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  1. Join Date
    Apr 2009
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    1,902
    #1
    http://en.wikipedia.org/wiki/Nissan_QG_engine
    The QG engine is a 1.3 L, 1.5 L, 1.6 L, 1.8 L, and 2.0 L straight-4 piston engine from Nissan. It is a lean-burn aluminum DOHC 4-valve design with variable valve timing and optional NEO Di direct injection.

    http://en.wikipedia.org/wiki/Lean-burn
    Lean burn refers to the use of lean mixtures in an internal combustion engine. The air-fuel ratios can be as high as 65:1, so the mixture has considerably less fuel in comparison to the stoichiometric combustion ratio (14.7 for petrol for example).

    A lean burn mode is a way to reduce throttling losses. An engine in a typical vehicle is sized for providing the power desired for acceleration, but must operate well below that point in normal steady-speed operation. Ordinarily, the power is cut by partially closing a throttle. However, the extra work done in pumping air through the throttle reduces efficiency. If the fuel/air ratio is reduced, then lower power can be achieved with the throttle closer to fully open, and the efficiency during normal driving (below the maximum torque capability of the engine) can be higher.

    The engines designed for lean burning can employ higher compression ratios and thus provide better performance, efficient fuel use and low exhaust hydrocarbon emissions than those found in conventional petrol engines. Ultra lean mixtures with very high air-fuel ratios can only be achieved by Direct Injection engines.

    The main drawback of lean burning is that a complex catalytic converter system is required to reduce NOx emissions. Lean burn engines do not work well with modern 3-way catalytic converters, which require a balance of pollutants at the exhaust port in order to carry out both oxidation and reduction reactions, so most modern engines run at or near the stoichiometric point. Alternatively, ultra-lean ratios can be used to reduce NOx emissions.
    Last edited by isa1023; February 24th, 2010 at 10:11 AM.

  2. Join Date
    Apr 2009
    Posts
    1,902
    #2
    http://en.wikipedia.org/wiki/Lean-burn

    Lean burn refers to the use of lean mixtures in an internal combustion engine. The air-fuel ratios can be as high as 65:1, so the mixture has considerably less fuel in comparison to the stoichiometric combustion ratio (14.7 for petrol for example).
    I think it also goes to say it has more air than fuel in the mixture.
    So, does this mean I will get better response if I install a free-flow short-ram air intake system like KNN cone filters?

    The engines designed for lean burning can employ higher compression ratios and thus provide better performance, efficient fuel use ...
    Does this mean you can install turbo without having to strengthen/upgrade vital engine internals like the pistons (ie no need for forged pistons)??? Considering you opt to keep the pressure to a minimun, say 3 psi...

    ... and low exhaust hydrocarbon emissions than those found in conventional petrol engines.
    So can you go full exhaust , cat-less, straight midpipe to muffler without having to worry on emission issues, especially during renewal of registration?

    The main drawback of lean burning is that a complex catalytic converter system is required to reduce NOx emissions. Lean burn engines do not work well with modern 3-way catalytic converters, which require a balance of pollutants at the exhaust port in order to carry out both oxidation and reduction reactions, so most modern engines run at or near the stoichiometric point. Alternatively, ultra-lean ratios can be used to reduce NOx emissions.
    But on second thought, should you keep the cat?
    If you don't go full exhaust, would the IHE upgrade be optimised by just using an AFC (fuel controller) tuned just on o2 sensors?
    Last edited by isa1023; February 24th, 2010 at 10:13 AM.

  3. Join Date
    Aug 2004
    Posts
    22,710
    #3
    You're overestimating the amount of lean-burn in the "lean-burning" QG13DE. It's a regular street engine with a safe 9.5:1 compression. Only the direct injection models (and the local QG isn't) employ ultra-lean-burn strategies.

    You can go catless, drive it on kerosene and belch clouds of black smoke and still pass emissions. If you care for the environment, though, leave the cat in.

    RE: turbo? 3 psi? not worth the time or money if you limit yourself to that amount. You can safely boost 7-10 psi on a stock engine with that compression and see around 140-160 bhp (around 120-130 whp), but I don't know if the transmission can take it.

    If you're getting an engine management system, the best ones are piggybacks like the Unichip and the E-Manage. Costly, but they'll give you much better power gains than a simple AFC on an engine with electronic ignition like the QG13. Typical gains from this mod alone should be around 10-12 hp in the midrange for an engine like the QG13.

    With simple intake, exhaust and management mods, your car should make an extra 15+ hp. Still won't be as quick as a 1.6, but should be enough to satisfy you for a while. Anything more might be like squeezing blood from a stone, and it would make more sense just to swap in a bigger engine (like an SR20 or a QR25).
    Last edited by niky; February 24th, 2010 at 11:25 AM.

    Ang pagbalik ng comeback...

  4. Join Date
    Apr 2009
    Posts
    1,902
    #4
    Yep I think I wouldn't want to take the cat out.
    The way I see it though, going the turbo way won't make much power gains on the QG13DE, although it's nice to know you can boost it safely at 7psi (didn't know much about turbo upgrades).

    The Unichip looks like a promising mod for now. Since I can still keep it come the time (years from now, probably) for an SR20DE swap (I want the red one without the distributor cap).

    I hope someone does the sr20de swap on the local n16 soon so we can get feedback ...

  5. Join Date
    Aug 2004
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    22,710
    #5
    You'll have to look at the US boards for more info on that one... or get the wiring diagram for the US version that comes with the SR20 as stock. That will help you a lot with the swap.

    At 130 whp (approximately 160 bhp) with the turbo, your Sentra would already be much faster than stock SR20-equipped one. It's fine if that's all you want, but if you have big plans in the future, an SR is the way to go. Only issue is, you'll have to weigh what you'll need to spend against the benefits... a secondhand B13 or B14 will cost just 150-200k pesos... with an SR20 already installed. It might cost you 100k to install a newer direct ignition SR20 into the N16, and it won't be as quick as one of the older cars (heavier).

    Ang pagbalik ng comeback...

  6. Join Date
    Aug 2004
    Posts
    22,710
    #6
    You'll have to look at the US boards for more info on that one... or get the wiring diagram for the US version that comes with the SR20 as stock. That will help you a lot with the swap.

    At 130 whp (approximately 160 bhp) with the turbo, your Sentra would already be much faster than stock SR20-equipped one. It's fine if that's all you want, but if you have big plans in the future, an SR is the way to go. Only issue is, you'll have to weigh what you'll need to spend against the benefits... a secondhand B13 or B14 will cost just 150-200k pesos... with an SR20 already installed. It might cost you 100k to install a newer direct ignition SR20 into the N16, and it won't be as quick as one of the older cars (heavier).

    Ang pagbalik ng comeback...

IHE mods effect on lean-burning QA13DE