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Thread: 2.4L SMEC base cal questions and mods

  1. #1
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    2.4L SMEC base cal questions and mods

    Who's using the 2.4L base cal and how well does it run out of the box?

    What timing changes should be made when switching from the ski ramp pistons to the old style dish pistons?

    I do have a bit of experience with MPTune over the past few years so I do know where and how to make the changes, just not sure how much timing to pull and where.
    Don't get me wrong, I can log and tune, but I figured someone has to have a similar setup.

    Engine is a 2005 block, arias pistons with BC rods, arp 625+ rod bolts, machined bed plate for crank strap kit, main studs and billet oil pump gears. Top end is mildly cleaned up with BC titanium retainers and springs and stock cams for brake in.
    For tuning I have WB, EGT and mpscilink

  2. #2
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    Re: 2.4L SMEC base cal questions and mods

    Quote Originally Posted by player1up View Post
    Who's using the 2.4L base cal and how well does it run out of the box?

    What timing changes should be made when switching from the ski ramp pistons to the old style dish pistons?

    I do have a bit of experience with MPTune over the past few years so I do know where and how to make the changes, just not sure how much timing to pull and where.
    Don't get me wrong, I can log and tune, but I figured someone has to have a similar setup.

    Engine is a 2005 block, arias pistons with BC rods, arp 625+ rod bolts, machined bed plate for crank strap kit, main studs and billet oil pump gears. Top end is mildly cleaned up with BC titanium retainers and springs and stock cams for brake in.
    For tuning I have WB, EGT and mpscilink
    I believe a number of folks on FB maybe able to comment as well
    Regards,
    Miles

    DD '87 Sundance T1, 12PSI, SLH with rear disks
    '87 CSX #432

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    Re: 2.4L SMEC base cal questions and mods

    Quote Originally Posted by chromguy View Post
    I believe a number of folks on FB maybe able to comment as well
    I was afraid of that, most of the conversation has moved there. Unfortunately searching social media after the fact is lame.. :/

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    Re: 2.4L SMEC base cal questions and mods

    Quote Originally Posted by player1up View Post
    I was afraid of that, most of the conversation has moved there. Unfortunately searching social media after the fact is lame.. :/
    Yes I agree it is a PITA.
    Regards,
    Miles

    DD '87 Sundance T1, 12PSI, SLH with rear disks
    '87 CSX #432

  5. #5
    Supporting Member II Turbo Mopar Contributor tryingbe's Avatar
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    Re: 2.4L SMEC base cal questions and mods

    Quote Originally Posted by player1up View Post
    Who's using the 2.4L base cal and how well does it run out of the box?

    A.J. did and poor out of the box, he had to add more timing advance if I remember correctly.

    And the end, stock coil wasn't enough for 25psi and E85 so he changed to Megasquirt with 420A coil, zero ignition problem since.

    http://www.turbo-mopar.com/forums/sh...-Caravan-build

  6. #6
    Supporting Member II Turbo Mopar Contributor jonnymopar's Avatar
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    Re: 2.4L SMEC base cal questions and mods

    I'm running the base 2.4 cal on a mostly-stock long block and it runs beautifully compared to a certain trusted vendor's cal that I wasted my time with before.

    I had spark issues as well, but all I did was move to the later E-core type coil mounted close to the distributor and everything was fine after that. Granted, I've never pushed as far as 25psi with it, but it's seen 20psi on a stock turbo before.
    Jon J.

    1989 Daytona ES 2.4L DOHC
    2003 Neon SXT - gone but never forgotten

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    Re: 2.4L SMEC base cal questions and mods

    Thanks guys, I should have given a bit more info since a base cal would run way differently based on engine mods.
    I switched to an e-coil years ago and am super happy with it.

    tryingbe, I must have read that thread a hundred times, lol
    A.J. is using the ski ramp pistons and based on the timing map, the 2.4 base cal has way less timing than a stock map for ski ramp pistons. I'm guessing that's why it ran like crap.


    Jon, What pistons are you running?

    My boost target is about 18 on the +40 injectors, but I have some big ones sitting on the shelf waiting on tuning progress

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    Supporting Member Turbo Mopar Contributor 2.216VTurbo's Avatar
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    Re: 2.4L SMEC base cal questions and mods

    Quote Originally Posted by player1up View Post
    Who's using the 2.4L base cal and how well does it run out of the box?

    What timing changes should be made when switching from the ski ramp pistons to the old style dish pistons?

    I do have a bit of experience with MPTune over the past few years so I do know where and how to make the changes, just not sure how much timing to pull and where.
    Don't get me wrong, I can log and tune, but I figured someone has to have a similar setup.

    Engine is a 2005 block, arias pistons with BC rods, arp 625+ rod bolts, machined bed plate for crank strap kit, main studs and billet oil pump gears. Top end is mildly cleaned up with BC titanium retainers and springs and stock cams for brake in.
    For tuning I have WB, EGT and mpscilink
    Im looking at building my 1st 2.4 head, full P&P and oversize valves. You did mild porting springs and retainers, why did you decide against the +1 valves, did you consider them? I haven't done any research yet, is there a tuner/builder with flow numbers shared? Pretty much I'm counting on poking a rod outta the block at some point on GoldMember so I wanna pre-emptively build a new slug

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    Re: 2.4L SMEC base cal questions and mods

    Quote Originally Posted by 2.216VTurbo View Post
    Im looking at building my 1st 2.4 head, full P&P and oversize valves. You did mild porting springs and retainers, why did you decide against the +1 valves, did you consider them? I haven't done any research yet, is there a tuner/builder with flow numbers shared? Pretty much I'm counting on poking a rod outta the block at some point on GoldMember so I wanna pre-emptively build a new slug
    I did consider the big valves and may do a full built top end at some point, but here is the reasoning behind the decisions I made.
    The springs were to replaced because of the unknown state of the original springs and reports that stock springs are pretty bad at keeping holding pressure as they get old. The retainers had to be replaced anyway when going to the new springs due to the larger diameter and I picked titanium really because, why not? Those retainers are so light, they feel like they're made of plastic.
    I'm only planning on 350-400hp and the stock head should get me there. The bottom end was built to withstand 100k miles not really 1000hp AND if I want to go crazy on the top end in the future, I know the bottom end can handle it and a head swap is half a days work

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    Supporting Member II Turbo Mopar Contributor jonnymopar's Avatar
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    Re: 2.4L SMEC base cal questions and mods

    Quote Originally Posted by player1up View Post
    Jon, What pistons are you running?

    My boost target is about 18 on the +40 injectors, but I have some big ones sitting on the shelf waiting on tuning progress
    I am running the ski ramp pistons. I'm essentially running a "stock" SRT-4 shortblock, except for the 1st gen 2.4 block and crank.

    I'm surprised to hear that the ski ramp pistons would use less timing. My impression was that they respond well when you add timing. If the base cal is conservative, that might explain why.
    Jon J.

    1989 Daytona ES 2.4L DOHC
    2003 Neon SXT - gone but never forgotten

    Can't polish a turd? Sure you can! Just don't reuse the rag afterwards, dummy!

  11. #11
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    Re: 2.4L SMEC base cal questions and mods

    yes, The ski ramp pistons like MORE timing. I'm running dish top arias pistons so I'll start with the base low timing.
    I have gotten it fired up but I'm having an issue where the engine light comes on as soon as it hits any boost at all. since the entire harness was moved and everything was touched, I have to go back thru it and have a look

  12. #12
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    Re: 2.4L SMEC base cal questions and mods

    ok, so, it runs. Here's my take on the base cal:

    Starting: Starts fine when cold albeit a little smokey. Hot starts are super rich and flooded my car when trying an immediate restart after a shutdown or stall.

    Idle: Seems to idle well. AFR at 13.8-14.2 on my engine and cal scaled for the +40 injectors

    Drivability: Revs high ( 2kish ) when coming to a stop until it gets warm, but that goes away at operating temp and runs well out of boost.

    Problems: Knock...ugh...
    I've not been able to test the knock curve yet as the stock 2.2 knock sensor mounted on the block is SO sensitive it seems like it will pick up a wrench dropped on the garage floor at my neighbors house!! :/

    Driving around out of boost under 4k rpm while logging knkv shows the base noise level of the engine to be about 0.5v which seems quite a bit high BUT it has forged pistons and no balance assembly.

    I do have a way to actually listen for detonation so I'll drive a bit while listening to verify the base noise level before changing the tune.

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