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Upgraded Fuel system On stock Gtr


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Hey Peeps!

Im getting ready to do my engine build and im thinking of things i can do before the car goes in to get the engine taken out and the work begins .I was thinking of getting 

Frenchie's performance in tank baffle kit(https://frenchysperformancegarage.com/products/nissan-skyline-r32gt-r-in-tank-surge-tank-kit) running a walbro 450 as the lift pump

and a 525 as the main feed.. then running -8 lines feed and return to A radium fuel rail and matching Fpr.. I want to do this with the stock ecu and still drive the car around

until it time to drive it to where the build will start.. it currently is running 270rwkw on 15psi with a flashed stock ecu and steel wheel exhaust turbines.. being the only mods

Anyone see a problem doing this? ( i would bypass the factory fuel controller and just run the 2 fuel pumps through 2 dedicated relays triggered by the ecu.

Cheers! for any input.

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47 minutes ago, Duncan said:

It's hard to advise what you should/could do without knowing your plans/power targets.

more asking if there would be any issues running 2 fuel pumps on stock setup before the build

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no, no issues. you aren't really running 2 pumps when they are lift + main, and you aren't intending to use the stock wiring so no issue there either. It will circulate way more fuel than you need so the fuel may get warm, but it's not a motorsport application so you will never notice.

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Make sure the FPR you buy can actually return a ton of fuel if you plan on running it with the stock ECU, otherwise you are going to seriously overfuel as the fuel pressure will overshoot. Or you will have to come up with some kind of alternate solution to replace the stock FPCM to slow down the pumps at low RPM. You don't actually want to have too much fuel flowing on the return line, it heats up the fuel and eats away at reserve amps on your alternator. You could also cavitate the pump running the tank low much more easily. Only pulling 40A for a short period at WOT is a very different thing compared to pulling 40A all the time just to run your fuel pumps. I've also heard that the stock fuel rail actually flows just fine for big power, so you may want to think about how necessary that really is.

I've been agonizing over something similar on my R33 and I think my conclusion is to run a 5 bar FPR on a DW440 brushless fuel pump to get just enough flow to max out my dinky little twin turbos. The hard part is the controller, I don't really see any simple drop-in replacement that can use the OEM ECU fuel pump signals to set an appropriate fuel pump duty cycle. It really shouldn't be that complicated, just 3 speeds instead of the 2 speed variants I've seen and some method of programming the desired duty cycle for each speed.

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7 minutes ago, joshuaho96 said:

Make sure the FPR you buy can actually return a ton of fuel if you plan on running it with the stock ECU, otherwise you are going to seriously overfuel as the fuel pressure will overshoot. Or you will have to come up with some kind of alternate solution to replace the stock FPCM to slow down the pumps at low RPM. You don't actually want to have too much fuel flowing on the return line, it heats up the fuel and eats away at reserve amps on your alternator. You could also cavitate the pump running the tank low much more easily. Only pulling 40A for a short period at WOT is a very different thing compared to pulling 40A all the time just to run your fuel pumps. I've also heard that the stock fuel rail actually flows just fine for big power, so you may want to think about how necessary that really is.

I've been agonizing over something similar on my R33 and I think my conclusion is to run a 5 bar FPR on a DW440 brushless fuel pump to get just enough flow to max out my dinky little twin turbos. The hard part is the controller, I don't really see any simple drop-in replacement that can use the OEM ECU fuel pump signals to set an appropriate fuel pump duty cycle. It really shouldn't be that complicated, just 3 speeds instead of the 2 speed variants I've seen and some method of programming the desired duty cycle for each speed.

Most people seem to think the fuel pump/pumps going full tilt 24/7 will be fine and the heat negligible , but as u say the fpr needs to be up to scratch (mine is rated to 800hp Aeromotive ) as for pump modulation  on factory ecu

this is the only one ive been able to find

https://aeromotiveinc.com/product/billet-fuel-pump-speed-controller/

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3 minutes ago, boomtheroom said:

Most people seem to think the fuel pump/pumps going full tilt 24/7 will be fine and the heat negligible , but as u say the fpr needs to be up to scratch (mine is rated to 800hp Aeromotive ) as for pump modulation  on factory ecu

this is the only one ive been able to find

https://aeromotiveinc.com/product/billet-fuel-pump-speed-controller/

I don't think the fuel heating issue is quite as big a problem as it is on stuff like the R35 because the transmission is up front, in the R35s it is actually bad enough with some fuel pumps to cause fuel to boil at the pump inlet which almost immediately causes cavitation and fuel pressure loss. So in that situation you absolutely want to avoid running higher duty cycle than necessary. Deatschwerks makes a fuel pump controller that takes a PWM signal, all I'd need to get it to run on the stock ECU is yet another microcontroller sitting between the stock ECU fuel pump signal that translates the digital signal from the ECU into a PWM signal going into the fuel pump controller. Or I'd have to take apart their 2 speed controller, look for another digital input that could be used, and somehow figure out how to rewrite the code to be able to specify arbitrary duty cycles for "full speed", "medium speed", and "low speed".

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20 minutes ago, Dose Pipe Sutututu said:

Get a modern ECU, a solid state relay (with internal fly back diode OR wire one in) and run PWM.

No need for an expensive fuel controller and no need to heat up your fuel with a 500+ watt fuel heater

Right, the actual answer is don't bother with the stock ECU and just use a standalone to drive the PWM. Brushless fuel pumps mandate and come with a motor controller.

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1 minute ago, joshuaho96 said:

Right, the actual answer is don't bother with the stock ECU and just use a standalone to drive the PWM. Brushless fuel pumps mandate and come with a motor controller.

already have the walbro pumps.. will be getting the linkg4x ecu.. is meor just a a temp solution as i said above..cheers!

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2 minutes ago, boomtheroom said:

already have the walbro pumps.. will be getting the linkg4x ecu.. is meor just a a temp solution as i said above..cheers!

With a standard brushed fuel pump there's no controller needed, once you transition to a standalone you just do what @Dose Pipe Sutututu described, a relay controlling the connection to ground driven by a digital output on the Link. This approach unlike the stock dropping resistor doesn't run into issues with high flow fuel pumps getting unhappy when driven at low voltages.

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4 minutes ago, boomtheroom said:

would it be all good to run the lift pump at 100 all the time? and the us a  controller on the feed pump?

Can't see an issue with that.

With my setup, I have a DW200 lift pump that runs at 100% with the factory drop resistor deleted and the FPCM disconnected.

In my SPR400 surge tank, there are twin Walbro 460 pumps which are connected to a SSR and PWM at 100hz. At idle, they're run at 40% DC. This increases in a linear fashion as MAP increases till 230kPA where both pumps are at 100% DC.

The above setup will keep fuel temps under 50 degrees Celsius after 10 laps of Wakefield Park. I can't imagine what fuel temps would be like with all 3x pumps at full tilt.

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2 minutes ago, Dose Pipe Sutututu said:

Can't see an issue with that.

With my setup, I have a DW200 lift pump that runs at 100% with the factory drop resistor deleted and the FPCM disconnected.

In my SPR400 surge tank, there are twin Walbro 460 pumps which are connected to a SSR and PWM at 100hz. At idle, they're run at 40% DC. This increases in a linear fashion as MAP increases till 230kPA where both pumps are at 100% DC.

The above setup will keep fuel temps under 50 degrees Celsius after 10 laps of Wakefield Park. I can't imagine what fuel temps would be like with all 3x pumps at full tilt.

what ssr u using?

 

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7 minutes ago, Dose Pipe Sutututu said:

@boomtheroom this one from Jaycar, I suspect it's just a rebranded Crydom one. Make sure you use a good diode as the flyback diode. If not, the voltage spikes will fry the SSR.

https://www.jaycar.com.au/solid-state-relay-4-32vdc-input-30vdc-100a-switching/p/SY4086

 

any that have a built in flyback diode? ... also would 1 be enough to run 2 20a fuel pumps?

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