[Skippy597]

Hey guys, asking if anyone with a 500-550hp build has felt the need to upgrade to a 1/2 fuel feed line? According to the online charts you need to but I don't put much into those type of guide charts. Would love to here some real world experience. Finally Making progress on my build and putting the fuel system in next.

[moneypit]

I haven't had any issues with mine, 500 hp 467, carter mechanical pump. I haven't done any serious racing and usually shift at 5000 rpm.

[Tom Vaught]

I ran a Pontiac A-Body (Convertible 3/8" fuel line) down the drivers side of the 64 GTO.
https://www.sstubes.com/?gad=1&gclid...saAs80EALw_wcB.

I ran a 3/8" 1966 Chevelle (Convertible) line down the passenger side of the 64 GTO. (same supplier).
(All factory looking using Stainless Steel pre-bent lines. I was very happy with them installation. (Posted on this in the past).
No mechanical fuel pimp installed.

The fuel tank is a Tanks,inc (dual in tank fuel pump set-up) with TWO 400 liter/Hr fuel pumps.

I use fuel from the (26 gas pump) station that offers No Ethanol gasoline.

Two switches (independent) supply the fuel to the induction system.

The system has the ability to feed a 862 HP Vortech Supercharged (T-Trim), 455 engine.

Tom V.

1/2" fuel pump line is a smart move. Upgrade the pick-up line in the tank too.

[jhein]

My motor Dyno'd at 430 hp (many here think it should have been more like 500). I have a 3/8 factory line and with a BOP Carter style 120 gph pump it was starving bad. It would suck the bowl dry by about 4000-4500 rpm. I went to a RobbMc 550 hp pump and there was a dramatic improvement with no obvious starvation but I think it would still benefit from a 1/2 inch line. I'm planning on doing that next spring along with a baffled tank from Tanks Inc.

[steve25]

If your going racing and you get decent 60’ft times, keep this in mind.
you will find that for every foot of fuel line running from the rear at the tank to the front of the car that fuel pressure will drop .3 psi per ft due to G forces.

[Skippy597]

This is all really good info. Thanks guys. Sounds like I'll up to a 1/2 line and pickup. I'll be running a robbmc pump and I'll just order on of his pickups too. Still in the early stages but shooting for low 500hp range.

[OCMDGTO]

I'd go 1/2" feed and return with a regulator and a fuel pressure guage you can read while driving.

[steve25]

A true 500 hp motor would have about a .5 BSFC number showing up on a dyno print out, this converts to a need of 250 GPH.

This means with certainty that a 120 GPH pump will not support anywhere near 500 hp.

[78w72]

Originally Posted by steve25

A true 500 hp motor would have about a .5 BSFC number showing up on a dyno print out, this converts to a need of 250 GPH.

This means with certainty that a 120 GPH pump will not support anywhere near 500 hp.

Myself & many others have used the common carter/edelbrock mech pumps that are rated at ~120GPH that support 500 hp engines. My 467 engine dyno'd on a "strict" crank dyno at ~520hp using an edelbrock mech pump, did numerous pulls and didnt have any issues but not sure what fuel ratios were since it wasnt a real dyno tuning session with all sensors hooked up, just some pulls on break in to verify no leaks, all parts like Q-jet carb & HEI dist were set up by cliff & suntuned & just bolted on with no real tuning.

The edelbrock pump says its rated "up to" 600 hp and was proven to support 500+ on a dyno with no problems, it did fine on the street too, however at the dragstrip it would only do low 12s with pretty bad starvation issues, using 1/2" pickup & lines to pump & pump to carb. Changed to a robbmc 1100 mech pump but was dialed down to 7psi with no regulator, with no other changes besides some skinny front tires the car has went 11.2-11.3 at 119-123mph... but still have occasional starvation on good runs.

Just wanted to give an example of a 120GPH pump supporting over 500hp when sitting still on a dyno, add in G forces from good launch & into the 11's and most cars will have problems.

For the OP's question, 1/2" lines arent usually needed for street use but a good pump like robbmc is a good idea, if doing any drag racing you may want to upgrade the lines.

[OCMDGTO]

Originally Posted by steve25

A true 500 hp motor would have about a .5 BSFC number showing up on a dyno print out, this converts to a need of 250 GPH.

This means with certainty that a 120 GPH pump will not support anywhere near 500 hp.

Completely wrong. Check out the Tanks, Inc offerings and tech. I have their 340lph pump which converts to 90gph with zero starvation. They say their 250lph pump will support 500+ hp

[Skip Fix]

I think the Q jet if a big factor in this equation-one needle and seat one small bowl.
My personal experience in my 78 TA Stock motor added a 228@ 0.050 cam -stock pump and 3/8 line ran out of gas top fo second. Added a small AC Delco electric pusher.
Added a real 430 hp 455 through mufflers on dyno with a Qjet-fell on it's face. Tried every mechanical pump-no help. Added a dead headed Mallory 140. Solved -until I uncorked the headers probably adding another 30 hp. Issues again. Added -8 from Mallory to carb and dropped the mechanical pump and it supports me into the 11s with a Qjet and now 10s with a Holley with still a factory 3.8 pickup-no sock.

[78w72]

Qjet may be a factor, just wanted to post a real world experience with a 120gph mech pump supporting over 500hp when it was said these pumps will not support "anywhere near" 500hp.

Back in the early to mid 90s i had a mild 455 (462) in a 78 t/a with a holley dbl pump mech secondary carb, milled .030 6x4 heads, 280 magnum cam, headers, 2.5" exhaust, th400, 3.90 gears. that car ran stock lines & pickup with a stock large canister AC mech pump... it was never dyno'd or went to the drag strip but on the street it would beat mid 12 sec cars that would come cruise our avenue with time slips in hand, i would easily beat them on stop light to stop light short runs and when we went to a divided highway section we had marked for 1/4 mile, it would beat them the entire run... that was my only verification for how fast the car was, im sure it would run mid 12s or better with good tires. I would guess at least 425hp on that motor that ran great on the street with stock pump & lines. The 120gph pumps can & do support 500hp engines.

[steve25]

Sorry, I forgot to convert my number I posted, so yes 120GPH will support 500 Hp.

[70GS455]

Originally Posted by steve25

Sorry, I forgot to convert my number I posted, so yes 120GPH will support 500 Hp.

Need to figure in 6 lbs/gal, so 41.6 gph

Sent from my SM-S901U using Tapatalk

[grandam1979]

My buddy dynoed the 400-495 we assembled with stock intake q jet and stock pump and line from carb to pump it made 541hp at 5500rpm it was just starting to go lean over 5500 but not damaging lean. I wish we could have tried a mcrobb at that time but didn’t have one yet. The stock pump got a stock body 69 gto with stock everything else but drag radials to 11.80’s. All cars are not the same even with the same size lines my 80 t/a with stock line needed an electric pump by tank not to nose over in third gear a 110 Mallory fixed that problem that car only went low 12’s. The purestock Firebird my buddy runs goes 113-115mph with all stock parts being used.

[ta man]

My car years ago with a 550hp engine? picked up almost 2 mph just by swapping from stock pickup and 3/8 line to all 8an lines and half inch pickup. At that time it was running high 11's.

[Formulajones]

Like has been mentioned, most will get away with smaller 3/8 line and never know there is a fuel delivery problem on the street, as most here don't bother or even worry about track performance, but will quickly find out there is ET and MPH to be found in that area as soon as they hit the track.

In nearly every scenario when I've been involved with a decent running street car, they've benefitted from 1/2" line and a good pump feeding it. Surprising the amount of people that spend a bunch of money on engines, worry about the HP they make, then skimp on the fuel delivery system. We've all done that, myself included. I quickly found decades ago as power level keeps increasing the fuel delivery becomes a key player. These days right off the bat I just spend the money and shoot for an in tank pump and 1/2" lines and call it done so I never have to revisit it again as the car evolves further.

[Tom Vaught]

Originally Posted by Formulajones

Like has been mentioned, most will get away with smaller 3/8 line and never know there is a fuel delivery problem on the street, as most here don't bother or even worry about track performance, but will quickly find out there is ET and MPH to be found in that area as soon as they hit the track.

In nearly every scenario when I've been involved with a decent running street car, they've benefitted from 1/2" line and a good pump feeding it. Surprising the amount of people that spend a bunch of money on engines, worry about the HP they make, then skimp on the fuel delivery system. We've all done that, myself included. I quickly found decades ago as power level keeps increasing the fuel delivery becomes a key player. These days right off the bat I just spend the money and shoot for an in tank pump and 1/2" lines and call it done so I never have to revisit it again as the car evolves further.

A LOT OF TRUTH AND EXPERIENCE IN THAT POST.

I KNOW TANKS, OFFERS A "TRAP DOOR" YOU CAN ADD TO YOUR FUEL TANK (to service a failed fuel pump) BUT I JUST SET UP
MY FUEL SYSTEM WITH A PRIME FUEL PUMP AND A BACK-UP FUEL PUMP ON THE FUEL PUMPS FUEL PUMP MOUNTING COVER.

Food for thought there people.

Tom V.

[Skippy597]

Originally Posted by Formulajones

Like has been mentioned, most will get away with smaller 3/8 line and never know there is a fuel delivery problem on the street, as most here don't bother or even worry about track performance, but will quickly find out there is ET and MPH to be found in that area as soon as they hit the track.

In nearly every scenario when I've been involved with a decent running street car, they've benefitted from 1/2" line and a good pump feeding it. Surprising the amount of people that spend a bunch of money on engines, worry about the HP they make, then skimp on the fuel delivery system. We've all done that, myself included. I quickly found decades ago as power level keeps increasing the fuel delivery becomes a key player. These days right off the bat I just spend the money and shoot for an in tank pump and 1/2" lines and call it done so I never have to revisit it again as the car evolves further.

Thats a very good point. And when put like that I guess it's a no brainer to upgrade with all the money going everywhere else to.make power. Thank you.

[DaleO]

Thank you 78w72, pictures not needed, I see that a 1/2" OD line will fit through there fine and it sounds like it will be able to take the slight curves necessary to hook up and not kink or anything like that. Do you have an in-line filter along with the regulator too? I've usually used in-lines as it seems the in-housing filters (short/long) are so small but I see that Cliff sells pleated filters so they must be able to do the job. It would be a cleaner instl without.

The clockability is a cool feature. I'm really impressed with the quality and heft of the unit.

Just an FYI, the pump I took out had the outlet (bottom) on the same side of the pump as the inlet (1969 428) and I also looked at the pump on the 1969 400 in my other car and the outlet is on the opposite side of the pump. I would not claim either configuration is original or correct or whatever but the lines for both go up between timing chain cover/pump bracket/head.

thank you for your help