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  1. #1
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    Recipe for 2005 300C buildup?

    Hi everyone,

    I wanted to poll people out there who have done upgrades as to what is a a good recipe for building up my 2005 300C to 400 RWHP or somewhere thereabouts while keeping in mind cost effectiveness. Currently, I have a CAI, 85mm TB and Predator 91 CAI canned tune. My goal is to add the power without losing MDS, driveability, idle quality, emissions and reliability.

    I realize supercharging solves a lot of problems but it creates some as well. Also, I've been discouraged on what I've read so far on the reliability of the '05-'06 heads (valve seats) and the durability of the pistons under boost.

    I was thinking heads, cam, headers, intake - to start. I'd love to have a roots-type blower but I think that would require rebuilding the whole bottom end. Also, it seems like the rear end would need work as well to handle the added power - but where the line is draw isn't clear to me.

    I'm not looking to track the car and it is my daily driver. There needs to be some refinement and safety factor built in just in case the wife drives the car. I know there's a ton of experience on this forum, so please feel free to correct any of my assumptions and make any recommendations you feel are me worth looking into.

    Thanks, guys!
    2005 300C Magnesium Pearlcoat



  2. #2
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    I think Heads, Cam , Intake would be a good start. You definitely don't want to run into issues with the valve seats dropping on you so anything you can do to combat that is a plus. If it's a street car I think your rear will be fine for now. I'm an advocate for over building, but typically things only break back there when you hook if there are no plans for drag radials or slicks in the near future I think you'll be fine.

  3. #3
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    Cool - thanks for the quick reply. I was less worried about the back end, but it's good to hear from someone with experience.

    For the build, should I use Eagle heads, 6.1 heads, some other modified 5.7 heads? I'm guessing the 6.1 is out since I'd like to keep MDS. For the cam, my understanding is that the sidewinder idles smooth and can ever run on a canned Predator tune. However, it might be limiting the potential of the build because it is on the milder side.

    And for the intake, would that just be a ported 5.7L intake or a 6.1L intake or some aftermarket one? If I eventually go the supercharged route, does it make sense to mess with that at all?

    Thanks again for your feedback,
    Dave

  4. #4
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    I once had an 05 300C, I did an HHP heads and cam combo and was close to what your wanting... Get ahlod of srt8_hmi on here ask him his thoughts
    2005 Bright Silver Metallic 300C (Stolen, Recovered, Sold to another member)
    2007 Yellow Super Bee Charger SRT8 #0960 of 1000 (KB 2.8 Super Charged and keeping forever)
    2009 Modern Blue Pearl Grand Cherokee SRT8 (Traded for something that wasnt such a lush)
    2012 Black Avenger R/T
    2012 Maximum Steel Grand Cherokee Altitude

    "Viewed from half a world away, a bomb is a political concern; viewed from less than a foot away, a bomb is just a high-stakes exercise in problem-solving, where making a mistake means a final, terminal education in the physics of expanding gases"


  5. #5
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    I'm guessing that would be the Stage 1 heads/cam from HHP? Would that setup allow adding a supercharger down the road - say the Arrington kit with 8 psi boost?

    Speaking of SC's - are they going to cause problems with dangerously lean conditions in certain cylinders? I know some kits use an extra injector at the intake, but that seems to be risky move too.

  6. #6
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    No, on a 5.7 I did the Stage 3, but you do lose MDS... However I can say MDS is crap on the early LX cars. My car went from 21-24 hwy with mds, to 20-22 without mds

  7. #7
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    sub'd. also have an 05 C

  8. #8
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    Interesting - my personal best (tank) was 27.3 mpg on a trip from Columbia, SC to Raleigh, NC -I used cruise and thought the MDS was working pretty well in that context. Funny thing is I have logged every single fillup since I've bought the car, but since my computer crashed I lost the spreadsheet showing the running tally MPG. I need to get off my lazy butt and re-enter all of that data someday.

    After doing the 91CAI tune, it does seem like my MPG has gone down a bit lately (~2mpg) but there's other variable like new tires at play. Does the use of a SC prevent using MDS? I'm not clear on how the system would handle the switch between 4/8 cyl. I know the bypass line acts like a turbo's waste gate in a typical SC - but the constant 4/8 switch seems like it would be tricky (unless in that mode, it would never be using boost anyway).

  9. #9
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    All my questions have been answered in this thread.

    I love every single one of you.

    That is all.

  10. #10
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    I have an EARLY 05 build Magnum and I will say they are a little strange than later ones.The 05-06s that have dropped valves have alot to do with overheating.An untuned hemi runs hot!Thats for emissions but,Ive changed my theromstat to a 180 and set the fans lower.It stays at 181-185 all the time.You just need to keep an eye on how hot its running.I have seen some cars that run 220-235deg all the time!I have 150000 miles on my heads.They were off once for a cam swap and 6.1 exhaust springs and pushrods.It still goes like he11!I did the cam swap at 24k so I have beat on it ALOT!!So dont be too afraid of the 05 heads.There are alot of better and nicer heads out there now.If I was gonna do heads I would say the Eagles are some of the better ones and dont have to port them.Oh well Im babbling thats my .02
    05 Magnum R/T RWD inferno red
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    for converter call (203)969-2886

  11. #11
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    Thanks, BIGDAVE - that's good to know. I'm still running the stock t-stat for now, but I do have a Diablo 91 CAI tune loaded. When I put the DIC in diagnostic mode, I see the car settling in around 203 degrees and peaking around 208 during WOT runs. Since ambient temp is low right now, I'm willing to bet I'm peaking a lot higher in the summer. So, it sounds like a t-stat is a good bit of insurance for me. One question: does a 180 t-stat mess with emissions inspections (would a 190 be safer)?

    If anyone has a brand/part number for a recommended replacement, please let me know (don't want to get a cheap one that sticks open or closed).

  12. #12
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    Quote Originally Posted by Daphod74 View Post
    Hi everyone,

    I wanted to poll people out there who have done upgrades as to what is a a good recipe for building up my 2005 300C to 400 RWHP or somewhere thereabouts while keeping in mind cost effectiveness. Currently, I have a CAI, 85mm TB and Predator 91 CAI canned tune. My goal is to add the power without losing MDS, driveability, idle quality, emissions and reliability.

    I realize supercharging solves a lot of problems but it creates some as well. Also, I've been discouraged on what I've read so far on the reliability of the '05-'06 heads (valve seats) and the durability of the pistons under boost.

    I was thinking heads, cam, headers, intake - to start. I'd love to have a roots-type blower but I think that would require rebuilding the whole bottom end. Also, it seems like the rear end would need work as well to handle the added power - but where the line is draw isn't clear to me.

    I'm not looking to track the car and it is my daily driver. There needs to be some refinement and safety factor built in just in case the wife drives the car. I know there's a ton of experience on this forum, so please feel free to correct any of my assumptions and make any recommendations you feel are me worth looking into.

    Thanks, guys!
    You can run the Inertia Super Spartan W/MDS.

    On a 113 LSA it is very sreetable & make $hitloads of midrange TQ.

    W/a set of free flowing heads/intake manifold, a moderate stall & 3.06 gears W/< 26" drag radials it has 11 second potential & can still get 25-26 MPG on the highway.


    The results of such a combo are in my sig below. (the results below are W/a 3.23 axle ratio on 28" rubber, the 3.06/< 26 combo should do slightly better)

    EDIT: Oh yeah, go W/a 180ish TSTAT on the street & swap in a 160 @ the track.
    Last edited by PowerWagon896; 01-07-2012 at 11:45 AM.




    426 RWHP/460 RWTQ on motor, 555 RWHP on a 150 shot of juice
    12.062 @ 113.97 on motor, 11.306 @ 121.87 on a 125 HP shot
    Stock 5.7 rotating assembly, still MDS enabled

  13. #13
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    Quote Originally Posted by Daphod74 View Post
    I'm guessing that would be the Stage 1 heads/cam from HHP? Would that setup allow adding a supercharger down the road - say the Arrington kit with 8 psi boost?

    Speaking of SC's - are they going to cause problems with dangerously lean conditions in certain cylinders? I know some kits use an extra injector at the intake, but that seems to be risky move too.
    Quote Originally Posted by 05Silver_C View Post
    No, on a 5.7 I did the Stage 3, but you do lose MDS... However I can say MDS is crap on the early LX cars. My car went from 21-24 hwy with mds, to 20-22 without mds
    The heads have nothing to do W/MDS.

    It's all about the cam specs.

  14. #14
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    Quote Originally Posted by Daphod74 View Post
    My goal is to add the power without losing MDS, driveability, idle quality, emissions and reliability.
    Best bet to achieve this is with a blower simple and plain run 5-6 psi and keep it out of part throttle boost for long periods of time and you will be fine.

    my 05 has stock heads and they see 15psi of boost daily sonn gonna turn it up a little more .pacharger was running his 5.7 @9 psi on stock heads and had well over 100 passes at the track with the blower.

  15. #15
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    Thanks for all of the great feedback guys! At what point do you need to consider upgrading the bottom end of the 5.7L motor? It sounds like a cam/heads/headers upgrade can go pretty far and the stock 5.7L can handle it provided the compression is within spec. Once you start to add significant boost, it seems like that's when you should consider bolstering the bottom end with forged components and eutectic pistons, etc. Is that right?

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