M1 or Port-Matched LD4B on 408

Discussion in 'Small Block Mopar Engine' started by MuuMuu101, Dec 5, 2018.

  1. MuuMuu101

    MuuMuu101 Well-Known Member

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    I have a 408 built by IMM engines. I currently have a port-matched LD4B on it and am making 523 hp @ 6000 rpm and 522 ft-lbs @ 4500 rpm on their engine dyno. I'm planning on installing a Holley Sniper on the car (hopefully before next spring, not sure if I'll upgrade to a Holley EFI Dual-Sync distributor). Is it worth it to replace the LD4B for a Mopar M1 intake (no port work done)? I figure the intake is a big restriction as the LD4B was meant for 273/318's. But how much of a hp/tq increase do you think I'd get? Do you think it will ruin the driveability with the EFI?

    Crank: Forged Scat 4"
    Rods: Forged Scat I-beam
    Pistons: Forged Icon dish (4.030")
    Camshaft: Custom Comp Hydraulic Roller (card was lost but I believe IMM said it was a 238/242 or 242/246).
    Lifters: Morel Hyd. Roller
    Timing Set: True Double Roller
    Oil Pan and pickup: Milodon Road Race Pan
    Headers: TTI Shorty
    Compression: Approx. 9.6-10:1

    Heads: EngineQuest reworked by IMM
    Intake valves: 2.02"
    Exhaust valves: 1.60"
    Rocker Arms: 1.6
    Intake manifold: Edelbrock LD4B port-matched
    Carb: Holley 850 DP w/ 1" spacer
    Total Timing: 34 deg

    This car will have a mix between cruising and racing (autocross and road racing). Probably 50/50 (respectively) at most but could potentially be 75/25. What are your thoughts?
     
    Last edited: Dec 5, 2018
  2. toolmanmike

    toolmanmike FABO Staff Staff Member FABO Gold Member

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    Interesting that the LD4B could feed a stroker. Proof that It's a good manifold. And not ported just port matched?
     
  3. MuuMuu101

    MuuMuu101 Well-Known Member

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    He didn't write anything on my build sheet regarding the intake aside from "Edelbrock 4." IIRC, IMM specifically said they "Port-Matched" the intake because they ported the EQ Heads.
     
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    • toolmanmike

      toolmanmike FABO Staff Staff Member FABO Gold Member

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      Those are some good numbers!
       
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      • MuuMuu101

        MuuMuu101 Well-Known Member

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        That's on 91 octane too!
         
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        • SSG_Karg

          SSG_Karg Dismember

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          I’d bet the M1 would be good for another 20-30 hp.
           
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          • toolmanmike

            toolmanmike FABO Staff Staff Member FABO Gold Member

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            Yep.
             
          • 72bluNblu

            72bluNblu FABO Gold Member FABO Gold Member

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            Edelbrock air gap RPM. A good flowing dual plane is the way to go on a street car.

            Bunch of dyno pulls for different small block intake manifolds. No M1 unfortunately, but a modified Edelbrock Torker II is included, as well as an Air Gap. The Air Gap wins horsepower and torque below 5k rpm, then gives up a little of both from 5200 to 5800, then pulls up even again from 6k to 6200. I’d rather have the advantage down low than from 5200-5800.

            Dyno-Testing Small-Block Intakes - Induction Extravaganza - Mopar Muscle Magazine
             
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            • rumblefish360

              rumblefish360 so close yet so far away

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              Hard call because the fuel distribution on the M1 intake can be fixed, enhanced and ported for higher flow way over the dual plane. And yes I’d call it restrictive. Even though there very good intakes.

              But the low end trade off could make you unhappy in the street and strip considering you have a small cam inside of the engine. And that “small” is for ether cam listed. A hair more so being it is a 4 inch arm stroker.

              I don’t know how well the FI will be on the dual plane. Try it, what the heck! Do you have the M1 single now? If you don’t, wait on the purchase.
               
            • 360duster

              360duster Well-Known Member

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              regarding the switch to sniper efi: i run it on my 408, works fine. I had some trouble with RF interference, could be solved with some adjustments in the tune. This was with a magnetic trigger distributor, you should check out the new Holley Hyperspark distributor, it´s got a hall-sensor and no un-necessary advance mechanism, and it´s cheaper and more easy to install than the dual sync.

              regarding the intake: i switched from port matched EDE Performer RPM to a port matched EDE Victor.....lost a few hundreds 60ft. So i think the EDE Performer RPM is the best bet for a true street / strip.

              Michael
               
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              • rumblefish360

                rumblefish360 so close yet so far away

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                @360duster Is you car full weight and interior?
                Can you tell us about it some more. Cam size etc..
                Thanks.
                 
              • gzig5

                gzig5 FABO Gold Member FABO Gold Member

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                I thought that some of the low end advantage of a dual plane intake was negated with an EFI throttle body and a single plane was the way to go??

                I would guess that the M1 would be much better at the top end and the EFI would help maintain the low/mid range HP and drive-ability, but that is a guess.
                 
              • MuuMuu101

                MuuMuu101 Well-Known Member

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                I have it and it's sitting on my shelf. I believe it's unmoddified. It's what was on the engine when I bought it. It was a bone stock 360 with cast internals and a Paxton supercharger. I don't really want to buy another intake.

                Car weighs about 3500 lbs with a full tank of gas and no driver. No back seat. Full 6-point cage with swing out arms.

                I honestly don't know anything about the cam size. IMM said they gave me the cam spec sheet when they gave me the engine, but I've never seen it and it's not in my folder. But the cam is pretty aggressive. The car needs about 5-10 minutes to warm up before it will want to move. Otherwise it will die.

                I would think the EFI would give it better manners at the low rpm and since it's a big engine there will be plenty of torque down low. I would also think that if the LD4B is so restrictive, the M1 may not lose that much down low. But I have no personal experience with it, yet.
                 
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                • 12many

                  12many Well-Known Member

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                  So you haven't actually driven the car with the engine as setup yet (with whatever fuel system is on it)?? Why yank shit apart that looks to be pretty impressive (from the dyno results) as it is now? Pretty easy to swap intakes later and be able to compare them.
                   
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                  • MuuMuu101

                    MuuMuu101 Well-Known Member

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                    Correct. I have not driven it with EFI. I have driven it with a carburetor.
                     
                  • rumblefish360

                    rumblefish360 so close yet so far away

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                    OK, so you have both intakes. Changing them is only going to cost time, gaskets and beer.

                    Sounds like a party!
                    And time to experiment!
                    Ahhhhhh, the old fashion way of doing things, trail and error. Loved it back in the day. I still fool around with it. People ask why. I say why not. Some shake there heads.
                     
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                    • B3422w5

                      B3422w5 Well-Known Member

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                      MuuMuu.....
                      I have an M1 single plane i have no need for. Was on my 360 when i bought the car( motor was fresh) was on a very short while before i swapped it.
                      Unmodified, like new, cheap
                       
                    • 12many

                      12many Well-Known Member

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                      I think he mentioned he already had one lying around, but I don't. I'd be interested, but your inbox is full!
                       
                    • 360duster

                      360duster Well-Known Member

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                      Mine is a 68 Valiant V100 2dr Sedan, full interior except front bench (one racing seat at the track instead), full weight (has got a roll bar and subframe connectors, too). Engine is a cast crank 408 with KB 356 hypers, around 10:1 with cnc´d procomps, ede Victor intake and the Sniper EFI, 248/248° hydraulic roller cam around .620" Lift, 113° LSA. It ran 11.38 in this condition…..but ran 11.40 before with a shelf cam (comp XR286HR-10), ede Performer rpm intake, 750 carb and Indy X-Heads.....so far no significant improvement to me. I suspect the cam, it seems not to like the LSA, so i´m going back to a shelf cam (Lunati Voodo 243/251° / .600" Lift, 110° LSA) to see if it´s faster. And i bought a "real" converter now, a PTC 8" made for my car…...definitely wanna get this 10.99 timeslip ;-)

                      Michael
                       
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                      • myduster360

                        myduster360 FABO Gold Member FABO Gold Member

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                        I would think so too. When tuned properly, EFI "adds" more off idle and low end than you expect.

                        Case in point: I ran this giant M1 single with multiport on a 9:1 360 Magnum in my Duster.

                        When i installed a Comp XE274H cam [230 int./236 exh .520/.522] I was concerned it would be a dog off the line with the huge plenum, adapter and 950cfm throttle body since the Duster was Rocking 3:21 and 9" wide 28" tall tires. lol those worries ended quickly. Stone cold I could fire it up, back out of the driveway and lay a 20ft patch a 1/4 throttle. lol

                        upload_2018-12-6_14-8-42.png
                         
                      • rumblefish360

                        rumblefish360 so close yet so far away

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                        Michael, that is awesome brother! Now that’s layin out the indoy! Dang! Yea!
                        Best of luck with the combo!


                        Thanks! This is the real world experience I and the OP certainly needed to hear. That is awesome.
                        You don’t, by chance, have any time slips of the before and after would you?
                        Oh! Great picture as well! Nice!
                         
                      • rmchrgr

                        rmchrgr Skate And Destroy

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                        If the LD4B is making 523 HP and 522 ft lbs of torque, KEEP IT! My 416" motor has more Ricky Racer go-fast parts but makes less power and torque than your milder 408.

                        Switching to the single plane will essentially move the usable RPM band up which IMO makes little sense for street driving and road courses. Drag racing, yes but because that's only WOT. Can't vouch for your driving style but you generally don't stay at WOT for long periods on the street or road courses. Having more torque available at a given RPM would be of more benefit.

                        Staying with the LD or any dual plane will theoretically keep the torque peak in a more usable RPM range. Maybe an LD340 or as suggested already an RPM Air Gap would be what you want? The AG gives up very little on the top end, probably be a better choice over an M1.

                        Torque benefits you most coming out of turns, the car will accelerate quicker at a lower rpm and would be easier to rev match. Don't think you want to slow for a turn then alternately have to zing it to 7 grand to get to where the torque starts coming on.

                        Sniper - I had mistakenly thought that EFI on a dual plane was a no-go becuase of fuel distribution issues but I was corrected on that by a well-known builder. If the combo does OK with the dual plane and a carb, it will be fine with EFI.
                         
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                        • AJ/FormS

                          AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                          Jus thinking
                          5 to 6 seconds gets you 60 mph.
                          300/350 is more power than most street chassis can handle. From zero to 60, you will only pass thru the power peak once, and in all likelyhood will be roasting the tires at WOT. So on the street, pick one with nice manners for cruising 30mph in Drive at like 1200 or something,lol.
                          But you didn't build your combo for street, yet you say 50% street, so, it kind needs to be civil.
                          The LD4B is already port matched.

                          5 to 10 minutes warm up, at what ambient.
                          I agree that the street tune in the 850 might need some help. She might need a bit more fuel from the transfers and a little less idle timing, to get the rpm back down. Yeah I'm guessing.
                           
                        • MuuMuu101

                          MuuMuu101 Well-Known Member

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                          Maybe I'll post an ad sometime asking if anyone wants to trade for an RPM Airgap. I honestly don't see what I need the M1 for unless I was doing a turbo build or drag racing as you said.

                          I'm pretty mellow on the streets. On the freeway I try to cruise at 60 mph in 6th gear.

                          Anywhere between 50-90F.
                          Everyone says that, but I've had two people look at it and set the carb and timing exactly the same. She idles at about 850 RPM. She just dies if you try to move her before the water temp reaches 150F. If water temp is around 150F and I am at a stop sign and try to slowly ease from the stop, the car wants to die. She runs at 190F all day and doesn't have any problems once at temp. That's the reason for wanting to go EFI.
                           
                        • rumblefish360

                          rumblefish360 so close yet so far away

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                          Sounds like it needs a little more choke on.