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Injectors for a 13bNA SP

Old 08-13-09, 04:37 PM
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Injectors for a 13bNA SP

I asked this in the 2nd Gen section and didn't get any real solid answers other than my own. I already have balanced/blueprinted 460cc injectors back in the car and got to thinking they might not be enough. Before I go to the dyno and find out for sure, I am thinking I should just go ahead and change them out now. More money.

According to RC, if the desired BHP is 285, 4 injectors, .65 BSFC (per RC's recommendation on a 13bNA), 80% cycle and 43.5PSI, a 612CC min injector is needed.

This is a 13bNA SP motor, fully built. I am thinking I should get some RC 660CC injectors as the 460CC would max out around 215BHP with the BSFC, cycle and PSI above according to their calculator http://www.rceng.com/technical.aspx

Can anyone definitively say the 460CC won't work for the desired HP and that a 660CC is a good choice before I waste more money?
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Old 08-13-09, 04:47 PM
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You may be doing better than .65 BSFC.

Working backwards on the RC calculator (neat gadget), my car is at about .55 BSFC and that is running still a little too rich (12.5:1 under the test conditions) and ignition timing is probably not 100% optimized.
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Old 08-14-09, 12:09 PM
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I think you will be ok.... You can always crank the FP up
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Old 08-14-09, 01:20 PM
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You will be fine with the stock injectors if this is your EP engine. And if you get 285 out of an EP engine you will be doing better than everybody else.
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Old 08-14-09, 01:46 PM
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Originally Posted by jgrewe View Post
You will be fine with the stock injectors if this is your EP engine. And if you get 285 out of an EP engine you will be doing better than everybody else.
Yes, the EP motor. So 460cc is fine for these setups or do you mean 550cc when you say "stock injectors"? Seems small when I do the math.

The 285 number is crank HP I plugged in, I figured 18% drop for driveline which gives 233RWHP. I know that is a very lofty goal but have heard it's attainable, whether that is true or not is unknown. I'll have my numbers in 2 weeks when my tuner gets back in town and we head to the dyno.
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Old 08-14-09, 02:13 PM
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Yes, 4 460's and 42psi will get you all the fuel the engine needs.
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Old 08-14-09, 02:28 PM
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Originally Posted by jgrewe View Post
Yes, 4 460's and 42psi will get you all the fuel the engine needs.

Thanks John.
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