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L series tuning guide

Discussion in 'Freelander' started by Bigwheel, Jan 9, 2012.

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  1. Bigwheel

    Bigwheel New Member

    Jan 9, 2012
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    After studying the L series engine for its design faults and strengths, I have tried a few bits and bobs for relatively little cost, leading to more expensive, to try and pep up the performance and make it seem a little less lethargic. Most of my previous experience has been tuning VAG petrol and diesel engines, and the rover T series.


    The factory air box in most cars is more than enough to flow the amount of air needed, even by a tuned diesel. But for space limitation reasons, the freelander has quiet a small air box, and the air filter has a very small surface area which also hinders flow. I tried this airbox on my 1.9 tdi golf to see if it reduces performance, and too be totally honest, on standard boost I couldn't realy feel the difference from the std golf box, but as the boost was raised to the higher setting, it started to struggle a little bit, boost response fell noticeably, and my accelerometer dyno displayed a 3bhp loss repeatable. So in the freelanders case, an aftermarket panel filter or similar would help, but somewho fitting a larger airbox helps more. In my case, a BMC carbon air box (cylinder shape with internal cone filter) makes a bigger difference, and can be sealed and linked to a snorkel if need be.

    The pipe between the airbox and the turbo is another weak point, although its size and shape is near enough perfect, to give it strength, rover made it ribbed. This is no good for turbo response as the air becomes turbulant and does not flow smoothly into the compressor wheel, some 1.8t owners have reported a gain of nearly 5bhp when a new turbo pipe was fitted with a smooth bore, so I have swapped out mine for a custom silicone one. I cant confirm any real world bhp gains, my accelerometer has not picked anything up, but im more than certain that initial boost onset has been reduced a bit, meaning better response :).

    Never underestimate port matching, its sometimes overlooked, and seen as only something for guys in the no, but really its very simple, virtually free, and one some engines, not nessesary, but on others can make a noticeable difference! I found that my inlet manifold and inlet over-cam pipes didn't match. There was as much as 1mm of metal to be removed to get a perfect match. A good dremel and die griner set with some different burrs is ideal for this. Make sure you use an old inlet gasket to do the matching, and dont remove any more than needed, otherwise you can hurt air velocity. If you can , polishing the inside after you are done can also help a great deal. an extension of this part is to get the head port matched and polished, obviously this would cost a few £££ for someone to do, although it is not has hard as it sounds as long as you are only port MATCHING and not opening out the ports fully. Polishing internal air ways aids in keeping up the velocity. I am yet to do this on my L series, but has made a worth while 7bhp gain on my 1.9tdi golf.

    If you are feeling brave, there are small gains in turbo response to be had from polishing the inside of the compressor housing on the cold side. But make sure you dont remove any metal, just remove the rough texture anywhere needed and polish to the highest shine possible.

    The turbo elbow is another subject of mass production. Take a look inside, its as rough as a badgers back. This is hugely detrimental to exhaust speed and pulse carrying. Smoothing and polishing the elbow internally will make a noticeable difference to both response and delivery. Heat wrapping also helps, keeping the exhaust as hot as possible when leaving the turbo downstream keep the gasses moving faster.

    Polishing the inside of the exhaust manifold is another good idea, I have not done this fully yet (I have only port matched so far as I am waiting for some longer sanding stones), but the fast you can get the gasses to the turbo, the sooner it will spin.

    Needless to say, removing the restrictive soot filter from the exhaust makes a very noticeable difference to economy, the willingness to rev, and turbo response. Gutting out the soot filter is a quick and easy job, but for max benefit a replacement pipe matching the diameter of the rest of the system is a must for max flow. Like so many have said on this site and others, beware of cheap replacement pipes as some are smaller in diameter.

    The exhaust system in standard form is fairly good, and to be honest about the right diameter. You would not see any worthwhile gains or difference if going larger. It is true that diesels don't need any back pressure, and the less the better. But they do need some, the turbo needs a small amount so that the seals don't leak. 2.5' - 3.0' diameter is ideal. The freelander L series has a 2.5' pipe. Having a stainless steel one made from the turbo elbow back is a good idea, they are usually mandrel bent as opposed to crush bent like most cheap ones are made, meaning optimum flow. The rear box is actually quiet good in standard form, but after time can get blocked and coked up, so replace this at the same time. If you can get a SS one made then even better as it completes the lifetime guarantee most places offer.

    There is a fairly well documented fact that for every 10 degrees of inlet temperature dropped, equals a 1 bhp gain. So fitting a larger intercooler when the boost has been raised, or even on std boost, can and will help engine output. Economy can be improved, and as the larger intercooler will flow better it will aid spool up time too. An alloy front mount is possible, especially if you dot have a/c like me, with a bit of head scratching. I will get some pics of my setup and do a separate write-up when I get the chance. Allard are the kings of this sort of thing if you need sound advice or someone to custom build a setup.

    Larger injector nozzles are a very good idea. They allow slightly more fuel into the cylinders, while maintaining the same timing and input pressures. The result of this is that (with a good set of nozzles like bosio ones with a better spray pattern than standard) produce hardly any extra smoke on a mild upgrade in size. Going for a larger size like 0.216's will produce loads of torque, but smoke alot too. A re-worked ecu chip will help considerably, but I recommend something mild like 0.205s. If yo are swapping nozzles, I strongly suggest getting the injectors pop balanced to enable them to work at their best. Even having your injectors pop balanced and cleaned on the std nozzles will help both engine output and especially economy on a high mileage engine, and isn't usually too dear.

    A fuel tank lift pump would make a nice addition to any fueling or boost mods made. When the pump is working hard, it is having to draw its on fuel all the way from the tank, through a filter too. This can cause issues with pump timing when the pump is close to its max rating of about 134bhp. Supplying fuel to the pump at low pressure, say a couple of psi, helps to keep the timing spot on, and prevent any air locks from developing.

    After the above improvements, the most logical place to go is to ecu tuning, and there are 3 routes to go.

    1) Fool the ecu into supplying more fuel by telling it that the fuel entering the pump is a different temperature to what it actually is. This can be done with a dial resistor, 2 lengths of wire and a some connectors. You basically tap into 2 wires into the pump harness (there are loads of guides on Google, search for 'every mod') and then turn the dial until the engine starts to idle rough. From this point you back off slowly until it starts to idle smoothly, this is the 'sweet spot'. There is no denying that it works, and makes the car go like a rocket. But I am not a fan of fooling the ecu, not without some kind of intelligent monitoring or adjusting of the progression and rate of fuel advance and flow.

    2) This leads me onto a tuning box. This does much the same as above, by fooling the ecu into supplying more fuel my intercepting certain sensors. BUT the difference between tuning boxes (good ones with good feedback) and the above, is that tuning boxes are progressive in the way they up the fueling, meaning its not a simple case of being on or off. This means better fuel economy and better manners at low engine revs and off boost response. All in all, much safer and reliable :)

    3) Physically replacing the chip(s) with the fuel maps store on them in the ecu, with ones that have been reworked to give more more and better economy while staying with the tolerances of engine components and retaining all engine and ecu safety features. Re-chipping is my choice of tuning, and makes a huge difference to response, power and economy, especially if done after all the above improvements. There are not many people about now that can do good old fashioned chip tuning, as most have gone to OBD remaps. My chip I had made for me has yielded a 26bhp gain and a huge chunk more torque. Fuel economy is also alot better under normal driving conditions, I have seen a 5 mpg repeatable gain. I have used a chap I met on ebay who tunes diesel maps, and can take request such as fuel maps for economy only.

    The small turbo fitted to these engines is a GT15, and with std boost levels, is perfectly suited to the L series, giving very little lag, and holds boost well up the rev range almost all the way to the limiter with very gradual tail off in the last 700rpm. Boost cuts in at 1700rpm, where as the same turbo on the 1z tdi vag engine cuts in at 1500rpm. This is down to the better design of the vag manifold, sadly the set on the freelander means that only a custom manifold can be used, at more cost than the gains given are worth. If budget does not stretch to a hybrid turbo (gt15/20 combined), improvements can be made to the standard turbo and its boost delivery and holding. Std boost is 1.2 bar or 17psi. The safe limit for reliability with the GT15 is 20psi. They are rated at 28psi but this is the breaking point as opposed to the safe limit. Without a larger intercooler, anything past 19psi and the gains stop as the air gets far too hot. Mine is set at 19psi for max power and turbo life for when constant power is needed e.g. towing and making good time on the motorways ;) and 17psi for economy. This is switchable using an electronic boost controller which locks onto the target psi and does not allow the wastegate to creep open until this pressure is met. This is a more expenive option, although it is a good one. Another option to increase boost to a set psi is a dawes device. this device uses a pressurised gate spring and ball bearing, and unlike a bleed valve, sits in line with the wastegate pipe feed. It holds tightly closed allowing boost to cut in faster and sooner until the set pressure is met, it then 'pops' open allowing the pressure to feed to the waste gate. I highly recommend these if you want to set the boost under the bonnet, allowing faster spool up and no waste gate creep.
    I did try having a 22psi over boost setting on a 10 second hold for overtake and high torque requirements, but even with my modified ecu map and larger intercooler, the gains where not as much as going from 17 to 19 psi. This is inherent in the design of the turbo, not engine design or limitations.

    There are other small and cheap things to be done too aid power. But pushing the engine much further than this on the standard pump and you are into the realms of the unknown as to how long everything will last.

    I hope this is of some use to someone, this is just info I have found out through trial and error.
    Last edited: Jan 13, 2012
  2. Bigwheel

    Bigwheel New Member

    Jan 9, 2012
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    Any input would be good guys, especially if you have tried any of the above etc. :)
    Last edited: Jan 14, 2012
  3. kieranm105

    kieranm105 New Member

    Aug 21, 2012
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    I have the L-series in my 1999 5dr freelander.
    I currently have a blanked egr, turbo psi increased to about 18psi, silicone and alloy top intercooler hose, bottom intercooler hose to sort out (bit trickier), de-cat pipe (DarkIce designs) and a big twin cone filter with heat shield fitted. All this was cheap and easy to do and has made a huge difference to the driving of the freelander.
    Combined with a 2" lift kit, all terrain tyres, roof rack, extra lights and some under body protection (soon).

    Have you changed the bottom intercooler to turbo pipe? If you have what did you use?
    This is the only re-chipping I have found and was thinking of getting next rather than using a ecu tricking box.


    Last edited: Aug 21, 2012
  4. newcyboots

    newcyboots New Member

    Jun 2, 2011
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    In a ditch, or any jet wash in south wales......

    Where did you purchase that cone filter & heatshield, and how much did it cost.

    I want one for my identical 99 XEDi (even the colour!!)

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