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best fuel pressure ??

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Old Feb 25, 2016 | 08:58 PM
  #1  
rusty vango's Avatar
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From: knoxville tn
Car: 86 IROC
Engine: 5.0 TPI
Transmission: 700-R-4
Axle/Gears: 2.73 open
best fuel pressure ??

i searched ,but no answer to this one . if one has a bone stock LB9, what would be considered the optimum fuel pressure ? and why ? im thinking of getting a adjustable FPR , just for S&Gs. is there any truth to the idea that a higher than stock pressure at the injectors increases their efficiency?
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Old Feb 26, 2016 | 04:48 PM
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From: Milwaukee
Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: best fuel pressure ??

I'm surprised you're asking this, Rusty. I've read debates on this over the years. You may have asked a question that opens a can of tpi worms but I think that's the fun of TGO. Personally, I think the factory chose 43.5 for whatever their reasons were and am willing to follow suit like a lemming. Now why were different pressures chosen over the years for different manufactures? Dunno? Better atomization per injector design maybe? Southbay may have some good insight.
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Old Feb 27, 2016 | 10:29 AM
  #3  
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From: knoxville tn
Car: 86 IROC
Engine: 5.0 TPI
Transmission: 700-R-4
Axle/Gears: 2.73 open
Re: best fuel pressure ??

since i just got a set of bosch3s from south bay , AND a FPR kit. it got me to thinking ,does changing from multecs to bosch3s change the pressure requirement at the injector??? im gonna give SB a call monday .ill post what i learn
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Old Feb 27, 2016 | 11:08 AM
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From: Mass
Engine: 350 TPI
Transmission: A4
Axle/Gears: 3.23
Re: best fuel pressure ??

Ive wondered if the bone stock L98s and LB9s benefited from an increase in fuel pressure. SD TPIs mainly.
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Old Feb 28, 2016 | 08:00 AM
  #5  
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Car: 1987 IROC-Z
Engine: 406 on N20 w/ EFI
Transmission: P.B. 700R4
Axle/Gears: 12 bolt w/ 3.91
Re: best fuel pressure ??

im curious to know also
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Old Feb 28, 2016 | 08:52 AM
  #6  
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From: knoxville tn
Car: 86 IROC
Engine: 5.0 TPI
Transmission: 700-R-4
Axle/Gears: 2.73 open
Re: best fuel pressure ??

i thought asking this question would get more responses than it has , so far. i mean , one would think changing the design of the injector . would also change the fuel pressure requirement . maybe it dont , but im trying to learn all i can BEFORE i put my TPI car back together , i only want to do this ONCE
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Old Feb 28, 2016 | 10:35 AM
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From: West of Toronto
Car: 89 IROC
Engine: 305 TPI / ZZ4 cam
Transmission: Stage 2 700R4, LS1 driveshaft
Axle/Gears: Strange 3.42 w/ Auburn
Re: best fuel pressure ??

There was an article done a few years ago ( I think Hot Rod mag...but don't quote me) addressing fuel pressure and HP. They added an AFPR and wanted to copmare the results. It compared stock (42 psi), 46 and 50. 50 gave the best HP but for overall power and fuel "economy", 46 was a better choice. I have the chart results somewhere if needed but the article itself you'll have to find.....
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Old Feb 29, 2016 | 08:36 PM
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Re: best fuel pressure ??

Originally Posted by rusty vango
i searched ,but no answer to this one . if one has a bone stock LB9, what would be considered the optimum fuel pressure ? and why ? im thinking of getting a adjustable FPR , just for S&Gs. is there any truth to the idea that a higher than stock pressure at the injectors increases their efficiency?

Hey Rusty, first of all, thanks for the purchase. Second of all...the fuel pressure setting for the multecs and the bosch lll's are the same...43.5psi.
Raising fuel pressure does not increase the efficiency of an injector...if anything it will increase the flow rate which will increase the flow of fuel. More is not always better. You can have a little variation that will not affect the performance of the engine. ie: 45psi or 46psi
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Old Mar 1, 2016 | 01:16 AM
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From: knoxville tn
Car: 86 IROC
Engine: 5.0 TPI
Transmission: 700-R-4
Axle/Gears: 2.73 open
Re: best fuel pressure ??

thanks guys ,
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