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  1. #1
    Join Date
    Jun 2006
    New Orleans, LA
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    2005 Magnum 5.7 has low compression on 2 & 5 - need head advice

    I have a one owner, well maintained - regular synthetic oil changes - 130,000 mile 5.7 that has dropped a couple of valve seats/seals.

    I will need to install new heads - might as well go 6.1 Apache - I guess?

    While in there, thinking about a mild cam upgrade too?

    Looking for advice/suggestions.

    I haven’t even changed the factory tune yet! So I’ll need suggestions on the best software manipulator to painlessly settle in any mods I make.

    Thanks in advance...

  2. #2
    Join Date
    Apr 2019
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    No such thing as "6.1 apache" (I hate the internet...)
    Either 6.1 heads OR apache (6.4/392 heads), two different heads. 6.1's are better than the 1st gen 5.7's but use the same valve covers and valve length but bigger valves and different ports. Apaches are more related to the later eagle 5.7 heads port and valve length wise, with the apache having even bigger valves. The valves are so big you cannot use them on a 5.7 (bore size to small) unless the bore is notched. Your options are modified stock style heads, (which will bolt right back on no problem), 6.1 heads (which will bolt on, but will raise your compression and you will need adapters to keep the port mismatch from your stock intake manifold from being insanely horrible) or eagle 5.7 heads (same problems as 6.1 heads, as well as needing the later valve covers for the taller valves). Also 6.1 and eagle heads don't use EGR (your Magnum does) so you either live with the CEL or get it custom tuned to turn it off. A cam is definitely good idea and if you're actually considering anything than your stock style head then an intake manifold change is as well, as your stock intake will be the choke point.
    Last edited by Magnoom; 07-10-2019 at 12:28 PM.
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  3. #3
    Join Date
    Sep 2006
    Calgary, Alberta
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    ^^excellent information.

    Even if Apache heads were used, the losses due to cylinder wall impingement on air flow would negate the larger valve gains.
    Last edited by Hemissary; 07-10-2019 at 12:24 PM.
    2005 Magnum RT---Viper Venom Red----440ci Aluminum block----Short Runner Valve Intake--410mm BAER 6S Monoblock Extreme--Eibach Multi-Pro 2

    Custom--Grille Work--Hood--Headlights--Side View Mirrors--Rear Spoiler--Rear Diffuser--SRV Control System--Turbine Wheels

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