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Enzo (& others) Variable Geometry Intake Questions

Discussion in 'Technical Q&A' started by Samg16, May 4, 2021.

  1. Samg16

    Samg16 Rookie

    Jan 31, 2019
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    S J Gilding
    First off, I hope I’m writing this in the correct place, it seemed the most logical but forgive me if it is not!

    I am currently writing a paper for my fluid dynamics class at university, the subject for which I have chosen the application of variable length/geometry intake systems on naturally aspirated vehicles; for a large part of this paper I will discuss the systems used by Ferrari, and how these have developed over time starting with their most simple systems when they first began to explore this technology to their modern systems.

    A lot of information can be found online about these systems, but with the Enzo I’m struggling as there seems to be conflicting information with some sources claiming the intake runners were infinitely variable (like the LaFerrari) and others claiming they were 2-position only - does anybody know for sure how the system works?

    Thanks in advance!
     
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  3. tazandjan

    tazandjan Three Time F1 World Champ
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    Here is what the OM says about it:

    Variable volume intake manifold with F1 telescoping offtake system.
     
  4. luccio

    luccio Rookie
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    I worked on dynamic intake manifold systems in the past and the closest to the above description I can think of is either a linear actuation like this:

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    Or in the case of a V configuration, more likely a sort of "marching tuba" principle which is still linear but allows greater amplitude in the variation of the length for better results.
    In both cases, the goal is to increase the volumetric efficiency of the engine by getting a better pulse on the intake (matching the frequency of intake valves opening and closing) to optimize a ram effect. There's quite a bit of litterature on these and they're relatively easy to implement, starting with calculation then simulation and ultimately adjusting a few set points on the actual engine on a torque bench...
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Some of the wording in the Enzo SPC describing the parts ("variator") indicates that it is a variable position system, not just 2-position -- but that's just an observation, not really conclusive.
     
  6. luccio

    luccio Rookie
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    Agreed, I haven't seen it (would love to) but it sounds like a continuous actuation and not flap based. It could be linear (likely) but also rotational (unlikely, seeing how the intake is built). Anyone has any blueprint or diagram about the engine (ref 140B) ?
     
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  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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  9. luccio

    luccio Rookie
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    Absolutely.
    I've done electric actuation before, and once dealt with an engine that had flap based short/long channel intakes energized by the vacuum line.

    Wondering how this one works. According the diagrams (and thanks: I was looking for one of these parts sellers that show these - awesome) this is valve actuated.
    Also according to diagram on the pneumatic page, only depression hoses are connected to the intake plenum, so I assume it's hydraulic and probably using the oil pressure to energize the linear actuators... still looking at diagrams :rolleyes:
     
  10. Samg16

    Samg16 Rookie

    Jan 31, 2019
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    S J Gilding

    thanks for all your responses guys. I’m pretty sure it’s definitely a telescoping trumpet-type system like the LaF, I’m just unsure whether it was infinitely variable or 2 position only. I searched hard as I didn’t want to waste anybodies time but even on this forum there are posts where people suggest both different options.

    also, regarding terminology, even a 2 position intake runner is technically ‘variable’. The vvt system on the 360 is controlled by a ‘variator’ on the exhaust cam, but is 2 position only. (Not trying to be a smart ass, rather playing devils advocate
     
  11. luccio

    luccio Rookie
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    I was looking around some more and do believe it's a two position variable length intake, not a continuous one. It makes sense anyway as the resulting VE curve is already pretty smooth and above 1.0 with such a system, and V12s don't lack torque :)
     
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  13. brogenville

    brogenville Formula Junior
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    The Enzo intake system appears to be pneumatically controlled, and with no apparent encoder to feedback intake position, it must just be two position.

    Could see if we could pull up the maps that control variable intake on various V12 Ferrari's if thats helpful?
     
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  14. luccio

    luccio Rookie
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    Agree that it would settle the speculation. It may not be more than a few set points (RPM) between which the intake should be in either upper or lower position... One aspect that bothers me to conclude it's pneumatic is the vacuum line wouldn't offer enough force to overcome the force created by the same (de)pressure on such a large surface with the tiny linear actuators seen in the diagram. The surface of the piston(s) of the actuator(s) would have to be greater than the surface of the lower plan of the plenum.
    Therefore it's probably either hydraulic (using oil pressure) or if pneumatic there might be a compressor nearby... IMO the vacuum line can actuate flaps, but not pneumatic cylinders to beat itself.
     
  15. brogenville

    brogenville Formula Junior
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    The intake vacuum will act on little diaphragms in order to actuate the runners. Its not shown on the parts diagram as a separate entity, but I expect that the intake manifold comes complete with a couple of these (or something similar) hidden under it:

    https://www.ferrariparts.co.uk/part/ferrari/168275
     
  16. Samg16

    Samg16 Rookie

    Jan 31, 2019
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    S J Gilding
    So, after a little more digging around the subject, it appears the system may be controlled via the same ‘variator control valve’ that is used to control the VVT on the 360 and other vehicles (indeed the Enzo top), which is shown on this diagram as number 29:

    https://www.ferrariparts.co.uk/Diagram/Ferrari/Enzo/012-Air-Intake-Manifold-And-Air-Box

    It appears there is one of these valves on each bank of 6 intake runners, located centrally - it can be seen fairly clearly in this picture:

    https://www.carthrottle.com/post/wqg82eq/

    Looks like it is mounted vertically into the intake casting between the 2 central runners. Also in this cutaway picture you can see it looks like there is one vertical actuator rod for each bank mounted centrally, with 4 additional stabiliser/guide rods between each runner.

    I guess the use of these valves to control the system would indicate it is actuated hydraulically rather than pneumatically, although the valve may work with air as all it is really doing is directing fluid. It’s a shame the drawings in the parts catalog do not show the actuating mechanism in more detail!!

    Either way, if it is controlled by hydraulics or pneumatics, I would be fairly certain it is a simpler on/off system, rather than an truly variable system, where you would expect to see a mechanical linkage (as with the LaF)
     
  17. Samg16

    Samg16 Rookie

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    S J Gilding
    That would be very helpful if you could & it’s not too much trouble for you! Thanks again for all your help guys!
     
  18. Samg16

    Samg16 Rookie

    Jan 31, 2019
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    S J Gilding
    Something else I’ve just noticed upon further exploration of the parts diagram for the intake (https://www.ferrariparts.co.uk/Diagram/Ferrari/Enzo/012-Air-Intake-Manifold-And-Air-Box) part no’s 22 & 23 are listed as a ‘threaded union’ which appears to be a male-male pipe fitting, and a ‘gasket’ which I think is actually a copper crush washer in this case. There is one of these per bank of six, so 2 total, which screw into the casting between runners 2 & 3 and again this can be made out in this picture along with the supply hose that connect to the fitting (https://www.carthrottle.com/post/wqg82eq/)

    As I can see no other reason for an oil feed to the intake runners, this would indicate to me that it is indeed oil pressure which moves the actuator.
     
  19. brogenville

    brogenville Formula Junior
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    Hmmmm.... maybe... I do also note that there is a "variator valve" in there too... maybe it is hydraulic...

    Need to see if I can get the workshop manual off a pal to check.
     
  20. Samg16

    Samg16 Rookie

    Jan 31, 2019
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    S J Gilding
    yeah, both the variator valve & the threaded union are missing from the parts diagram for the MC12s intake which did not receive the variable intake system. If you could get your hands on that it would be awesome.
     

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