Fuel injector question
Thread Starter
Pro
Joined: Feb 2018
Posts: 699
Likes: 20
Fuel injector question
My research indicates the stock injectors are good up to 400 HP. I’ve also seen guys upgrading injectors with mild upgrades. With my car going under the wrench shortly to install :
Comp cams 54-444-11 cam
BTR trunion upgrade
spring upgrade
under drive pulley
Ls2 timing chain
1 7/8 inch headers/X pipe/ Ti axle back, already on
follwed by a dyno tune
I should be around 400HP. As I’m trying to make the best of my first upgrade, will I benefit from injector upgrade ?
04 6 speed 50k miles
Interestsd in the most aggressive daily driver. No auto cross. Couple passes down the track for results.
Thanks guys
Comp cams 54-444-11 cam
BTR trunion upgrade
spring upgrade
under drive pulley
Ls2 timing chain
1 7/8 inch headers/X pipe/ Ti axle back, already on
follwed by a dyno tune
I should be around 400HP. As I’m trying to make the best of my first upgrade, will I benefit from injector upgrade ?
04 6 speed 50k miles
Interestsd in the most aggressive daily driver. No auto cross. Couple passes down the track for results.
Thanks guys
Melting Slicks
Joined: Nov 2013
Posts: 2,049
Likes: 316
From: USA
Headers/tune, 390whp on a C5Z, I was around 85-90% injector duty cycle IIRC.
Probably not worth upgrading at this point, unless you think you'll add more down the road.
Or another way to look at it is you'll already be getting the car tuned/re-tuned, putting injectors in now would be a good time to do it.
I ran the GTP 36 lb/hr injectors on my NA setup.
Probably not worth upgrading at this point, unless you think you'll add more down the road.
Or another way to look at it is you'll already be getting the car tuned/re-tuned, putting injectors in now would be a good time to do it.
I ran the GTP 36 lb/hr injectors on my NA setup.
Melting Slicks
Joined: Feb 2001
Posts: 2,803
Likes: 357
From: Northville, MI
A lot depends on what you want the car to do. If you are into autocross/HPDE/drags then you will be in the upper range of the injector duty cycle and 36 lb injectors would be of use. If it is for occasional fun driving/ canyon runs etc., then you can get by with the stock injectors.
Drifting
Joined: Sep 2017
Posts: 1,959
Likes: 690
From: Avon Lake OH
Headers/tune, 390whp on a C5Z, I was around 85-90% injector duty cycle IIRC.
Probably not worth upgrading at this point, unless you think you'll add more down the road.
Or another way to look at it is you'll already be getting the car tuned/re-tuned, putting injectors in now would be a good time to do it.
I ran the GTP 36 lb/hr injectors on my NA setup.
Probably not worth upgrading at this point, unless you think you'll add more down the road.
Or another way to look at it is you'll already be getting the car tuned/re-tuned, putting injectors in now would be a good time to do it.
I ran the GTP 36 lb/hr injectors on my NA setup.
Thread Starter
Pro
Joined: Feb 2018
Posts: 699
Likes: 20
All good feedback guys. I want this car to make the best out of the upgrades. I drive it the same everyday. Translation, she gets a workout every time I turn the key. Without seeing over 6k RPM and fanning the clutch. I pretty much wash my day off between 2nd and 3rd and start my day with a decent rip on my way to work.
Last edited by C5 for life; Feb 11, 2019 at 03:04 PM.
4th Gear
Joined: Jan 2018
Posts: 4
Likes: 0
From: Cape Coral, FL
The way to determine what size injectors you need, is to run the numbers through a fuel injector size calculator. A web search will turn up several calculators.
Assuming 400 HP on a naturally aspirated engine, and a max duty cycle of 85%, the smallest injector you can run works out to 31.3 lb/hr. That would mean you need 32 lb injectors or larger.
Assuming 400 HP on a naturally aspirated engine, and a max duty cycle of 85%, the smallest injector you can run works out to 31.3 lb/hr. That would mean you need 32 lb injectors or larger.
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Former Vendor
Joined: Feb 2012
Posts: 26,512
Likes: 351
From: ST. CHARLES IL
Once you start passing that 90% duty cycle range it would be wise to upgrade. We have tons of options and some great deals. We also have a injector tech page that shows all the injector calculator math and some break downs on how it all works.
4th Gear
Joined: Jan 2018
Posts: 4
Likes: 0
From: Cape Coral, FL
While I agree with you, I'm not aware of a better way to figure what size you need. Using a calculator requires you to guesstimate 2 things, HP and BSFC. Naturally aspirated will typically get you between .5 and .55 BSFC. You would need to dyno the engine to determine both BSFC and HP exactly.
Acct Suspended APR 2026 by request
Joined: Dec 2010
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2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
you could also raise the fuel pressure to get more flow out of your injector assuming you have enough pump for it and an adjustable regulator