Club G40 Forum
Technical => Engine and Transmission => Topic started by: JonnieG40 on October 01, 2009, 12:04:23 pm
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At the moment my g40 has the following spec:
Decat stainless exhaust system, 4-2-1 manifold, de-wedged throttle body, R1 rebuilt Gladder, Jabba induction kit, boost return mod, basic jabba chip.
If I were to install the 265cc g60 injectors would it be worth while? would I notice torque/power increase or would this just increase my fuel bill. Im still undecided.
John
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you need a chip to suit.
high powered g40s sometime reach the useable limit of the fuel g40s can deliver, so people upgrade to avoid potential of maxing out the injectors and running lean
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g40 injectors should be fine unless you put a g60 charger
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^ What ?! Where have you heard that ??? ???
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you don't just swap and change injectors for the fun of it.
the whole idea of tuning an engine is to make it consume more fuel (and hence make more power if you are doing things right). So at some point you get to the stage where the standard injectors are at (or almost at) their maximum flow rate and the only way to continue tuning the engine is to replace the injectors for bigger ones that can flow more fuel. The standard g40 injectors generally cope up to about 160bhp and then you are running the risk of the engine running lean at some points because the injectors are being pushed beyond their limits at high load. Plus you run the risk of wearing out the injectors prematurely because they could be going "static" where they are being held constantly open instead of being pulsed which is how they are designed to work. However, it's not just a case of putting in the biggest injectors you can find because with big injectors on a small engine you get a lot of poor spray pattern and fuel drop out at low loads/rpm, this affects economy and day to day drive ability, plus possibly makes it difficult to pass an mot emissions test. You even get this to some extent with 310cc injectors on a g40.
You cna't just change injectors either, you need a remap to suit whatever size of injectors you are using. The ECU doesn't know how big the injectors are which it is connected to, if you use a fuel map designed for standard ~190cc injectors with 250cc "g60" injectors then you'll be running very rich all the time because the ECU will still be keeping the injectors open as if it only had 190cc ones in. Might not be too noticeable at full load but possibly runs the rick of dangerous bore wash at lower loads.
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Another big myth is that simply swapping injectors alone can somehow increase power. With any engine there are certain air-to-fuel ratios that produce the most power, this is generally fixed for a petrol engine but does vary from car to car and forced induction engines generally need to be a bit richer than naturally aspirated engines. Anyway, long story short, as long as the injectors you are using are capable of suppling enough fuel to hit these sweet spot ratios without being pushed too hard then swapping for bigger injectors will have no effect what so ever. One thing that oftens fools people into thinking that a difference is made is that you of course need a remap to suit the bigger injectors, if you are going from a standard-ish map to a tweaked one then this itself will increase power slightly. But you could have just as easily kept the standard injectors and just got the remap alone to suit these.