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Holley Style FPR
$85 - FPR suit Blow-Through Carby Turbo
Brand
new Holley style Fuel Pressure Regulator (FPR) – modified to suit turbo or
supercharged blow through carby applications. Designed for use with EFI fuel injection pumps and other high pressure pumps whilst regulating fuel pressure down to carby levels.
The FPR delivers a 1:1 rise in fuel pressure as boost rises.
The FPR is: - modified to use a return line - the internal spring force is been altered - a boost reference nipple fitted to increase fuel pressure as boost rises - top housing machined and fitted with o-ring to seal in boost pressure
The FPR uses 3/8” NPT ports and comes with mounting bracket. Hot
up shops quote around $200-$300 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 less than half 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, causing the engine to starve
for 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), 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 itself. For the fuel pressure to remain
above the boost pressure, you need two components.
This FPR is designed to allow
the base fuel pressure to be adjusted in the range of 5psi to 15psi, (depending
on pump output). This base
fuel pressure is adjustable to suit your carby, as different carbys require
different fuel pressure to operate properly. 5-6psi of fuel pressure is ideal for various downdraught Weber carbys like the 32/36DGV and the 38DGS as more fuel pressure than this and you will overpower the needle and seat resulting in 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 specific maximum base fuel pressures 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.
I modify and test these FPR’s myself to make sure they operate
correctly and will do the job right. The FPR is modified to utilise
a return line to allow
the use of a high pressure pump, such as a typical EFI pump, and off the shelf
high pressure carby pumps like Holley Blue or Carter, whilst still delivering low enough fuel pressure to allow
adjustment in the 5-15psi base fuel pressure range.
NOTE: I can supply the FPR to work as a traditional non-return "dead head" type reg for those that do not want to use a return line. Fuel pump output pressure must be no greater than 20psi.
A small barbed fitting has been
installed to allow connection of boost pressure.
The fuel pressure will be increased by approximately 1psi for every 1psi
of boost pressure. This gives an
approximate 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 need a 1:1 rate regulator like this one.
Cost = $85. Postage is a
flat rate $9 to anywhere in Australia. Contact me to organise payment and
postage, or if you have any other questions, and I will try to reply ASAP.
benw@ncable.net.au
Installation diagram of FPR:
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