injectors
TECH Apprentice
Joined: Aug 2004
Posts: 321
Likes: 0
From: Buffalo, N.Y.
Well, you really have to know a few things about your car's power output, first. As a general rule of thumb, injectors should be "sized" so they run at ~80%-85% duty cycle. There are a few things you need to consider before choosing a rating for your injectors.
BSFC (Brake Specific Fuel Consumption) is the ratio in fuel an engine consumes in lbs/hr for each HP produced. Depending upon what your goals are, here are a few BSFC numbers you can shoot for:
.60 nitrous, turbo, & supercharged engines
.50 naturally aspirated street engines
.45 naturally aspirated performance engines
.40 naturally aspirated race engines
Once you decide what type of engine you're going to shoot for, you can start crunching some numbers. You'll need to know the weight of your car, the ET's you want to run, and the trap speed your aiming for. To know that, you'll need to know how much HP it's going to take to get you there. You can calculate HP from trap speed and weight...I don't have all the mathematical symbols on my keyboard, but you should get the idea.
If you have a typical 3,500 Lb or so F-Body, and you want to run 10.5 @ 130 mph, the calculation would be (plug in your own, actual numbers for an accurate answer):
((130/234) >3)X 3500 = 600HP The arrow in the formula is supposed to be pointing up...it signifies taking the quotient to the power of 3.
So, now that you know your HP, you need to figure out your fuel requirement. To do that: BSFC X HP = fuel consumption. So if you chose .50 as your goal BSFC: 600 HP X .5 lbs./hr = 300 lbs/hr fuel required.
With the fuel requirement now known, you can then determine flow capacity...simply divide your fuel requirement by the number of injectors: 300/8= 37.5 lb/hr injector size.....but that's at 100% duty cycle.
The final step to size your injectors, is to divide the injector capacity (37.5 lb/hr in this example) by the duty cycle, which is usually calculated at 80%, so:
37.5 lb/hr / .80 duty cycle = 46.87 lbs./hr. ALWAYS round up to the next largest size. Also, most fuel injectors are rated at 3-bar (43.51 PSI), but the LS1 fuel system operates at 4-bar (58.02 PSI), so you'll have to convert the advertised 3-bar rate to 4-bar to get the correct sizing.
Hope this helps........
BSFC (Brake Specific Fuel Consumption) is the ratio in fuel an engine consumes in lbs/hr for each HP produced. Depending upon what your goals are, here are a few BSFC numbers you can shoot for:
.60 nitrous, turbo, & supercharged engines
.50 naturally aspirated street engines
.45 naturally aspirated performance engines
.40 naturally aspirated race engines
Once you decide what type of engine you're going to shoot for, you can start crunching some numbers. You'll need to know the weight of your car, the ET's you want to run, and the trap speed your aiming for. To know that, you'll need to know how much HP it's going to take to get you there. You can calculate HP from trap speed and weight...I don't have all the mathematical symbols on my keyboard, but you should get the idea.
If you have a typical 3,500 Lb or so F-Body, and you want to run 10.5 @ 130 mph, the calculation would be (plug in your own, actual numbers for an accurate answer):
((130/234) >3)X 3500 = 600HP The arrow in the formula is supposed to be pointing up...it signifies taking the quotient to the power of 3.
So, now that you know your HP, you need to figure out your fuel requirement. To do that: BSFC X HP = fuel consumption. So if you chose .50 as your goal BSFC: 600 HP X .5 lbs./hr = 300 lbs/hr fuel required.
With the fuel requirement now known, you can then determine flow capacity...simply divide your fuel requirement by the number of injectors: 300/8= 37.5 lb/hr injector size.....but that's at 100% duty cycle.
The final step to size your injectors, is to divide the injector capacity (37.5 lb/hr in this example) by the duty cycle, which is usually calculated at 80%, so:
37.5 lb/hr / .80 duty cycle = 46.87 lbs./hr. ALWAYS round up to the next largest size. Also, most fuel injectors are rated at 3-bar (43.51 PSI), but the LS1 fuel system operates at 4-bar (58.02 PSI), so you'll have to convert the advertised 3-bar rate to 4-bar to get the correct sizing.
Hope this helps........
Originally Posted by bichin95redta
Well, you really have to know a few things about your car's power output, first. As a general rule of thumb, injectors should be "sized" so they run at ~80%-85% duty cycle. There are a few things you need to consider before choosing a rating for your injectors.
BSFC (Brake Specific Fuel Consumption) is the ratio in fuel an engine consumes in lbs/hr for each HP produced. Depending upon what your goals are, here are a few BSFC numbers you can shoot for:
.60 nitrous, turbo, & supercharged engines
.50 naturally aspirated street engines
.45 naturally aspirated performance engines
.40 naturally aspirated race engines
Once you decide what type of engine you're going to shoot for, you can start crunching some numbers. You'll need to know the weight of your car, the ET's you want to run, and the trap speed your aiming for. To know that, you'll need to know how much HP it's going to take to get you there. You can calculate HP from trap speed and weight...I don't have all the mathematical symbols on my keyboard, but you should get the idea.
If you have a typical 3,500 Lb or so F-Body, and you want to run 10.5 @ 130 mph, the calculation would be (plug in your own, actual numbers for an accurate answer):
((130/234) >3)X 3500 = 600HP The arrow in the formula is supposed to be pointing up...it signifies taking the quotient to the power of 3.
So, now that you know your HP, you need to figure out your fuel requirement. To do that: BSFC X HP = fuel consumption. So if you chose .50 as your goal BSFC: 600 HP X .5 lbs./hr = 300 lbs/hr fuel required.
With the fuel requirement now known, you can then determine flow capacity...simply divide your fuel requirement by the number of injectors: 300/8= 37.5 lb/hr injector size.....but that's at 100% duty cycle.
The final step to size your injectors, is to divide the injector capacity (37.5 lb/hr in this example) by the duty cycle, which is usually calculated at 80%, so:
37.5 lb/hr / .80 duty cycle = 46.87 lbs./hr. ALWAYS round up to the next largest size. Also, most fuel injectors are rated at 3-bar (43.51 PSI), but the LS1 fuel system operates at 4-bar (58.02 PSI), so you'll have to convert the advertised 3-bar rate to 4-bar to get the correct sizing.
Hope this helps........
BSFC (Brake Specific Fuel Consumption) is the ratio in fuel an engine consumes in lbs/hr for each HP produced. Depending upon what your goals are, here are a few BSFC numbers you can shoot for:
.60 nitrous, turbo, & supercharged engines
.50 naturally aspirated street engines
.45 naturally aspirated performance engines
.40 naturally aspirated race engines
Once you decide what type of engine you're going to shoot for, you can start crunching some numbers. You'll need to know the weight of your car, the ET's you want to run, and the trap speed your aiming for. To know that, you'll need to know how much HP it's going to take to get you there. You can calculate HP from trap speed and weight...I don't have all the mathematical symbols on my keyboard, but you should get the idea.
If you have a typical 3,500 Lb or so F-Body, and you want to run 10.5 @ 130 mph, the calculation would be (plug in your own, actual numbers for an accurate answer):
((130/234) >3)X 3500 = 600HP The arrow in the formula is supposed to be pointing up...it signifies taking the quotient to the power of 3.
So, now that you know your HP, you need to figure out your fuel requirement. To do that: BSFC X HP = fuel consumption. So if you chose .50 as your goal BSFC: 600 HP X .5 lbs./hr = 300 lbs/hr fuel required.
With the fuel requirement now known, you can then determine flow capacity...simply divide your fuel requirement by the number of injectors: 300/8= 37.5 lb/hr injector size.....but that's at 100% duty cycle.
The final step to size your injectors, is to divide the injector capacity (37.5 lb/hr in this example) by the duty cycle, which is usually calculated at 80%, so:
37.5 lb/hr / .80 duty cycle = 46.87 lbs./hr. ALWAYS round up to the next largest size. Also, most fuel injectors are rated at 3-bar (43.51 PSI), but the LS1 fuel system operates at 4-bar (58.02 PSI), so you'll have to convert the advertised 3-bar rate to 4-bar to get the correct sizing.
Hope this helps........
I HATE MATH....
why cant it be like..ok u have this...this.. and this... so get these injectors... its sooooooo much easier...
Originally Posted by exSSer
Just get SVO 30s, they should be fine.
TECH Apprentice
Joined: Aug 2004
Posts: 321
Likes: 0
From: Buffalo, N.Y.
You should talk to as many "knowledgeable" people (speed shop owners, engine builders, any trusted mechanics you may know, etc.) as you can, before you make your decision. Picking a fuel injector is a lot like picking a cam, or any other component. Good fuel injectors are NOT cheap. Mis-matching the injector to the rest of your components can easily leave HP on the table. What type do you want to go with; pintle, disc, or ball (ball & socket)? BTW, your LS1 uses a high impedance injector. What type of tune do you plan on doing after you get 'er all together?
You have a 2000 which along with 1999 fbodies had the smallest injectors for the ls1 era. They are 26.6lb injectors where the 1998, 2001, 2002 have 28.8lb injectors.
So, I would say that if you are going to be racing your car, I'd put in some 30lb injectors which are really 36 I beleive at our fuel pressure.
I have kept my stock injectors (2000) and I beleive that they are not doing so well. I have one that ticks really badly, and the rest are noisy as well. I'm not sure if that's a result of the injector being pushed beyond it's limit, but I am going to get a larger set one of these days.
So, I would say that if you are going to be racing your car, I'd put in some 30lb injectors which are really 36 I beleive at our fuel pressure.
I have kept my stock injectors (2000) and I beleive that they are not doing so well. I have one that ticks really badly, and the rest are noisy as well. I'm not sure if that's a result of the injector being pushed beyond it's limit, but I am going to get a larger set one of these days.
