Blow Through Fuel Pressure Regulator

$125  -  FPR suit Blow-Through Carby Turbo

NOTE: this is NOT a Turbosmart brand regulator.

Brand new Fuel Pressure Regulator (FPR) – to suit turbo or supercharged blow through carby applications.

Designed for use with EFI fuel pumps and other high pressure pumps whilst fully adjustable to regulate fuel pressure down to carby levels. 

FPR delivers a 1:1 rise in fuel pressure as boost rises.  For example, if set at a base fuel pressure of 5psi, and running 10psi of boost, the FPR will deliver 5psi fuel pressure off boost, and 15psi fuel pressure at full boost.

SPECS:

                 - custom spec internal spring & machined housing generate 1:1 fuel pressure rise at low carby pressures using high pressure pumps

                 - can be adjusted from 2-10psi base fuel pressure

                 - boost reference nipple to increase fuel pressure at 1:1 rate as boost rises

                 - lock nut to stop accidental fuel pressure changes

This FPR has 3 x 1/8” NPT ports and comes with fitting kit including mounting bracket.  The ports are inlet, outlet and return to tank.

Hot up shops quote over $200 for an off the shelf FPR that will let you use a high pressure pump and blow through a carby in a turbo or supercharged application.  Get the item that will deliver the fuel pressure control you need for half the price.   These are the FPRs that we use in our blow through turbo kits, they work great and you can't beat the price.

A blow through turbo/supercharger application requires a special fuel system that has to stick to a very important rule: The fuel pressure must remain above the engine boost pressure at all times.  Otherwise the boost pressure generated from the turbo or supercharger will stop fuel flowing into the carby fuel bowl, starving the carby of fuel. 

Allowing the carby to starve of fuel not only makes the engine die in the bum, (like you’ve just run out of fuel obviously), but it’s also dangerous to your engine, as low fuel pressure can cause a lean running condition that will allow detonation/pre-ignition to destroy your pistons, head gasket or head/engine itself.

For the fuel pressure to remain above the boost pressure, you need two components.

1. A fuel pump that will deliver enough flow and more fuel pressure than the boost pressure you plan to run.
2. A Fuel Pressure Regulator (FPR) that will control the fuel pressure and make sure it always stays above boost pressure, but not so far above that you flood the carby.

This FPR is designed to allow the base fuel pressure to be adjusted in the range of 2psi to 10psi, (depends on pump output, return line back pressure, etc. - 2-10psi has been tested with our 070 EFI pumps).   This base fuel pressure is adjustable to suit your carby, as different carbys require different fuel pressure to operate properly.  FPR has a lock nut to stop accidental changes.

4-7psi of fuel pressure is ideal for most downdraught Weber carbys like the 32/36 DGV and the 38 DGS.  Any more fuel pressure than this and you will overpower the needle and seat resulting in a high fuel level or a flooded fuel bowl.  Holley carbs can handle about 7psi of fuel pressure, whilst other carbys such as Edelbrock, Rochester or Carter will all have a maximum base fuel pressure that they can run up to.  This depends mostly on the brand of carby and the needle and seat fitted.

I’ve run many different blow through turbo setups myself using downdraught Weber carbys like the 32/36 DGV, so I know what’s required, and I know what works and what doesn’t.  We modify and test these FPRs ourself to make sure they operate correctly and will do the job right.

The FPR utilises a return line to allow the use of a high pressure pump, such as a typical EFI pump or an off the shelf high pressure carby pump like a Holley Blue or Carter, whilst still delivering low enough fuel pressure to allow adjustment in the 4-7psi base fuel pressure range.  I have a suitable high flow EFI pump for sale which works perfectly with this FPR and is ideal for a blow through carby setup, click here.

A small barbed fitting allows connection of boost pressure.  The fuel pressure will be increased by approximately 1psi for every 1psi of boost pressure.  This gives a 1:1 rate rise in fuel pressure vs. boost pressure.  For example, if you set your base fuel pressure at 5psi and you want to run 10psi of boost, this regulator will deliver 5psi fuel pressure off boost, and approx 15psi of fuel pressure when on 10psi of boost.  Keep in mind you need a fuel pump capable of delivering at least 15psi of fuel pressure, at enough flow to keep your engine fed with fuel at full noise.    

NOTE: "Rising Rate Regulators" - a rising rate regulator delivers more than a 1:1 ratio of fuel pressure increase vs. boost pressure.  A rising rate is more than 1:1.  Some typical rising rate regulators give 2:1 and 6:1 rates of rise, which means when you're on boost, you're fuel pressure skyrockets.  This is ok if you have an EFI system and you tune your injectors/computer to suit, but no good for a carby setup, because you will simply flood the carby.  Remember the carby needle and seat will only hold back a certain amount of pressure, and most pumps, particularly EFI pumps will provide more pressure and flow than what your engine can use, flooding it.  You do not need a rising rate regulator for a turbo carby setup.  You only need a 1:1 rate regulator like this one.

Cost = $125.  Shipping is a flat rate $12 to anywhere in Australia.  I use a courier with tracking and insurance, or Express Post.  Contact me to organise payment and postage, or if you have any other questions and I will try to reply ASAP.  sales@turbodatsun.com

Installation diagram of FPR: