Which Way Does An Inline Fuel Filter Go

An important part of building a performance motorcar for either the street or the race rails is ensuring the fuel delivery system operates at its peak potential. You can't make horsepower if there'south no fuel to burn. In the one-time days of small carburetors and mechanical fuel pumps, machine builders relied on those tiny niggling contumely filters used in the inlet of a Holley carburetor or a small-scale inline fuel filter.

Those parts worked sufficiently for engines that barely made 400 horsepower. Still, today's supercharged EFI engines take pushed the horsepower height well into the four-digit range. A 1,000 horsepower pump gas street engine would have been unthinkable thirty years agone, just today inappreciably raises an eyebrow. More than chiefly, those engines can inhale an astonishing corporeality of fuel in a very short time. The days of 5/xvi-inch fuel line and fuel filters no larger than the size of your pollex can be assigned a spot in automotive museums alongside one-barrel carburetors and red plastic fuel line.

In the instance of a fuel filter, besides small-scale tin crusade problems but there's really no size limit for too large. At that place'south no need to go overkill on a filter as long as it provides acceptable protection. The mid-size Holley 175 gph filters in the middle will likely never get a restriction to menstruation on most road-going vehicles.

We've disassembled a 162-554 Holley inline 175 gph filter so you can come across the filter and spring. The body of the filter is marked to signal the direction of menstruum. Fuel flows into the body of the filter housing, past the capped end of the filter cartridge and through the filter medium and exits from the contrary finish. The spring allows fuel to featherbed the filter should it go completely clogged.

The point is that while horsepower has never been easier to make, y'all must be able to feed the engine with the fuel it demands. Then a mild 500 hp EFI street engine places sufficient demand on the fuel commitment system – which includes the fuel filter. A tiny filter stuck in the middle of the fuel line running to an EFI fuel rail won't become the task washed.

The best fashion to illustrate the importance of designing and constructing the proper fuel arrangement is with a short, anecdotal story. This is non a hand-me-down urban myth. Nosotros watched this happen. A good friend was hired past Galpin Auto Sports (GAS) in Van Nuys, California to perform an engine swap. The owner of a '67 Chevelle was frustrated with his 621 hp 572ci big-block carbureted crate engine. According to the possessor, the car was lazy and could barely spin the tires. Several shops had failed to remedy the trouble. The owner was and then frustrated that he purchased a supercharged EFI LT4 engine and asked GAS to perform the swap.

It's of import to keep track of the micron rating in any filer, merely especially with inline filters such equally this Holley 175 gph version. While the filter body is externally marked with the filter micron rating, yous tin also ensure the filter is correct past looking for the laser etched micron rating on the finish of the filter. This is a 100 micron filter.

This Holley illustration shows the placement of the 100 micron pre-filter before the pump with the finer screen x-micron filter after the pump and earlier the fuel injectors. Information technology'south very common for installers to incorrectly switch the positions of these filters, which will reduce pump output and maybe make the pump run hot.

Gillman inherited the project but after the Rat motor had been removed and sold. He was curious why the big-block didn't perform since those engines have an splendid reputation for making good ability. While removing the original fuel delivery system, he discovered the culprit. The original builder arbitrarily installed a tiny screen fuel filter with the surface area roughly equivalent of a silver dollar and tasked that minor filter with the impossible task of removing debris and flowing 600 horsepower's worth of fuel. When dirt and junk chock-full the pocket-size filter, fuel period dropped precipitously which seriously handicapped horsepower.

The moral of our fuel flow equivalent of an Aesop fable is that every part of the fuel delivery organization – including the fuel filter – must be sized properly to ensure proper fuel period. Simply as we'll reveal, the size of the filter is just half the story. The other half is the micron rating of the filter. Let's jump right into that.

This is the entire filter chapters of that 572ci big-block Chevelle example. This filter measured roughly ¾-square inch of filter surface area. That'southward pretty pocket-sized. This is later on Gillman cleaned all the debris that had clogged it nearly shut.

We laid out these three face masks that represent the filter area of a typical Holley 175 gph filter such as Holley PN 162-554 using a cellulose ten micron filter. The Kennedy one-half dollar we're holding is really 20 pct larger than the filter area of a 1-inch diameter flat screen filter used in that big-block Chevelle. It should be obvious which filter area would be best for a 600 hp performance engine.

In the sometime days of carbureted engines, no one talked most micron ratings of fuel filters. But with the advent of electronic fuel injection and high pressure fuel delivery systems, this became an important attribute. The main reason is that the rather large orifices in a carburetor practice non demand a fine filter chapters. Only high pressure fuel pumps operate because of very tight clearances. Plus, electronic fuel injectors can exist quickly plugged with material that would have hands passed through a typical carburetor. This places a fine signal on improving filtering chapters. Enter the micron rating.

A micron is defined equally one millionth of a meter. Expressed as a decimal information technology comes in at 0.000039-inch. Aye, that's pretty tiny and invisible to the naked centre. Even with this microbial diameter, electronic fuel injectors can quickly become fouled unless protected by a x micron filter. That 10-micron rating means that the filter is capable of catching 90-plus percent of all dirt and debris measuring x microns or larger In diameter. That'south a slice of debris measuring only 0.00039-inch or larger. To put that in perspective, a high output big-block Chevy main begetting clearances are by and large close to 0.003-inch, and then that 10micron filter volition remove dirt i-tenth this dimension.

Most Holley inline filters are available with either tapered pipage thread or ORB fittings. The near popular has go the ORB (o-band boss) filters using specific AN fittings that use simple o-rings to seal the plumbing fixtures to the body of the filter (shown). These fittings are easier to remove and replace compared to national pipe tapered (NPT) fittings that require piping thread dope to ensure a good seal.

High catamenia, high chapters fuel delivery systems demand a big filtering area to minimize pressure level drops in the organisation. Holley's VR series filters identify 2 of the smaller filters end-to-end to double the filtering chapters while minimizing flow loss.

High pressure EFI applications crave a 10-micron cellulose filter to foreclose debris from clogging fuel injectors. Pre-filters for EFI pumps apply a stainless mesh 100 micron filter. Even so, if your plans telephone call for running E85 or methanol fuel, make sure to e'er use stainless steel mesh fuel filters. Cellulose or paper elements can react to the organic elements in the fuel and create a gel-like material that can cause problems.

Only the story now gets a bit more complicated. While a ten micron filter does a corking job of removing dirt, this fine filtering capacity besides means it creates a fleck of a restriction to period. All fuel pumps are designed to button and pressurize liquid fuel, merely in guild to practice so, they demand an unrestricted inlet. The most important betoken in any fuel delivery arrangement is the inlet to the pump. Creating a restriction on the inlet side of the pump is guaranteed to reduce volume and force per unit area and make the pump work harder which will reduce its life expectancy.

Simply electronic fuel pumps all the same need to exist protected from debris that could reduce efficiency or fifty-fifty render information technology inoperative. Since a x micron filter is too restrictive on the inlet side, a less restrictive filter is preferred. For inline pumps where it is located outside the tank, a 100 micron pre-filter is recommended. This larger filter minimizes the brake into the pump and effectively dust material volition still be filtered by the 10-mircon filter located downstream of the pump before information technology reaches the injectors.

A great pre-filter for in-tank pumps is Holley's HydraMat system. This unit of measurement performs double duty as an excellent pickup for fuel for EFI system and it also works as a great pre-filter with its fifteen micron rating.

At present you might be thinking "Wait, that HydraMat is way too restrictive," given the information in the previous paragraph. On the surface that may appear to exist the instance, but according to Holley fuel organization engineer Matthew Sosa, the HydraMat's large surface surface area reduces the restriction and employs a coarse outer layer to forbid large debris from clogging the filter. Combined with the weight of fuel sitting on the mat to help button the fuel into the pump, the HydraMat and even the white colored pre-filter "socks" (which are rated at 10 microns) do not represent a major restriction again because of their large area.

Holley has combined a uncomplicated pressure regulator with a filter that allow you lot to place this regulator just after the fuel pump which will besides filter the fuel with its included 10 micron filter. The inlet and outlet are along the long line of the filter while the outlet from the regulator is plumbed as return back to the tank. This eliminates two sets of connections which also reduces price. The regulator is pre-set to 59.5 psi.

Along these lines even so, nosotros have seen several instances where the 10 and 100 micron filters have been accidentally reversed, and this can reduce the fuel pump's effectiveness although it's not a bargain breaker.

1 place where Holley has reduced the complication of plumbing the fuel system is with the EFI Filter Regulator. This unit of measurement combines a 175 gph, ten micron filter with a pre-set and non-adjustable 59.5 psi regulator. This unit of measurement can be placed downstream of the EFI fuel pump. This parcel eliminates 2 AN fittings between a dissever regulator and filter which as well reduces the same number of potential leak paths. The filter is completely serviceable and can exist easily disassembled for cleaning.

Some Holley carburetors used minor sintered brass fuel filters but within the fuel bowls. These volition work, simply because of their small-scale size will need to be monitored and replaced regularly. These are considered mail service or secondary filters since older, carbureted cars used a mesh screen every bit a pre-filter.

The main tasks for any EFI system filter is to both cull out the clay before it accomplish the fuel injectors while also offer sufficient menses chapters so that the engine is not starved for fuel. This is best accomplished past increasing the filter's total expanse. This brings united states back to the original example of the 572 Rat motor starved for fuel. The filter installed on that Chevelle offered less than one square inch of total filtering surface area.

Conversely, a typical 175 gallon-per-hour (gph) Holley inline filter with a 10 micron paper element offers 37 square inches of surface area. That's a 50x increase in filtering area. Let that sink in for a moment. If the original 572ci Chevelle builder had but used the advisable twoscore micron stainless mesh version such as a Holley 175 gph filter, the fuel delivery system would take flawlessly fed that big-block with enough fuel to demolish those rear tires.

Nosotros mentioned the xl micron stainless filter considering that micron rating is more than than enough to filter fuel for a carbureted application. So when we combine a large surface area like the stainless steel mesh filter with a 40 micron filtering rating, this allows the fuel pump to deliver its maximum potential flow rate with but a minimal force per unit area drop through the filter. Ideally, this would be installed in a return style fuel delivery system.

Holley'southward HydraMat is an first-class addition to custom fuel tanks because the material will pull fuel even if only a portion of the mat is contacting the fuel. Plus, HydraMat makes for a good pre-filter with xv micron filter capacity. This does non represent a serious restriction because of the mat's large surface surface area.

Holley's HydraMat is also a great pick for a fuel pickup in a custom or one-off application where a Sniper fuel tank or Holley in-tank conversion is not available. The HydraMat acts nigh similar a siphon or sponge where if any portion of the mat comes in contact with fuel, the HydraMat will direct the fuel into the pump inlet. This volition aid to minimize that sag or hesitation with electronically fuel injected engines where the fuel sloshes away from the pickup, creating a serious drop in fuel pressure. Plus, as we've mentioned, information technology besides works equally an splendid pre-filter for a high-pressure EFI fuel pump.

One of the all-time ways to mount inline filters is with a gear up of Holley's billet fuel filter clamps that will non only secure the filter housing to the car but practice it fashionably at the same time.

This should serve equally a keen introduction to fuel organisation delivery and how of import filters are to whatever high functioning engine. While delivering fuel to the engine is critical, the fuel likewise needs to exist clean – which also serves to reduce other maintenance problems. It's also all-time to call back of the unabridged fuel system every bit integrated components rather than private parts. A combination of the right parts and a professional installation will create a organization that will deliver lots of fuel, horsepower, and fun for a long fourth dimension.