Stock fuel pressure regulator vs lower pressure regulator

Octanee · Feb 16, 2019

I am completely curious on this, and Have tried to google and not found my answer. My sled has the Fuel pressure regulator from the yamaha apex, It runs If I remember right 45 psi all the time, then if you hook the line up, it adds 1# per # of boost however most don't run the line and will remove 1# below 45 if applying a vacuum. Then many/most kits? for the sleds Run the stock FPR.

Why would a kit want to run lower FPR?

2XM3 · Feb 17, 2019

Cause they work flawlessly and will support 20+ psi boost with no issues....:face-icon-small-hap

Octanee · Feb 17, 2019

2XM3 said:
Cause they work flawlessly and will support 20+ psi boost with no issues....:face-icon-small-hap

If your referring to the apex FPR, yeah they do a good job for sure, I had one running 19#, However still had to have an aftermarket fuel pump haha.

but my main curiosity is why would anybody want to reduce the fuel pressure on the sled from stock. I can't seem to find a reason to do that. Lower fuel pressure makes your injectors flow less and have to increase the pulse width to fuel the same to a degree.

ez-ryder · Feb 17, 2019

When using an XIC controller to meet the demands of fueling for boost. You don't have control over the stock injectors.

A turbo will decrease the power of the motor pre-boost
So removing fuel from the stock injectors prior to boost is necessary for it to run properly. Lowering the fuel pressure accomplishes this without actually having control over them. From looking at some of the boost-it numbers. It appears they may have lowered it to the point where they needed to add fuel with the XIC prior to boost. This appears to have gave them the ability to control a larger portion of rpm range effectively.

Using a fuel pressure regulator to increase the fuel pressure 1 lb for every 1lb of boost is pretty standard in fueling a turbo charged engine.

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Stock fuel pressure regulator vs lower pressure regulator

Octanee

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2XM3

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Octanee

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ez-ryder

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