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Thread: An article on Dual mass flywheel and tuning your engine

  1. #1
    Regular Member Chocki's Avatar
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    Default An article on Dual mass flywheel and tuning your engine

    Found this snippet of information which if true, could have implications for anyone tuning their cars to the levels Spoons and Nutron are going.
    The worrying bit is, that it seems to make sense.

    Can anyone shed some light on this matter?...

    Some notes on application pros and cons:

    The dual mass systems are designed to transmit less engine vibration to the driveline, and give a better more car like driving experience. They also reduce some of the jarring and stress on the transmission and remainder of the drivetrain. They work fine as long as the engine remains unmodified and the vehicle is not used/abused beyond manufacturers recommendations.

    As soon as you start to increase the engine power over stock, or load the vehicle beyond design parameters, you run into problems. Dual mass flywheels are tuned systems and must be matched to the engine torque curve, engine resonant characteristics, vehicle load curves (including axle ratio/tire size calculations). They work by having a set of springs inserted between two rotating masses (thus dual mass). The springs are sized to soak up some of the resonant vibration from the diesel engine under load conditions. A dual mass fly wheel generally also contains an over torque friction release, so if it gets suddenly overloaded, rather than damage the springs, it slips. This works fine as a safety valve, but if it does it much it burns up. In short, overloaded they burn up and the springs get destroyed and they are worse than if it were a single mass FW.

    The single mass part WILL tend to transmit more engine pulse (vibration) tot he drivetrain, and will seem a bit rougher. But it is straight forward to design a single mass flywheel and clutch package for pretty much any engine torque curve and vehicle loading combo you can come up with. Drives more like a TRUCK, but has much better reliability at extreme use levels.


    Got it from here: http://www.high-impact.net/transmiss...svsSolidFW.htm
    Last edited by Chocki; 4th November 2007 at 20:23. Reason: Added link

  2. #2
    Regular Member Gsi3.2's Avatar
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    the design facts are correct.. i can't comment on the tuning side of it thou..but they must stand some degree of tuning if VXRpc/888 will remap your car up to 185BHP..so they must have some degree of tolerance in them...you think VX DMF's are bad, you should look at new transit and their DMF's...failure rate is shocking..

    where'd you find that article BTW?

  3. #3
    Regular Member nutron's Avatar
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    That might explain why the clutch slips in 4th, 5th and 6th when pushing past 320-330lbft.

  4. #4
    Regular Member Chocki's Avatar
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    I was doing a quick google for dual mass flywheel problems and it seems most manufacturers are plagued with issues.

    Maybe spoons could ask 888 if they have any plans for developing an uprated or solid flywheel.

    Also, do either of you know any Vauxhall techs who could confirm if the VX flywheel has the over torque friction ring etc...

  5. #5
    Regular Member Chocki's Avatar
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    And another quicky:

    What is the DMF's function? It is designed to isolate torsional crankshaft spikes created by diesel engines with high compression ratios. By separating the mass of the flywheel between the diesel engines and the transmission, torsional spikes can be isolated, eliminating potential damage to the transmission gear teeth.

    Engine-side flywheel damper springs The damper springs that are visible on the engine side of DMF are designed to dampen heavy torsional spikes that occur when the diesel engine's torsional frequency matches the torsional frequency of the transmission. When torsional frequencies match (have the same amplitude), severe damage can occur to the transmission if not isolated. DMF's isolate the torsional frequency match between the engine and transmission to an r.p.m. range below the operating range of the engine (usually between 200-400 r.p.m.). These damper springs only work hard when the engine passes through 200-400 r.p.m. at vehicle start up and shut down.

    DMF damper springs and/or damper springs nylon retainers usually fall because the diesel engine is not running correctly. Bad fuel injectors, worn pistol rings, bad valves, etc, will change the resonant frequency of the engine. A change in the resonant frequency of the engine can force the torsional frequency match between the engine and DMF to fall within the operating range of the engine. This forces the damper springs to work continuously, resulting in failure.

    Friction Ring The friction ring located between the inner and outer flywheel is designed to allow the inner and outer flywheel to slip. This feature saves the transmission from damage when torque loads exceed the vehicle rating of the transmission. The friction ring will wear out if excessive torque loads are continuously applied. Loading the vehicle beyond the rated load capacity is often the root cause of friction ring failures in DMF's.


    Taken from :http://www.standardtransmission.com/dmf.html

    I know it's not specifically aimed at the Vectra, but in principle the same things apply.

    Watch yourself Nutron with that slipping or it could lead into trouble.

  6. #6
    Regular Member Gsi3.2's Avatar
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    yep, DMF problems are widespread..they just aren't strong enough and where only ever introduced to get over the NVH levels associated with diesels..I don't know why VX would be introducing a soild or uprated flywheel as they don't do high performance diesels..maybe the 150 is a 150 (even though we know it can develop more) for a reason..

    i've never bothered to take a DMF apart to see this 'clutch'..just binned the failed item..

  7. #7
    Regular Member nutron's Avatar
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    Not to worry, after about 7 months, the other one stopped slipping... Seems to work better without the slipage.

    maybe they have a new clutch for the twin turbos? Does the 93 Saab TTDI have a different clutch?

  8. #8
    Regular Member Chocki's Avatar
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    Can't find anything on uprated clutch, but there is a new 4wd transmission mentioned. But they have reduced the compression ratio a little which may help with these torsional spikes on startup etc.

    Anyway, here's a snippet on the new engine:
    New 1.9 TTiD engine

    The 9-3 range features a powerful new four cylinder diesel engine with a unique two-stage turbocharging system, a world ‘first’ in the premium car segment, giving class-leading levels of efficiency. The 1.9-liter, 16-valve engine, badged TTiD, produces 180 hp (132 kW) and 400 Nm of maximum torque, specific power outputs that are unmatched among competitor products on the market. With combined fuel consumption of 5.9 l/100k projected for the Sport Sedan, this engine also offers class-leading economy, together with in-gear performance on a par with the 2.8V6 turbo gasoline engine.

    The two-stage turbocharger housing is integrated with the exhaust manifold and contains two turbochargers of different sizes. The pair of turbine/compressor wheels are sequentially mounted and each is able to by-pass the input and output feeds of the other, while also being able to operate in tandem.

    This arrangement provides a driver with ‘the best of both worlds’: good, instant torque at low engine speeds - via the low-inertia small turbo when the exhaust pressure is light - and strong ‘top end’ power at higher revolutions, when the bigger turbo is engaged.

    Saab’s two-stage turbocharging uses a system of by-pass valves that directs the exhaust gas stream between the two turbine wheels and also separates the air intake charge from the compressors. From tick-over to 1,500 rpm the exhaust feeds only the small turbo. Between 1,500 and 3,000 rpm the flow is split between both turbines, giving stronger boost and ensuring a smooth transition phase to full power operation, above 3,000 rpm, when only the larger turbo is engaged.

    The compact design provides more efficient packaging than systems using two separate turbochargers linked together externally in series. It ensures that the complex control and regulation of gas flows on both the exhaust turbine and intake compressor sides is achieved with a minimal number of seals and connections.

    The TTiD engine is a substantial development of the current 16-valve 1.9TiD unit, using common rail, direct and multiple fuel injection. It operates with a maximum boost pressure of 1.8 bar (1.4 bar for the current engine) together with a slightly lower compression ratio of 16.5: 1 (17.5:1). The cast-iron block, alloy cylinder head and all internal components are strengthened as necessary to withstand the higher thermal pressures.

    The exhaust gas re-circulation (EGR) system is characterized by extremely efficient cooling and now includes an electronically controlled by-pass for improved emissions. This feature, together with the fitment of a maintenance-free exhaust particulate filter, is expected to ensure compliance with more stringent future Euro 5 emissions standards.

    Other technical enhancements include the adoption of a larger air-to-air intercooler, for better cooling of the intake charge; the introduction of more efficient pre-heating elements inside the cylinder head, for faster starting in cold conditions; and the use of a weight saving plastic intake manifold.

  9. #9
    Regular Member Gsi3.2's Avatar
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    so they up the power..double the turbo's but STILL whack a DPF on it....

  10. #10
    Regular Member BigP's Avatar
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    Is it just diesels that have DMF?

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