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Originally posted by st5150:
It depends on how efficient the motor is and how much fuel pressure you run through the injector. A typical NA 5.O with 40 psi through 30lbs injectors is good for about 350 rwhp.

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I have 30s and was putting out 365 or so hp. Now i have a bigger TB,MAF,and headers. Sounds like a step up in fuel should be next for me.
 

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Posted by st5150 (Member # 51) on :
 
1SLOWLX- The 4something HP numbers you heard were flywheel, not RWHP.


season'd 88- Probably but not necessarily. Your motor is very efficient, thus for the same unit(drop) of fuel, it makes more RWHP than a stock 5.O motor for example. For the mods you listed, I wouldn't swap MAF & injectors. Maybe bump up fuel pressure a tad, but some engine/maf combos take care of the extra fuel themselves. Basicly, its all guesswork with out a wideband....but I wouldn't worry about it too much right now.
 

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Posted by 1SLOWLX (Member # 558) on :
 
I have a set of 42lb's and with thinking about using them
 

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Posted by 1SLOWLX (Member # 558) on :
 
Anyone else have an opinion about how much power these 30lb injectors will hold NA??
 

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Posted by Jeff S (Member # 371) on :
 
I'd say ~375rwhp for an injector that is flowing 30#/hr on a NA application with 8 injectors and peak power under 6500rpms.
 

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Posted by Camara90 (Member # 134) on :
 
my old setup did 386rwhp on 30lb injectors with no problem.
 

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Posted by 1SLOWLX (Member # 558) on :
 
I bought your 42lb's injectors so why not use them right mike?
 

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Posted by Camara90 (Member # 134) on :
 
i would run the 42lb, it wont hurt as long as you get it tuned and it wont put as big as a stress on the fuel system with having to run so much pressure. I guess it all depends on what you plan on doing with the car. If you think it will make about 390 like you said id run the 42's to be safe.

[ November 14, 2003, 02:02 AM: Message edited by: Camara90 ]
 

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Posted by DropTopFox (Member # 1689) on :
 
I would talk to Flea albert, he has a whole little sheet that says and I believe a 30 is upwards around 500, don't take my word on that but he told me not to change from 19's until I hit 350
 

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Posted by boosted89Saleen (Member # 2243) on :
 
I thought the 30's were good up to around 400RWHP, hmmm
 

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Posted by 1SLOWLX (Member # 558) on :
 
I think I will probably just use the 42lbs because I have them and why not right. Ryan you interested in buying some 30lbs??? It will have to get tunned again with the exhaust mod and the new valve springs
Albert
 

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Posted by wilit (Member # 3367) on :
 
You know, there actually is a formula for figuring out what size injectors will support how much HP. Of course, if you don't want to do the math, there is a calculator to figure it out for you.

http://www.rceng.com/technical.htm
 

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Posted by Jeff S (Member # 371) on :
 
Every engine is different and some require more fuel than others to make the same power. There are many variables.
 

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Posted by st5150 (Member # 51) on :
 

quote:

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Originally posted by wilit:
You know, there actually is a formula for figuring out what size injectors will support how much HP. Of course, if you don't want to do the math, there is a calculator to figure it out for you.

http://www.rceng.com/technical.htm

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Thanks for the link. I like how it solves for BSFC, even though its still a ball park figure. I've always calculator from the download section of www.racesystems.com which is based on equations in the "Auto Math" book ( http://www.mathbook.com/m/Engineering_Mathematics/Auto_Math_Handbook_Calculations_Formulas_Equations_and_Theory_for_Automotive_Enthusiasts_1557880204.htm )
 

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Posted by 1SLOWLX (Member # 558) on :
 
That does it for me here come the 42lb's
 

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