what size fuel injectors?
Thread Starter
Racer
Joined: Nov 2000
Posts: 415
Likes: 0
From: mauriceville texas
what size fuel injectors?
i am going to replace the stock injectors and would like to go up one size. what size are the stock injectors on a 92 lt1? i am also going to put a adj fuel reg on and figured this would be the time to do it. i have already replaced the fuel pump and have been told that an adj reg would really help. any advice would be app. the car has over a 100 thou on it now and sometimes gets a litle hard to start when it is hot. i have been told that this is a sign of leaking injectors. if i am missing the boat here please chime in and get me headed in the right direction. thanks robert
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: what size fuel injectors? (robert kirk)
Unless you have lota mods, stay with stock size injectors. You can send the set to Rich at Cruzin Performance (link on my site) to be rebuilt, flow tested and leak checked for about $80/set plus shipping. Shop time is 48hrs.
Before you pull the injectors, put a gauge on the Schraeder and record stock fuel pressure at idle with the vacuum line disconnected. This will be your initial setting for the AFPR.
Before you pull the injectors, put a gauge on the Schraeder and record stock fuel pressure at idle with the vacuum line disconnected. This will be your initial setting for the AFPR.
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: what size fuel injectors? (robert kirk)
The stockers are good unless youre gonna go up in cubes or alot of hp.
Thread Starter
Racer
Joined: Nov 2000
Posts: 415
Likes: 0
From: mauriceville texas
Re: what size fuel injectors? (65Z01)
what is AFPR? i was under the impression that this was a straight swap. pull the reg and inj, install new set fuel pressure at 40. stock it is. this is not a hot rod but a daily driver. i have noticed on several other motors hp changes were made by just increasing carb size, i assumed that injectors worked the same way. being an old fart has its draw backs sometimes. thanks for the advice. robert
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: what size fuel injectors? (robert kirk)
My L98 dynoed at close to 300hp, up from the stock 240hp.
I have an AFPR set to 47psi and a wide band O2 sensor during the dyno pulls showed about 12.7:1 air/fuel at WOT, which the dyno operator said was just about right.
So you can use the AFPR to increase fuel flow at WOT, where the ECM enters open loop. During normal driving the ECM uses the O2 sensor to reduce injector pulse width to maintain good street manners, fuel economy and emissions control.
As mentioned, unless you have heavy mods, this is better than increasing injector size.
I have an AFPR set to 47psi and a wide band O2 sensor during the dyno pulls showed about 12.7:1 air/fuel at WOT, which the dyno operator said was just about right.
So you can use the AFPR to increase fuel flow at WOT, where the ECM enters open loop. During normal driving the ECM uses the O2 sensor to reduce injector pulse width to maintain good street manners, fuel economy and emissions control.
As mentioned, unless you have heavy mods, this is better than increasing injector size.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Drifting
Joined: Jul 2002
Posts: 1,273
Likes: 0
From: Olathe, KS USA
Re: what size fuel injectors? (robert kirk)
Stock injectors are the best way to go. Setting fuel reg. With the ignition ON and engine OFF (zero vacuum )system fuel pressure @ pressure test connection (fuel rail) should be 284-325 kPa (41-47 psi ) As per 92 GM Ser. Manual You will need a fuel line Quick Connect Separator. Also a Fuel Pressure Gage to set fuel reg. and to releave fuel pressure. Do Not open fuel lines on a hot engine or without releaving fuel pressure. Good luck and let us know how it goes. :flag
Advanced
Joined: Jun 2002
Posts: 71
Likes: 0
From: Hummelstown Pa.
Re: what size fuel injectors? (robert kirk)
As everyone else has stated --- Stay with the stock injectors. I put 30's on and the car did not idle for s@#*. I put the stock ones back in. Set the afpr at 47 - runs fine. dynoed at 345 hp with a f/a mixture of 11.96
Safety Car
Joined: Mar 2000
Posts: 3,620
Likes: 2
From: Hillsboro OR
Re: what size fuel injectors? (robert kirk)
Your hot start problem is probably caused by leaky injectors. I would replace them since they have 100k miles on them. Get some Ford Motorsport 24# units and you should be okay. Stock is 22# but the ecm should be able to compensate for the larger size.
Change the fuel pressure regulator only if it leaks fuel into the intake through the vacuum line or it doesn't regulate the pressure properly. You can use an afpr but the ecm will adjust out any changes you make with it so its not really very useful on your setup.
Change the fuel pressure regulator only if it leaks fuel into the intake through the vacuum line or it doesn't regulate the pressure properly. You can use an afpr but the ecm will adjust out any changes you make with it so its not really very useful on your setup.
