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302 vs. 351, same setup

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    #1

    302 vs. 351, same setup

    I know this subject has been beaten to hell and back but I was thinking about feasible engine swaps into my Merc [unlike that supercharged Exploder setup I had planned], and was wondering about this: If I took the heads, cam, and upper intake off an Explorer 302, and put them on a 351 roller block, with the GT40 Lower intake for a 351 [yes I know, about as easy as finding an albino in Harlem], would mileage really suffer, and would I notice any signifigant power gains? This is including a set of GT40-P headers from FRPP and 1.7 RR's, if I can use them on a standard 351 block.

    The drivetrain would be a stock AOD, possibly a light shift kit, and a 3.27 TL rear end. Exhaust would be a custom, catted H-Pipe with Impala 2.5" tails.

    Opinions?
    Nick
    88 Colony Park LS
    G-pa's old car, but he's cruisin around heaven in his 69 wagon now
    Future plans:Semi HO conversion, or Explorer motor swap, shift kit, PI springs and sway bars, KYB-GR2 shocks
    Tags: None
    #2
    Feasable, yes.

    Mileage probably won't be too great tho. 351s are gas hogs...

    In reality, the cost of mileage usually balences out with all the insane torque and power you are now making
    1983 Grand Marquis 2Dr Sedan "Mercules"
    Tremec TKO conversion, hydraulic clutch, HURST equipped!

    Comment

      #3
      But with the same setup on the 351, how much mileage would I actually lose?
      Nick
      88 Colony Park LS
      G-pa's old car, but he's cruisin around heaven in his 69 wagon now
      Future plans:Semi HO conversion, or Explorer motor swap, shift kit, PI springs and sway bars, KYB-GR2 shocks

      Comment

        #4
        Nate's car gets like 15 mpg, but thats a carb. If you went EFI, I'd guess somewhere in the 15-18 mpg range, all things being equal.
        86 Lincoln Town Car (Galactica).
        5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

        91 Lincoln Mark VII LSC grandpa spec white and cranberry

        1984 Lincoln Continental TurboDiesel - rolls coal

        Originally posted by phayzer5
        I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

        Comment

          #5
          superlinc 96 exploder 302= 20 mpg
          nate's vic 351 4bbl 15 mpg
          any questions?

          1986 lincoln towncar signature series. 5.0 HO with thumper performance ported e7 heads, 1.7 roller rockers, warm air intake, 65mm throttle body, 1/2" intake spacer, ported intakes, 3.73 rear with trac lock, 98-02 front brake conversion, 92-97 rear disc conversion, 1" rear swaybar, 1 3/16" front swaybar, 16" wheels and tires, loud ass stereo system, badass cb, best time to date 15.94 at 87 mph. lots of mods in the works 221.8 rwhp 278 rwt
          2006 Lincoln Town Car Signature. Stock for now
          1989 Ford F-250 4x4 much much more to come, sefi converted so far.
          1986 Toyota pickup with LSC wheels and 225/60/16 tires.
          2008 Hyundai Elantra future Revcon toad
          1987 TriBurner and 1986 Alaska stokers keeping me warm. (and some pesky oil heat)

          please be patient, rebuilding an empire!

          Comment

            #6
            That's where EFI kicks yall's carbs ASSES! An EFI 351 properly running and tuned will easily get 20mpg, if you drive nice. The disadvantage of a larger motor is that is can more easily suck down more gas. The the more you use the gas, the more is uses gas. Unlike a 302 which is not as impacted by how much to the floor you do. And more so, unlike a 4cylinder which can run WOT all day long and not see as much of an impact on the milage.

            Explanation: (These numbers are not accurate, it's an example of the effect.)
            Driving a EFI 302 at no more than 40% throttle yields 20mpg.
            Driving a EFI 351 at no more than 40% throttle yields 19mpg.
            Driving a carb 351 at no more than 40% throttle yields 16mpg.

            (In EFI 80% is about the cut off point where computer no longer dictates amount of fuel based on sensors, but instead goes to "open loop" where a predefined amount of fuel is dumped, general a little rich. This is a performance oriented programed condition)
            Driving a EFI 302 at no more than 80% throttle yields 16mpg.
            Driving a EFI 351 at no more than 80% throttle yields 13mpg.
            Driving a carbed 351 at no more than 80% throttle yields 12mpg.

            Under normal steady driving conditions an efi 351 will be only slightly lower gas milage than a 302. However, if you are a city dweller, a 351 will hurt mileage, EFI or not.
            Last edited by Blaze86Vic; 06-28-2006, 10:08 AM.

            Comment

              #7
              All 351's I've ever drove suck gas. Of course, that was in a Bronco and a F250. One was 2bbl, the other was a 4bbl. And of course no OD.

              The plan sounds good, though.

              The EPA has done some testing for us:

              1993 Bronco 5.0/Auto - 14/18
              1993 Bronco 5.8/Auto - 12/16
              1990 Country Squire - under restoration
              1988 Crown Vic LTD Wagon - daily beater

              GMN Box Panther History
              Box Panther Horsepower and Torque Ratings
              Box Panther Production Numbers

              Comment

                #8
                Hrmm...I'm generally not to heavy footed, and with the Explorer cam+long stroke, I might be able to keep my foot out of a 351 a little bit less than a 302. Blaze, thanks alot for taking the time to explain all of that, it really helps. I'm goin to keep playing with this in my head for awhile, but it sounds like a very considerable option.
                Nick
                88 Colony Park LS
                G-pa's old car, but he's cruisin around heaven in his 69 wagon now
                Future plans:Semi HO conversion, or Explorer motor swap, shift kit, PI springs and sway bars, KYB-GR2 shocks

                Comment

                  #9
                  Oh yea, a couple last,, retarded questions...can I use an HO ECM with all of this? And 19 or 24lb injectors?
                  Nick
                  88 Colony Park LS
                  G-pa's old car, but he's cruisin around heaven in his 69 wagon now
                  Future plans:Semi HO conversion, or Explorer motor swap, shift kit, PI springs and sway bars, KYB-GR2 shocks

                  Comment

                    #10
                    EFI better? LAUGHABLE! I'm not gonna let some dopey computer do my engines thinking for it. I'M in control! I don't fully trust an engine computer that uses Intel chips anyway
                    Pebbles-1968 Ford F250
                    Pile of Junk! An Electronics Project Site (To get wet by)<---Clicky! NEW STUFF!!!!

                    Comment

                      #11
                      Mang, get an exploder motor, with an HO cam and 1.7s, and go with it.

                      You will NOT be disapointed...
                      1983 Grand Marquis 2Dr Sedan "Mercules"
                      Tremec TKO conversion, hydraulic clutch, HURST equipped!

                      Comment

                        #12
                        Originally posted by Grand_Marquis_GT
                        Mang, get an exploder motor, with an HO cam and 1.7s, and go with it.

                        You will NOT be disapointed...
                        I have to agree, it wil be much esier tha a 351 EFI. Though a 351 will be a monster with an EFI setup.

                        Comment

                          #13
                          Originally posted by Blaze86Vic
                          I have to agree, it wil be much esier tha a 351 EFI. Though a 351 will be a monster with an EFI setup.
                          This is why I'm considering it. That and...well...its different, but the Exploder motor sounds like the most likely choice.
                          Nick
                          88 Colony Park LS
                          G-pa's old car, but he's cruisin around heaven in his 69 wagon now
                          Future plans:Semi HO conversion, or Explorer motor swap, shift kit, PI springs and sway bars, KYB-GR2 shocks

                          Comment

                            #14
                            Originally posted by 88MercWagon
                            Oh yea, a couple last,, retarded questions...can I use an HO ECM with all of this? And 19 or 24lb injectors?
                            Maybe 19 lb with a mass air ECM but its iffy. a Lightning ECM would be the shit, but you could do it with a standard HO mass air ecm and a tune I bet.
                            86 Lincoln Town Car (Galactica).
                            5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                            91 Lincoln Mark VII LSC grandpa spec white and cranberry

                            1984 Lincoln Continental TurboDiesel - rolls coal

                            Originally posted by phayzer5
                            I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                            Comment

                              #15
                              Originally posted by 88MercWagon
                              If I took the heads, cam, and upper intake off an Explorer 302, and put them on a 351 roller block, with the GT40 Lower intake for a 351 [yes I know, about as easy as finding an albino in Harlem], would mileage really suffer, and would I notice any signifigant power gains?
                              Cast iron Marine 5.8 GT40 style lowers are available used for less than $150. You should see 50HP over a 302 with the same cam and induction.

                              Comment

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