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mace plenum spacer - throttle response

Discussion in 'Mace Engineering' started by vsv6dude, Aug 14, 2016.

  1. vsv6dude

    vsv6dude Member

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    Hi Mace

    ECOTEC PERFORMANCE 12MM PLENUM SPACER Holden 3.8L V6 VS VT VX VU VY - Mace Engineering Group

    I have given up on the aluminum spacer and try the plenum the space as per the link above.

    Quote from the website
    "Plenum spacer is a special spacer that sits between your plenum cover and intake manifold. Its main purpose is to improve air distribution (like our twin throttle manifold) between cylinders by slowing down the air speed inside the plenum chamber. As a result there is less of a pressure drop inside the plenum chamber between cylinders, and less air momentum, resulting in better air distribution and power. Not only will our spacer help you make more power, it will also help prevent any costly rebuilds through dangerous lean outs that occur with these standard manifolds in high horsepower/boost applications (due to poor air distributions). In addition to improving air distribution between cylinders, the increase in plenum volume also increases low down torque."

    I would like additional infromation in how increasing the plenum chamber volume and slowing the down the air speed increases low down torque. There is not enough science in the above statement as to the how the evening out of the distribution and less pressure drop increases low torque over and above what Holden did with the original plenum design. Did Holden get it wrong ? Does your R&D work and calc's to resizing the plenum spacer thickness prove Holden wrong ?

    It is also sold as it improves throttle response ie quicker. How can the throttle response be quicker if there is a slow down in air speed.
    Engine builder has told me with the plenum spacer the throttle response will be less responsive and slower due to the slow down in the air speed.

    These are genuine questions not internet trolling to take the mickey out of you.
     
    Last edited: Aug 14, 2016
  2. MACE

    MACE Well-Known Member

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    HI vsv6dude

    With the stock size plenum chamber, depending at what RPM you're at, air is rushing into the chamber and making its way down which ever runner it chooses. Sometimes it doesn't always take the right path or due to its turbulence, end up in the right place and this is why unbalanced amounts of air can enter each cylinder, compromising performance.

    By increasing the plenum chamber by 18% using our 12MM plenum spacer, the air entering the chamber now has time to properly fill any voids above each intake runner because its travelling slower, meaning as soon as the intake valve opens, regardless of which cylinder it is, it will have a sufficient amount of air for combustion, increasing the efficiency and performance of the motor.

    The factory plenum chamber poses as a restriction to airflow so the motor can only accelerate as fast as the amount of air available in the plenum chamber. Hence, by increasing its volume and through the dynamics discussed above, throttle response will also improve.

    When Holden designed this plenum chamber, their goal wasn't performance orientated. The chamber was engineered to be economical, cost effective and have the capability of comfortably fitting under the VS-VY commodore bonnet.

    For an even more detailed approach on the topic, please download and read the pdf in the link below:

    http://www.m3post.com/forums/attachment.php?attachmentid=1035835&d=1401483147

    Kind regards
    Damian
     
  3. delcowizzid

    delcowizzid on holiday

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    that article probably doesnt have much info being that the results are more carby signal and air/fuel mix homogulation effects more than anything and they obviously didnt correct the carby jetting to correct the air fuel ratio so as expected torque and hp changed and emissions
     
  4. commodore665

    commodore665 expat Saffa

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    They do work , I had one on my VX and have had one om my SV6 for the last 3 years , I would suggest also in getting a CAI as well .
     
  5. vsv6dude

    vsv6dude Member

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    Damian

    I note in the test engine main benefits was between 1700 to 2600 rpm above this it was negative. After the 2600 rpm, the effect of the increase in volume on the intake pressure level became worse and decreased the engine performance characteristics. Is the case with 3800 engine.

    In your testing on V6 3800 is the throttle response improved immediately from idle at 600rpm all way through the range less pressure on the pedal ?
    Is becuase it slightly shifts the power curve earlier in the rev range.

    I note it states that there is potential for the fuel to lean out is this possible for engines with oxygen sensor systems.

    Steve from Mace did comment in another thread where some members were getting improved fuel economy (upto 20% with the manifold spacer) it was from leaning out of the mixture. Is this correct or misinterpreted.

    Where I am confused is that some members have responded that the throttle feels spongy with the 25mm spacer on the natural aspirated vehicle as this provides more volume. Sometimes more is not beneficial. Is this because the 12mm spacers adds the correct volume for pressurization of the chamber.

    Thanks

    VSV6
     
    Last edited: Aug 16, 2016
  6. vsv6dude

    vsv6dude Member

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    Commy665 did you notice better throttle ie quicker response requiring less pressure on the pedal from idle and across the whole rev range ?
     
  7. Commo Baba

    Commo Baba Active Member

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    On my V6 I have the 12mm plenum spacer and the 'other' 12 mm (Insulator?) so the bonnet still closes and installation is easier. My two bits worth is that I'd suggest getting the MACE PCM (Brain 'Chip'). That is really only a slight remap but it uses the new airflow that the spacers give you and changes the shift a little I think too.

    You don't have your 'Location' filled in so I can't tell what sort of driving you'll be doing. In the country with my cooling system working fine I could prob have done *without* adding the CAI. For me it just added a sucking sound that makes it harder to hear if any pulleys might be noisey. Since I got the CAI with the clear lid I left it there once I'd put it on just cos it looks good ;P

    They all make *incremental* improvements. Don't expect a massive difference with just the 'bolt ons'.
    Combined with a full exhaust is what moved my torque down the range a bit.

    Think of a diff ratio change if you want to get serious with a quicker pickup. I didn't cos I'm all about country cruising.
     
  8. NeddyBear

    NeddyBear Veteran Mountain Biker

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    Me no understand, what is this CAI.
     
  9. vsv6dude

    vsv6dude Member

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    746rwhp vr v6 turbo ute 8.95 @ 148mph - Street Commodores Online Forum

    In the link attached there is a turbo-ed VS V6 doing 746rwhp approx 556 rwkw using the standard plenum.

    I infer the standard plenum be can be that inefficient despite the turbo if figures like this can be extracted.

    NA street driven cars are different to track cars yes but the 5+ times the stock 105 rwkw on a VS V6.
    Please help explain the inefficiency of the stock plenum or my misunderstanding or correlation.
     
  10. commodore665

    commodore665 expat Saffa

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    Cold air induction or intake
     
  11. VS_Pete

    VS_Pete Donating Member

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