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Stradale power output

Discussion in '360/430' started by robinh, Jan 27, 2004.

  1. robinh

    robinh Formula Junior

    Jan 3, 2004
    622
    Cambridgeshire, Engl
    Full Name:
    Robin
    Yesterday I contacted Ferrari GB to ask which of the power output figures is correct, a) 305kW (409bhp) from the handbook or b) 317kW (425bhp) from the marketing literature.

    After confirming that both numbers are being used by Ferrari, Ferrari GB contacted the factory to ask which is correct - the answer from the factory is that they both are.

    The lower figure is the 'static power reached at the homologation bench' ie the figure you would get by taking the engine, bolting it to a bench, running it up and measuring the power at the crank.

    The higher figure is the power output reached under dynamic conditions, ie the power that the car will produce in road conditions with the full ram effect of the intake etc.

    I didn't ask about weight
     
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  3. wazza

    wazza Formula Junior

    Oct 9, 2003
    614
    Thanks for checking that out Robin.

    I don't know whether to believe that or not.
    It just sounds like a typical political answer.

    Oh Well,

    Over to you Brian, Thomas, any thoughts ?.

    Thanks anyway Robin.

    Wazza
     
  4. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,603
    Dallas, TX, USA
    That certainly sounds plausible. And maybe even justifiable if the CS intake is designed such that it produces that degree of "ram air effect"... but rules dictate use of homologation bench to do measurements.

    However, a 4.4% increase from ram air effect is pretty high! Not out of the question, but it would mean there's some pretty careful engineering of the airbox. But given the money Ferrari spends on F1, I am sure since the elimination of turbos that they've studied and extracted as much as possible from "ram air effect".

    With that said, it would make me think twice about messing with the air box! And a leaf blower is a necessity at all dyno runs!

    OTOH, if Ferrari was doing that, I would assume they measured with the most optimal of "dynamic conditions"... IOW "dynamic conditions" means "in their wind tunnel at 187mph"... soooo, you'll only see your full 425hp if you're doing a top speed run... and assuming linear relationships, that means we'd typically see 410-419hp at speeds of 30-120mph.

    And we should be able to show this by dyno'ing with and without a 100mph leaf blower... you should see a 5-10hp increase with the leaf blower (assuming the leaf blower is moving adequate air... might need two leaf blowers).

    Thoughts?
     
  5. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,603
    Dallas, TX, USA
    Another thought on this... I remember seeing two different numbers for the Modena as well... sometimes 400bhp and sometimes 395bhp. I need to go figure out where I have seen each number. I always wrote it off as some number that changed, and at a mere 5hp (1.25%), it was fairly easy to ignore. But I wonder if that's the same source... static vs. dynamic.

    I need to look for the 395 numbers and see if they came from manuals or where.
     
  6. dan360

    dan360 F1 Rookie

    Feb 18, 2003
    2,669
    Boston
    I think the 395/400 thing is the good old CV vs PS vs BHP thing. Two different but very close standards.

    I now have the image of a complex arrangement of scaffolding, 2 leaf blowers, duct tape, CS and Dyno imprinted in my head :)

    May I suggest that is one test too far and we accept that this is the modern incarnation of special italian HP. I think the weight topic should be our main focus, since is clear that US HP = EURO HP but this is not true for weight.
     
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  8. robinh

    robinh Formula Junior

    Jan 3, 2004
    622
    Cambridgeshire, Engl
    Full Name:
    Robin
    The new wind tunnel that Ferrari have I would guess would be able to do the test at max speed, something your average dyno would not be able to do. Ferrari are also very knowledgable about airflow at high speed, not just ram effect but down force etc and the response from the factory seems plausable - dynamic conditions 'give birth' to richer mixture in intake and cylinder is basically what they said - loved the 'gives birth' comment - guess that why the CS screams at high revs :)
     
  9. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,603
    Dallas, TX, USA
    Good point.

    Robin, since you had such good response getting a factory answer on the HP numbers, how about using that same channel for one more question (THE question for some of us):

    Marketing says 2822lbs. Some of the Euro manuals say 2844lbs. The US manuals say 2998lbs. All are curb weight with fuel. Actual weight has been measured at 3096lbs for a US model CS with only fire extinguisher added (full tank, no driver). And Autosport measured a Euro model CS at 3058lbs. (Note that the Modena's marketed to be 3064lbs.)

    So, what explains the weight differences?? (Details, please!)
     
  10. 4sfed4

    4sfed4 Karting

    Dec 22, 2003
    231
    From my dyno tests with forced induction on a 4 cylinder, I can say that an extra 16 hp (409 to 425 hp), takes about 1 psi more boost. So, if we just totally rough it and call the CS double the engine size and say it will make double the power from a given increase in intake pressure, then the ram air effect would need to be something on the order of at least 0.5 psi and that would be at the intake manifold (i.e past all the intake tubing, filter, throttle body, etc). I have not calculated the air velocity required to acheive that at a given density, but I suspect you are right in that it will be substantial (i.e. the 187 mph top speed)!

    Leaf blowers sure would be a good test if someone were to take the time to do it. It would really put things to rest. Ill volunteer my Ryobi!
     
  11. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,662
    This article indicates the actual test conditions of a motorcycle with ram-air. it is instructive in that the testers actually got 'useful' gains in performance (around 7%) at 170-ish MPH, which translates into 1.7%-ish around 85 MPH.

    http://www.sportrider.com/tech/146_9508_ram/

    But notice where they measure x milibars at the intake head, they only measure 0.6 milibars at the airbox where the engine feeds. This says that the intake is only 60% efficient at delivering head pressure to the air inlets.

    Still, this article indicates that useful performance gains can be achieved.

    In addition, at least in the F355, there is a passage at the bottom of the air inlets (sides of car) to dump water (raining) out of the engine air. This water dump will also dump most of the head pressure of the intake tract (if there is any to dump).
     
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  13. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,603
    Dallas, TX, USA
    In the 360 Modena there is also a whole in the bottom of the airbox to dump water... but it is very small, so I wouldn't expect it to dump all pressure achieved by the MUCH larger air inlet.

    It would be interesting to know if they removed that in the case of the CS in order to maintain that pressure... in which case they might need some form of baffle to reduce water entry through that inlet...

    Thomas, any chance the parts you were talking about at the inlet are for channeling water rather than reducing sound? And that would explain why the Challenge teams remove it... they don't have to worry about the intake boxes filling with water.

    Just speculating... I need my CS so I can look at these things.
     
  14. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    no the water is collected in a little box further upstream that has I believe two holes

    the resonator is a big enclosure around thr original pipe made air tight and connected through several holes

    furthermore the shop manual states that it is a air duct resonator
     
  15. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    This would be a nice explanation but it unfortunately opens the door for more questions (lengthy).

    Some observations
    - the intake design of the Modena & CS are the same with the exception of the carbon air filter boxes and different air flow meters as far as I can see
    - the 360 does not look to me like a RAM air intake design
    - CS 409 HP vs. Modena 400 static – so we have a 9HP increase for the CS
    - CS 425 HP vs. Modena 4?? dynamic – i.e. no significant changes to the air intake 9HP delta ?

    This all supports the believe I stated before that the CS engines are blueprinted to ensure that they are in the top percentile of 360 engines regarding performance and maybe the engineers did find a few HPs (exhaust, ECU map, …).

    I don’t believe the 360 is a RAM air intake design. A RAM air system usually has a forward facing scope and a long air intake tube that enlarges towards the end – the goal is to convert air velocity into pressure by slowing the air down – this would pressurize the air intake system (at high speed) similar to forced air induction systems - in fact the 360 design is the opposite the tube diameter at the air box is smaller than the diameter at the scope – additionally a RAM air intake is usually a completely air tight sealed design, which the 360 air box is not - so I would stay away from the over hyped RAM air intake as design in this case

    The 360 air intake manifold is a highly optimized system with variable length intakes, a valve that connects the manifold of each bank and all controlled by the ECU. All this is optimized to use resonance to increase the strength of the pulsing air. Very nice. Nevertheless the result is a single pulse emanating from each of the manifold to suck air out of the air box.

    The air box has the goal to act as air reservoir between the air inlet and the manifolds, i.e. its volume is designed that it is (should be) never emptied by the engine during an intake cycle and that it is able to replace the consumed air through the air inlet during the time period in which no air is withdrawn. Assuming that the cycle in which air is withdrawn is shorter than the cycle in which the air is replaced the air box can buffer between an air hungry engine and a “slow” air intake.

    To cut a long story short I don’t believe that the 360 air intake system use RAM or natural forced induction at all (pressure (blow) vs. vacuum (suck)). What happens is that at high speed air is pushed through the forward facing inlet into the air box. If hat component is missing (on a dyno) the engine will exhaust (suck dry) the air reservoir in the air box and the inlet can not replace the missing air fast enough. The effect is air starvation of the engine but I believe that the manifold is not pressurized as found in RAM = natural forced air induction systems .

    Considering a 16 HP increase in HP at the top end we are talking about a 3.7% increase in HP because of increased air flow at high speed. This is not an outrageous number especially if one considers that the engine ECU has a hand in this.

    Note, that the Challenger cars remove the resonator at the inlet and replace the system by a straight tube. This make the air flow into the air box more efficient but by no means convert velocity into pressure.

    My last dyno run shows a significant drop of power above 8000rpm. Assuming that the engine runs out of air - the ECU sensing the missing air flow (for its pre-programmed a/f map) would have to protect the engine by reducing throttle. This would be a very nice reasoning for such a significant reduction in power.
     
  16. arakisfilip

    arakisfilip Formula Junior

    Jan 25, 2004
    295
    dude that would explain your figures at the dyno, ferrari says it has the ram effect, why not beleve otherwise, they sure as hell would not lie to you b/c you could simply sue them, go to a ferrari mechanick at your local dealer or wereever, by him a six pack and nicely ask him to explain where execly is the ram effect in stradalle and how it works, I am not implying that you are ignorant, just that Ferrari air flow experts know just a bit aboud Ram efect and if they say its in the Stradalle then it is, if you find out it isn't sue them for everything they've got you should walk out a millionare
     
  17. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    you missed my point - I did not say that there is no effect caused by the car moving - I said that this is not the RAM Air Intake mechanism which is a specific way to pressurize the intake

    sort of "ram" vs. "RAM" - the RAM Air Intake has a special design I don't find while I clearly see that they ram air through the forward facing air inlet into the intake

    I have not seen anywhere that Ferrari claims that they have a RAM Air Intake system
     
  18. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,603
    Dallas, TX, USA
    Hmmm... you might be right... but...

    Look at it from filter to engine... you have two pipes that are indeed enlarging from filter to engine and ultimately dump into a larger cavity... that design is very reminiscent of a ram air setup... I don't think they'd have done it that way except to gently slow the air, creating a pressurized chamber. Presumably the length and other dimensions are set to tune the resonance.

    Behind the filter you want to make sure you maintain adequate pressure to force air through the filter at a fast enough rate to feed the filter-to-engine space (described above) fast enough to maintain the pressure there. To do that, you need much greater pressure on the outside of the filter (because the filter will absorb much of the pressure differential).

    So, to do that they have a much larger air box being fed by the inlet on the outside of the car. So, its somewhat like a second ram air system from outside to filter... though they seem to have taken much less care to smooth that airflow... happy to just dump it into a larger cavity.

    Thus, although the outside inlet is much larger than the final pipe inlet to the engine, if you remember the tremendous effect on airflow that the filter has, I think it could be argued that such is appropriate.

    I suggest you're right... the 360 does not have a ram intake system, but rather a dual ram intake system. One pressurizing the outer surface of the filters adequately to feed the second stage; the second stage generating pressure at the engine.


    Disclaimer: I have nothing to base this on other than the fourth-hand comments collected by Robin and the basic shapes of a 360 Modena intake.


    Thoughts???
     
  19. robinh

    robinh Formula Junior

    Jan 3, 2004
    622
    Cambridgeshire, Engl
    Full Name:
    Robin
    The answer Ferrari gave does not say that the car is getting a ram air effect, they simply said the dynamic conditions provide the extra power, ram effect was my add on (sorry), given it is the result of the forward motion of the vehicle, something usually associated with a ram effect.

    Brian is right, RAM effect, is usually designed by going from large to narrow (aircraft engine shape). It seems to me that the shape of the air intake from the filter box to engine could give rise to low pressure in the filter box causing air to be sucked into it from outside. I'm not a fluid dynamics expert in any way but it may also be that the design from outside to the filter box could also create pressure differentials so that the final effect is to force air into the cylinders.
     
  20. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    I love the dual ram effect theory! - Unfortunately the two pipes of the 360 stock are not enlarged they are of same diameter as far as I can judge by looking at them

    Here is a picture of a proper GT race setup (fyi I love the relocation of the coolant expansion tank – gets heat away from the air box):
     
  21. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    no - sorry I have to disagree - if you look at an aircraft engine the air intake widens from the intake diameter to the diameter of the first compressor - the narrowing of at the exhaust side if you reefer to that I think is there to increase velocity

    I am running out of knowledge - the only rule I remember is that if you narrow you increase velocity - if you widen you increase pressure - counter intuitive
     
  22. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,603
    Dallas, TX, USA
    Hey, I didn't say that! I said its going from wide to really wide to the filter; and then it goes from narrow to somewhat wide at the engine. Yes, dynamic fluid flow is a bit bizarre... but you want to gently slow it to most efficiently convert velocity into increased pressure.

    Thomas, you're right that the Challenge setup replaces those pipes with shiny ones that go from even narrower at the filter... but I thought that was because of the restrictors... but in any case, I believe the stock setup is also going from narrow to wider, just not as much so as the Challenge setup.

    Its too cold to walk out to the garage and check that right now (its 1am here)... but I'll check it out in the morning... maybe I'm remembering wrong.
     
  23. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,603
    Dallas, TX, USA
    The exhaust by-pass thread got me thinking...

    There's basically three configurations of 360 or CS:
    • US version
    • RoW catalyzed version
    • RoW non-catalyzed version
    So, I wonder if 425HP is the non-catalyzed output, while 409HP is the catalyzed output. They therefore use 425HP in the marketing (some parts of the world do get that), and use 409HP in the users' manuals where the cars are catalyzed??? We know they use 2822lb (non-catalyzed weight) in the marketing. And 16HP from removing the cats is certainly reasonable!

    Any CS owners that are sans catalysts? Can you look at your owners' manual and tell us the HP it reports??

    Just a thought.
     
  24. loungedog

    loungedog Formula Junior

    Nov 6, 2003
    286
    New Market, Ontario
    Now...THAT'S WHAT I AM TALKING ABOUT ;) I would love to see what test pipes would do for the Stradale! I understand someone has installed test pipes on the 360 Modena...has there been any testing of the car to see what HP increase it has with the test pipes yet?
     

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