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fuel delivery

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  • fuel delivery

    I've got a fuel pump question for the S14 in my M2. When I put the S14 in back in 1995, Pete McHenry recommended using an in-tank prepump from an '84 318i and an electric pump from 2002 tii. I took Pete's recommendation, and saw 45 psi at the fuel rail. However, I'm a little concerned with my CF airbox and MegaSquirt that I may have a higher fuel demand than the stock S14. Back in '95 Jim Conforti burned a custom chip for me, and at the time said he was getting 210 hp from stock S14s with that eprom.

    Now that I've deleted the MAF and have a straight shot to the intake plenum with a CF airbox and big ITG free-flow airfilter and can program the fuel and spark with MegaSuirt, I'm wondering if I might get a little more air for more hp and need larger injectors, and thus more fuel. I made some quick fuel calculations based on 200 hp, and assuming an 80% duty cycle it looks like I might need 32 lb/hr injectors instead of stock 24 lb/hr. This also means I'd need minimal 128 lb/hr fuel flow, and probably a little higher for safety. I'll have to actually measure the pump output from the fuel rail, but if the tii pump flows 174 lb/hr then I should be able to keep my current pump setup but need larger injectors.

    Does this sound right, or have I missed a decimal place somewhere?
    '76 M2

  • #2
    If you didn't solve your fueling issue, I have 2 sets of 30 lb./hr injectors (high or low impedance), with a 3.5 or 4 BAR (Porsche / Bosch 944S) FPR you can get the added fuel you need.


    • #3

      Totally unrelated to answering your problem...

      I just wanted to let you know that your M2 was the first S14 powered 2002 I ever stumbled across. This was back on your previous website. I think I must have read your whole site almost weekly for a few months with my own twisted visions of a M2 in the future. I'm glad to see the car is still around and progressing forward!

      Best of luck on the fuel resolution.
      Chris L.

      Spray paint and tire shine doesn't equate to a "restoration!"


      • #4
        Thanks, Chris. Always glad to provide entertainment in the "rust meets S14" category! It is a fun car.
        '76 M2