Facet Fuel Pumps

[tom pritchett]

Why would CAV install Facet Fuel Pumps which flows 35 GPH when most engines we will put into these machines require closer to 100GPH? My local Napa dealer looked at the pumps and they said that "we see these on forklifts". I was wondering why I was leaning out at higher rpm and further research, I found this to be the root problem.

I installed the new HP Holley fuel pumps (125 gph) and it seems to have fixed the problem. They are also much quieter.

Has CAV gone to something else or are these pumps still being installed from the factory? My car is a pre 100 car.

 

[Ron Scarboro]

Could you post a pic of the Holley installation? We're building mine and I don't think the Facet's will flow enough for my motor.

I agree on the flow rate, but the Facets are a marine solid-state pump that can take a lot of abuse. Good pumps, but don't flow enough for 500+ hp motors.

The formula is bhp X .45 / 6 so a 35 gal/hr pump is good to 467hp (well above even the race GT-40s of the day). Rarely are you putting that much hp unless you race.

 

[Ian Anderson]

Why not use Facit Red Tops?
Rated at 45gph and by the above calculation that will allow up to 600hp

Ian

 

[Ron Scarboro]

I'm conjecturing and this has my bias, but...

They make only a MK1 that originally took SBF 302 based engines. Getting 500+ hp out of those motors w/o stroking it or forced induction is very difficult. My guess is that most of their customers will be fine with those pumps at that cost and that 500+hp and 5.7l motors are outside the design parameters of a MK1 GT-40. My need for different pumps is due to fuel injection not HP.

IMHO, pumping 600hp in a stroked 351 through a 2,400lb car is an insane amount of power that struggles to get to the pavement. However, our differences are the spice of life (though that is a "hell" of a lot of spice) ;-)

 

[Lynn Erickson]

I'm conjecturing and this has my bias, but...

They make only a MK1 that originally took SBF 302 based engines. Getting 500+ hp out of those motors w/o stroking it or forced induction is very difficult. My guess is that most of their customers will be fine with those pumps at that cost and that 500+hp and 5.7l motors are outside the design parameters of a MK1 GT-40. My need for different pumps is due to fuel injection not HP.

IMHO, pumping 600hp in a stroked 351 through a 2,400lb car is an insane amount of power that struggles to get to the pavement. However, our differences are the spice of life (though that is a "hell" of a lot of spice) ;-)

then you need a pump for fuel injection. they put out about 100 psi. the carburator pumps are only about 6 psi.

 

[Johann]

The std. CAV GT is fitted with the Facet Red Top fuel pumps. These are more than good enough for cars with up to 450HP carburettor motors. They will not work for fuel injected motors that need 100GPH or more.

 

[Ron Scarboro]

then you need a pump for fuel injection. they put out about 100 psi. the carburator pumps are only about 6 psi.

Agreed. The general solution (and the one I'll employ) is a small tank that is fed by the regular pumps. The injector pump then pulls from that small tank (2-3gal) and feeds the fuel rails. PSI isn't important as that is only the pressure between the FI pump outlet and the regulator (fuel rails).

When the pressure in the small tank drops below the psi on the pump more fuel will flow into the small tank. You have to make sure that the gph on the regular pumps exceeds that on the injector pump as it always pumps with excess returning to the tanks all the time. Most FI systems are 45-60 psi (if I remember correctly).

Swapping the Facets for higher gph is critical more for recovery than max flow rate.

 

[tom pritchett]

I am running a 351w 383 stroker with the 48 ida webers. One the dyno, it really leaned out to where we had to stop the session with fear of melting a piston. All of my research on this issue of fuel flow is that a 600 hp engine should have about 100 gph. I am going from memory and my numbers could be off. The Facet 35 gph pumps that came on my car should be good for about 300 hp. I got 350 hp at 2900 rpm when I hit 14.5 a/f ratio.

I do like the idea of the fuel injection, especially when it comes to fuel milage, but I just love the webers.

I am taking this to the track tomorrow. I'll be running it in the slower groups as I don't want to break it before I go back to the rolling road and checking where things are.

I will take a picture of the Holly install in the am using the stock fuel lines. I may need some help to get the pictures on here as I am a little computer stupid.

 

[Ron Scarboro]

GPH is very dependent upon how the system is set up and what the flow is at what PSI versus "Free Flow". Here is a good source of info on fuel pump sizing.

Century Performance Center, Inc. :: Fuelish Tendencies - Understanding Fuel Pressure and Volume

 

[tom pritchett]

Ronald, that is a great article. I especially liked the diagrams. With a return system, I was visualizing a different system of return and not at the regulator. I was visualizing a return per side after the carbs. That would require solenoids to work and that was something I just didn't want to do. This looks much easier for a return system. It also explains why a larger pump is needed for higher volume / pressure to make up for smaller orifices in the fuel delivery system.

Thanks

 

[johann hamm]

My car CAV 106 runs a 563hp 408cu.in powerplant carbureting thru a 950cfm Holley and had issues with Facets. To run a Holley carb you need 6-7psi fuel pressure and the red top Facets only delivered about 3psi measured (maybe ok for a 302 and Webers) and flow through the tiny regulaor orifices also not up to the job. Installed Holley Blue with pressure regulator, 7/16 lines with fittings and it runs like it should.
Also installed inline cutoff that automatically switches the pump off when fuel pressure drops below 5psi.

 

[Cashburn]

To add to this conversation. We have #153 (which is actually a BDRGT) here that we maintain for the owner. We have struggled to get higher (and necessary fuel pressures) from the CAV factory system for years. We finally gave up this week and have replaced the entire system with fantastic results.

The Facet pumps installed have the filters after the pumps (a big problem with the poor filtering of fuel out of the gas pump). They also were not capable of delivering more than 3psi of pressure as others have pointed out.

The car is going to be listed by the owner for immediate sale, so we have gone through it one more time and addressed this issue properly.

In general the interactions with the CAV factory over issues have been extremely poor with unfulfilled promises of replacement parts and warranty coverage. Really too bad since the car is full of potential, just does not have the support and follow through of the company from what we experienced.

 

[Cliff Beer]

OK, so here's a (probably dumb) question......

I like simple...maybe because that's all I can understand....but why not just have a large pressurized header tank? In other words, if the mixture is going lean because the pumps can't flow enough to keep the carb bowl(s) full (causing a lean condition) then why not just plumb in something like a one-gallon header tank downstream of the pump/filter which supplies directly to the carb (with appropriately sized lines)? Essentially, it's an external carb bowl.

I'm thinking the above would work because even on a track day the car is not running at WOT all the time...probably something like 40% WOT on the track and 10% or less on the street. Seems to me the real problem isn't just needing the ability to pump a ton of fuel all the time, rather, it's the merely the ability to handle the fuel demand spikes at WOT so the AFR doesn't lean out.

Am I over simplifying it??

 

[Cashburn]

Actually you cannot simplify anything by adding components

 

[Cliff Beer]

Actually you cannot simplify anything by adding components

Very true. My solution is (in theory) much simpler than many of the other suggeted solutions. In other words, relative simplicity....

 

[tom pritchett]

I only got the one side in so far. It's the right tank. The pump is a 125 gph and is factory set at 7psi. I have the stock fueling set up and added this pump. I reset the pressure with the fuel pressure regulator at the carbs and all of this on the right side. Easier than the left side due to the extra plumbing required and bracketry due to the air conditioning unit. I ran the track on the new pump and the left on cool down, paddock and to get more gas. I had a blast. I don't think that I leaned out, but when I get the other fuel pump in, I'll have it dynoed again and make sure that I'm good. We have another track day on August 18, Sept 3 and Sept 30. That will be the end of the season for my responsibilities. I have learned that I could use larger stickier tires as I have a bit of understeer in turn 2.

 

[Ron Scarboro]

OK, so here's a (probably dumb) question......

I like simple...maybe because that's all I can understand....but why not just have a large pressurized header tank? In other words, if the mixture is going lean because the pumps can't flow enough to keep the carb bowl(s) full (causing a lean condition) then why not just plumb in something like a one-gallon header tank downstream of the pump/filter which supplies directly to the carb (with appropriately sized lines)? Essentially, it's an external carb bowl.

Am I over simplifying it??

First - I think you'd have to mount the header tank above the intake manifold so that you'd get the benefit of gravity feed from the bottom of the header tank. This would allow you to vent the tank. You'd have to mount some sort of float to keep the tank from overflowing from the pumps.

Mounting the tank below the intake manifold is unworkable as there is no way to allow air in and out so the tank can drain. You're really then into a surge tank or swirl pot setup.

The simplest solution is to run both pumps at the same time instead of switching. This would give you 70gph (probably a bit less). Using my math that would be good to 500+ HP.

Alternatively (if you wanted to keep the switching) you could run Facets in parallel (4 in total) fed by larger lines. This is simplest to implement as you just need to have a couple of Y connectors.

Regards,


Ron

 

[Cliff Beer]

First - I think you'd have to mount the header tank above the intake manifold so that you'd get the benefit of gravity feed from the bottom of the header tank. This would allow you to vent the tank. You'd have to mount some sort of float to keep the tank from overflowing from the pumps.

Mounting the tank below the intake manifold is unworkable as there is no way to allow air in and out so the tank can drain. You're really then into a surge tank or swirl pot setup.

The simplest solution is to run both pumps at the same time instead of switching. This would give you 70gph (probably a bit less). Using my math that would be good to 500+ HP.

Alternatively (if you wanted to keep the switching) you could run Facets in parallel (4 in total) fed by larger lines. This is simplest to implement as you just need to have a couple of Y connectors.

Regards,


Ron

Thanks Ron. I follow your logic, but what I was really thinking about was a sealed tank (non-vented) plumbed at roughly the carb bowl height. In other words, a pressurized and sealed tank to quickly supply a large volume of fuel to handle the WOT fuel spikes that tend to drain the float bowl (causing a lean out condition) because the pumps simply can't pump enough fuel to keep the bowl full. One line in at the top of the tank and one line out at the bottom of the tank. Workable?

 

[Lynn Erickson]

Thanks Ron. I follow your logic, but what I was really thinking about was a sealed tank (non-vented) plumbed at roughly the carb bowl height. In other words, a pressurized and sealed tank to quickly supply a large volume of fuel to handle the WOT fuel spikes that tend to drain the float bowl (causing a lean out condition) because the pumps simply can't pump enough fuel to keep the bowl full. One line in at the top of the tank and one line out at the bottom of the tank. Workable?

if the tank is under the same pressure as the lines then the pump is still doing all the work. the tank is just a fat pipe and because the fuel is not compressable as soon as the float valve opens the pressure will drop the same as before. with big pump and small lines the lines cause a restriction and limit flow. with big line and small pump the pump is the limiting factor.
the best way is big pump pumping through big lines. if you want the closed tank to work it wiil need to be like a hydraulic accumulator. it needs to have a compressable bladder inside and mounted close to the carb . easier and cheaper to replace the pump with a bigger one. spend $300 on a pump that can handle up to 700HP. or $ 300 on a tank and plumbing that will not help the situation

 

[Chris Martino]

I thought that Facet/Purolator recommends the pumps be mounted as close to the fuel tank as possible. Does it matter? I do recall seeing photo's of an original Mk II car with a fuel pump on both sides of the engine bay.

Chris