AN fitting size vs. HP output?...

[Falcon67]

That Aeromotive diagram just confuses people.  Their stuff is all over the place - one pump uses -10 AN for 1500 HP, the next uses -12 AN in -10 AN out for 2000 HP, then they recommend a return reg that either won't go below 18 PSI or uses a #8 return which may or may not be enough when you're feeding 550 HP with 420 GPH @ 7 PSI.  I'm researching methanol for up to 650 HP and it's surprisingly hard to find a consensus on pumps and regulators in the 100~250 GPH ranges.  That includes BLP, Aeromotive, MagnaFuel, Holley/QuickFuel, APD, Product Engineering, Weldon, etc.

More or less as above - on gas, #8 should be good to 750HP or better.  Note that #10 flows more and if your fuel comes from the rear, increases in line size increase the head pressure, requiring larger pumps to move the fuel forward.  That where my pipe rack has an advantage - when I leave, all the fuel up front WANTS to go back to the motor LOL.  The return line has the inertia problem.

[scott foxwell]

Thanks for that information. I can see where space would be an issue, especially with my factory oil cooler lines adding to the mix. I still think I'll give it a go, for reliability reasons.

Ken, I don't think I'll be pushing enough G's to have that issue, but I'll deal with it if it becomes one. I know it'd be wise to keep a half tank full to help keep that from happening, and I can modify the pick-up to extend further rearward, if need be. I'd like to stay away from a fuel cell or welded on sump for several reasons.

Russ, thanks for that link, but I'd prefer to stay mechanical. Electrics just add more complexity and chances of failure. During Drag Week, Freiburger said something that rings true every year: Closely paraphrasing..."The three main issues causing breakdowns during Drag Week are roller lifters, electric fuel pumps and automatic transmissions". I can't even count how many guys had issues with their automatics. I know of at least two guys who had to rebuild their transmissions 3-4 times during the week! I may not be able to avoid the roller lifters, but I can the other two.
Edit to add that it does give some interesting info on the AN sizes required though. Thanks again for that link.

Most electric fuel pump issues come from inadequate wiring. Seen it a thousand times in the marine world.

[cjshaker]

Chris, you and Ken bring up good points about a larger line and the effect it has on pulling that extra volume forward. So after thinking about it, here's my plan:

Use a RobbMc 1/2" pickup/return unit with optional #10 fittings. Drop the line to #8 to get volume weight down and run to the Clay pump. That way I can step up to #10 if I find it's needed. Although I think the Clay pump will work fine on either, I can go with a pusher electric if it doesn't work as expected.

Scott, you're right about electrical problems being a big culprit. Electrics draw a lot of current, and a lot of guys don't do the electrical work necessary to see it's fed right. And like offshore racing, drag use is a violent activity that will expose weak or unsupported connections in a hurry. But I've also seen plenty of failures of pumps. Much more than mechanical anyway. I'm also not a big fan of the noise they generate. Not a big deal for a strictly drag car, but for something that gets road use, it's just irritating.

[scott foxwell]

Chris, you and Ken bring up good points about a larger line and the effect it has on pulling that extra volume forward. So after thinking about it, here's my plan:

Use a RobbMc 1/2" pickup/return unit with optional #10 fittings. Drop the line to #8 to get volume weight down and run to the Clay pump. That way I can step up to #10 if I find it's needed. Although I think the Clay pump will work fine on either, I can go with a pusher electric if it doesn't work as expected.

Scott, you're right about electrical problems being a big culprit. Electrics draw a lot of current, and a lot of guys don't do the electrical work necessary to see it's fed right. And like offshore racing, drag use is a violent activity that will expose weak or unsupported connections in a hurry. But I've also seen plenty of failures of pumps. Much more than mechanical anyway. I'm also not a big fan of the noise they generate. Not a big deal for a strictly drag car, but for something that gets road use, it's just irritating.

Couldn't agree more on electric vs mechanical.
If you're thinking that the fuel in a larger line between tank and pump will be more effected by G forces and acceleration than a smaller line, that's a myth.

[Falcon67]

Don't resize the line based on potential G forces.  Size your lines to carry the fuel needed.  Note that 700 HP on gas works to 51.5 gallons/hr.  Figuring losses in the system, people usually add 50~100% to that more or less.  So a 110 GPH pump would be more than sufficient.  - 8 lines are plenty good for 140 GPH pumps.  Usually the 250+ GPH pumps go to -10 AN outlets.  Note, this is all for gas - For methanol, you can about double everything.  When you start looking at the pumps, you'll note that the bigger pumps are all putting out flow numbers at levels like 18 PSI, requiring either a fuel return from the pump or a return regulator at the carbs to knock it down to the 6~8 PSI for carb feed.  IMHO all power applications benefit from a return style fuel system.  I avoid dead head regulators like the dentist.

[jayb]

I like the Mallory 140 gph electric pump, it is nice and quiet and I haven't had one quit on me.  The Holley vane pumps are horribly loud, and I have seen a couple fail.  I also really like the Aeromotive A1000 and Eliminator pumps; they are not too loud and I use them for all my EFI stuff, but I have had a couple of those quit on me.  Both times on Drag Week, in fact,once in 2009 and once in 2015.  Fortunately for me I had spares on hand during those events.  Aeromotive is really good for repairing or replacing a failed electric pump at a very modest charge.

I think the only mechanical pump I'd run on a really strong engine is that Clay Smith, and after the hassle it was to install it, I'm sticking with electrics.

[scott foxwell]

Don't resize the line based on potential G forces.  Size your lines to carry the fuel needed.  Note that 700 HP on gas works to 51.5 gallons/hr.  Figuring losses in the system, people usually add 50~100% to that more or less.  So a 110 GPH pump would be more than sufficient.  - 8 lines are plenty good for 140 GPH pumps.  Usually the 250+ GPH pumps go to -10 AN outlets.  Note, this is all for gas - For methanol, you can about double everything.  When you start looking at the pumps, you'll note that the bigger pumps are all putting out flow numbers at levels like 18 PSI, requiring either a fuel return from the pump or a return regulator at the carbs to knock it down to the 6~8 PSI for carb feed.  IMHO all power applications benefit from a return style fuel system.  I avoid dead head regulators like the dentist.

Spot on. I do the 100% for gas and that's using .5 lb/hp/hr which is really more than most engines will use. I don't believe you can have "too much" fuel pump or fuel delivery. I've also seen power gains with 4.5 - 5 psi @ the carb vs 6.

[scott foxwell]

Use a RobbMc 1/2" pickup/return unit with optional #10 fittings.

What's that?

[thatdarncat]

Use a RobbMc 1/2" pickup/return unit with optional #10 fittings.

What's that?

Link: http://robbmcperformance.com/products/1085_fordsend.html

Others available too.

[cjshaker]

Thanks for all the great input. I think the 140 gph Clay pump with a #8 line will feed enough, but may have to discuss that more with Blair. Having 2 carburetors should ease the demand slightly on the pump, at least initially in the run, having more bowl volume on hand. Maybe I'm wrong about that. Any other mechanical won't be enough, so it's the Clay pump, or electric.

I have had that Mallory pump on my list for a while after seeing past threads about electric pumps, and that's the way I had originally intended to go. If I can stick with mechanical though, I'd prefer that. I just like mechanical stuff, it seems to be more reliable. However, I do have some concerns about grinding on the block in that area, and how much it would require. I'm sure the SOG block won't require as much as the Shelby block, but the iron will also be much thinner than the aluminum. It may not be worth it. I may wait and see how it works out for Kevin.

Kevin, is your machinist near the point of checking the fit out? Could you give me a heads up on how it works out on your block? I'm not sure if you're using a BBM or stock block, but they both should have roughly the same fitment clearance as the SOG block.

[thatdarncat]

Mine's a original Ford 427 block. I didn't take a picture at the time I looked at it, but the area of interference I have pointed out with the pencil on the stray 390 block in the picture below. It's right on the corner and about a 1/4" trimmed with a grinder will do it in my case. Like Jay said you could take a little off the pump body as well.

[AlanCasida]

I am also running a Clay Smith mech pump in my Galaxie as I'm sure you already know. I am using a bottom feed kit on my pump. It replaces the bottom plate on the pump and allows you to run either or both line from the bottom. I don't know if Clay Smith sells them but mine is Edelbrock. I am also using a RobbMc dead head regulator with his small orifice fitting to the return line to help prevent vapor lock. It only requires a 1/4" line running back to the tank. Right now I am running a 1/2" line from the tank and have had no issues with the pump/line. The fuel system issues I thought I had earlier this year turned out to be related to my street carb and nothing else. I am the same as you, for DragWeek I prefer to run a mechanical pump too.

[scott foxwell]

Use a RobbMc 1/2" pickup/return unit with optional #10 fittings.

What's that?

Link: http://robbmcperformance.com/products/1085_fordsend.html

Others available too.

Nice! And he has one for a Fairlane! Thanks! Looks like a nice part...something else I don't have to make.

[TomP]

The dual quads are much easier on the fuel system needs, you have enough bowl volume to make it to half track so unless you plan ten mile flat out runs you can get away with less pump than a single carb.

I wouldn't run and larger line than 1/2". Mechanical pump may have trouble sucking.

[cjshaker]

Kevin, thanks for taking the time to post that picture. I thought it would be in the recessed area, which is thinner and near the water jacket. The area you show should provide enough meat to clearance it.

I am also running a Clay Smith mech pump in my Galaxie as I'm sure you already know. I am using a bottom feed kit on my pump. It replaces the bottom plate on the pump and allows you to run either or both line from the bottom. I don't know if Clay Smith sells them but mine is Edelbrock.

Alan, I didn't notice that you were running a Clay pump, and I wasn't aware of that bottom feed kit. It looks like a nice piece but I think that may cause interference with my oil cooler lines. One of the lines runs right below the pump, so space is a little tight around there, and I'd like to keep the cooler for those longer runs on hot days. I had also planned on plumbing an oil accumulator into the top of my adapter.



Now that I look at this closer, the inlet/outlet may cause an issue with my filter adapter for the cooler, or possibly even the plumbing for the accumulator. Crap, I hate to spend the money and not have it work, but I guess there's only one way to find out.

The dual quads are much easier on the fuel system needs, you have enough bowl volume to make it to half track so unless you plan ten mile flat out runs you can get away with less pump than a single carb.

Tom, that's what I was thinking, but it wouldn't be the first time I've been wrong. I'll be running 2 660 center squirters, so it may not be quite as much reserve as 2 VS carbs, but should still help a bit.