[Tom Vaught]

Originally Posted by Dragncar

Not trying to compare myself with Langer but that BG 400 pump of his I bought, he runs 2 of those things making his 1300 some odd horsepower.

That is because there is a 7 second time factor involved in that fuel calculation to feed his high HP engine. The formulas work fine on steady state 5000 rpm boat engine applications on a large lake or the ocean.

Tom V.

[Formulajones]

Yep, there is way more to a fuel system than a simple formula. I don't believe that formula takes into account things like G-force, the bends in the system, friction, and we haven't even talked about proper line sizes. So it's best to overbuild the system a bit.

I was only using it as a simple example for Dragncar as he was playing with various fuel delivery methods on a car he reports running very low 12's, and mentioned he already had a 140 on it. I car running those times, a 140 pump is way overkill as it's probably making ~400-450-ish HP. Shouldn't really need a huge fuel system for that, unless you just like to experiment or have big plans in the future.

As far as "in the tank" cost goes, guys have taken many different approaches to save money here and there. I can only tell you how I prefer to do it, and it's been rock solid for me.

I go to the Tanks Inc site, order an EFI tank, the floatless sender, usually a trap door, and a Walbro 400 LPH pump. That usually runs a pinch over $600

I like to use Aeromotive 13301 regulators that are capable of simply changing the spring for EFI pressures, or will regulate down to carb pressure. I like the versatility and they have provided me with rock solid pressures and reliability for years. They run about $150

I'll then run 1/2" nylon braided lines for feed and return that is ethanol friendly. It's about $8 a foot, I just grab a 50 foot roll, enough to run a full length return line so the regulator can be mounted as close to the carb (or EFI) as possible for more accurate control. So the lines aren't that expensive but the AN fittings add up. I usually spend around $100 on fittings.

By the time I'm all done I usually spend about $1000 to $1200 to set a car up from scratch. When done I never have to fool with it again and it's enough system to support over 1,000 HP.

I just like to over do the fuel supply system so there is no question of it ever being an issue. And with the Tanks Inc setup, and EFI ready tanks, everything is pretty much just a bolt in deal and pretty easy to do.

[Skip Fix]

Buddy with a higher end mechanical pump on his 500"/383 Charger was having issues and pulled the pump apart the diaphragm was soft and starting to turn gooey. So he went to an in tank electric. Then ditched the carb and found a set of Hilborn Stacks converted to EFI and has not looked back. Idles smoother computer keeps the AFR more stable than a carb could on pump gas in Texas.

[uneasyrider]

Originally Posted by 78w72

does he run the car at the track? what are the times? im about the same HP level & doing low 11's & the carter/edelbrock type pumps definitely had starvation issues at those times with a q-jet carb.

Thanks, it’s a street car. I found my receipt and it was a RobbMc I had on there. It worked great! 😎👍

[Formulajones]

Originally Posted by Skip Fix

Buddy with a higher end mechanical pump on his 500"/383 Charger was having issues and pulled the pump apart the diaphragm was soft and starting to turn gooey. So he went to an in tank electric. Then ditched the carb and found a set of Hilborn Stacks converted to EFI and has not looked back. Idles smoother computer keeps the AFR more stable than a carb could on pump gas in Texas.

I'm still working on the stable part. Converted 2 cars over to Holley Sniper Stealth. One still has lean spots I'm trying to work out on light tip in, and WOT up top goes dangerous lean. The other one seems to be better in those areas. Light throttle cruising is pretty nice though.

[OCMDGTO]

Formula spells it out in post 62 with the Tank's setup if you want to do it right once. If you're never going to the track you could get by with that Holley or Robbmc mechanical. I had both of those pumps on my car at one time, they ran great on the street but both lost pressure on hard acceleration, from 6 1/2 to 3 psi. I had a 1/2" sending unit, 8an lines to the pump, and 6AN to the carb. I even had the 1100 Robbmc pump with a regulator. Maybe that short 6AN hose was the problem? Both got me to 12.1 at the track. TC is the fastest Pontiac I know of with the 1100 who obviously makes a lot more power than me. I changed over to the Tank's setup last winter and wish I would have started there.

[70GS455]

Originally Posted by Formulajones

If you use the generic 10hp per GPH rule, that 140 pump you have will support all the power you'll throw at it without the need for any mechanical pump in the system. I'd run that solo and call it done. Have done that for decades on one of the cars here with all stock lines well into the low 11's.



My only issue with those external pumps is I tend to only get about 4-5 or maybe 6 years out of the pump before the brushes are gone. Got tired of rebuilding pumps which is why I started going the in tank route years ago.

It's actually 12 (approximately): 6 lbs/gal of fuel density, divided by 0.5 lb/hp-hr (BSFC) = 12 hp per gph. BUT, it's gph AT the proper pressure; some reasonable real-world back pressure. Those "140" numbers are for marketing only and are useless, they are free flow (at 0 psi) into a bucket. Most of our systems operate at 3 or 4 or 5 psi WOT: a pump's output will drop vs increasing pressure. A chart of gph vs psi would be most helpful, no one produces those like the ones found for the EFI pumps. Robbmc site has a few pumps at free flow and 4.5 psi, which is better than nothing.

Sent from my SM-T817V using Tapatalk

[Formulajones]

Originally Posted by OCMDGTO

Formula spells it out in post 62 with the Tank's setup if you want to do it right once. If you're never going to the track you could get by with that Holley or Robbmc mechanical. I had both of those pumps on my car at one time, they ran great on the street but both lost pressure on hard acceleration, from 6 1/2 to 3 psi. I had a 1/2" sending unit, 8an lines to the pump, and 6AN to the carb. I even had the 1100 Robbmc pump with a regulator. Maybe that short 6AN hose was the problem? Both got me to 12.1 at the track. TC is the fastest Pontiac I know of with the 1100 who obviously makes a lot more power than me. I changed over to the Tank's setup last winter and wish I would have started there.

This doesn't matter now since you've switched the fuel system but for others reading, I highly doubt your short run of -6 (3/8) up to the carb from the regulator was causing any of your issues. I do that sort of thing all the time to keep stock appearances up around the top of the engine where it's most visible.

On one of the cars here I used the stock OEM holley fuel lines from the pump to carb which actually goes from 3/8 down to 5/16 at the fuel block before it enters the holley carb, as they did on all OEM holley carb applications when new.

I went into the low 11's with that setup at 118 mph with rock solid pressure, lol.

[taktikian]

I realize this is a dated conversation but I am considering making my first major deviation from bone stock on my 70 GTO and I need all the help I can get. I am on my third new Carter fuel pump in one month. All fuel starve after a 5500 rpm first gear pull ,stumbles and then recovers after a second or two. I am considering going to the Tanks pump in tank setup. My primary question is how and where to make a clean electrical connection. I can't botch up the unadulterated look of the harnesses but I know you all have and do deal with electric pumps all the time and I am hoping to benefit from your accumulated knowledge. I need a connection that will be 'keyed' - no toggle switches. Any advice appreciated. Thanks much, Paul

[AG]

Originally Posted by 70GS455

It's actually 12 (approximately): 6 lbs/gal of fuel density, divided by 0.5 lb/hp-hr (BSFC) = 12 hp per gph. BUT, it's gph AT the proper pressure; some reasonable real-world back pressure. Those "140" numbers are for marketing only and are useless, they are free flow (at 0 psi) into a bucket. Most of our systems operate at 3 or 4 or 5 psi WOT: a pump's output will drop vs increasing pressure. A chart of gph vs psi would be most helpful, no one produces those like the ones found for the EFI pumps. Robbmc site has a few pumps at free flow and 4.5 psi, which is better than nothing.

Sent from my SM-T817V using Tapatalk

Just for reference, i run a Mallory 140 at 5 psi and run 10.00 at 134.5 mph with a 3558 # car. My brother's car that has a 530 Hp 464 cid motor has no fuel delivery issues using a Carter HP mechanical fuel pump with stock fuel lines in a 1970 LeMans 350 2 bbl.

[Formulajones]

Originally Posted by AG

Just for reference, i run a Mallory 140 at 5 psi and run 10.00 at 134.5 mph with a 3558 # car. My brother's car that has a 530 Hp 464 cid motor has no fuel delivery issues using a Carter HP mechanical fuel pump with stock fuel lines in a 1970 LeMans 350 2 bbl.

I knew there had to be someone here that's been faster than I have with that simple setup. It's so easy to do. I still see some cars at the track to this day running 10's with that deal.

[Formulajones]

Originally Posted by taktikian

I realize this is a dated conversation but I am considering making my first major deviation from bone stock on my 70 GTO and I need all the help I can get. I am on my third new Carter fuel pump in one month. All fuel starve after a 5500 rpm first gear pull ,stumbles and then recovers after a second or two. I am considering going to the Tanks pump in tank setup. My primary question is how and where to make a clean electrical connection. I can't botch up the unadulterated look of the harnesses but I know you all have and do deal with electric pumps all the time and I am hoping to benefit from your accumulated knowledge. I need a connection that will be 'keyed' - no toggle switches. Any advice appreciated. Thanks much, Paul

As I mentioned I went in tank pumps on a couple cars many years ago when I got tired of the short life span of the external stuff. Ran the external stuff for maybe 30 years.

On the electric pumps, whether external or in the tank, I've always run my power supply from the keyed on source at the fuse block, to trigger a relay placed near the pump itself, with an inline fuse of course. Generally I'll run it through a switch in the car as well where I can manually turn it on and off. It's easy to do and has served me well for decades.

If going EFI, even the less expensive throttle body stuff, they make it super simple with it's own circuit and relay that runs the pump straight from the EFI system without the need to monkey with the car wiring.

[turbo69bird]

Weldon pumps are very reliable.

[wolf]

another data point for the Carter. 525 HP, 1.5/11.2/120, lots of street miles, Drag Week survivor, ethanol fuels, etc. and never had an issue with fuel supply. I do have 1/2" fuel line and pickup though.

[taktikian]

Thanks much. What about getting a keyed source from the oil pressure switch? Is this do-able or advisable. Thanks,Paul

[62posbonny]

For a carb setup, I wired a car up for a tanks inc tank and in tank pump using one of these recently.

https://www.ebay.com/p/1229616987


I used that to trigger a bosch 30A relay to power the pump. You get a 3 second prime on key-on and after that the pump only runs when the box gets a tach signal. Been in for a couple months and working flawlessly. In my mind this is the only way to run an elec pump on a carb system.

[taktikian]

62 what did you use for switched 12volt ? I assume the tach lead could be from the coil. Am I correct?

[i82much]

i am a poser. i run a carter mechanical on my e-head 505. never been down the track. like one of those guys with a lifted truck, big mud tires, and a polished-up warn winch in the mall parking lot that has never been off the pavement, lol.

[TCSGTO]

Originally Posted by i82much

i am a poser. i run a carter mechanical on my e-head 505. never been down the track. like one of those guys with a lifted truck, big mud tires, and a polished-up warn winch in the mall parking lot that has never been off the pavement, lol.

If it works for what you do that’s all that matters. I don’t really have any great desire to go to the dragstrip anymore. My days of semi-serious bracket racing are behind me and I know what times the car is capable of so been there done that. The new generation of intank pumps are impressive and versatile but nothing is simpler or more reliable that an engine driven mechanical pump IMO.

[i82much]

Originally Posted by TCSGTO

If it works for what you do that’s all that matters. I don’t really have any great desire to go to the dragstrip anymore. My days of semi-serious bracket racing are behind me and I know what times the car is capable of so been there done that. The new generation of intank pumps are impressive and versatile but nothing is simpler or more reliable that an engine driven mechanical pump IMO.

it’s true! there is a lot to be said for simplicity and being able to stop at an auto parts store in any town in the country and get a fuel pump for a Pontiac V8 to get back on the road.

i went into this thinking I was building a street strip car, ran a Holley black fuel pump and then an HP150 holley gerotor pump. But without a sump they didn’t really work right anyway. I switched to the Carter and haven’t had an issue on street tires, so I think I’m good to go.

I do like the in-tank electric setups and if I ever changed directions to go racing that is how I would go.