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Thread: Holden Captiva - Opinions?

  1. #21
    Ext User(Noddy) Guest

    Re: Holden Captiva - Opinions?

    On 23/07/13 11:00 AM, John_H wrote:

    > With the appropriate gearing I'd expect the performance to be exactly
    > the same, but not for long.


    But I'm not talking about changing anything *other* than the engine.

    > The reason being that heavy diesels work best from around 80% of their
    > maximum power output, and need to be able to maintain that level of
    > output continuously whereas most car engines can't. A suitably
    > detuned petrol engine with the same power output, as typically used in
    > aircraft, would be a vastly better basis for comparison and there'd be
    > SFA difference in performance, other than fuel efficiency.
    >
    > It's the power to weight improvement associated with forced induction
    > that has allowed diesels to compete with petrol engines in cars... not
    > the increase in maximum torque which is necessary to attain similar
    > power outputs from a similar weight engine, albeit at lower rpm.


    You avoided answering the question :)

    In this case I'm not concerned about the effects of longevity, or making
    changes to suit each particular type. I'm simply asking that if
    horsepower remained the same but torque dropped off to one third of what
    it was, what would the likely performance differences be?







    --
    --
    Regards,
    Noddy.

  2. #22
    Ext User(John_H) Guest

    Re: Holden Captiva - Opinions?

    Jason James wrote:
    >
    >Torque times RPM =Power. If you add another gear-set in the gear-box,
    >with the driven gear having 1/4 the amount of teeth than the gear it's
    >driving, revs will drop to 1/4 of what they were, but torque will
    >quadruple bringing the formula back to the same power out.


    Except you've got it arse about. You need lower gearing to increase
    the torque at the drive wheels... ie to increase the torque
    multiplication the revs need to increase (at the same road speed).
    IOW you'd normally expect to have better acceleration in a lower gear
    but it doesn't always work that way either.

    The maximum acceleration in any particular gear will always be at the
    engine's maximum torque rpm (which is what fools many into believing
    that torque is the major factor)... however maximum acceleration is
    achieved by keeping the engine as near as possible to its maximum
    power rpm (as determined by the gearbox step up ratios), which kinda
    defeats the perceived benefits of having an engine with higher maximum
    torque and less power.

    Continuously variable transmissions also exploit maximum power rather
    than torque for the best acceleration and pulling ability (as do close
    ratio gearboxes). The more you load a CVT the higher the engine will
    rev.

    --
    John H

  3. #23
    Ext User(John_H) Guest

    Re: Holden Captiva - Opinions?

    Noddy wrote:
    >On 23/07/13 11:00 AM, John_H wrote:
    >
    >> With the appropriate gearing I'd expect the performance to be exactly
    >> the same, but not for long.

    >
    >But I'm not talking about changing anything *other* than the engine.


    I which case you want to operate one under optimum conditions
    (performance wise) but not the other.

    It's a meaningless comparison.

    --
    John H

  4. #24
    Ext User(D Walford) Guest

    Re: Holden Captiva - Opinions?

    On 23/07/2013 11:00 AM, John_H wrote:
    > D Walford wrote:
    >>
    >> Hilux has 343nm and the lighter Forester has 229nm, Hilux weighs 1710kg,
    >> Forester 1475kg both have 126kw so the Forester has a better power to
    >> weight ratio.
    >> Hilux diff is 4.56, Forester is 4.444.
    >> When it comes to towing or climbing hills the Hilux wins by a huge
    >> margin, the Hilux effortlessly climbs hills in 5th gear but the Forester
    >> needs to be down shifted to maintain speed, there is a slight difference
    >> in the final drive which should be offset by lighter weight, the main
    >> difference is engine torque.

    >
    > Nope, the difference is the rpm range over which the Forester produces
    > it's useable power... which is the rev range between maximum torque
    > output and its maximum power output. Keep the Forester within its
    > power band and it'll shit all over the Hilux!


    No it won't on a hill or when towing which is the conditions I was
    talking about, down shifting will just allow it to keep up, down
    shifting the Hilux will leave the Forester for dead, down shifting 2
    gears on the Forester might make it go harder but it would be revving
    very hard and drinking lots of fuel whilst the Hilux would be doing it easy.
    >
    > I'd also surprised if the Forester didn't have a wider band than the
    > Hilux, albeit at higher revs.
    >
    > The acceleration figures (ie 0-100kph, or 0-400 metre) will prove the
    > point.
    >

    On a flat road and not towing is where the Forester wins easily.

    --
    Daryl

  5. #25
    Ext User(John_H) Guest

    Re: Holden Captiva - Opinions?

    D Walford wrote:
    >
    >On a flat road and not towing is where the Forester wins easily.


    If it's towing then the power to weight ratio isn't the same!

    You've obviously forgotten to include the weight of the trailer which
    negates your original assertion that the performance difference is due
    to torque instead of power. :)

    --
    John H

  6. #26
    Ext User(Noddy) Guest

    Re: Holden Captiva - Opinions?


    "John_H" <john4721@inbox.com> wrote in message
    news:popru81aheinjt0vjpoil5mk4qntomg738@4ax.com...

    > I which case you want to operate one under optimum conditions
    > (performance wise) but not the other.
    >
    > It's a meaningless comparison.


    Not really. All I'm talking about is what effect pulling two thirds of the
    torque out of the equation would be likely to have. I expect it would be
    lots, but it seems that the effects of torque can't be taken in isolation as
    it's impossible to not impact on other things that have an effect in and of
    themselves.

    If that's the case, then I'm wondering how the reverse is true.



  7. #27
    Ext User(John_H) Guest

    Re: Holden Captiva - Opinions?

    Noddy wrote:
    >"John_H" <john4721@inbox.com> wrote in message
    >news:popru81aheinjt0vjpoil5mk4qntomg738@4ax.com.. .
    >
    >> I which case you want to operate one under optimum conditions
    >> (performance wise) but not the other.
    >>
    >> It's a meaningless comparison.

    >
    >Not really. All I'm talking about is what effect pulling two thirds of the
    >torque out of the equation would be likely to have. I expect it would be
    >lots, but it seems that the effects of torque can't be taken in isolation as
    >it's impossible to not impact on other things that have an effect in and of
    >themselves.


    Then look at it from a slightly different perspective.

    Heavy diesels typically have a very narrow power band and a high
    torque rise... meaning that power is relatively constant over the
    power band. They also have close ratio multi speed gearboxes to allow
    them to stay within the power band under heavy loads.

    If you drop in a car engine of the same horsepower, but with vastly
    different torque characteristics, once you get it moving it will
    perform exactly the same within the gear range that matches the
    engine's power band.

    The main difference being that you'll need to operate the engine at
    close to it's maximum power revs, which is the same as with the diesel
    except it develops its maximum power, or very close to it, at much
    lower revs (hence the high torque figure).

    Where the diesel will win is when the prime mover is operating under
    light load conditions where it isn't necessary to use aything like
    maximum revs to generate sufficient power...ie you can short shift,
    the same way as most mechanics drive cars. ;-)

    --
    John H

  8. #28
    Ext User(Xeno Lith) Guest

    Re: Holden Captiva - Opinions?

    On 23/07/2013 2:38 PM, John_H wrote:
    > Noddy wrote:
    >> "John_H" <john4721@inbox.com> wrote in message
    >> news:popru81aheinjt0vjpoil5mk4qntomg738@4ax.com...
    >>
    >>> I which case you want to operate one under optimum conditions
    >>> (performance wise) but not the other.
    >>>
    >>> It's a meaningless comparison.

    >>
    >> Not really. All I'm talking about is what effect pulling two thirds of the
    >> torque out of the equation would be likely to have. I expect it would be
    >> lots, but it seems that the effects of torque can't be taken in isolation as
    >> it's impossible to not impact on other things that have an effect in and of
    >> themselves.

    >
    > Then look at it from a slightly different perspective.
    >
    > Heavy diesels typically have a very narrow power band and a high
    > torque rise... meaning that power is relatively constant over the
    > power band. They also have close ratio multi speed gearboxes to allow
    > them to stay within the power band under heavy loads.
    >
    > If you drop in a car engine of the same horsepower, but with vastly
    > different torque characteristics, once you get it moving it will
    > perform exactly the same within the gear range that matches the
    > engine's power band.
    >
    > The main difference being that you'll need to operate the engine at
    > close to it's maximum power revs, which is the same as with the diesel
    > except it develops its maximum power, or very close to it, at much
    > lower revs (hence the high torque figure).
    >
    > Where the diesel will win is when the prime mover is operating under
    > light load conditions where it isn't necessary to use aything like
    > maximum revs to generate sufficient power...ie you can short shift,
    > the same way as most mechanics drive cars. ;-)
    >

    You get a few funny looks from your passengers when you short shift.
    Seems like they've been taught to progress through the gears and ONLY
    ever that way.

    --

    Xeno

  9. #29
    Ext User(Noddy) Guest

    Re: Holden Captiva - Opinions?

    On 23/07/13 2:38 PM, John_H wrote:

    > If you drop in a car engine of the same horsepower, but with vastly
    > different torque characteristics, once you get it moving it will
    > perform exactly the same within the gear range that matches the
    > engine's power band.
    >
    > The main difference being that you'll need to operate the engine at
    > close to it's maximum power revs, which is the same as with the diesel
    > except it develops its maximum power, or very close to it, at much
    > lower revs (hence the high torque figure).


    I appreciate that, but if you're saying that the Petrol engine would
    have the same "pulling power" (for want of a better term" as the diesel
    and not be bogged down under load despite only having a third of the
    torque then I have to say that I disagree.

    --
    --
    Regards,
    Noddy.

  10. #30
    Ext User(D Walford) Guest

    Re: Holden Captiva - Opinions?

    On 23/07/2013 1:32 PM, John_H wrote:
    > D Walford wrote:
    >>
    >> On a flat road and not towing is where the Forester wins easily.

    >
    > If it's towing then the power to weight ratio isn't the same!


    It is if both vehicles tow exactly the same weight, they both have 126kw
    and the Forester's kerb weight is 235kg less so it already had a power
    to weight advantage yet its towing performance is abysmal.
    >
    > You've obviously forgotten to include the weight of the trailer which
    > negates your original assertion that the performance difference is due
    > to torque instead of power. :)
    >

    Nope, if both tow the exact same trailer with the exact same load the
    Hilux does it effortlessly but you have to down shift the Forester and
    rev the hell out of it to do exactly the same job.
    --
    Daryl

  11. #31
    Ext User(Noddy) Guest

    Re: Holden Captiva - Opinions?

    On 23/07/13 7:53 PM, D Walford wrote:

    > Nope, if both tow the exact same trailer with the exact same load the
    > Hilux does it effortlessly but you have to down shift the Forester and
    > rev the hell out of it to do exactly the same job.


    That's where the value of torque comes into play in my opinion. The
    ability to maintain the status quo.


    --
    --
    Regards,
    Noddy.

  12. #32
    Ext User(Clocky) Guest

    Re: Holden Captiva - Opinions?

    D Walford wrote:
    > On 23/07/2013 1:41 AM, Clocky wrote:
    >> D Walford wrote:
    >>> On 22/07/2013 4:27 PM, Noddy wrote:
    >>>> On 22/07/13 3:37 PM, Marts wrote:
    >>>>
    >>>>> We looked at them too. The equivlanet Highlander Santa Fe was a few
    >>>>> grand more and the earlier models aren't as "loaded" as the Captiva.
    >>>>
    >>>> What does the 2011 Sorento/Santa Fe lack that the same vintage Captiva
    >>>> has?
    >>>>
    >>>>> And yes, the 6th and 7th seats aren't all that practical but may be
    >>>>> useful. In any case, I'm told that the 5 is a bit shorter so if the 7
    >>>>> has more room then that'll be handy for us.
    >>>>
    >>>> If they're anything like the ones in our Territory, they'll spend their
    >>>> entire lives folded up for more cargo space :)
    >>>>
    >>>>> What makes the Hyundai/Kia engine better than the Captiva's?
    >>>>
    >>>> More power & torque and better economy I expect.
    >>>
    >>> Considerably more.
    >>> Captiva diesel has 123kw and 230nm, Santa Fe 145kw and 436nm, the
    >>> Captiva torque figure seems too low to be true but I double checked
    >>> Holdens web site.
    >>> Captiva 8.8lts/100km, Santa Fe 7.3lts/100km so they Hyundai wins by a
    >>> country mile on all the numbers, 206nm more torque would be very
    >>> noticeable especially when loaded or climbing hills.
    >>>

    >>
    >> The 2.2L Captiva Diesel has 400nm of torque and 135kw. Fuel economy is
    >> 8.2L/100km.
    >>
    >> Not that much in it. I haven't checked but I think the Captiva is a bit
    >> lighter then the Kia.
    >>

    > I got the torque figure from Holdens web site and I did think it was
    > wrong, possible its the number for the smaller petrol engine.
    >


    Yes they stuffed it up the dickheads.

  13. #33
    Ext User(John_H) Guest

    Re: Holden Captiva - Opinions?

    Noddy wrote:
    >On 23/07/13 2:38 PM, John_H wrote:
    >
    >> If you drop in a car engine of the same horsepower, but with vastly
    >> different torque characteristics, once you get it moving it will
    >> perform exactly the same within the gear range that matches the
    >> engine's power band.
    >>
    >> The main difference being that you'll need to operate the engine at
    >> close to it's maximum power revs, which is the same as with the diesel
    >> except it develops its maximum power, or very close to it, at much
    >> lower revs (hence the high torque figure).

    >
    >I appreciate that, but if you're saying that the Petrol engine would
    >have the same "pulling power" (for want of a better term" as the diesel
    >and not be bogged down under load despite only having a third of the
    >torque then I have to say that I disagree.


    Then you still don't get it!

    The diesel with 1500Nm of torque will also bog down under maximum load
    once the revs drop below the power band.

    If you were to consider the rpm at which the maximum torque occurs
    relative to max power rpm instead of the maximum torque figure in
    isolation, as motoring journos and salesfolk are apt to do, then it
    might become a little more obvious.

    Once we've established the relevance you may then wish to discuss
    precisely why the 'torque monster' you built couldn't possibly achieve
    the outputs claimed, since the bmep (which is also a theoretical
    figure, derived from torque) isn't likely to have matched NASCAR's
    best for comparable engines (as it did, based on dyno measurements
    that don't stand up to the established theory).

    I chose that example because it demonstrates what is obviously your
    perception of torque, based no doubt on a mechanic's intuition,
    whereas mine's based on the physics textbook! :)

    In point of fact you can't separate torque from power since the two
    are inextricably related and bound by revs, with power being the
    empirical figure when it comes to performance.

    --
    John H

  14. #34
    Ext User(John_H) Guest

    Re: Holden Captiva - Opinions?

    D Walford wrote:
    >On 23/07/2013 1:32 PM, John_H wrote:
    >> D Walford wrote:
    >>>
    >>> On a flat road and not towing is where the Forester wins easily.

    >>
    >> If it's towing then the power to weight ratio isn't the same!

    >
    >It is if both vehicles tow exactly the same weight, they both have 126kw
    >and the Forester's kerb weight is 235kg less so it already had a power
    >to weight advantage yet its towing performance is abysmal.


    Because of the gearing.

    Even though the final drive ratios are similar, because the Hilux
    develops it's maximum power (and torque) at lower revs it's
    effectively much lower geared.

    >> You've obviously forgotten to include the weight of the trailer which
    >> negates your original assertion that the performance difference is due
    >> to torque instead of power. :)
    >>

    >Nope, if both tow the exact same trailer with the exact same load the
    >Hilux does it effortlessly but you have to down shift the Forester and
    >rev the hell out of it to do exactly the same job.


    That's because its maximum power is at much higher revs (a couple of
    thousand at a guess) and very little to do with maximum torque, which
    only determines the lower end of the power band.

    Try calculating the power at maximum torque from the previous formula
    (Power = Torque x rpm / 9549). The figure will be substantially less
    than 126kW, which should tell you something you appear to missing...
    ie there's a fundamental relationship between power and torque and you
    can't treat torque in isolation.

    To put it another way, 400Nm of static torque is a piddling figure
    which you can easily produce with a short stick and a weak arm.
    However don't try to absorb 126kW unless you don't mind your head
    spinning at a rapid rate... provided it doesn't rip your arms off
    first.

    Like most mechanics, you appear to have an aversion to revs... for
    which torque is no substitute! :)

    --
    John H

  15. #35
    Ext User(D Walford) Guest

    Re: Holden Captiva - Opinions?

    On 24/07/2013 8:24 AM, John_H wrote:
    > D Walford wrote:
    >> On 23/07/2013 1:32 PM, John_H wrote:
    >>> D Walford wrote:
    >>>>
    >>>> On a flat road and not towing is where the Forester wins easily.
    >>>
    >>> If it's towing then the power to weight ratio isn't the same!

    >>
    >> It is if both vehicles tow exactly the same weight, they both have 126kw
    >> and the Forester's kerb weight is 235kg less so it already had a power
    >> to weight advantage yet its towing performance is abysmal.

    >
    > Because of the gearing.
    >
    > Even though the final drive ratios are similar, because the Hilux
    > develops it's maximum power (and torque) at lower revs it's
    > effectively much lower geared.
    >


    That's an odd way of looking at it.

    >>> You've obviously forgotten to include the weight of the trailer which
    >>> negates your original assertion that the performance difference is due
    >>> to torque instead of power. :)
    >>>

    >> Nope, if both tow the exact same trailer with the exact same load the
    >> Hilux does it effortlessly but you have to down shift the Forester and
    >> rev the hell out of it to do exactly the same job.

    >
    > That's because its maximum power is at much higher revs (a couple of
    > thousand at a guess) and very little to do with maximum torque, which
    > only determines the lower end of the power band.


    2600 higher for power and 3000 higher for torque which equates to the
    Hilux doing it easy and the Forester making hard work of the same job.
    >
    > Try calculating the power at maximum torque from the previous formula
    > (Power = Torque x rpm / 9549). The figure will be substantially less
    > than 126kW, which should tell you something you appear to missing...
    > ie there's a fundamental relationship between power and torque and you
    > can't treat torque in isolation.
    >
    > To put it another way, 400Nm of static torque is a piddling figure
    > which you can easily produce with a short stick and a weak arm.
    > However don't try to absorb 126kW unless you don't mind your head
    > spinning at a rapid rate... provided it doesn't rip your arms off
    > first.
    >
    > Like most mechanics, you appear to have an aversion to revs... for
    > which torque is no substitute! :)
    >

    I don't know any drivers who think its OK to rev their engines to near
    red line at high load for long periods which is what would be needed to
    keep up with the Hilux when towing, even without wondering if its doing
    bad things to the engine the noise and the doubling of fuel consumption
    is enough to not want to do it.

    --
    Daryl

  16. #36
    Ext User(Noddy) Guest

    Re: Holden Captiva - Opinions?


    "John_H" <john4721@inbox.com> wrote in message
    news:fjvtu8dj2q5ai1rqdmocuiimbu4jhb2oks@4ax.com...

    > Like most mechanics, you appear to have an aversion to revs... for
    > which torque is no substitute! :)


    Here's the next challenge :)

    The "Mazda Roadpacer" was a rebadged HX Holden Premier that was sold in
    Japan to compete against the big Japanese luxo-barges, with the only
    difference being that the Roadpacer had a 13B rotary in it's engine bay
    instead of a red motor or plastic. The 13B made 103kw & 138nm compared to
    the Red 202's 81kw & 251nm, yet there was almost nothing in their
    performance figures despite the Roadpacer having a 20% power advantage.

    Roadpacer 0-100km/h 15.4sec - Red powered HX 16.4 sec.
    Roadpacer 0-400mtrs 19.9 sec. - Red powered HX 19.9 sec.

    Both cars had a similar top speed, were three speed automatic with a Holden
    rear axle, and the only significant difference between them was the 22kw
    advantage to the Mazda and the 113nm advantage of the red motor.

    Anyone who has ever sat their backside in anything powered by a rotary will
    tell you that their lack of torque is their biggest disadvantage, yet here
    we have a clear example of a considerably more powerful engine in the same
    car not being considerably quicker, and one can only conclude that the
    distinct lack of torque was a contributing factor.

    --
    Regards,
    Noddy.



  17. #37
    Ext User(Jeßus) Guest

    Re: Holden Captiva - Opinions?

    On Wed, 24 Jul 2013 10:44:10 +1000, "Noddy" <me@home.com> wrote:

    >
    >"John_H" <john4721@inbox.com> wrote in message
    >news:fjvtu8dj2q5ai1rqdmocuiimbu4jhb2oks@4ax.com.. .
    >
    >> Like most mechanics, you appear to have an aversion to revs... for
    >> which torque is no substitute! :)

    >
    >Here's the next challenge :)
    >
    >The "Mazda Roadpacer" was a rebadged HX Holden Premier that was sold in
    >Japan to compete against the big Japanese luxo-barges, with the only
    >difference being that the Roadpacer had a 13B rotary in it's engine bay
    >instead of a red motor or plastic. The 13B made 103kw & 138nm compared to
    >the Red 202's 81kw & 251nm, yet there was almost nothing in their
    >performance figures despite the Roadpacer having a 20% power advantage.
    >
    >Roadpacer 0-100km/h 15.4sec - Red powered HX 16.4 sec.
    >Roadpacer 0-400mtrs 19.9 sec. - Red powered HX 19.9 sec.
    >
    >Both cars had a similar top speed, were three speed automatic with a Holden
    >rear axle, and the only significant difference between them was the 22kw
    >advantage to the Mazda and the 113nm advantage of the red motor.
    >
    >Anyone who has ever sat their backside in anything powered by a rotary will
    >tell you that their lack of torque is their biggest disadvantage, yet here
    >we have a clear example of a considerably more powerful engine in the same
    >car not being considerably quicker, and one can only conclude that the
    >distinct lack of torque was a contributing factor.


    I've always paid more attention to torque figures rather than
    horsepower.

  18. #38
    Ext User(John_H) Guest

    Re: Holden Captiva - Opinions?

    D Walford wrote:
    >On 24/07/2013 8:24 AM, John_H wrote:
    >> D Walford wrote:
    >>>
    >>> It is if both vehicles tow exactly the same weight, they both have 126kw
    >>> and the Forester's kerb weight is 235kg less so it already had a power
    >>> to weight advantage yet its towing performance is abysmal.

    >>
    >> Because of the gearing.
    >>
    >> Even though the final drive ratios are similar, because the Hilux
    >> develops it's maximum power (and torque) at lower revs it's
    >> effectively much lower geared.
    >>

    >
    >That's an odd way of looking at it.


    Only to some it would seem! :)

    Perhaps you've never heard of, or else don't understand, the concepts
    of under gearing and over gearing, which are the design factors that
    have the most influence on a car's performance in relation to the
    final drive ratio.

    It used to be common practice in competition cars (the serious ones at
    any rate), and probably still is, to change their axle ratios to suit
    the type of competition or even to suit a particular race track. It
    involves selecting the axle ratio that matches the maximum power revs
    (not torque) to the maximum speed expected to be attained.

    For example, if setting up car for a quarter mile drag race the ideal
    ratio is the one where it just hits maximum revs as it crosses the
    line. (Noddy may or may not agree.) :)

    As it applies to road cars an overgeared car is one that's too high
    geared to ever attain its potential maximum speed in top gear. The
    term 'overdrive', which you've almost certainly heard, implies that
    situation... ie a gear ratio which over gears the car.

    An undergeared car is one that will exceed it's maximum power rpm (not
    torque) in its highest gear. It's also the one I'd expect to have the
    best performance through all of its gears.

    Getting back to your examples, most modern petrol engined road cars
    are overgeared (because they're geared for economy rather than optimum
    performance) as is your Forester.

    Diesels are mostly undergeared, and especially commercials, ranging
    from utes to prime movers. It's done solely for performance and
    economy isn't such an issue since diesels are at their most efficient
    when operating within their power band. It's also the reason why
    diesels with lower maximum power outputs can have similar performance
    to their petrol engined counterparts (and nothing to do with maximum
    torque).

    You could easily verify what I'm telling you by comparing the maximum
    power revs of both (and not the maximum torque revs) against their
    likely maximum speeds in the absence of a speed limiter. In any case
    your Forester almost certainly won't hit the speed limiter in top gear
    whereas your Hilux almost certainly will, which also reflects their
    gearing status.

    If you've managed to get this far, it's the reason why you can't
    simply replace a 500kW diesel with a 500kW V8 petrol engine and get
    the same performance through all of the gears... which is what seems
    to bother Noddy.

    It's also the reason why your Hilux is better suited to towing than
    your Forester (and has SFA to do with their respective maximum torque
    figures). Put higher ratio diffs in the Forester and it will be more
    than a match for the Hilux, in spite of its lower maximum torque
    figure.

    FWIW my petrol engined ute will easily hit the speed limiter in top
    gear, as well as the two below it, because its geared to suit the
    application (and has a raging thirst as a result). Neither of the
    last two cars I've owned would come within a bull's roar of hitting
    the speed limiter in top (and neither would make particularly good
    towing vehicles).

    --
    John H

  19. #39
    Ext User(John_H) Guest

    Re: Holden Captiva - Opinions?

    Noddy wrote:
    >
    >Here's the next challenge :)
    >
    >The "Mazda Roadpacer" was a rebadged HX Holden Premier that was sold in
    >Japan to compete against the big Japanese luxo-barges, with the only
    >difference being that the Roadpacer had a 13B rotary in it's engine bay
    >instead of a red motor or plastic. The 13B made 103kw & 138nm compared to
    >the Red 202's 81kw & 251nm, yet there was almost nothing in their
    >performance figures despite the Roadpacer having a 20% power advantage.
    >
    >Roadpacer 0-100km/h 15.4sec - Red powered HX 16.4 sec.
    >Roadpacer 0-400mtrs 19.9 sec. - Red powered HX 19.9 sec.
    >
    >Both cars had a similar top speed, were three speed automatic with a Holden
    >rear axle, and the only significant difference between them was the 22kw
    >advantage to the Mazda and the 113nm advantage of the red motor.
    >
    >Anyone who has ever sat their backside in anything powered by a rotary will
    >tell you that their lack of torque is their biggest disadvantage, yet here
    >we have a clear example of a considerably more powerful engine in the same
    >car not being considerably quicker, and one can only conclude that the
    >distinct lack of torque was a contributing factor.


    The distinct lack of a respectable power band in the rotary will be
    the main factor... along with a wide ratio gearbox that won't anything
    like provide the step ratios needed to utilise the rote's power band.

    Since I can't be bothered chasing them up how about you provide the
    respective maximum power and maximum torque figures with their
    corresponding rpm. The transmission ratios would also be useful.

    At that point I'd expect the answer to be very obvious (to me at
    least).

    And FFS don't snip the figures you've already provided as they're also
    a vital part of the story, even if you have omitted the most important
    bits. :)

    --
    John H

  20. #40
    Ext User(John_H) Guest

    Re: Holden Captiva - Opinions?

    Noddy wrote:
    >
    >Here's the next challenge :)


    Perhaps you might also answer one for me. :)

    Ignoring forced induction (only because it obfuscates the basics)...
    when you modify an engine for performance what do you expect to
    increase... torque or power?

    If the answer does happens to be torque you might also explain what
    you need to do to increase it significantly (excluding forced
    induction).

    --
    John H

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