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What is in a gear box?

Discussion in 'Technical' started by Raj_pol, Sep 4, 2015.

  1. asimpleson

    asimpleson Esperto

    Messages:
    3,000
    Heptanesia
    Linea 1.3
    @KKAUL

    What I am really not convinced is for remappers blatantly experimenting with engines at the customer's expense. Real time data is available with real time logging tools. But mechanical stress such as the one on lifters, cam lobes, crank, the pistons, rods and such will definitely be affected. And that effect shows not immediately but as you said in overall engine life. That too if one is willing to accept pre-mature failures and willing to investigate deeper. More often than not Fiat will end up getting blamed more by the customer and the gully mechanic.

    This has some thread to discuss. Although here the remap is a workaround to the gear ratios which too have been discussed in the past, although not at length for sure; but having said that the present gearbox irrespective of the fact that FIAT tunes it for FE and some power and in higher gears does have its limitations, and part of this equation is the engine size as well. I have no doubt in my mind that Fiat could have done a better job for those who drive in traffic. Agreed that the shifting needs an adaptability to how the engine responds to throttle and timing it perfectly as per RPM. But reality is that esp. on Linea MJD, my observation is one needs to consistently be in 3rd even in smaller lanes or by lanes to make it feel effortless a drive. Therefore, in my simple non-engineering logic I try to avoid or rather dislike downshifting to 1st and 2nd. Of course if it comes to it which it does often in traffic scenario here, I shift fast throught the first two gears and you cannot feel the strain of a heavy to haul vehicle feel.
    prabhjot likes this.
  2. KKAUL

    KKAUL Amatore

    Messages:
    205
    delhi
    Grande Punto 1.3
    @Raj_pol

    Pardon me for continuing OTT on this thread.

    @asimpleson

    I totally agree that the remapper is experimenting with owners money no denial to this fact and the owner will come to know of its benefits or losses on long run though if he is willing to investigate it deeply.
    About the mechanical stress doubt: Nothing is going to happen to engine mechanically if it is retained within the factory set safe limits with appropriate FS on design spec.
    Now comes the question if a remapper can do wonders to the ECU then why can't FIAT:
    The reason is that the programme provided by Fiat has lot many Fail safe so that it works in whole of the India.
    Say I tuned the car in Mumbai where ambient is around 35 degrees. Assuming the general tuning usually removing limiter maps which are more or less 8 in no. Primarily being torque and turbo boost.
    Now I bring this car to NCR region in peak summers what will happen
    The peak outside temp is 52 degree . The density of the air is low and the entry temp of the air is high thus the pressure ratio will increase there by bringing turbo to a limit where it needs to keep open the waste gate so as to prevent its seal faliure.
    But we have removed the factory set boost limiter map and readjusted it so eventually a breakdown or part lost good amount of its life.
    You are standing in jam on a very hot day driving a remapped car. Have you ever wondered the exhaust pipe of the car in front of you is pointed directly on your radiator there by increasing the overall temp.The remapper would have always checked the Coolant temp on a open road so here data logging also fails.
    The gear box does not need a change. The basic is that 1.3 is not suitable for this setup and this is a jugaad some how assembled seeing the japnese. It is like if they can do it and sell then we can also fool and make profits.
    I was reading a post where water has entered the compartment. Nobody in whole writeup has written what is the basic reason of water entering the compartment in a car which has 185 + ground clearance and cannot wade through merely 400 mm of water
  3. asimpleson

    asimpleson Esperto

    Messages:
    3,000
    Heptanesia
    Linea 1.3
    I cannot comment which remapper has taken how many parameters and altered the maps in what way. That's not something I ever digged into. From my perspective, there are marginal risks with remaps which are slightly altered but make a good difference nonetheless. So yes, Fiat company also should have tested lots of parameters with original tools meant for the specific engine or drivetrain. Although at the same time we must also acknowledge that some remappers such as Rajiv (Wolfmoto), hold a lot of indepth knowledge from what I read and I am told and also some of them develop and alter their maps also based on user experience and combining their own knowledge about an engine and other things that affect car performance.

    FPT or ZF especially are companies that can make a custom gearbox, best suited for a specific engine and power output and curves. But maybe we will see the best of products in the future. For now we should probably look at remaps, only if it hurts that bad to drive. I have a very limited personal use of the Linea MJD once in a while, so definitely that is one reason I haven't looked at remaps too seriously in the past. But the one I drove a 90hp Punto (of a friend) had all that I could ask of a car, from ergonomics to handling and now driveability too. And believe me it worked like a charm without feeling overworked an engine with perfect NVH levels, infact better than the Linea MJD.
    prabhjot likes this.
  4. KKAUL

    KKAUL Amatore

    Messages:
    205
    delhi
    Grande Punto 1.3
    Mr. Rajiv might have good knowledge on the subject as I have also read his appreciation but there is a difference.
    Performance has no limits but Fiat simultaneously has to give 1L km warranty which they don't have to give so that is the reason for uder tuning. FIAT also knows once they increase the throttle response the wear and tear is bound to increase.

    As far as engine NVH are concerned a Densely filled compression chamber will always resonate less amount of combustion noise than same chamber filled less amount of air and Fuel Simple logic.That is the reason 90 hp is silent than 75 hp
    Drop a stone in water filled pot you will hardly notice the sound than you drop the stone in half filled pot.It is how the sound propogates
  5. asimpleson

    asimpleson Esperto

    Messages:
    3,000
    Heptanesia
    Linea 1.3
    @KKAUL,
    I guess it matters not what just we think on the subject. There will always be many who will opt for a remap rather than staying upset about the gearbox or how right it is of Fiat or how wrong. Part of these discussions is it to find a workaround to problem areas that people think they need to address.

    I do know why Fiat specifically undertunes and so do so many other manufacturers to keep things from early damage or excessive wear and tear. But at the same time whether that is bothering or something to let go, that remains an option with the owner.
    prabhjot likes this.
  6. Vidhyashankar Kannan

    Vidhyashankar Kannan Regolare

    Messages:
    271
    Hyderabad
    Hyderabad
    Avventura 1.3 90 HP
    @KKAUL : I had a nice time reading through all your technical notes. You should keep posting on this forum as it will do the rest of us a lot of good by learning.

    @asimpleson : I think the reason that most manufacturers purposely undertune their engines is because there is supposedly an extra excise cost imposed by the government on cars above 100 bhp out of the factory. That is one reason the GT TSI is expensive as it has 109 bhp for the same 1.2 litre engine. The MJD is quite a lovely engine that accepts a range of modifications on it. But like you both have been saying, I too have the niggling doubt that perhaps the remaining components on the engine block may not be able to handle a remap as the engine works harder. Right from the gaskets to the valves to the plugs, all of them may have to be upgraded. However, there are numerous people who have remapped their ECUs and are very happy and do not complain of higher wear and tear. We will know only when they cross 1 lakh kms perhaps. I have sat in a friend's remapped Vento TDI. He had it mapped to the "Sport" mode. The way the car behaved, I knew exactly where my heart was situated. But on the other side, I could also hear the grinding of the engine components. He really wasn't bothered and said if something happens, he would replace with higher grade spares.

    Coming to the gearbox of the Fiats, I for one find the gearing of the 1st gear too short. Agreed that a larger cog is required to get that bulk moving so that it can be slotted into 2nd quickly. But my main issue is that I live in an area where there are plenty of inclines. Getting out to the main road is a steep incline followed by a jammed red light that is nearly half a km of a steep incline. The irritating thing is that I have to start off in 1st and never get enough momentum to slot into 2nd. If I slot too early, I'm completely out of the powerband and may stall or move so slowly in 2nd that the cars behind me honk. If I slot too late, then I'm well into the turbo band and end up jerking forward. But most of the times, its the former.

    I understand that diesel turbocharged engines are a totally different ballgame from petrol. The S10 on the other hand is just a smooth mover in any situation. Slopes, straights, corners, abrupt braking and acceleration. Throw any situation at it and the car just keeps going. Being an NA engine helps too I guess. But the more important thing is the longer 1st and 2nd gear ratios. You can operate it over a very large without worrying about stalling. It would have been nice if similar gearing was available on the MJD too. And to be honest, in city driving, the constant shifting between 1st and 2nd is irritating on the MJD. On flat roads, I leave it in 2nd and release the clutch most of the times. Perhaps a slightly smaller cog for the 1st may do the trick?
    asimpleson likes this.
  7. KKAUL

    KKAUL Amatore

    Messages:
    205
    delhi
    Grande Punto 1.3
    @Vidhyashankar Kannan

    Though I have never driven GP in ghat section but I think the case you mentioned will be same as that we face in Delhi Gurgaon on Flyover as we have a Traffic Jam on this section everyday.
    I think you are new on GP that is the reason You are facing it. Let few month pass and you will pass with Flying colors be it any condition.
    Diesel engine are never meant for speed, They are meant for power both are different. In India we have a very common misconception about diesel engine which the car companies have noticed and that is the reason they are dumping all sort garbage in Indian market and we are very happy seeing them.
    There is lot of cheating going on and some of the points are life threatening with some companies. I am surprised why don't people see and ask.
    abhinav_nani likes this.

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