Throttle bodies versus a plenum chamber | FerrariChat
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Throttle bodies versus a plenum chamber

Discussion in '308/328' started by duck.co.za, Mar 19, 2010.

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  1. duck.co.za

    duck.co.za Formula 3

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    #1 duck.co.za, Mar 19, 2010
    There are some really great threads going around Fchat at the moment . So while we are at it can I throw in another ??
    I have this crazy plan ( once I've finished building my std motor ) that I want to try and graft a 360 motor onto a 308 gearbox !! I already have a good 360 motor and I bought a burnt motor to see if it possible before I tear into the good motor .
    Due to deck clearance issues the idea is to ditched the 360 plenums and I have been working on converting it to ITB using Ducati 999 items ( similar to a 355 )
    It would seem even with the ITB I'm going to have deck clearance issues so here's the question ? What difference will the ITB make ??
    The 360's have dual plenums with a butterfly between them to change the plenum volume and different inlet track lengths controled by a set of butterflies . Assuming I can get an aftermarket computer to controle all of this ! Is it worth considering keeping all these bits or are ITB going to be better ?
    Did Ferrari change from ITB's ( on the 355 ) to plenum chambers for cost reasons or was it to improve the low end torque ??
     
  2. mk e

    mk e F1 World Champ

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    #2 mk e, Mar 19, 2010
    All hard questions and assume all the answer start and end with "I think".

    The easy one is can an aftermarket ECU control the 360 manifold and the answer is yes I believe so.

    The switch Ferrari made from ITB 355 to plenum 360 was most likely about low end torque….possibly with cost thrown in to.

    I don’t believe you will not be able to get the TBs under the stock deck lid, but may need to lose the high mount injectors. I’m going to do some flow bench playing to see if I can set them a touch lower maybe to help my clearance problem, but mounting injectors in the intake will save you an inch.

    A good plenum intake should make about the same hp as ITBs but will have a touch less throttle response. I’m sure you could cut the 360 intake down a couple inches to get it to fit, you’d lose a little top end power, but fitting is good. It wouldn’t be as way cool as the ITBs though :)
     
  3. duck.co.za

    duck.co.za Formula 3

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    #3 duck.co.za, Mar 19, 2010
    You hit the problem right on the head , even if I use the bottom piece of the factory manifold keeping the injector in it original position and putting the TB's above . I'm going to have very little room for an airbox and filter . Ideally I would like to have a stock look ( carb airbox ) , but if I can't have this and I have to modify ( make a new ) deck lid !
    Is it an option to keep the plenums ? ITB's are still my first choice !!I must go and look what the torque difference is between a 355 and 360 .
     
  4. mk e

    mk e F1 World Champ

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    #4 mk e, Mar 19, 2010
    Normally all you need is about ½” above the stacks to get decent flow, an inch is plenty. You could pull the stacks off the TBs and make new ½” tall replacements, or build them right into the air box bottom and I would think you’d have it.

    I see no reason why you couldn’t use the 360 plenum as is or with a section of the runners cut out to make it fit if you wanted to.
     
  5. ramosel

    ramosel Formula 3

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    #5 ramosel, Mar 19, 2010
    I guess my answer is a question. What do you intend to do with this motor? Street car/Race car?

    You have to think Ferrari engineers hit on something when they designed the 360 (road) with a common plenum. On the other hand, their race motors are ITB.

    Rick
     
  6. mk e

    mk e F1 World Champ

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    #6 mk e, Mar 19, 2010
    I’d bet Ferrari is giving up 20 hp on top to gain 20 hp from 2000-4000 with the intake they are running on the 360.
     
  7. mk e

    mk e F1 World Champ

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    #7 mk e, Mar 19, 2010
    Another don’t forget thought is that ITBs with a common air box is a plenum intake effectively and the air box volume is a tuning parameter.
     
  8. duck.co.za

    duck.co.za Formula 3

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    #8 duck.co.za, Mar 19, 2010
    Road car , possibly a track day or two nothing serious . The reason behind it was you can't really get more than +/-300 streetable HP out of a 308 without throwing driveablity and reliability out the window !! Although now with the 355 3,5L derivative it's looking better !! But I've started down my path already and think of 400 NA HP in a 308 !!!
     
  9. duck.co.za

    duck.co.za Formula 3

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    #9 duck.co.za, Mar 19, 2010
    Mark on the 355 they kept the plenums seperate ( two 4 cylinder motors) I think . That motor was initially designed to rev to 10K I think . Is that deemed common ?
     
  10. st@ven

    st@ven F1 Rookie

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    #10 st@ven, Mar 19, 2010
    you might be right (just don't tell mk e) :):):)
     
  11. mk e

    mk e F1 World Champ

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    #11 mk e, Mar 19, 2010
    The reason they would do it as 2 4cyls banks is because the plenum volume probably gets too big otherwise. I think the F1 air boxes are divined inside too.
     
  12. mk e

    mk e F1 World Champ

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    #12 mk e, Mar 19, 2010
    I will point out that a 3.6 making 400hp is at 111hp/l so a 3.0 in a similar state of tune should be making 333hp….and 111hp/l is pretty mild ;)
     
  13. duck.co.za

    duck.co.za Formula 3

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    #13 duck.co.za, Mar 19, 2010
    I looked up the power differences
    355 380HP @ 8250
    268 lbs/ft @ 6000
    360 400HP @ 8500
    275 lbs/ft @ 4750
    Not much difference !!! But look at the torque peak 6000 in the 355 and 4750 in the 360 does this make a more driveable road car ??
     
  14. mk e

    mk e F1 World Champ

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    #14 mk e, Mar 19, 2010
    It will "feel" more powerful because more power is available at the rpms you are driving at more of the time. A quick down shift and the 355 is good to go and will hang right with the 360, but the 360 doesn't need the downshift.
     
  15. duck.co.za

    duck.co.za Formula 3

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    #15 duck.co.za, Mar 19, 2010
    That a pretty good discription ! so here's another one . Are the plenum chambers holding the 360 back ? Will ITB's make more top end power ?
    Also we only have 5 gears ( well 4 actually 1st is not good for much ! ) does the 355 and 360 not have 6 ? For a narrower power band ?
     
  16. duck.co.za

    duck.co.za Formula 3

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    #16 duck.co.za, Mar 19, 2010
    Went back and read the thread again you have already answered that !!
     
  17. mk e

    mk e F1 World Champ

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    #17 mk e, Mar 19, 2010
    It's not that the plenum pre se that is holding the engine back, it's the all the little things like the size of the runners, runner junctions, the mass air flow meters....little stuff.
     
  18. Pizzaman Chris

    Pizzaman Chris F1 Rookie

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    #18 Pizzaman Chris, Mar 19, 2010
    Dave, when do you have time to do all this thinking??

    For Gods sake man, get some sleep. :)
     
  19. duck.co.za

    duck.co.za Formula 3

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    #19 duck.co.za, Mar 19, 2010
    I'm dreaming Marks doing all the thinking
     
  20. duck.co.za

    duck.co.za Formula 3

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    #20 duck.co.za, Mar 20, 2010
    Last edited by a moderator: Sep 7, 2017
  21. mk e

    mk e F1 World Champ

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    #21 mk e, Mar 20, 2010
    Nice!

    The throttle plates are too small, but that can be fixed.
     

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