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post #1 of 7 (permalink) Old 05-09-2013, 10:44 PM Thread Starter
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Location: richmond ky
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can anyone tell me how engine will act if injectors are to big.
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post #2 of 7 (permalink) Old 05-09-2013, 11:11 PM
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Aside from acting sluggish and bad fuel consumption you may get excessive soot build up around the exhaust ends.

Give us some more information on your set up and some of the more knowledgeable builders can chime in on their ideas.

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post #3 of 7 (permalink) Old 05-09-2013, 11:41 PM Thread Starter
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i put 53.2 in it it got 58mm 107 in ,rev. heads, v&h power dualls rev fuel system, put them an it ran pretty good . dynoed it with the stock injectors an it was runnig out up on top in (fuel) have not dyno with new inj yet.
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post #4 of 7 (permalink) Old 05-09-2013, 11:54 PM
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Math is math. If the math doesn't work out where flow meets demand, you will have issues.

What's that mean? It means that as long as the ECM is aware of the flow rating for an injector it will compensate to make the math work. A bigger than stock injector will be turned on for a shorter period of time if the demand is the same.

Where a higher flow injector plays a role is in it's ability to get the fuel out quickly. Too small injector will have to be held open longer to flow make the math work. The intake valve intake is only open so long...

You can't hurt having higher flow, but you will be limited by too small if the math doesn't work out.

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post #5 of 7 (permalink) Old 05-10-2013, 10:30 PM
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What rageglide is saying is you need to have it dyno'd again so that the injector pulse width will match the injector size. Putting in larger/smaller injectors doesn't work well if the fuel tables are not adjusted in the ecm, you end up with rich/lean conditions due to the ecm not able to adjust the injector pulse width properly. If you go to a larger injector without adjusting the pulse width you end up with a large amount of fuel being injected in the chamber, hince overly rich condition, vice-versa for smaller injectors. The injector nozzles are sized accordingly to injector flow size, higher flow rate injector larger nozzle. Ran into same problem on a ZL-1 Camaro build, loaded proper injector fuel maps and wow what a difference. Went from 43 gph injector to 80 gph injector, tuner loaded a base map for the changes just to start it, then tuned from there, 760 hp by 750 tq.
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post #6 of 7 (permalink) Old 05-11-2013, 12:10 PM
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I run the 5.3 gram per second injectors in my 50mm TB and never had the bike dyno tuned but I use a Thundermax auto tuner and the correct base map needs to be programed in for the bigger injectors pulse. I used the same base map for the 58mm TB and the 50mm TB all I did was use the same 5.3gps injectors, I went back to the 50mm TB because it had more of a low end response then the 58mm TB and for me was more cruising friendly. The 5.3gps injectors will work you only need to change the program in your ECM and if you don't have a auto tuner you will need a dyno tune.

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post #7 of 7 (permalink) Old 05-11-2013, 06:18 PM
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Sorry I was trying to explain how bigger injectors deliver more in less time... but what Glenn said is probably true. That said, I think the ECM should automagically accomodate for the higher flow with a shorter pulse. But the ECM needs to know what it's working with. In most tuners one of the critical static parameters you need to set is injector size, along with engine size. From there the ECM does the math to make the injector deliver the targeted air fuel ratio. A dyno tune probably will bring some fine tuning to the mix, but I'm not sure it would be required...

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