confused about injector size!
Thread Starter
Junior Member
Joined: May 2007
Posts: 71
Likes: 0
From: Lansing, MI
Car: 1988 Formula
Engine: 305 TPI
Transmission: t-5
confused about injector size!
hey guys i am getting really confused over what sized inectors i should be using... iv got a 350 with 202 heads, flat top pistons, hooker high flow headers, an rv cam, and the stock 305 tpi intake.. i need to swap the old 19 ers out with bigger ones.. iv been looking around and the whole duty cycle issue is confusing the carap out fo me.. all the injectors iv been looking at are rated at 100% duty cycle.... so i guess what im asking is would 24LB injectors rated at 100% duty cycle be enough or too much for my setup? thnx!
Joined: Feb 2007
Posts: 4,767
Likes: 63
From: Trumbull CT
Car: 87 TA clone
Engine: 70/70 Turbo 5.3 LS
Transmission: bullet proof 2004R
Axle/Gears: ford 8.8, 3.55 gears
Re: confused about injector size!
24 is ok, depending on ur hp output ur gona have to adjust the pressure. stock 350tpi run 21lb. and are good for 300hp if u dump the pressure to 50psi.
Supreme Member
Joined: Jul 1999
Posts: 2,149
Likes: 4
From: Mims, Florida
Car: '87 IROCZ
Engine: 395 ZZ4
Transmission: ProBuilt 700R4
Axle/Gears: 9 bolt 3.70s
Re: confused about injector size!
I recommend the 24#/hr Ford racing fuel injectors, and buy a good AFPR, and a good fuel pressure gauge. An AFPR is a very valuable tool when it comes to tuning, and to use it properly, you must have the fuel pressure gauge.
Measure the fuel pressure now, and then set the AFPR at that pressure after installing the 24#/hr injectors. Adjust from this starting point to maximize your performance which could be done at your local dragstrip.
I am assuming you have a MAF car being an '87 like mine. You probably have enough adjustability in the ECM to account for the 24 #/hr injectors. However, if you dont, you will need to get an Eprom chip burrned for the 24s.
Measure the fuel pressure now, and then set the AFPR at that pressure after installing the 24#/hr injectors. Adjust from this starting point to maximize your performance which could be done at your local dragstrip.
I am assuming you have a MAF car being an '87 like mine. You probably have enough adjustability in the ECM to account for the 24 #/hr injectors. However, if you dont, you will need to get an Eprom chip burrned for the 24s.
Senior Member
Joined: Jun 2000
Posts: 599
Likes: 0
From: Glenbeulah, WI
Car: 1988 Firbird
Engine: 406
Transmission: T-56
Axle/Gears: 4.10
Re: confused about injector size!
The stock 19 LB injectors will probably work fine with your combination and then you would not need a new chip. The 19 lB injectors will work fine to about 325 flywheel HP.
Joined: Feb 2007
Posts: 4,767
Likes: 63
From: Trumbull CT
Car: 87 TA clone
Engine: 70/70 Turbo 5.3 LS
Transmission: bullet proof 2004R
Axle/Gears: ford 8.8, 3.55 gears
Re: confused about injector size!
19lb injectors can run on a 350 but u will be maxing them out bc u will be bumping the pressure to 50psi or they will create a lean condition... not good for the motor, on a 305 the 19lb injectors are good for 300hp id say maybe... but on a 350 u might get away with 260hp. i would def go with 24lb SVO ford injectors.... they are good quality. i got the ford SVO 30lb for my 500hp HSR 383
and def get an adjustable regulator and fuel gauge as doc said. u will need to adjust it for tuning purposes
and def get an adjustable regulator and fuel gauge as doc said. u will need to adjust it for tuning purposes
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