Fuel Pumps Revisited

[Rich McD]

So I was all set to order some pumps for my RCR40 project. My plan is for -an8 to manual tank selector valve, to 100micron filter, to low pressure pump, to swirl pot, to high pressure pump, to 10micron filter, to fuel rails for the Classic Injection System. Return fuel to the tanks via -an6 lines. In reading posts on here and other sites, a geroter low pressure pump was in order since fuel had to be lifted out of the tanks. I liked the specs of the Holley billet pumps(12-600) and called their tech line to confirm my choices for filter and pump.

Tech dude put me on hold for a couple of minutes to consult someone who knew the answer. He came back to say all those pumps need to be gravity fed. My reiterating the positive displacement of the geroter design did not cause him to budge from his position. I concluded that, in order to get a reasonable life from their pumps, they want it insured to be constantly bathed in fuel for lubrication.

So to stick with Holley products I would have to proceed against tech dude's advise and hope the pump will hold up to the possibility of some air passing through such as during the initial prime. If someone has some long term experience with a particular pump holding up pulling fuel I'd appreciate the info.

In the same conversation I asked about T'ing their hydramats together inside our long narrow fuel tanks, one in the back of the tank and one in the front. He was all over that idea. Unfortunately that is the better part of a $600 decision. FYI

 

[Rich McD]

So, should I stick with the plan for the Holley pump or would someone advise another product that has proven reliable? Vane pumps seem problematic for mounting over the top of the fuel tank.

 

[DaveM]

I would look elsewhere than Holley. Had 2 gerotor type pumps (12-125) leak due to failed shaft seals and 1 red top vane type fail due to electrics after 3 months. Have since run a Carter vane type with no problems. It sits a foot above the tank.

 

[Robert May Eng.]

So, should I stick with the plan for the Holley pump or would someone advise another product that has proven reliable? Vane pumps seem problematic for mounting over the top of the fuel tank.

I would keep away from a vane type pump unless you can keep the inlet in the drink. They just dont handle air very well if you think how fast they run its no wonder they fail if running dry. If space permits the engine driven pumps take some beating , other than fit the pumps down low or get a couple of the facet red tops. They are happy enough dealing with air.

Bob

 

[Rich McD]

Thanks for the replies gentlemen. I'm going to contact MagnaFuel about their ProTuner gear pump. It is advertised as self-priming. If they can show some confidence that it can operate reliably with a 12" lift and some horizontal piping with some bends that may be the answer. Their stuff is pricy and oriented to the race community so the question of long-term reliability comes up.

From what I have read, vane pumps are operating on borrowed time with our needs for packaging. They would work well in-tank but I was trying to avoid two LP pumps feeding the HP pump.

Belt driven pumps appear bullet-proof. Packaging on the '40 could be a challenge. I'm already working with a mechanical water pump, alternator, AC compressor and dry sump oil pump. With attendant piping and hoses, there's not much room left.

I'll let you know what MagnaFuel has say on the subject.

 

[Rich McD]

I talked to the MagnaFuel tech department describing my requirements and asked whether their ProTuner pump would be a good choice to pull fuel from the tanks. He stated 12 inches of pull is comfortable but up to 24 inches is possible with their geared pumps. Their vane pumps are good up to 12 inches of pull but their design makes self-priming less effective. As far as longevity is concerned, he recommended pulling the pump and sending it in to them every two to three seasons for a tune up, as required, and test; the ProTuner pump is the best unit in their line for a street application such as my setup. Most of their pumps are designed for drag racing with attendant overkill for street applications.

An interesting aside: Counter to common knowledge, they recommend the return line be a size larger than the supply line. For high capacity pumps, you do not want to see the plumbing downstream of the pump restricting flow and building unwanted pressure. Under low demand conditions(idle) the surge tank could see up to 150psi. That doesn't sound good to me.

GTBob, I looked into the Facet pumps. They say all I want to hear about capability except their max flow is only good for 350hp. I have a little over 500 so am SOOL with that brand.

 

[Robert May Eng.]

I am not so sure the Facets are too small, they will pump 45 gallons an hour at about 6 psi. If that was feeding carbs through a needle it would probably not be enough to keep up with a 500hp engine. The truth is its freeflowing round a swirl pot with a small restriction back to the tank to maintain a minimal pressure in the line. I cant see any engine getting through 45 gallons an hour.

Bob

 

[Ron Scarboro]

One thing to note is that the Manafuel pumps are REALLY loud. If you mount them on the firewall, that is all you will hear.

 

[Rich McD]

Bob, I believe the Facet has 1/4 inch NPT inlets and outlets. The 750hp and up pumps have -an8 or 10. I'm not knowledgeable enough to debate the subject but the Facet web site lists 350hp max. Hate to ignore that and have issues later. Two pumps running parallel would work and provide some redundancy for limp home but my original plan was to simplify by having one LP and one HP pump for the injected system.

Thanks Ron, a lot of the high capacity pumps seem to be pretty loud. Seems if they were originally designed to go in a dragster, SPL wasn't a design consideration. If I go with the MagnaFuel product I would rubber mount it on the shelf forward of the battery sump.

I'm going to study up on PWM control of pump output. That may be an option to prevent a high output positive displacement pump trying to over-pressurize the system downstream. I was advised simple voltage modulation would not work as the pump will just draw more current to maintain output.

 

[Dave Wharran]

Rich,
I use Walbro brand pumps, 1 for each tank to the swirl pot. They are not too noisy (you can hear them, but then you hear a lot of other things on the car too!) and they tolerate periods of running dry due to fuel running away from the pickup. They lift fuel from the tanks well.
I also use a Pollak valve so fuel overflow from the swirl pot goes back into the tank it came out of.
The model Walbro I use has been discontinued, but they list alternative models that replace them.

Auto Performance Engineering - Walbro Series 6000 Fuel Pumps

Dave

 

[Rich McD]

Thanks for the Walbro endorsement Dave, looks like a solid enough product.

I said I'd get smart on PWM control of fuel pumps and have gotten minimally so. There are a couple of manufacturers familiar to this crowd, Weldon and Aeromotive, that offer controllers and several small outfits that cater to the DIY folks. The above products primarily use a tach sensor either via the 0-5 volt sensor already installed for an EFI system or an analog one off the spark to control pump rpm from about 40% to 100% at peak torque rpm. Their advertised purpose is to prolong the life of a race pump when used in a street application where, for a good percentage of the time, it would be pushing fuel at a rate far below capacity, excessively heating the fuel as it constantly cycles through the tank.

Looking at the Weldon web site I noted their pumps advertised as self priming so placed a call to them and was referred to Jim in the automotive division. He confirmed their pumps are vane style but are rated to pull fuel up to 15 vertical feet. Fifteen feet! I stated they were the first manufacturer of a vane pump I've read of or heard from that wanted anything but at or below the bottom of the tank installation. He said they had been mounting their pumps on top of the tank for a long time with good reliability. He recommended putting a check valve on the outlet of the pump so that fuel does not syphon back to the tank.

I asked how the such and such model pump with their speed controller would sound for my application. He said skip the controller and go with the A600-A pump for my sub-600hp motor. It has been installed in a few GT40's, has a good track history and runs quiet. Their web site was modified kicking that series of pumps off the page but a separate search will bring it up. He wants it ensured that the tank is vented well, at least -an6, and that the plumbing is adequately sized on the feed end as these pumps are quite aggressive in their demand for fuel feed.

This Weldon option gets me back to the original simplified system of one LP and one HP pump fed from a swirl pot. As this pump is capable of being a one-size-fits-all high pressure unit , I could T off its output with a manual shutoff valve to bypass the HP pump, should it decide to stop working, to give a limp home mode. A possible downside: Weldon pumps are designed to go in aircraft so are priced accordingly.

I provide this as FYI but feel free to comment positively or negatively. I'm going to allow the dust to settle before pulling the trigger on pump purchases.

 

[Dr. Bob Woods]

Have you seen the fuel pumps and swirl tanks offered by Torques?

www.torques.co.uk
-Bob Woods

 

[Rich McD]

Thanks Dr. Bob. There is an Aussie company that offers similar setups, can't recall their name, maybe the same outfit. Certainly an option for the swirl pot/HP pump combo.

 

[Craig Cumming]

Don't know if this is pertinent or helpful, but in my RCR Lola, with a carbureted engine, I use an ordinary Holley Blue pump, one per side and there has been no problem with the lift out of the tank. Its not a flooded suction or gravity fed as you term it.

 

[Cliff Beer]

I've used standard LP Facets well above the top of the tank (pulling probably 12 inches) and they seem to do well. However, I wouldn't trust them to pump enough fuel to power anything more than 350hp/tq reliably, even with a swirl pot plumbed in-line.

For high pressure stuff I've been impressed with Bosch pumps, particularly the 044. Seems to pump a helluva lot, and have no problem with priming the line above the level of the top of the tank.

Just my little bit of experience.

 

[Rich McD]

Thanks for the opinions guys. I'm beginning to come to the conclusion that many vane pumps can operate with suction, despite their manufacturer's warning against such, as long as they operate at 100% and, a big and, they are not allowed to draw any air. For many brands, sucking air leads shortly to their demise, whether that be from overheating, lack of lubrication of seals and bearings or a form of cavitation leading to degradation of the vane. So to guarantee the reasonable life of the pump it is necessary to design the fuel pickup so that air is not allowed into the pickup and a reasonable minimum amount of fuel is kept in the tank.

I agree with you Cliff regarding the Bosch pump from what I have read. If one is not interested in pump bling, the Bosch is reliable and does the business.

 

[Paulbav]

I have taken this from a post I made on a similar thread...

I'm using these, Southern GT use them in all there cars and they do seem to be very well regarded...

Fuel pump - The best electrical fuel pump - Fuel pumps - Carburettor, air filter and petrol system - Tuning, internal and external fixtures - General Accessories - SC Parts Group Ltd

 

[Bill Musarra]

Rich if you add a reservoir to the pickup of your tank and the return flow to this same area your pickup should be "underwater" 99% of the time.(unless driving down a very lonnnnnng downgrade). I have one with a flap valve that allows fuel in and not out(mostly), and it works great. It keeps the swirl pot filled. Given that the return from the injectors to the swirl pot helps maintain that fullness also, as most of that is recirculated back to the injectors. Only the excess goes back to the tank, and that is the fuel being supplied from the tank. Keep everything full and you won't have any issues. It makes pump selection a little easier.

Bill

 

[Rich McD]

Paul, I saw your post in an earlier search, thanks. I wish there were some amplifying information on the manufacturer and specs of the pump. From the 1/4 ports, I'd say I'd have to parallel two pumps for 500+HP.

Bill, I've followed your modifications to your fuel tanks. At some point I will have to get brave and cut access ports in the RCR tanks to see what baffling is installed and determine what can/should be done to trap fuel where it is needed in the rear of the tank. Maybe the use of a borescope in the near term is in order. Anyone know how the RCR tanks are constructed?

I'm also considering Holley's hydramat. Their on-line literature is scant regarding flow rate of their product and the reps don't have that off the top of their heads. Jim at Weldon said a fitment of hydramat and their pump hadn't been done yet and he is concerned with it restricting the flow to his pump. Stuff is expensive also.