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Old 04-26-2007, 12:08 PM   #1
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Default when to upgrade fuel pump?

ok im almost ready to up my boost to like 8-9 lbs. i have 1.8 injectors the 1.8 rearend swap im running a saab fmic greddy bov and msd sebring timing control. what boost level will i need to upgrade my fuel pump. will i see a difference in upgrading my fuel pump?
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Old 04-26-2007, 12:13 PM   #2
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At 8 psi, you probably are already in need of a pump.
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Old 04-26-2007, 12:20 PM   #3
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with 1.8 injectors and a good stock pump, i couldn't fuel past 165-170rwhp
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Old 04-26-2007, 12:36 PM   #4
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What about 330cc injectors, stock pump, JRSC AFPR and an EMB with all the goodies?
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Old 04-26-2007, 12:38 PM   #5
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With 330ccs you should be able to push things to around 200whp ... but the pump should be upgraded that point regardless.
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Old 04-26-2007, 12:45 PM   #6
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Upgrading the pump is cheap insurance. You OEM pump is probably tired and how reliable is the flow going to be? Get the Walbro 190HP, take you probably 1 hour to install. At least you'll know the pump is up to the tast.

When you are running an AFPR setup and a piggy back there are a lot of things that can make the car not run correctly. Putting in a capable pump is easy and cheap and will remove one part of a complex system.
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Old 04-26-2007, 12:47 PM   #7
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200whp? try at least 260rwhp at 100psi with 330ccs

i agree the walbro is a much easier install....i installed one in 30mins. didn't take much longer for the pierburg, but it was a bit more of a pita.


i guess to answer the original question more clearly.....you need to upgrade the pump when you need to fuel past 70psi; usualy due to running small injectors on an FMU setup. Raising the fuel pressure raises the size of the injectors. 330cc injectors at 100psi are now 495cc injectors. Since it requires an aftermarket fueling device to control +20/30% larger injectors, adding more fuel pressure is the logically solution. The stock pump can only output around 70-80psi, and even then it doesn't supply much at those psi level. An aftermarket walbro 190hp can support enough fuel per HP at 100psi. Other than that, you don't need one. If you have an aftermarket ECU, the stock pump more than enough at 50psi. Changing the fuel pump does nothing but allow enough fuel...it doesn't change any other factors in the fuel entering the combustion chamber.
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Old 04-26-2007, 01:07 PM   #8
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Quote:
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200whp? try at least 260rwhp at 100psi with 330ccs

i agree the walbro is a much easier install....i installed one in 30mins. didn't take much longer for the pierburg, but it was a bit more of a pita.


i guess to answer the original question more clearly.....you need to upgrade the pump when you need to fuel past 70psi; usualy due to running small injectors on an FMU setup. Raising the fuel pressure raises the size of the injectors. 330cc injectors at 100psi are now 495cc injectors. Since it requires an aftermarket fueling device to control +20/30% larger injectors, adding more fuel pressure is the logically solution. The stock pump can only output around 70-80psi, and even then it doesn't supply much at those psi level. An aftermarket walbro 190hp can support enough fuel per HP at 100psi. Other than that, you don't need one. If you have an aftermarket ECU, the stock pump more than enough at 50psi. Changing the fuel pump does nothing but allow enough fuel...it doesn't change any other factors in the fuel entering the combustion chamber.

I meant 200rwhp with the stock fuel regulator. I have 460ccs in there now and at around 260-270whp they are getting maxed out.
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Old 04-26-2007, 01:08 PM   #9
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correct.
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Old 04-26-2007, 01:18 PM   #10
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From what I read I thought the larger the injector the lower overall fuel pressure needed. Your post cleared it up. I will just pick up a 190HP and call it a day. Thanks.
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Old 04-26-2007, 02:40 PM   #11
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Originally Posted by miataspeed1point6 View Post
From what I read I thought the larger the injector the lower overall fuel pressure needed. Your post cleared it up. I will just pick up a 190HP and call it a day. Thanks.

It really depends on the setup....you dont really need an FMU with a 450cc injector becuase they can already fuel 250rwhp at 50psi of fuel. But a 300cc injector can fuel the same with 100psi of fuel. The delema is, it's hard to control 450cc injectors without a stand alone ECU and once you do...are 450s enough .

Your EMB setup should still utilize the FMU....then you can fine tune your fuel maps. This way you can also "limp home" without the EMB if it fails.
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Old 04-26-2007, 02:52 PM   #12
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For the price of the Emanage I'd def do a megasquirt ... especially in an OBDI car.

On the BP, 550ccs will get you over 300whp and are still easily tunable for a good idle and cruise using a standalone.

Personally I don't like multiple points of control because it results in multiple points of failure. Of course many combinations will do the job.
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Old 04-26-2007, 04:12 PM   #13
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11psi 430cc injectors and the stock fuel pump here, no problems what so ever
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Old 04-26-2007, 04:14 PM   #14
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yeah, i think we've covered that :gay:
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Old 04-26-2007, 09:29 PM   #15
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I will do a stand alone one day, but for now I need to stick with the EMB. I'm not making alot of power anyway, still at 5 psi. I think I'll do megasquirt after I get a BEGi setup.

I'm slowly learning about the details of fuel pressure and injector stuff. Before I learn anything else I need to get that damn wideband...

EDIT!!! I just bought the Innovate LC-1! Should be here soon! I have the laptop and autometer NB gauge ready to go, should be tuning for real soon.

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Old 04-27-2007, 04:02 AM   #16
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Running larger injectors does allow you to run lower fuel pressures for a given target boost or hp level. There's no misunderstanding there.

I'm currently running 305's and I have plenty of fuel to run 8 psi of boost at stock fuel pressures. If I want to go to 10 psi, I'll either have to go to larger injectors, or raise my fuel pressure. Since the EMB limits the size of the injectors I can run, I have to raise my fuel pressure, or go to an ECU that can handle larger injectors.

Pretty straightforward.
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Old 04-27-2007, 06:11 PM   #17
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a walboro it is then.
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