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wildcat

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Posts posted by wildcat

  1. 1 hour ago, Barry said:

    One thing I've learned since I started working on cars and machinery is that experience is good but nobody knows everything and every day is a school day.

    9 hours ago, desertdude said:

    if your sanctimonious behind was so concerned about the members on this forum, should have chimed in earlier with your pearls of wisdom and enlightened us all.

    9 hours ago, desertdude said:

    Nothing of value..

    @desertdude, come on now, if you are going to continue "spouting rubbish" as someone else said, you must expect to be called out on on it, and resorting to personal attacks does not help your credibility at all- it only makes you look stupid.

    But here is the thing- you demand fact and figures, while you don't supply any of your own to support your claims. Referring people to opinion pieces on the internet means nothing, except to show that you either don't know anything about the topic, or that you expect people to believe anything you say because you've read it on the internet.

    But to facts and figures. You are of course right that water injection is nothing new, but you are not telling the whole story, and I believe that @hanif will be along shortly to call you out again. Anyway, water injection on competition engines is computer controlled, whereas in your method, there is no control over the amount of water the engine ingests.

    In a computer controlled system, the amount of distilled and purified water injected amounts to only a few parts per million relative to the total air/fuel mix, and contrary to what you claim, the primary purpose of the water is not to keep inlet temps down, but to partially quench the detonation flame, (just like EGR does) as well as to create small amounts of hydrogen when the water molecules are ionized.

    If you didn't know, the hydrogen increases combustion pressure when it burns, which then boosts power, but for this to work as intended, the ECU makes adjustments to valve timing, ignition timing, fuel injection timing/pulse width, and other settings whenever water is being injected. If it did not make these adjustments, the engine is likely to not run at all, or shut off when the water is injected.   

    This however only works in high compression engines, which forced induction engines running on petrol typically are not, which is why water injection is mainly used on diesel engines that have higher compression ratios. Moreover, water injection is typically used on new engines that have no carbon, so there is nothing to remove. Get it now?

    As for your method to remove carbon with water, do you even know why it works? I guess not, so if you are interested, here is what happens, assuming that there is carbon in a petrol engine to remove in the first place...

    Anyway, if you get the amount of water just right at any given engine speed, the water molecules get broken up, but not enough to create hydrogen because there is not enough heat and pressure. What happens instead, is that the oxygen content of the water is released, which raises the combustion temperature, which if it is high enough, burns off the carbon, or some of it at any rate.

    If you get the amount of water wrong at any given engine speed, the water quenches the combustion flame, so instead of liberating the oxygen in the water, you create super-heated steam that only loosens the carbon. Some of it may be expelled through the valves, but much of it is turned into sludge that lodges in the rings, where it works as grinding paste. This is particularly true if the engine had been burning oil for a long time, which can cause major carbon deposits, but you knew that, right?

    But there are another problems if you create steam in the engine, the first being that steam washes the oil film off the cylinder walls, so while you are adding water all day long, as you say can be done, you are removing ALL the lubrication off the cylinder walls, which I am sure even you will agree is NOT a good thing.

    (If you did not know, during normal combustion, (without water being poured into the engine) the detonation flame never reaches the cylinder walls or the top of the piston, which is why the oil film on the cylinder walls can be maintained.) 

    In addition, some of the steam escapes past the rings to condense in the crankcase, where it forms sulfuric acid when it comes into contact with most types of combustion products. Apart from contact with heat and oxygen, sulfuric acid is one of the main drivers of the process that breaks down oil additives like detergents, anti-foaming agents, and viscosity improvers (you've heard of those, right?). So while you think you are removing carbon, you are actually destroying the oil in the engine, which in all fairness to other members of this forum, you should perhaps have mentioned.  

    So yes, professional mechanics will call you out when you make silly, unfounded, and dangerous claims and statements- not because they don't like you (I'm sure they don't), but because they know a lot more about the topic than you do, or ever will. 

     

  2. Gaurav is right about a lot of the advantages of an automatic, but only as far as petrol engines are concerned. The only real disadvantage of  an automatic on either a diesel or petrol engine is that is does not offer the benefit of engine braking when one goes straight down a sand dune unless you have a lock-up torque converter. 

    However, a manual geabox on a diesel engine will beat any automatic anytime, since it develops most of its power at low RPM's, which prevents a lot of wheelspin on loose sand, because a lot of gear changes can be eliminated with a diesel running at about 3000 RPM.

    • Like (+1) 3
  3. I fully agree with Gaurav, but allow me to share one last bit of irrelevant information here before we call it quits-

    Apart from rock crawling, which is something I have never done, the fact is that the more you modify a vehicle, the less reliable it becomes. So to perform extensive modifications just to get some performance and handling from a vehicle intended for off road use is a really bad idea. Oh, and there is a lot of sand in Africa too!

    Thanks guys, it is always interesting to learn about other experiences and ways of doing things. 

  4. The strange thing with Pajeros is that while everything you say is true,  I have yet to see one complete an African transcontinental trip. I have completed more than 200 000 kms crossing Africa in all directions over the past fifteen  years or so, and the only Pajeros we ever see are broken ones. 

    As for the Dakar- you must remember that all teams have massive technical support, which can make anything complete, and even win the event. You mus also remeber that the Pajeros competing in the Dakar bear very little technical resemblance to the production models ordinary peope can buy. 

    Pajeros may be perfect for dune bashing, but all SUV's are useless in serious off roading driving conditions where there is no technical back-up, no spare engines, no spare  transmissions, or a dozen mechanics available to repair any break downs. You may want to try some real off-roading on a grade 5 trail- I think you will change you mind about what makes a real off road vehicle.

    I am also an accredited off road driving instructor, and my experience with Pajeros and other soft roaders have been uniformly bad, and these days I refuse to take any SUV on even grade three trails, simply because they do not have the suspension articulation and flexibility required to cope with seriously uneven terrain. Moreover, they have too many electronics and driver assist systems, and disabling the ABS to make them safe to drive off road is more trouble than it is worth. 

    I should perhaps also mention that you cannot fit a winch to a Pajero without extensive modifications, which makes it useless as a serious off road vehicle.

    I don't think we are talking about the same thing when we speak of off road driving, but you should perhaps put a Pejero to a real test sometime.

  5. The "weird noise" is only the traction control trying to save your friend from himself.

    Side-sloping is one of the most dangerous things an inexperienced offroad driver can do, and without traction control to keep the vehicle in line, he is very likely to cause serious damage to himself and his vehicle in the very near future.

    If you really wanted to help your friend, ask him not to deliberately drive on side slopes.

    • Like (+1) 1
  6. This is a strange problem, but we will do our best to figure it out.

    The first thing to do is to apply the brakes very lightly when you hear the sound. You only need to bring the pads into contact with the disc. If the sound goes away when you do this, it means that the pads don't fit into the calllipers properly, and that normal vibrations in the vehicle are causing them to "bounce" around in the callipers. This means that you have to have the brakes inspected to see if all the anti-rattle plates are in place, or that nothing is obviously out of place.

    It is likely that the ABS system is registering this as a fault, which is why the light comes on. However, you need to have a proper OBD II diagnostic check performed to see if there is not some other problem that could cause the ABS, or other system to activate the brakes at the speeds you mention.

    It could also happen that the ABS is deactivating itself due to a problem it is registering, which is why the light stays on until you turn off the engine. The best advice I can offer you with the amount of information available is to have a diagnostic check done before you do anything such as replacing pads and discs. You may not need to do this, since the problem may not be with the discs and pads- it could be in the ABS (or other) systems. 

    • Like (+1) 2
  7. It depends on what you want to do, because  both springs and coils have advantages and disadvantages.

    If you want to drive on fairly good surfaces, you are better off with coils since the suspension setups that go with coils almost always give a better ride quality than leaf springs do. Moreover, the trailing arms in coil suspensions allow for greater wheel travel, and with some modifications, it is possible to double the amount of wheel travel, which is what you want when you do rock crawling, or cross deep gullies. In addition, trailing arms prevent "axle bounce" that can break differentials and prop shafts under high power at large suspension extensions.

    On the other hand, leaf springs can cope with point impacts much better than coils ever can, so if you are going to drive on uneven surfaces such as rocks that are all about the same size, you are better off with leaf springs. Leaf springs can also cope with higher vehicle weights than coils can , which is why you never see vehicles with coil spring suspensions on vehicle that do long overland trips.

    In general, shock absorbers work much harder on coil spring suspensions than on leaf spring setups unless you modify the coils. You can change both the compresion and rebound rates to lessen the loads on the shocks. Also remember that the suspensions on so-called "off-road capable" SUV's and trucks are set up for highway use, which means that in off road conditions, these suspensions will always perform less efficiently than any standard leaf spring system.

    So it all comes down to what you want to do, but I suggest you talk to the local off-road clubs to see what works best for your local conditions.

  8. Hi Guys,

    My response may a bit off-topic, but you should try the off-road conditions in Africa whenever you get the chance. I have been around the African continent twice for a total of about 80 000 km, and like some other things in life, everybody should traverse Africa at least once in their lifetimes.

    Check out this link if you want to know more about conditions in Africa:

    http://4x4africa.co.za/overland/africa-overland-expedition-vehicle/ 

  9. Hi Mark,

    AES suspension failure is a known and very common problem on some Land Rovers, and especially vehicles with the following VIN numbers:

    Discovery 3/LR3 - 5A000360 to 9A513325

    Discovery 4/LR4 - AA513326 to CA638964

    Range Rover Sport - 5A900302 to 9A215622

    Replacing the balloons does not work, since the problem involves the Hitachi cmpressor that is known to fail prematurely because of wear to the piston and seals. An additional problem involves the filters on the compressor that clog up, or become saturated with moisture, which causes the compressor to either rust, or be starved of an adequate air flow. 

    Bear in mind that the control system is calibrated to not register fault codes only if the suspension system can be pressurised in a predefined time. If it takes too long because the compressor cannot deliver enough air fast enough, the system will automatically release all the air in the system, and trigger limp mode and the warning light.

    It is possible to replace the compressor with another brand, but all changes to the compressor must be accompanied by software updates to the AES system to recoqnise the new compressor, or thesystem will not work at all. 

    The updates will depend on the specific replacement compressor, so make sure that the vendor or repair shop has the software for the specific compressor you buy, or that the shop is able to update the system.  Many aftermarket parts suppliers have developed software for their replacement compressors, so shop around in your area for a compressor to replace the Hitachi unit.

     

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