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Discussion Starter #1
i need to know how much boost i can run on my stock 240 cc injectors??
 

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88 crx dx
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mrcivichybrid said:
i need to know how much boost i can run on my stock 240 cc injectors??
It's all about the math baby!!! Don't look at it as psi, but rather hp goals. Also, it depends on your afr and duty cyle.
Here's an example:

1) convert from metric(cc) to standard(lbs):
In your case 450cc/10.5=42.86lb/hr

2) choose you duty cyle and # of cylinders, multiply that product by the inj flow
4(cyclinders) x 0.9(duty cycle @ 90%)=3.6 => 3.6 x 42.86=154.30

3) Divide that by your B.S.F.C.(brake specific fuel consumption). NA car use about .5 pounds of fuel/hp/hr. You're turbo, so you will be slightly higher (unless
you're running extremely lean, or running high octane fuel), around 0.6 - 0.65
154.30 / 0.6 = 257.16 horsepower max @ 90% duty cycle

You can push 450's farther with leaner(.5 bsfc) and a 100% duty cycle(1.0), but that's up to you and what you are willing to risk. I showed all the math to help with the understanding and so people can play around with different injector sizes, duty cycles, and fuel consumption(richer or leaner). If you have a hp goal in mind you can run the formula backwards to get the supporting injector size for that hp. Hope this helps.
-Andy
taken from here

which means for 240cc injectors....

1) 240 / 10.5= 22.86
2) 4 * .9 = 3.6, 3.6 * 22.86 = 82.3
3) 82.3 / .6 = 137.2

137.2 hp max with a 90% duty cycle.
 

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^^^I agree with him, however you could make more power with them if you bought an adjustably FPR, and cranked up the fuel pressure...but I wouldn't recommend it.


You can find a set of DSM injectors for pretty cheap, I bought a set for 30 bucks :TU: If you decide to go that route, you will have to buy a resister box and wire everything up.
 

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98_4drCivic said:
^^^I agree with him, however you could make more power with them if you bought an adjustably FPR, and cranked up the fuel pressure...but I wouldn't recommend it.


You can find a set of DSM injectors for pretty cheap, I bought a set for 30 bucks :TU: If you decide to go that route, you will have to buy a resister box and wire everything up.
+1 390's are the lowest id go on a turbo setup
 

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rickles8099 said:
taken from here

which means for 240cc injectors....

1) 240 / 10.5= 22.86
2) 4 * .9 = 3.6, 3.6 * 22.86 = 82.3
3) 82.3 / .6 = 137.2

137.2 hp max with a 90% duty cycle.
is that whp or chp??
 

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dsm's rock. or check out supra or mr2 turbo injectors if you want. you can basically make anything fit depending on whether its top feed or side feed and the pulse width/impedance/whatever other electrical shit is involved.
 
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Discussion Starter #11
im running a garrett t3. when i took it to the dyno the guy that owned the shop said the wideband o2 was saying at i was running just a tad bit on the rich side @ 6psi.so im thinking if i turn it up to 8psi or 9psi it will be right at stoich
 

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BOYURLAZY said:
is that whp or chp??
i would say horsepower at the crank since that equasion would need to have something inserted for a drivetrain loss in power. and since fwd cars have less drivetrain loss than rwd cars and different gear ratios, tire/wheel sizes and weights, rotor sizes affect powertrain losses, it would be difficult to come up with an effective equasion.
 

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mrcivichybrid said:
im thinking if i turn it up to 8psi or 9psi it will be right at stoich
uhh, your injectors are already at the max duty cycle...

turn the boost up and starve the engine of fuel and blow a piston, sounds like a great idea :TU:

do yourself and your motor a favor, get some bigger injectors. why put together a turbo kit only to skimp on one of the most important parts?
 

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If you are running an FMU then no more then about 6psi... otherwise i have seen quite a few people making 200whp+ on stock 240's... But like someone said dsm 440's are cheap as hell.

This little chart was taken from www.phearable.net

240cc = 180-190whp 310cc = 200-220whp 370cc = 220-280whp
440cc = 280-330whp 550cc = 330whp-380whp 660cc = 380whp-425whp
720cc = 425whp-475whp 880cc = 475whp-525whp 1000cc = 525whp-600whp
 

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sohc_sol said:
If you are running an FMU then no more then about 6psi... otherwise i have seen quite a few people making 200whp+ on stock 240's... But like someone said dsm 440's are cheap as hell.

This little chart was taken from www.phearable.net

240cc = 180-190whp 310cc = 200-220whp 370cc = 220-280whp
440cc = 280-330whp 550cc = 330whp-380whp 660cc = 380whp-425whp
720cc = 425whp-475whp 880cc = 475whp-525whp 1000cc = 525whp-600whp
These are more of the numbers i was thinking about.
 

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injector size calculator Hp x .60 (.50 for n/a)/number of injectors x .90 (duty cycle) so say your going for 180-200hp. 180x.60/4x.90 = 24.3 lbs/hr convert to cc/min 24.3x10.50 = 255.15. your going to max out your injectors before you even hit 180bhp.
 

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mrcivichybrid said:
im running a garrett t3. when i took it to the dyno the guy that owned the shop said the wideband o2 was saying at i was running just a tad bit on the rich side @ 6psi.so im thinking if i turn it up to 8psi or 9psi it will be right at stoich
you want to be rich under boost, not stoich. Stoich is 14.7 to 1 afr, way too lean for boost. The magic # mentioned many times on here is around 12 to 1 afr for boost.
 
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Discussion Starter #18
what if he planned to use a fmu? would that work or would it be a dumb idea? wat would happen is he did use 12:1 fmu on stock 240cc injectors on 6psi of boost? what owuld he have to do for that to work?
 
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