This is topic how much hp w/30 lb injectors??? in forum Tech Talk at Northern California Ford Owners .
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Posted by 91 5.0 (Member # 1527) on
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How much hp are 30lb injectors good for on a supercharged motor?
Posted by st5150 (Member # 51) on
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Is an FMU used? If so, how much fuel pressure will be pumped through the 30 lbs injectors under full boost?
Posted by 91 5.0 (Member # 1527) on
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I dont know. The FMU im using right now is for 24lb injectors. Ive got a 255lph intank pump, ill probably also be using a T-rex inline pump. I heard that my FMU raises the pressure to 80psi under boost. I want to run about 10lbs of boost with my A-trim. Ill also have minor bolt ons-headers, intake, throttle body, etc.
Posted by st5150 (Member # 51) on
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You really have to know how much fuel pressure you're pumping through the injectors to calculate how much horsepower they'll support.
If you haven't bought the T-rex yet.... get the WALBRO inline fuel pump instead. It flows more than the T-rex and you can never have too big of a fuel pump or fuel system.
Posted by 91 5.0 (Member # 1527) on
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ok, so with the walbro inline, a 255 intank, what should I set my pressure at, and at that pressure, how much hp can I safely push?
Posted by Yung Than (Member # 728) on
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How much boost psi are you planning to run at full boost? What ratio is your FMU?
Posted by 91 5.0 (Member # 1527) on
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about 10lbs. I think that is all I should run with an A-Trim. Im not sure what the FMU ratio is. It came with the supercharger. I was told its for 24lb injectors though.
Posted by TM88GT (Member # 105) on
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If you have stock heads, cam, intake....you can run the 30lb injectors without the FMU, but you'll need a chip. They'll support about 350rwhp.
Posted by st5150 (Member # 51) on
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Terrance, its actually 350 flywheel HP for a boosted application and 30 lbs injectors at 40 psi.
Figure a stock 5.O motor with 10 lbs of boost will make anywhere from 290-330 rwhp... more likely somewhere right in the middle (310rwhp), so yeah, 30 lbs injectors will get him by with a custom chip.
On a boosted car, 30 lbs injectors with a small FMU that will spike fuel pressure to 60 psi will be safe at 375 rwhp.
[ January 17, 2003, 02:10 PM: Message edited by: st5150 ]
Posted by 91 5.0 (Member # 1527) on
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So I should probably just go with 36's? I want to have around 380-400hp eventually.
Posted by st5150 (Member # 51) on
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36's will take you to 380ish rwhp just fine with out an FMU and 450-475 rwhp with an FMU, provided you're using a Walbro 255 lph intank and 225lph inline pump.
Posted by street_illegal_stang (Member # 1554) on
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using this table here---16x19lbs=304hp
---16x24lbs=384hp
---16x30lbs=480hp
---16x36lbs=576hp
this is how much the injectors can take or pistons rather.
-Street-
Posted by st5150 (Member # 51) on
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With all due respect, that 16X "rule" is complete BS. I bet the guy who came up with that joke 16X injector rule is rebuilding his short block right now after a lean condition burnt a hole in his piston.
Posted by street_illegal_stang (Member # 1554) on
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yeah, its hersay buddy i just didn't pull it outta my ass
Posted by TM88GT (Member # 105) on
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quote:
Originally posted by st5150:
Terrance, its actually 350 flywheel HP for a boosted application and 30 lbs injectors at 40 psi.
Figure a stock 5.O motor with 10 lbs of boost will make anywhere from 290-330 rwhp... more likely somewhere right in the middle (310rwhp), so yeah, 30 lbs injectors will get him by with a custom chip.
On a boosted car, 30 lbs injectors with a small FMU that will spike fuel pressure to 60 psi will be safe at 375 rwhp.
I've seen several boosted 5.0 with 30's and no FMU (chip tuned by Byron) making in the 350-360rwhp range and doing fine. Duty cycle was in the 90% range. Keep in mind - you wont be at WOT all the time so a duty cycle this high is not really a problem.
With his combination of parts, 30's will be fine.
Posted by st5150 (Member # 51) on
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True, you can get it done with duty cycle in the 90%+ range... but I don't like that and would never recomend it to anyone. I'd rather build it right the first time than barely skim by. This is especially try for a power-adder car where there is little to no room for error when it comes to fuel delivery.
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