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Fuel pump question/idea

Just wondering if anyone here has done an in tank performance fuel pump conversion?
A good in=tank pump would eliminate the need for the engine bay pump altogether and a pump like a Walbro could easily feed the thirstiest EFI/turbo motor.
Extra benefit: clean up the engine bay a little at cthe same time.
Just wondering.
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Old 11-24-2006, 06:12 PM
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OK, maybe it's a stupid question, sorry
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Old 11-25-2006, 04:57 AM
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I just don't have a fuel pump in my engine bay. It's below the frame rail out of the bay, only accessible from the bottom side of the car.

So, don't quite understand the question.
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Old 11-25-2006, 05:31 AM
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Maybe it's only the CIS cars, I don't know the earlier models.

I see the 930 guys and the turbo conversion guys talking about adding a second fuel pump up front to augment the pump in the engine bay.

My thought was why?
A newer style, in-tank pump is more than adequate to feed any EFI / turbo combination and it seems to me, a much simpler & cleaner approach to fuel delivery.

I'm planning on doing this mod when I switch to the tbitz EFI.
Will also utilize a return style FPR to circulate excess fuel back to the tank. it's easier on the pump and keeps cooler fuel available to the motor.

Every HP enthusiast knows to change from pulling the fuel to pushing it, the factory pump literally sucks!

The engine bay will look much cleaner without the fuel pump & fuel reservoir there and even the filter can be relocated down lower, out of sight.

Weight savings app. 3-4 #
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Last edited by paslantnose; 11-25-2006 at 06:22 AM..
Old 11-25-2006, 05:51 AM
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A stock 930 (CIS) has a fuel pump up front, just outside of the fuel tank, then another in the rear just below the frame rail. So not sure what they are adding, unless maybe upgrading to a bigger rear pump or something. But even that isn't really necessary I don't think.

Alot of people use the stock pumps until they die, then they simply upgrade to a bigger pump if they want to.

You know what you are trying to accomplish - go for it. And post pics.
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Old 11-25-2006, 06:50 AM
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Are you thinking of the fuel filter or the fuel accumulator? There is no fuel pump in the engine bay of any 930 that I know of. The two stock pumps are pretty good.
Old 11-25-2006, 07:57 AM
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Let me clirify.
The 911 guys that add a turbo talk about adding a fuel pump ala the 930 pump, up front.

If this turbo conversion requires the addition of a front pump, why not use a more modern approach and install a sigle pump into the fuel tank?

The 911's have the pump in the rear right?
This and the accumulator would not be needed with a modern, in-tank pump
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Old 11-25-2006, 08:23 AM
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I thought you were talking about an existing 911 Turbo engined car. If you were to turbo charge your car, I'm guessing you would need to add a 2nd pump like the one in back (an SC or Carrera has it up front from what I remember on mine). Or you could change to a Bosche 044 fuel pump that would supply enough for both (correct me if I'm wrong).

Back to your topic, it would seem like you could add a pump inside the fuel tank, but you'll need to consider the sloshing of gas and the pick up. You might need to add a baffle or box inside for the pickup. Just a guess.
Old 11-25-2006, 01:12 PM
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I'm not sure, but if you are using CIS, I believe you have to run an accumulator???? Not 100% sure. I trashed all of that CIS stuff. But, seems like I recall that there is a documented reason why the accumulator is required.
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Old 11-25-2006, 05:56 PM
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Seems like you would need an accumulator or check valve to keep the pressure up between starts or you will have to build it up each time you start.
Old 11-25-2006, 06:16 PM
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I'd like to see some form of proof (and i expect there is) as to needing an accumulator.
Any decent pump can deliver FP almost immediately.

Actual facts are required here, don;t ya think?
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Old 11-25-2006, 06:42 PM
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Just FYI but Walbro pumps tend to not like higher fuel pressures and can fail if the pressures get too high. I've noticed in the 911 forced induction world, for some reason most people seem to be running ~5-6bar fuel pressure typically. I'm not too sure if a Walbro pump could withstand those pressure levels reliably. It all depends on how much pressure you are running, but I'd highly recommend taking a look at the specs for whatever fuel pump you consider. Most typical aftermarket pumps you'd find on the market (like an Aeromotive A1000 for example) seem to be rated at their highest flow rate around the 40-60psi range. Higher pressure equals a lower flow rate of course.

AFAIK, I believe most n/a 911's (not sure on all years) have a single front pump at the tank. I know for a fact 3.2 Carreras do, and I know SC's do as well though I'm not as familiar with all of the older models' fuel systems. A single front Bosch 044 pump would be sufficient for most people as they are capable of handling up to around the 600hp level. Not to mention it would simplify things quite a bit over 2 pumps and you wouldn't have twice as many "failure" points to deal with should any issues arise in the future (ask me how I know )

As for which is better, in-tank or external, I really don't know. External pumps have worked just fine on plenty of cars making tons of hp for quite some time. An in-tank pump is going to require modification to the fuel tank. An external pump would be a heck of alot easier and would still work just fine.
Old 11-26-2006, 12:48 AM
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Hmmm, mine has a pump in the back.
That was what had me wanting to do such a mod (front pump).
Walbro was just a name, of course the pump used would have to meet pressure and flow requirments for the injection being used.

As for in-tank, it would take some modification to mount off of the sending unit.
I like the idea of pushing the fuel rather than pulling it, maybe it makes no real difference?

Anyway, probably enough P-bandwidth used on this thought already.
If I do this mod, I'll document & photo it.
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Old 11-26-2006, 04:19 AM
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I use a single pump on my turbo conversion and never had any fueling problems just overboost problems LOL!

so yours is in the back?? thats odd I remember the 74 NA 911s were like that but think they changed it to the front after that becasue of heat(?)

My single pump is simple is stock and flows great. also remember there are different sides to this those that are bulding 600hp engines and those building 3-350 hp cars(which is me) so requirements change.. I have been useing the megasquirt EFI and it handles everything very well
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Old 11-26-2006, 05:23 AM
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Quote:
Originally posted by mb911
I use a single pump on my turbo conversion and never had any fueling problems just overboost problems LOL!

so yours is in the back?? thats odd I remember the 74 NA 911s were like that but think they changed it to the front after that becasue of heat(?)

My single pump is simple is stock and flows great. also remember there are different sides to this those that are bulding 600hp engines and those building 3-350 hp cars(which is me) so requirements change.. I have been useing the megasquirt EFI and it handles everything very well
I'm with ya there mb.
If I can make around 350, i'd be plenty happy (for now).
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Old 11-26-2006, 05:33 PM
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My aftermarket turbo conversion requires two BOSCH 044 pumps in series (one up front and one in the rear).
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Old 11-26-2006, 05:55 PM
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FYI:
Bosch Part Number: 0580 254 044
Minimum Current: 12 Volts / 13 Amp
Operating Pressure: 72.5 PSI (5 Bar)
Minimum Flow @ Outlet: 80 GPH (300 LPH) High Pressure
Fuel Pump Location: In-Line
High Temperature Reduction: 8 GPH (30 LPH)
Weight: 1030 Grams (2.27 Pounds)

Bosch 044 fuel pumps are comparable to the Walbro GSL392 255LPH high pressure inline fuel pumps and will support up to 700 horse power. Can be used in sequence with an in-tank Walbro GSS340/GSS341/GSS342 or Bosch 040 fuel pump for even more support.
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Old 11-27-2006, 02:39 AM
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Hello!

Few facts:

CIS has higher system-pressure than EFI. CIS uses something like 7-8 bar and EFI uses 4-5 bar.

911 SC has one pump and runs CIS.
911 Carrera has one pump and runs EFI.
930 has two pumps in series and runs CIS.
There is no pump in engine bay on 930 or SC or Carrera, shiny thing is pressure accumulator.
One 044 pump is probably perfectly OK for 500hp as long as you run EFI, if you plan to make lot's of power with CIS, you would need twin pumps as you need both flow and pressure.

With other words, SC and 930 fuel system aren't the same, except that both use CIS which needs high system pressure. If converting to EFI, arguably one pump can be used.
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Old 11-27-2006, 11:55 PM
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Don't most guys using Bitz/MSII use Ford injectors? These would be high impedence rather than the low impedence peak and holds. From my experience (I race Fords) and my brother was the injector engineer at Honda in the 90's, the Bosche Ford style doesn't prefer 5-6 bar pressure. Most Ford injectors are designed to have a base of about 3 bar or 45psi to max flow pattern. This obviously is boost referenced so 3 bar going to 4 bar under boost.

Have your experiences shown different, Goran in respect to Ford style injectors? I brought this up because those converting with Porsche style injectors (Carrera) vs. those using Bitz or other have different requirements. From the test cell photos

Chrysler injectors flowed the most, appearing like a garden hose with miserable pattern. Honda was testing a lot of designs in the late 90's but I don't recall any Porsche injectors.
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Old 11-28-2006, 12:54 PM
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Quote:
Originally posted by Lukesportsman
Don't most guys using Bitz/MSII use Ford injectors? These would be high impedence rather than the low impedence peak and holds. From my experience (I race Fords) and my brother was the injector engineer at Honda in the 90's, the Bosche Ford style doesn't prefer 5-6 bar pressure. Most Ford injectors are designed to have a base of about 3 bar or 45psi to max flow pattern. This obviously is boost referenced so 3 bar going to 4 bar under boost.

Have your experiences shown different, Goran in respect to Ford style injectors? I brought this up because those converting with Porsche style injectors (Carrera) vs. those using Bitz or other have different requirements. From the test cell photos

Chrysler injectors flowed the most, appearing like a garden hose with miserable pattern. Honda was testing a lot of designs in the late 90's but I don't recall any Porsche injectors.
I don't quite understand what you are trying to say?

Most injectors need differential fuel pressure (across the injector) of 3 bar. That's where the spray pattern is optimal. This pressure is governed by FPR. Actual deadheading system pressure for particular pump is not critical as long as pressure is higher than 3 bar + boost and pump can deliver required mass flow at that pressure.

Remember, even if FPR raises system pressure to 4 bar at 1 bar of boost, injector itself will still see only 3 bar as it has 1 bar of boost "to fight against". Whole point of FPR is to obtain constant pressure across injector.

Further on, there are few injector manufacturers. Bosch, Siemens and Nippon-Denso are one of biggest.

There are two different types of injector coils: low impedance and high impedance. High impedance are cheaper to make, need less expensive EFI electronics annd are fitted in comercial vehicles.

Low impedance injectors require more expensive peak & hold circuitry which makes them open faster, and are usual type of injectors where you need good dynamics in pulse-width-ratio and where flow rating goes past 400cc.

There are also different types of nozzles. Like pintle-type, disc-type, multi-hole etc.

As far as I know, neither Porsche nor Ford makes their own injectors. It's all just a pick from AC Delco, Bosch or something elses shelf.

You can use any injector you like with MSII. Fully decked, it supports both low-Z and hi-Z injectors. Which one is up to user.
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Old 11-29-2006, 08:45 AM
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