How to Prepare a Hot Hatch

Discussion in 'T&AA - Travel and Anything Automotive' started by JD666, Apr 26, 2014.

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  1. JD666

    JD666 RAID Leader Staff Member

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    How to make a Hatchback HOT ?


    Other than dousing it in Petrol and setting it on fire or putting a giant poster of Sunny on both sides :D .. ofcourse

    Following a recent discussion on Facebook I was tempted to write an article on the available options and possibilities of modifying one's vehicle that would help boost the vehicles performance on parameters like acceleration, handling, top speed and braking.

    I pull upon my experiments on my poor M800 in the late 90s to 'soup' it up and the issues I faced and the mods I did to boost power.

    These modifications have been suggested, mentioned keeping in mind that not many modifications are road legal, so we are in a bit of a grey area. So proceed with these mods at your own risk. Some are cheap and in expensive, others would cost a lot of money.

    Now to improve performance of any vehicle let's first consider the following -

    Part 1 - Chassis Mods

    Petrol > Combustion > Power production > Conversion to force > Drive-train > Wheels to the road.

    However, there's one hidden factor, which stays constant throughout this process. Weight.

    Yep - Kinetic Energy = 1/2 * m * v * v , Where m = Mass of the moving body, and v = Velocity.

    So lower the weight, higher the velocity. That's how a 750 BHP 600 kg F1 car beats the crap out of a Veyron that's around 1500 kgs and 1100 BHP in acceleration and possible top speed.

    So first and foremost, if you want your vehicle to go fast... Reduce weight!

    Yes this means chucking out everything sanely possible that is not needed on your vehicle. People go to great lengths at reducing weight in their vehicles.

    Some common areas are -

    1) Reducing interior trim and fittings - This includes all panels, roof lining, trunk lining, unwanted items etc.

    2 ) Removing carpets - Sound deadening material (it makes the vehicle sound sporty as well :D )

    3 ) Rear seats - Yes, a Hot Hatch is a drivers car .. !

    4 ) Spare Wheel (if you have really good quality Tube less tires and don't drive around in the woods, go ahead).

    5 ) Lighter Seats - they'll save you about 2-3 kgs, but will surely give you that racer feel.

    6 ) Driving on a quarter tank of fuel at most - Hey this is a budget mod for a hot hatch, extra fuel weight means lower acceleration. And 1 Liter of Petrol weighs 770 Grams, so dropping about 20-25 Liters will make you 16 KGs lighters.

    7 ) Removing unwanted accessories like sound system, speakers, power windows. Install hand crank assemblies instead.

    8 ) Lightweight, and smaller RVM (Rear-View-Mirrors) that are lighter and more aerodynamic as well.

    9 ) Smaller, Lighter steering wheel - We have to get the feel right now, don't we.

    10 ) Some people would go to an extreme and trash the A/C unit as well, but then I love my little luxuries, so it stays for me. Though it will help reduce atleast 15-20 kgs weight from your vehicle.

    Now the interesting bits (Read expensive).

    11) Installing Fibre panels. These are made from Fiber glass or ABS (if you have a popular vehicle you'll find ABS parts). Metal panels like the bonnet, front fenders, rear boot etc can be replaced with Fibre panels, that would help reduce weight, but would be useless in the event of an accident, unless other suitable modifications have been done to re-inforce the structure.

    12) Additionally, Replace your rear wind screen, rear windows, quarter glass panels and other glass areas with plexiglass. Just gotta get a sheet, get it cut to the desired shape and stick it on. Plexiglass is again, plastic, that does not yellow as much as regular clear acrylic.

    It will give your car a funny look, but look at all the weight you've saved. You could remove the rear window hand winches even. See all the weight you saved!

    13) Sealing the rear doors - This will enable you to remove the hinges, locking mechanisms etc and weld them shut, improving the structural integrity of the vehicle as well.

    14) Alloy wheels - Now this is honestly a grey area (not legally). Unless the Alloys you are buying, are actually lighter than the steel wheels you are replacing them with, there isn't much to be gained. So do compare the weight and quality between your stock steel wheels and the alloys you looking at purchasing before making this decision.

    The reduction in weight will help handling, response, fuel efficiency and obviously make your vehicle look cool.

    15) Extreme weight reduction that would involve some modification like - Lighter headlamps (Using small projector lamps instead of the bulky stock headlights. Removing tail lights and fitting light weight LEDs in their place. Cutting the front and rear Bumpers where not required to further reduce weight. Removing parts of the dashboard, or the dash completely. This also involves mods like a plastic fuel tank (scary in an accident, but much lighter than the stock tank.

    16) Going on a diet yourself and dropping 10-15 kgs! :D

    Most of the above mods are in-expensive, can be done easily, and you could sell most of the extra parts you removed for scrap! Infact making some money in the process.

    These mods rely primarily on weight reduction to reduce that M factor of the equation mentioned above.

    Lower the mass, faster will be the acceleration and higher the top speed..

    If not done right.. Higher would be the chances of a grievous injury in the event of an accident.

    Part 2 - Performance Mods

    Note: This is an attempt at Performance Modification 101. You can opt for higher end specs as well, but it's always good to get your basics right first.

    First we look at how we can improve the Engine's power output.
    Now there are 3-4 areas that can be improved upon -

    1) How much and what quality of Air/Fuel enters the Engine.

    2) How well it burns.

    3) How quickly it leaves the Engine, so that fresh Air/Fuel can come in.

    4) How much Air/Fuel can be stuffed to increase power output.

    And another - How much of this power is lost to friction.

    1) How much and what quality of Air/Fuel enters the Engine.

    Simply put, When the piston in a 4-stroke engine moves downward, the inlet valve opens (operated by the cam). The downward motion of the piston creates a negative pressure (something similar to when you pull back on the pump of a syringe or your 'pichkari' during Holi.

    This causes the Air to enter the cylinder (along with fuel, that has either been mixed with the Air in a carburetor, or injected along with the Air in an MPFI engine).

    If we facilitate a smooth, straight, efficient path for the Air and fuel to travel, lesser energy will be wasted by the piston sucking the A/F mixture in. This can be effected by many ways -

    # Using a high flow air filter - The most common, and most recommended as well. Take a handkerchief. Fold it into many layers and try sucking air thru it. Now just use a single layer and try sucking air thru it, you'll get the drift.

    A good quality High flow Air Filter (like K&N) is one of the first and easiest steps to improve the air flow to your engine. Not only does it provide for better filtration, but also reduces hassle of changing and cleaning air filters. One filter, one time purchase and then you need to service it (washing with K&N specific oil) every 50,000 kms or so!

    This reduces the resistance offered by a stock filter, and makes it easier for the Engine to breathe.

    Many people try various types of filters, but for convenience's sake, I'll recommend a stock replacement.

    # Path of least resistance for the inlet - Most Air intake designs are hindered by the packaging and allowance that Engineers and designers have when making placements inside an Engine Bay.

    They try and find the coolest area from where air could be taken in by the Engine. However still it requires a decent amount of plumbing before the Air that enters the inlet, goes thru the filter and reaches the inlet port to the engine.

    There are many aftermarket mods that allow for a straight pipe design, and even a bigger diameter pipe to be used. Each one has their own pros and cons, so research well before buying. Will it help improve airflow? yes.

    Will the effect be dramatic? Not as much.

    # Feeding as much cool as air you can to the engine - Don't know if many people feel/observe this, but generally I find that a car/bike performs much better in cooler temps (humid especially) than hotter. Also right after it's rained. Why?

    Because the ambient air is cooler than what it normally is. And some law of Fluid mechanics or chemistry (or was it Physics) states that the cooler a fluid is, the denser it it. And denser the air, more is the oxygen content.

    Remember, combustion in an engine is reaction between the Hydrocarbon of fuel, with the O2 molecule of oxygen present in Air. And the reaction is by weight, not volume. So denser the air, more weight of air is available per unit volume.

    Hence it can burn fuel more efficiently and even in greater quantities, improving power output.

    So cooler the air entering the engine, higher would be the efficiency + power output.

    This can be achieved by using an air intake that has an inlet away from all the heat production (Radiators, Engine, A/C coil etc) sources. It can also be placed outside the Engine bay (on top of the Engine bonnet, on the front grille etc) to ensure that the coolest available ambient air enters.

    If it's placed above the Engine cover, you might just get a bit of ram air effect as well :D

    However it has to be properly insulated (The air duct) so that the air enters the engine at a cooler temperature, and does not get heated as it travels thru the inlet.

    # Porting polishing the inlet, Using bigger valves - Now these are again higher end mods that require a working knowledge of your engine and someone with sufficient Mechanical experience.

    Polishing your inlet is one of the lesser tasks that can be carried out by someone skiled enough. What it involves is well polishing the inlet of your engine head, so that it allows for a smooth passage to the Air coming in.

    Generally Heads and inlet ports are the outputs of a mass produced, time critical manufacturing process. So they are bound to be finished in a rough manner, that does not stress upon extracting each ounce of available efficiency, but allows for an acceptable operation.

    Using a suitable dremel, and loads of patience, inlet ports can be polished to a mirror finish (well nearly) that allow for smoother air flow (you'll feel the air flowing smoothly the moment you touch em).

    Porting is polishing done with a ?#@*&%!^$~ file :D Only it requires technical knowledge and skill to be carried out. What it effectively does is change the inlet shape to the engine, enlarging it (mainly) to facilitate the flow of additional air and fuel.

    Adding bigger valves to the head (with suitable seating) also facilitates this, however be advised. These 2 Mods, if not done correctly, can kill your engine for sure. I went till the extent of polishing the inlet port on my M800, and making sure the valve seat was good and properly ground.

    2. How well the Air/Fuel Mixture burns -

    An efficient burn is when there is no unburnt fuel left, and there is no un-used oxygen left in the mixture. To ensure this, Mods available are after market multi electrode spark plugs ( I read Iridium plugs a lot), hotter spark coils (Basically those which have a higher potential difference and produce a more powerful spark), and better quality ignition cables (mass production at work again).

    3. How quickly it leaves the Engine -

    Now once the combustion stroke is done, the piston moves down under the force of the air-fuel on it. In the meantime they combust and have transferred their energy (well most of it) to the piston. The exhaust valve opens, and partially the burnt gases exit under their residual pressure, and remaining is pushed out by the piston on the upward stroke.

    Alll the points mentioned above, are applicable for exhaust as well, however there are some minor changes.

    # Using a free flow exhaust - Similar to a free flow air intake, however it involves using a bigger diameter exhaust pipe, removing the cat-con, and the numerous baffles of the muffler. Why supress that sound, when partially it's gonna give us that go faster feeling.

    This is again a grey area, since removing the cat-con would void warranty on the vehicle (As if nothing else from this article will), and increase your pollution levels.

    The performance gain would be that the reduced back pressure will enable gases to exit quickly, in turn reducing load on the piston, in turn improving performance.

    # Using a header - A tuned header helps, since again due to mass production, a generic design which provides the best mix of efficiency and production cost is used. However a properly tuned header can help excavate the exhaust gases faster, due to some standing effect of waves or something that I remembered reading about.

    Again , highly technical, please don't go with any tuned header. You're better off building your own, using old exhausts. I did the same. Just took a length and got 3 pipes fabricated to meet that length and the space in the engine bay. Voila. It was crude, but worked!

    Note - Using any free flow exhaust without proper engineering also runs the risk of frying your exhaust valve. Part of the gases that exit the cylinder, also cool the exhaust valve. If they exit too quickly, or without modulation, you run the risk of burning and in extreme cases, even breaking the valve, again killing your engine.

    3. How much air can be stuffed in -

    # Turbo Charging/SuperCharging/Inertial charging - Again not for the faint hearted. This involves a lot of know how, and a lot of money. The benefits can be from anything from a 10% boost in power, to a whopping 60-70% even.

    Do remember that Turboing a stock engine, stresses all the components, and potentially reduces the life of the engine if not done properly. And an aftermarket turbo engine would not be as drivable.

    But they all work on the same principle. Rather than the piston deciding what/how much quantity of air it should suck in during intake, a turbo forces air (and in turn fuel) inside the engine, increasing the amount of air fuel inside. The higher air-fuel obviously produces more power when burnt and that gets transferred further.

    However this shoving of excess air fuel and the subsequent burning, produces temperatures and pressures that are beyond or higher than what the components are designed to handle. So any excess, and you run the risk of ruining your engine.

    4. How much of this power is lost to Friction -

    A lot. And a number of things can be done to reduce friction inside the Engine -

    #Better quality components - If you are rebuilding your engine this would be applicable. Don't just go for OEM. Remember they are OEM because they supply the mass production line that churns out an engine every minute. They would be reliable, yes, most efficient? no. Why? Coz they are built to a price.

    I remember this debate way back in 97-98, when there were 2 piston manufacturers for the M800, and one of them had lighter pistons (by about 10-15 gms). I instantly jumped on it, and made sure I got the lighter pistons :D

    Same bit is applicable for bearings, seals, crank etc.

    #You can get your crank balanced and machined even (at good tuning houses) to improve the engine rev ability (though losing some torque in the process). A lighter crank, piston, connecting rods etc will rev easily to higher rpm, and much more quickly as well (Due to reduced inertia).

    Another trick I learnt was that machining the flywheel slightly (Maybe a facing of 1-2mm on the whole wheel) reduced the weight of the flywheel. Now the flywheel serves many purposes (shock absorption, inertia, momentum). However the effort taken by the engine in rotating the flywheel, also bogs the engine down.

    It's the difference between turning a car's wheel on an axle and a bikes. The lighter wheel is easier to rotate and to take to higher speeds (which you will achieve much quicker as well).

    Again note - This will affect your torque (which will drop) and the vibration levels of the engine (which can go up, affecting the smoothness). So test before you finalize. I spoiled a fly wheel by shaving off too much. (They aren't much expensive though).

    Some after market companies offer Engine blue printing, which is essentially removing all manufacturing defects from the engine, and reworking it to the highest possible standards. Such assembled engines are in fact so good, that you could build one overnight, and participate in a rally in the morning.

    Again expensive, but does help improve power, efficiency and life of the engine!

    There are some ancillary mods that can be carried out, that help the net effect.

    Part 3 - Ancillary Mods

    These are in no particular order. But what they look at are extra/other modifications that help improve the performance of a vehicle.

    1 ) ECU Modding/Chip Tuning. -

    This ranges from the exotic ECU ReMapping to a regular piggy-back module that fools the ECU into thinking that the engine is performing in a different manner.

    Both aim to achieve the same effect, increasing power and output by modifying the engine parameters. Also most cars in India are tuned towards fuel efficiency than power output. So a simple ECU remap helps overcome this situations and helps unleash the additional power, that would not have been usually available.

    This is an extremely do-able mod, and in most cases, won't even void your warranty. :D

    2 ) Better brakes -

    With all the additional power available, generally brakes get overlooked. There are a variety of options from using higher friction brake pads (that'll wear out faster though), to bigger brake boosters, to even slotted discs.

    I did the slotted disc trick on one of my bikes, worked like a charm! However, Braking is an essential function. So be very very careful when messing around with your braking system.

    3 ) Gearbox modification -

    An old trick of yore for e.g. was to use the gearbox from a Maruti 1000 in a Maruti Esteem. The 1000 was geared lower, since it had lesser power and torque (45 bhp). The Esteem was geared higher, since it had more power (first 65 bhp in the carburettor, and then 85 in the MPFI model). Fitting the 1000's Gearbox was a direct mod job, and would bestow the car with cracking acceleration.

    The downside would obviously be high engine rpm at cruising speeds and lower mileage. But the acceleration was worth the effort!

    Similar modifications can still be carried out!

    4 ) Beefier Clutch -

    To handle all the additional power output. A stock clutch can take some additional power, but will have a tendency to burn out faster. So look at a good aftermarket option clutch, if you want all this power to be harnessed properly.

    5 ) Short throw Gear shifter -

    Does what it says. Reduces the gap that the gear lever has to travel between actuating gears. Does give you that sporty feel, but also helps shave off that 0.01 second during gear shifting.

    6 ) Using a lower amperage Alternator -

    Will again reduce the friction/load on the engine. However will also restrict the amount of electrical accessories you can power while driving.

    7 ) Using light weight pulleys and lightweight belts -

    Have the same effect. Reduce the rotational inertia, and in turn the load on the Engine. Allows it to rev faster, and more freely.

    8 ) Chassis stiffening -

    Now this is a vast arena, ranging from a strut bar supporting the front suspension, to spot welding the entire car, to installing a roll-cage. It all depends and goes by the purpose of the vehicle. Stiffer the vehicle, better would be the handling.

    A roll-cage would not only help with chassis stiffening, but also occupant protection.

    Also after-market suspension helps firm up the ride quality. And they do help a lot with handling. I got custom (read hardened) springs made from a friend's factory who makes, well car suspension springs. It did great for the handling, but my bum suffered a lot as a result. So it's a balance between comfort and handling, with one affecting the other inversely.

    Lightweight after-market suspension components, would not only help lower weight, but also lower the height of the vehicle overall. This will lower the center of gravity, making the vehicle more stable at speed.

    9) Performance Tires -

    There's a line between tires that grip and actually improve handling, and tires that simply are bigger in size, but offer no improvement in performance.

    Don't go by what looks right. Go by what's the right size to drive with. Generally manufacturer's tend to under-tire their cars (again in the interest of fuel efficiency, and longer lasting tires). So 1-2 upsize is pretty much what you should be looking at.

    Also remember, lower the profile, better the handling, higher the profile, better the ride quality. So decide accordingly.

    10) Higher flow fuel pump, bigger fuel lines, and bigger injectors -

    This should actually go with Part 2, but am mentioning it here in the 'interest of performance improvements'.

    11) Using good quality fuel and oil.

    Goes without saying, but merits a mention here. Don't just go out and buy the most expensive oil available in the market. Each oil has it's own merits and properties. Ask around, test a few oils before settling down for one that provides you the best performance.

    12) Nitrous oxide -

    Made uber cool by Fast and the Furious, however this again has the ability to provide that 60-70% power boost for the period of injections. And also has the ability to well make your engine go boom. So needs to be done right, and by the right person.

    It'll provide boost in a straight line, but unless you planning to have a steady supply of NO2 cylinders, it's for that occasional boost drag.

    With the above pointers and more that I shall keep adding as I remember them :D you should have a reasonable guide as to what all is possible with that vehicle parked outside your house (or if you are rich dude, inside your garage).

    Start slowly, and steadily, and build on a strong base, one by one. Don't go overboard and try everything at once.

    Remember most importantly, a durable, reliable Mod is any day better than a mod that gives you that extra ounce of power, but compromises on reliability.

    idutt likes this.
  2. idutt

    idutt RAID Rookie

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    great info bro.will need some info from your side regarding who is the best person in delhi to do a free flow k&n filter & free flow exhaust for my k10 & a ecu remap for my skoda laura tsi.if you have the info please send me an email.remember the person has to be trustworthy & who can do the best job.
  3. JD666

    JD666 RAID Leader Staff Member

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    You had to quote the whole article for that??!!
  4. dbg

    dbg RAID Staff Staff Member

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    Lol, but a good idea to include some references
  5. idutt

    idutt RAID Rookie

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    sorry about that guess i got carried away,but i needed your expertise & contacts on this matter whenever you can in a separate email if possible.Or should I stick to stock ?

    BANHAMMER Teh Almighty BanHammer Staff Member

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    This looks good to go everywhere.
    JD666 likes this.
  7. dbg

    dbg RAID Staff Staff Member

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    Look like a big body of text, might be a good idea to spruce it up with some pics.

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