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Base fuel pressure

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Hi all,

i have to raise the base fuel pressure as my duty cycle is @ almost 95%. Increasing the fuel pressure from lets say 43.5 psi to 58 psi gives me an extra fuel flow of more or less 15%. Can i take these 15% out of my entire fuel map as a starting point?

What ECU, what engine and what injectors?

Fueltech FT500, Bosch 210Lb injectors, 13b rotary, mechanical fuelpump, methanol

Are you staging injectors still? Or did you delete secondaries?

No they are staged at 0 bar.

Now I'm confused. Can you give a whole rundown of the engine?

Ok the link didnt work :-(

engine specs: 13b, large streetports, 8 x bosch 210 lb/h injectors, CAS, 4x aem smart coils, semi p-port, borg warner s475, castor oil premix ratio 1:80

I switched the unit in the fuelmaps that one can see the duty cycle and attached the datalog.

At only 29 PSI boost pressure, I'm running out of fuel. I can easily raise the fuel pressure as the Bosch injectors can run 72,5 psi base pressure without any problems . In order to save some work I asked the question.

Attached Files

The flow that you're describing is a static flow, you need to look at what the pump flow is at the boost level as the fuel pressure increases as well you may get flow drop off from the pump before dropping 15% from your fuel table.

With Methanol you can run rich mixtures safely to a point, I'd double check your pump flow at the increased pressure levels, if it can keep up remove 7-8% from your fuel map and test it, see what AFR's you're achieving and adjust to suit

The flow that you're describing is a static flow, you need to look at what the pump flow is at the boost level as the fuel pressure increases as well you may get flow drop off from the pump before dropping 15% from your fuel table.

With Methanol you can run rich mixtures safely to a point, I'd double check your pump flow at the increased pressure levels, if it can keep up remove 7-8% from your fuel map and test it, see what AFR's you're achieving and adjust to suit

Ah ok. Thank you.

I have only found a chart of our pump regarding the engine rpm as it is belt driven. I will test it.

Attached Files

I will admit, I don't normally run into mechanical fuel pumps on multi point port fuel injection. It's normally carburetor or fuel distributor or direct injection that has it. How exactly is the fuel pressure regulated? Does it use a return style regulator like a normal in tank electric pump?

Does your ECU have a basic "fuel injector size" setting? It looks like a table of speed, load, and injector duty, so I'm thinking no.

You will obviously have to correct the deadtimes if they are not pressure compensated.

So does your fuel map look otherwise linear up to where you are getting high DC? That will tell you if you are starting to have pump flow problems or just injector capacity. Just be mindful even with a mechanical positive displacement pump its flow rate may still drop off a bit at the combined base+boost pressures you will see.