Parallel or dead head? - Page 3 - Lateral-g Forums

Vegas69 · #21 01-26-2009, 06:15 PM

That would sure do it John. I have a screen BG 10 micron in the front. What Jody said makes alot of sense. On a carb setup your return fuel does not see engine temperature because it's bypassed in the engine compartment instead of after the fuel rail. In essence you have an engine temp of say 200 and that is going to heat the fuel way up in a fuel injected setup unless you bypass in front of the rail. I have mine bypassed at the frame rail just inside the engine compartment on a carb application. I have measured my fuel pump temp and fuel tank temp after 1 hour and it's only ten degrees above ambient temp. I also used aluminum 1/2 fuel line as much as possible since it disipates heat way better than AN. Mine are on the outside of the frame as well where they get plenty of cool air.

**parsonsj** · #22 01-27-2009, 07:32 PM

Latest news:

Aeromotive Tech Support tells me my scenario is common: the 10 micron filter gets dirty, forcing the pump to deal with fuel pressure in excess of 100 psi in order to put 40 psi at the rails. After some time, the pump gets hot, the fuel goes into cavitation, and it fails.

They recommend that you replace the 10 micron element after 100 miles or so after a newly built car or a newly built fuel system is placed into service, since the new system is the dirtiest it will ever be.

Add in my hose problems, and the whole scenario makes sense.

So there you go: an EFI vapor lock problem that has nothing to do with deadhead vs after-rail regulator plumbing.

jp

**camcojb** · #23 01-27-2009, 07:45 PM

thanks John.

Jody

Vegas69 · #24 01-27-2009, 09:10 PM

Sounds like I'll be cleaning my 10 micron soon.

JamesJ · #25 01-27-2009, 09:29 PM

And ill be ordering a few spares tomorrow.....

JRouche · #26 01-27-2009, 10:35 PM

Re: dead head or bypass. I think bypass is a better system for the street. With a properly set up regulator. Its ALL in the regulator. If the pump is up to the task for the injectors, the tank is properly baffled and sumped, the pick up is at the right location (below main tank, at sump level) and the lines are of sufficient size. It all comes down to the regulator. If its not giving consistent pressures and flow to the injectors you will have problems with consistency for HP and torque and drivability on the street..

A dead head system will over heat the pump in a street car. Its cavitating and pumping within itself. Trying to make its own bleed off, so it pumps back into itself, back into the tank as cavitation.

With a bypass system the regulator is the dead head. It should be coupled with a pump that can supply it with enough pressure to keep it on full regulation. So then it can bleed off the necessary fuel to the injectors and still bleed of the remainder back to the tank. But it needs to be operating at a full pressure (from the pump) so its at full head pressure all the times. So in essence its like a dead head system, locking the pressure, its determined pressure, at all times for the injectors. The advantage is it will still allow fuel flow when its at peak pressure.

A fluid pump needs to have some flow, even at max pressure, its what cools them. No fans. Take a look at a high pressure washer, the better pumps have a bleed. That bleed cools the pump.

A dead head fuel system works fine for a race system. Only short races, some races may last what a hour or two (Thats long). Not like a street car that needs to last years under stopped traffic and not much demand.. Unless you pack a spare pump and tools for every ride

Im thinking a bypass fuel delivery system for a fuel injected car is the best. Not like the days of carburetors and mechanical pumps where a dead head system works fine. Low pressures and remember, they are pulling fuel (mech pumps) not pushing it, big diff.

JR

**camcojb** · #27 01-27-2009, 10:50 PM

Quote:

Originally Posted by JRouche

Re: dead head or bypass. I think bypass is a better system for the street. With a properly set up regulator. Its ALL in the regulator. If the pump is up to the task for the injectors, the tank is properly baffled and sumped, the pick up is at the right location (below main tank, at sump level) and the lines are of sufficient size. It all comes down to the regulator. If its not giving consistent pressures and flow to the injectors you will have problems with consistency for HP and torque and drivability on the street..

A dead head system will over heat the pump in a street car. Its cavitating and pumping within itself. Trying to make its own bleed off, so it pumps back into itself, back into the tank as cavitation.

With a bypass system the regulator is the dead head. It should be coupled with a pump that can supply it with enough pressure to keep it on full regulation. So then it can bleed off the necessary fuel to the injectors and still bleed of the remainder back to the tank. But it needs to be operating at a full pressure (from the pump) so its at full head pressure all the times. So in essence its like a dead head system, locking the pressure, its determined pressure, at all times for the injectors. The advantage is it will still allow fuel flow when its at peak pressure.

A fluid pump needs to have some flow, even at max pressure, its what cools them. No fans. Take a look at a high pressure washer, the better pumps have a bleed. That bleed cools the pump.

A dead head fuel system works fine for a race system. Only short races, some races may last what a hour or two (Thats long). Not like a street car that needs to last years under stopped traffic and not much demand.. Unless you pack a spare pump and tools for every ride

Im thinking a bypass fuel delivery system for a fuel injected car is the best. Not like the days of carburetors and mechanical pumps where a dead head system works fine. Low pressures and remember, they are pulling fuel (mech pumps) not pushing it, big diff.

JR

the deadhead system we were speaking of still has a bypass regulator, just not up front at the rails.

Jody

Vegas69 · #28 01-28-2009, 07:18 AM

Then it's not really a dead headed system.

**camcojb** · #29 01-28-2009, 08:30 AM

Quote:

Originally Posted by Vegas69

Then it's not really a dead headed system.

GM refers to it as a dead head system on the late Vettes, yet they still bypass at the filter where the regulator is built in. I bypass at the rear of the car with a regulator right off the pump, so I've always referred to it as dead head, as there is no return of the fuel from the engine. Whether that's the correct terminology or not, those who commented on having a dead head system early on in this thread were speaking of one that bypassed from the rear of the car, either through the factory Vetter filter/regulator, or from a rear mounted regulator like me.

Jody

Vegas69 · #30 01-28-2009, 09:02 AM

Interesting...one of those deals where everybody has a different definition. To me dead heading is one fuel line and the pump bleeding off the pressure internally. Sounds to me like they are bypassing exactly like a carb setup. On the flip side after the regulator it is dead headed to the carb or injectors. I still think they should call it a bypass.