Changing a 2-Filter Car Into a One-Filter Car? | FerrariChat
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Changing a 2-Filter Car Into a One-Filter Car?

Discussion in '308/328' started by mwr4440, May 21, 2023.

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  1. mwr4440

    mwr4440 Five Time F1 World Champ
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    Mark W.R.
    #1 mwr4440, May 21, 2023
    I have an '81 GTSi that has 2 Fuel Filters. At some point after, Ferrari went to a Single Filter using the same brand and model number, IIRC.

    Anybody modify their car to remove the Dual-Filter set-up and convert it to a Single Filter design? It would at first-blush, ELIMINATE a number of potential fuel-leak points if nothing else.

    Any suggestions/comments "For" or "Against" and parts needed or 'things to know' to accomplish this task would be greatly appreciated.

    BTW, my car is a "Driver" and will NEVER 'See' a Concourse.

    Thanx in Advance,
     
  2. energy88

    energy88 Three Time F1 World Champ
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    #2 energy88, May 21, 2023
    I'd suggest comparing the pressure drop results of each alternative versus the max that the fuel pump can handle. One filter sounds like an improvement and probably less pressure drop and shouldn't hurt, but be sure. Also, the manufacturers (filter(s) and fuel pump) may have changed the specs in the past 40 years.
     
  3. mwr4440

    mwr4440 Five Time F1 World Champ
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    #3 mwr4440, May 21, 2023
    Here is a pic of the set-up in my car, borrowed off of ebay.

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    The fuel flow is from Bottom to Top.

    The top Single OUTLET has a line that screws into the hard fuel line that runs across the top of the front firewall of the engine bay to the Passengers side (LHD), where it ultimately connects to the Fuel Distributor.

    The Lower Single INLET is feed from the fuel pump/accumulator.


    So, I would think a fuel pump that can handle this, could easily handle a Single-Filter set-up.

    Yes/No?
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #4 Steve Magnusson, May 21, 2023
    The single fuel filter would be fine functionally. The difficulty will be the availability of any needed parts -- you might need to get some custom lines/fittings from CISFlowTech (Larry Fletcher), etc.
     
  5. energy88

    energy88 Three Time F1 World Champ
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    #5 energy88, May 21, 2023
    My first thought was that the filters were in series (some Mercedes diesels) and not parallel as shown. Wonder if the dual parallel arrangement was to extend service intervals if the original filters were loading up too fast and causing drivability issues and frequent trips back to the shop for consumers?
     
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  6. mwr4440

    mwr4440 Five Time F1 World Champ
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    #6 mwr4440, May 21, 2023
    That maintenance thought crossed my mind too.
     
  7. mwr4440

    mwr4440 Five Time F1 World Champ
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    #7 mwr4440, May 21, 2023
    Steve,

    Actually, a fair number of those parts are readily available here. And dirt cheap. Why? I have no idea. But Mega-Tons of the things are still bought and used daily.

    I can?/could buy 2 NEW Complete Sets of the Banjo Bolts found on the Bosch Fuel Distributor* (FDs), for the asking price of just ONE USED Bolt on ebay USA, as an example. (That was Pre-Covid. Haven't checked lately, so ......).


    * - I rebuild Ferrari FDs for 'Grins and Giggles' when I can buy them for DIRT CHEAP. Working on one right now, who's Plunger was Completely FROZEN, turns out from just years worth of collected Mouse Piss (fuel) 'Varnish.' It appears to now be working just fine. When done, ON GO all new Banjo Bolts and the old ones go into the 'Parts Bin.'
     
  8. dave80gtsi

    dave80gtsi Formula 3
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    #8 dave80gtsi, May 22, 2023

    Hey there Mark - My 1980 GTSi has the same dual fuel filter setup as yours. And I'd vote to keep it just as it is.

    Simple reason - I replaced both of my filters not too long after I first bought the car, and I now know that I will never need to replace them again during my lifetime!

    I like the idea of the fact that I have twice the fuel filter internal area as compared to later cars, and so any chances of my ever having the fuel flow disrupted due to a filter clog of some nature has been cut in half.

    I've always viewed the dual filters as sort of an endearing quirk of these cars, which is always good for a "Huh?" reaction when others view it for the first time at a car show.

    So, yeah, I'd for sure leave well enough alone!

    Cheers - DM
     
  9. Hannibal308

    Hannibal308 F1 Veteran

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    #9 Hannibal308, Jun 10, 2023
    This is a really common setup for aircraft fuel systems. Less resistance and more redundancy should something build up in one part.
     
  10. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #10 Rifledriver, Jun 10, 2023
    More Ferrari paranoia. In the old days really abominable gas was the norm in Italy. That plus when fuel injection came out there were 2 big differences. One was a much higher sensitivity to dirt and the FI system flowed a great deal more fuel, most going right back to the tank in a system that had a high degree of sensitivity to input pressure. The cars shortly after yours went to a single filter because it rightly seen as overkill.

    I'd change it in a heartbeat.
     

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