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12-21-2009, 08:59 PM | #251 |
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I know they make them both, let me see what I can come up with.
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12-21-2009, 09:05 PM | #252 |
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12-21-2009, 11:25 PM | #253 |
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I see a lot of systems with dual pumps, dual filters, etc. And I occasionally read about motors that popped when one pump died and the car ran on half the usual fuel.
We've got two fuel rails... So I have to wonder, if you're going to do a dual pump system, why not run one pump to each rail, each with its own FPR? If one pump dies, you'll have two cylinders seeing full fuel and two seeing none / hardly any. Stuff can still break at this point, but it seems less likely to kill the motor than running all 4 with half the usual fuel flow. Is there a reason nobody does this? |
12-21-2009, 11:47 PM | #254 |
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^^^^^
Not if u put a pressure switch into the line, so that if pressure drops below a certain value then you know theres something wrong with the pumps and the ecu will go into limp mode.. |
12-21-2009, 11:59 PM | #255 | |
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Say the motor in one fuel pump is slightly less efficient than the other and drops pressure by 3 psi instead of 1 psi at 60 psi. That's a half a point in AFR difference, one bank would be at say 11.3, the other would be at 11.8, that's pretty significant. Or say one fuel pressure regulator isn't as linear as the other, and instead of ramping up at exactly 1:1 it ramps up at more like .95:1. When your manifold pressure hits 25 psi, one bank will be at 68 psi, the other will be at 66.75, same problem as before. If the line feeding one bank is a different length than the line feeding the other bank, it could cause a resonance at a different IDC, which will cause one bank to randomly lean out at some RPM while the other doesn't. Just throwing out ideas why people don't usually separate the fuel system like that. |
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12-22-2009, 12:02 AM | #256 | |
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Of course this is all moot if you install a pressure sensor instead of a switch, and monitor fuel pressure - manifold pressure to check for a constant 43 psi differential. You would need a standalone ECU for that though. |
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12-22-2009, 12:33 AM | #257 |
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Or you could simply get a properly sumped fuel cell and run one pump. Weldon makes a hell of a single pump solution.
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12-22-2009, 12:33 AM | #258 | |
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12-22-2009, 12:55 AM | #259 | |
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i was just thinking about running 2 walbros in (paralel) i know spelled wrong. then into a single aeromotive regulator. then i would have double flow but equal pressure. right?
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12-22-2009, 01:02 AM | #260 |
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Sure, but then you run into the problem that NSFW was bringing up. With one pump, if it up and fails you essentially go 100% lean, no fuel, which is basically just engine breaking. With 2 pumps, if one fails you go lean, but not so lean to prevent combustion. Basically it's a recipe for a blown engine.
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12-22-2009, 01:11 AM | #261 |
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thanks egg. ^^^^but
im talking about 2 totally seperate lines clear from the tank/pumps to the rails, then if 1 pump dies then you basicly have one bank getting fuel and the other empty. i may hve to install check valves on the return lines just before the reg but i think it will work. |
12-22-2009, 01:15 AM | #262 |
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12-22-2009, 01:44 AM | #263 |
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12-22-2009, 04:10 AM | #264 | |
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A single regulator with check valves seems like a good way to work around the regulation problem that Eggroll brought up, though. Nice idea. |
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12-22-2009, 06:20 AM | #265 |
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The problem with a cell is even with a huge sump and foam you still get a ton of slosh, if you run one with any sort of capacity. If you are drag racing you are fine, but you start throwing the car around and starvation becomes an issue once again. I have tried several different setups and no one setup is a end all solution. I just wish we could find a way to get away from the multiple pump setups. It just adds more complexity to an already overly complicated setup.
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12-22-2009, 10:23 AM | #266 | |
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12-22-2009, 10:24 AM | #267 | |
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12-22-2009, 10:42 AM | #268 |
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I only had problems when the fuel cell was not full. At about 1/2 tank in a high g sweeper I would get starvation. Take in to account that I was feeding a bosch 044 through gravity with this setup. I did not have a tank inside the fuel cell. Keeping the tank full is not always and option, especially for street cars, or track cars that do long duration runs, which was the case in my miata.
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12-22-2009, 10:44 AM | #269 |
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I just don't like the approach of multiple pumps, even though it has been proven to work in a lot of cases. Like I said before it just makes the situation more complicated, and more of a risk of failure.
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12-22-2009, 11:20 AM | #270 | |
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Fuel tank can be whatever it is (fuel cell or stock tank), lifter pump feeds a ~1.5L fuel cell (which almost always stays completely full), main fuel pump pulls out of that to feed the injectors. Sloshing in the tank or fuel cell doesn't matter, because you have a ~1.5L buffer that can hold you over for at least 30 seconds to a minute in track use, plenty of time for the pickup in the tank to get fuel again and refill the surge. It's not overly complicated, it's pretty cheap, and as far as I can tell it is an end-all solution to high-G fuel starvation. |
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12-22-2009, 11:51 PM | #271 |
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is this the proper way to wire a Bosch 044 fuel pump? |
12-23-2009, 12:15 AM | #272 |
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You don't want to switch the relay with the line that feeds the factory pump. It's pulse width modulated at much too high of a frequency for the relay to keep up, and even if it could, the Bosch doesn't like to be switched. You want to switch the relay using the line that powers the stock fuel pump controller (goes hot when the key is switched ON for a few seconds, then goes cold until the vehicle is actually started).
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12-23-2009, 08:24 AM | #273 |
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so should i switch 86 and 30?
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12-23-2009, 09:11 AM | #274 |
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hmm found this on the web. |
12-23-2009, 10:03 AM | #275 | ||
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http://www.summitracing.com/parts/EAR-100181ERL/ It's actually cheaper to go with the Earls, but that little aermotive y is pretty sick. I need two of them. One to split the -8 feed into (2) -6 at the rails and one to split the (2) -6 from the pump to -8 feed line. |
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