Increase Compression

Discussion in '2005+ Ford Mustang v6 4.0L Tech' started by Benwhite911, Sep 11, 2018.

  1. Benwhite911

    Benwhite911 V6'ing & Dealing With It S197 Team Member

    Well, it's about that time again. This V6'er hasn't asked a stupid question in a while so I getting a little restless. If everyone could be so kind as to read the whole post first, then you can all take turns beating the sh*t out of me.

    I've been reading up a little on increasing compression on our 4.0 engines, because I read on the interwebs that that's a way you can increase performance. "Keep Reading" Now, in understand that the traditional method of doing this is through the use of a turbo or super charger to ram more air into the cylinder. I also came across something, of course I can no longer find it, that talked about decreasing the compressible volume as a way on increasing compression. I found that option interesting, as it's most likely to blow up in my face, and I can really only think of one cost effective way to do it. "Almost There"

    The pistons and valves, you can't really change those, unless you change them, and that wouldn't be cost effective. But what about the spark plugs? Is it possible to use a larger spark plug to decrease the compressible volume? When I say larger, I mean the part of the plug that gets screwed into the engine. It's an idea that's been rattling around in my head, so I wanted to put it out there and see if anyone had any thoughs on it. Ok, if you've made it this far, you are now free to do your worst.

  2. Wes06

    Wes06 forum member

    the only way to make it reduce compressible volume, is have it stick out into the chamber, which youd probably wind up smacking the pistons with.

    Correct way is change the pistons
    Benwhite911 likes this.
  3. 07gts197

    07gts197 forum member

    Wes nailed it. Besides increasing compression doesnt produce much power. Every full point of compression raised is worth about 10 hp, not worth it.
    Benwhite911 likes this.
  4. CammedS197

    CammedS197 forum member

    Thinner head gasket is another option. But that doesn't do a whole lot. Maybe .1 to .3 compression depending on the OEM thickness. But like said above that nailed it.
    Benwhite911 likes this.
  5. LarryJM

    LarryJM forum member

    I read a Chrysler report years ago on the Cross Rams that were offered in the late 50s and early 60's It was like 8 to 9 compression was worth 15% and 9 to 10 was 8% and 10 to 11 was 4% and 11 to 12 was 2% and 12 to 13 was 1%. They offered the Max Wedge in both 11.5 and 13.5 CR. One was 415hp and the other was 425. Then I know for sure a 8 MPG 70RR 9.5CR Magnum Cam 383 with 3.91 gears would not run on 29.9 cent reg gas.
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  6. Gab

    Gab Bullitthead

    While your thinking is correct (a larger plug will reduce combustion chamber volume), it isn't practical for another reason besides contact with the piston and/or valves: spark plug location isn't arbitrary, and it's location is determined for optimum combustion based on several factors (air/fuel mix, swirl, etc.).
    Benwhite911 likes this.
  7. Benwhite911

    Benwhite911 V6'ing & Dealing With It S197 Team Member

    Thank you all for your input on this. I have the say, that was relatively painless, as I as expecting a thorough A$$ Whoopin. I'll get back to hypothesisizen new performance ideas, and I'm open to suggestions too. So feel free to get thinkin, and remember, there are no bad ideas.

  8. stkjock

    stkjock ---- Madmin ---- Staff Member S197 Team Member

    I knew I'd be sorry opening this thread... I wasn't disappointed.
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