Fuel injector replacement - are 22#s enough?
Thread Starter
Advanced
Joined: May 2003
Posts: 60
Likes: 0
Fuel injector replacement - are 22#s enough?
I finally got the '90 running after 14 months of downtime due to a blown head gasket. It was bone stock when I started, now it has been completely rebuilt with the following mods:
'90 L98 6sp:
cut lid, 52mm, ported plenum, large tube runners, big mouth manifold, ZZ-9 cam, Crane Pro Magnum 1.6 rollers, hardened pushrods and guide plates, ported 113 heads, stock exhaust for now - TPIS headers and an adjustable fuel pressure regulator are on the shelf waiting for me to install.
It runs good although the idle is rough (it gets worse as it warms up), off idle has a bit of hesitation. I haven't tried WOT cause I'm concerned the AFR maybe too lean. I'm going to replace the injectors anyway (Multecs are crap), so are 22# injectors enough, or should I go with 24#s? How much horse power can you get out of 22#s?
PS thanks to all for the great info I got here during the rebuild process. Corvetteforum rocks!
'90 L98 6sp:
cut lid, 52mm, ported plenum, large tube runners, big mouth manifold, ZZ-9 cam, Crane Pro Magnum 1.6 rollers, hardened pushrods and guide plates, ported 113 heads, stock exhaust for now - TPIS headers and an adjustable fuel pressure regulator are on the shelf waiting for me to install.
It runs good although the idle is rough (it gets worse as it warms up), off idle has a bit of hesitation. I haven't tried WOT cause I'm concerned the AFR maybe too lean. I'm going to replace the injectors anyway (Multecs are crap), so are 22# injectors enough, or should I go with 24#s? How much horse power can you get out of 22#s?
PS thanks to all for the great info I got here during the rebuild process. Corvetteforum rocks!
Drifting
Joined: Aug 2000
Posts: 1,521
Likes: 0
From: West Islip New York
Re: Fuel injector replacement - are 22#s enough? (FullShred)
Since you have a ZZ9 cam, heres a FAQ from TPIS.
Q: I would like to order some bigger injectors, I was thinking about a 27-30lb/hr injector would be good for my 350ci motor, it has a ZZ9 cam, 10.5:1 compression, 4.09 gears, AFR heads, 1.6 rockers, 52mm throttle body, headers, your Big mouth intake and Large Tube runners. Will these work with my combination?
A: No these are much too big for any 350ci motor. Unless you are running an aftermarket engine management computer, which would allow you to run any size injector you want. We have found that by running a stock size injector and increasing the fuel pressure, via an adjustable regulator, you will get a better spray pattern. The better spray pattern gives better atomization (which is the mixture of the fuel and air) and increased horsepower. So if your stock injectors are working good, just do a custom PROM and boost the fuel pressure and you will be happy. Unless you have someone doing a custom PROM for you, and they want you to run a bigger injector. It really depends on who is tuning your car, they will determine your injector size. But if we were tuning it, we would recommend stock size.
Q: I would like to order some bigger injectors, I was thinking about a 27-30lb/hr injector would be good for my 350ci motor, it has a ZZ9 cam, 10.5:1 compression, 4.09 gears, AFR heads, 1.6 rockers, 52mm throttle body, headers, your Big mouth intake and Large Tube runners. Will these work with my combination?
A: No these are much too big for any 350ci motor. Unless you are running an aftermarket engine management computer, which would allow you to run any size injector you want. We have found that by running a stock size injector and increasing the fuel pressure, via an adjustable regulator, you will get a better spray pattern. The better spray pattern gives better atomization (which is the mixture of the fuel and air) and increased horsepower. So if your stock injectors are working good, just do a custom PROM and boost the fuel pressure and you will be happy. Unless you have someone doing a custom PROM for you, and they want you to run a bigger injector. It really depends on who is tuning your car, they will determine your injector size. But if we were tuning it, we would recommend stock size.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Fuel injector replacement - are 22#s enough? (FullShred)
I think your stock injecgtors will be fine.
Check out the L98 Mods Results page on my site (link in sig. below). Those guys did similar mods to a '90 Vette 6-speed and ran stock injectors.
You need a scan tool to see what's going on so you can determine what tuning is needed.
You might install the AFPR and see if adjusting fuel pressure helps but here again a scan tool will tell you what's going on inside.
Check out the L98 Mods Results page on my site (link in sig. below). Those guys did similar mods to a '90 Vette 6-speed and ran stock injectors.
You need a scan tool to see what's going on so you can determine what tuning is needed.
You might install the AFPR and see if adjusting fuel pressure helps but here again a scan tool will tell you what's going on inside.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Fuel injector replacement - are 22#s enough? (1MoorTym)
Since you have a ZZ9 cam, heres a FAQ from TPIS.
Q: I would like to order some bigger injectors, I was thinking about a 27-30lb/hr injector would be good for my 350ci motor, it has a ZZ9 cam, 10.5:1 compression, 4.09 gears, AFR heads, 1.6 rockers, 52mm throttle body, headers, your Big mouth intake and Large Tube runners. Will these work with my combination?
A: No these are much too big for any 350ci motor. Unless you are running an aftermarket engine management computer, which would allow you to run any size injector you want. We have found that by running a stock size injector and increasing the fuel pressure, via an adjustable regulator, you will get a better spray pattern. The better spray pattern gives better atomization (which is the mixture of the fuel and air) and increased horsepower. So if your stock injectors are working good, just do a custom PROM and boost the fuel pressure and you will be happy. Unless you have someone doing a custom PROM for you, and they want you to run a bigger injector. It really depends on who is tuning your car, they will determine your injector size. But if we were tuning it, we would recommend stock size.
Q: I would like to order some bigger injectors, I was thinking about a 27-30lb/hr injector would be good for my 350ci motor, it has a ZZ9 cam, 10.5:1 compression, 4.09 gears, AFR heads, 1.6 rockers, 52mm throttle body, headers, your Big mouth intake and Large Tube runners. Will these work with my combination?
A: No these are much too big for any 350ci motor. Unless you are running an aftermarket engine management computer, which would allow you to run any size injector you want. We have found that by running a stock size injector and increasing the fuel pressure, via an adjustable regulator, you will get a better spray pattern. The better spray pattern gives better atomization (which is the mixture of the fuel and air) and increased horsepower. So if your stock injectors are working good, just do a custom PROM and boost the fuel pressure and you will be happy. Unless you have someone doing a custom PROM for you, and they want you to run a bigger injector. It really depends on who is tuning your car, they will determine your injector size. But if we were tuning it, we would recommend stock size.
Someone needs to take this to the TGO, and share it over there with those guys that are convinced 300rwhp 350s need 36# injectors :lol: Live and learn I guess, but they think that 14sec 1/4 mile times are good out of a 383, so to each his own. Or Turbo GNs running 13s are extreme machines :jester :leaving:
Happy to see you guys see the light. Good post 1moortym :thumbs:
[Modified by ski_dwn_it, 2:22 PM 1/2/2004]
Drifting
Joined: Aug 2000
Posts: 1,521
Likes: 0
From: West Islip New York
Re: Fuel injector replacement - are 22#s enough? (ski_dwn_it)
Yeah I never got the mentality of buying large injectors and then turning down the pressure - probably the last thing you'd want to do.
Anyway, maybe using this info from TPIS will have more crediability then me saying it.
Anyway, maybe using this info from TPIS will have more crediability then me saying it.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Fuel injector replacement - are 22#s enough? (1MoorTym)
Yeah I never got the mentality of buying large injectors and then turning down the pressure - probably the last thing you'd want to do.
Anyway, maybe using this info from TPIS will have more crediability then me saying it.
Anyway, maybe using this info from TPIS will have more crediability then me saying it.
tjwong. yeah your right about bigger is better, but I only agree with that if your talking biznoobies :p:
Thread Starter
Advanced
Joined: May 2003
Posts: 60
Likes: 0
Re: Fuel injector replacement - are 22#s enough? (ski_dwn_it)
I just ordered the Bosch LS1 22lb/hr Design III Fuel Injectors from fiveomotorsports on Ebay. The injectors are mfg. rated at 22.4lbs/hr at 40psi.
Thanks for the help.
Bill
Thanks for the help.
Bill
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