406 v6 compression figures???
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  1. #1
    1000+ Posts cav91's Avatar
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    Default 406 v6 compression figures???

    Hi all, has anyone with preferably a low kms d8 (or all least the earlier engine) done a compression test on it? I gave my car some spark plugs (amongst alot of other things) over the weekend. While it was a part I gave it a compression test, which surprised me. With all most 400 thousand kms on it, it still got 150 psi evenly across all cylinders. My question is what we're they originally how much had mine lost?

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    Cheers Chris.
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  2. #2
    Fellow Frogger! Roland's Avatar
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    Hi Chris,
    That figure sounds about 10 - 20 psi down on what I would expect from a 10.5:1 compression ratio.
    However, all my reading indicates that 150psi is as good as new!

    Did you oil up the cylinders and get a second reading - a significant improvement here will indicate that the rings are worn!

    As soon as the red 406 V6 your father sold me three weeks ago arrives here in the west, I will be doing a compression test and I will post the results. It's done 225Kms and been regularly serviced by a Peugeot dealer so it should be interesting to compare results from the two cars.

    Of course there is the golden rule: Unless the pressures are abysmally low (say 120psi - rings definitely worn), then as long as they are all the same then you will have a smooth running engine!

    cheers
    Roland


    PS. I'm looking for the compression height measurement for a piston from a D8 V6 - haven't got any engines in bits have you that you could measure?
    Land Rover Discovery 4
    406 Coupe D9 - Manual (2002)
    307 Hdi Estate - Auto - (2007)
    307 Hdi Sedan - Auto - (2007)
    505GR Estate - Personal Import from UK 1971cc Manual (March 1986)
    405 Mi16x4 (all the parts ready to install into the LeMans body)

  3. #3
    1000+ Posts cav91's Avatar
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    Quote Originally Posted by Roland View Post
    Hi Chris,
    That figure sounds about 10 - 20 psi down on what I would expect from a 10.5:1 compression ratio.
    However, all my reading indicates that 150psi is as good as new!

    Did you oil up the cylinders and get a second reading - a significant improvement here will indicate that the rings are worn!

    As soon as the red 406 V6 your father sold me three weeks ago arrives here in the west, I will be doing a compression test and I will post the results. It's done 225Kms and been regularly serviced by a Peugeot dealer so it should be interesting to compare results from the two cars.

    Of course there is the golden rule: Unless the pressures are abysmally low (say 120psi - rings definitely worn), then as long as they are all the same then you will have a smooth running engine!

    cheers
    Roland


    PS. I'm looking for the compression height measurement for a piston from a D8 V6 - haven't got any engines in bits have you that you could measure?
    Well that's good to hear. I didn't add oil. However I did retest the front bank hot. And it came up exactly the same!

    That red car flew! In comparison to my car that one felt really good. Dad never actually drove that one but I was tempted to replace mine with it!! It would be interesting to here what the compression figures are on it. That was one very healthy engine! I think I've proven the longevity and reliability of the v6. Mines done some extraordinary things!

    Unfortunately the only v6 we have in bits is from a laguna v6. So it's the later engine. And in bits I mean missing 1 head. Haven't got any d8 ones apart.

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  4. #4
    Fellow Frogger! Roland's Avatar
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    Chris,
    That's the same engine just with a higher compression ratio. It's the "ES9J4S" engine. It has the same sized pistons but with a higher dome.
    The Compression Height is the same for both the ES9J4 and ES9J4S engines.
    It's the distance from the centre of the gudgeon pin to the piston top deck at the edge of the piston (not the top of the dome!)

    As far as I know the measurement is 32mm but I haven't been able to confirm this.

    You would have to pop a piston out to measure it - is that possible and not too much trouble?

    Cheers
    Roland



    PS. I may want the plastic inlet manifold off the Laguna if you still have it.
    I can confirm this sometime next week.
    Last edited by Roland; 6th March 2017 at 06:26 PM.
    Land Rover Discovery 4
    406 Coupe D9 - Manual (2002)
    307 Hdi Estate - Auto - (2007)
    307 Hdi Sedan - Auto - (2007)
    505GR Estate - Personal Import from UK 1971cc Manual (March 1986)
    405 Mi16x4 (all the parts ready to install into the LeMans body)

  5. #5
    1000+ Posts PeterT's Avatar
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    I'd check it. 150psi is too low for anything but a well worn engine. It should be 180-185psi min if healthy. You need to check with another engine and another gauge.

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  6. #6
    1000+ Posts cav91's Avatar
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    Quote Originally Posted by PeterT View Post
    I'd check it. 150psi is too low for anything but a well worn engine. It should be 180-185psi min if healthy. You need to check with another engine and another gauge.
    To be honest I expected a well worn engine! Sounds like a good supercharge candidate. But I think for what it is and what it's done I'm happy even with them being even! I was talking to my rwc mechanic today and he says as low as 90 is still useable of course it's a worn out motor but still useable. He was rather impressed when I told him the kms and the compression figures. It would be good to hear what Roland's car has.
    I did a compression test on a 240ish kms d8 406 v6 a few years back and got 120 across the board. Motor sounded healthy!
    Last edited by cav91; 6th March 2017 at 11:16 PM.
    2011 Renault Koleos manual petrol, yes it's boring, but not as boring as:
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  7. #7
    1000+ Posts cav91's Avatar
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    Quote Originally Posted by Roland View Post
    Chris,
    That's the same engine just with a higher compression ratio. It's the "ES9J4S" engine. It has the same sized pistons but with a higher dome.
    The Compression Height is the same for both the ES9J4 and ES9J4S engines.
    It's the distance from the centre of the gudgeon pin to the piston top deck at the edge of the piston (not the top of the dome!)

    As far as I know the measurement is 32mm but I haven't been able to confirm this.

    You would have to pop a piston out to measure it - is that possible and not too much trouble?

    Cheers
    Roland



    PS. I may want the plastic inlet manifold off the Laguna if you still have it.
    I can confirm this sometime next week.
    If I get a chance I'll whip a piston out. How soon did you need to know the answer? I thought demanu on here had a few engines stripped down?

    Sent from my SM-G930F using aussiefrogs mobile app
    2011 Renault Koleos manual petrol, yes it's boring, but not as boring as:
    2017 Renault Koleos auto

  8. #8
    Fellow Frogger! Roland's Avatar
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    Not urgent as in this week but if you have a moment spare in the next short while!
    I've been trying to get full dimensions of the original pistons with a view to having low compression forged ones manufactured and therefore dimensions is what I wil have to supply to the piston manufacturer (probably Wiseco or maybe Rosspistons)!
    This is for the turbocharger which will go on the car in a couple of months.

    From all my research 350hp is not hard to get especially with low compression pistons!


    cheers
    Roland
    Land Rover Discovery 4
    406 Coupe D9 - Manual (2002)
    307 Hdi Estate - Auto - (2007)
    307 Hdi Sedan - Auto - (2007)
    505GR Estate - Personal Import from UK 1971cc Manual (March 1986)
    405 Mi16x4 (all the parts ready to install into the LeMans body)

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