ITB EFI Fuelling Question

[Mr Beau]

Tattletale retains the highest reading reached. The restriction is most relevant at peak flow so you'd have to watch the gauge while the engine is producing peak power (if it's not a "tattletale").

[winders]

Originally Posted by Mr Beau

Tattletale retains the highest reading reached. The restriction is most relevant at peak flow so you'd have to watch the gauge while the engine is producing peak power (if it's not a "tattletale").

You mean a peak hold gauge? No, it always shows the actual pressure differential at any given moment.

The built-in gauge is just one tool in the tool box. I have always relied on fuel pressure data gleaned while the car is running at load in race conditions. As long as fuel pressure does not drop at full load at max RPM, I am pretty confident that the filter is not overly loaded. If the gauge starts to indicate an increased pressure difference at idle, I know I need to start paying closer attention to fuel pressure data.

[Jittery]

Referencing your dead-head configuration, how important is it to have equal lengths of fuel line between Tee and each fuel rail? There is a drop in pressure/flow due to friction, but is it enough to matter? If L1 ( length between Tee and 123 Fuel rail ) is 12" and L2 is 14" - would there be a measurable difference? Taking it to the extreme, if L1 = 1" and L2 = 48" I would expect slightly lower pressure presented to injectors 4,5 and 6. Would a couple inches difference on lines that are ~12" matter?

Originally Posted by al lkosmal

A couple of ways to plumb.....

flow through




and dead-head

[PeteKz]

No difference in hoses that short.

[Showdown]

Try to keep the lengths as close the same as possible but it won’t matter if they’re slightly different. Maybe in a low pressure setup like carbs, but with high pressure it wont matter.

[Jeff Alton]

Originally Posted by winders

Fuel pressure regulators go after the fuel rails before the fuel is returned to the tank.

The AEM 25-302BK FPR can be plumbed in series or parallel. If running in series, as proposed by the OP, you just use one of the inlet ports and plug the other.

If running in parallel, you would use both input ports on the FPR as this diagram shows:



The line with the Y plumbing is from the fuel pump.

Regardless of system design, you should put a filter somewhere before the fuel rails. The parallel setup is certainly "better"...but not required for most applications under 600 HP. Heck, my 450 HP race engine uses an in series fuel rail setup with zero issues. I would recommend a fuel damper be used in the system. My FPR has a damper built-in and it works great. I am using a Radium FPRD-RA fuel pressure regulator damper.

Scott's diagram is correct, and the way we do it.

IN to both rails, the way shown or a tee at one rail depending on your installation needs. You can plumb the inlet to Both rails as you see fit. Then, BOTH rails feed OUT to the regulator, which then has a single return line. Pretty simple and correct design.

Cheers

[Jittery]

The notion that differences in lengths are more impactful for low pressure than high(er) pressure designs makes sense. I like Scott's config a lot! I have been experiencing tuning issues and trying to identify and eliminate potential sources of trouble. Thanks a million! Cheers!!

[Joesmallwood]

Originally Posted by winders

I am using an Injector Dynamics F750 fuel filter and love it. I use the available fuel pressure/temp sensor option. I also use the Injector Dynamics ID1050-XDS fuel injectors.

https://injectordynamics.com/id-f750-fuel-filter/

This image looks like it's one bank feeding the other - not parallel like the image or implied by the convo.

[Jeff Alton]

Put the inlet "T" wherever it fits in your install. Just feed both rails and have both rails feed into your regulator. The regulator will equalize the pressure....

[winders]

Originally Posted by Joesmallwood

This image looks like it's one bank feeding the other - not parallel like the image or implied by the convo.

Did you read my posts?

Originally Posted by winders

Regardless of system design, you should put a filter somewhere before the fuel rails. The parallel setup is certainly "better"...but not required for most applications under 600 HP. Heck, my 450 HP race engine uses an in series fuel rail setup with zero issues. I would recommend a fuel damper be used in the system. My FPR has a damper built-in and it works great. I am using a Radium FPRD-RA fuel pressure regulator damper.

* I bolded some text in my quote of myself for clarity.