moment i am struggling to find an affordable flow turbine that is ok to run with gasoline, they all seem to sit around the £200 mark which is a bit silly imo.
i might revert to the simple "follow fuel pulse width" control law.
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