"hey grumpy?
I'm building a TPI 383 corvette engine and I'm sure the old factory fuel injectors I have are both well worn and more than likely to small for the new application, how do I find the correct injector?"
, ITS not a random guess its an easily calculated figure that you need to know to get the cars engine to run to its full potential, knowing the cylinder head port flow rates and compression ratio and cam timing will help a great deal, here, an engine will burn between 12.6 and about 15 pounds of air for every pound of fuel, the flow rate you need will be fairly easy to calculate if you know the approximate hp level your dealing with.
I don,t know why but its common for guys to assume they can install bigger heads and a radical cam and a free flow exhaust and still keep the stock injectors, the truth is that you MUST maintain a max .80 duty cyscle and a 12.5:1-13:1 f/a ratio and that can easily require a significantly larger than stock injector size upgrade
the sub links in the thread below have 90% or more of the info, youll need the stock computer will require you stay with similar TYPE of injector, (HIGH IMPEDANCE)
measure your current injector resistance its most likely near 12-14 ohms, thats what the computer wants to see, you can get 24lb, 30lb, 32lb, 36lb,38lb, 40lb, 42 lb,44 lb etc. what you need is an injector that supplies fuel at about 80% pulse duration and about 42 psi of fuel pressure that will supply your horsepower level at about a .50 BSF level
lets assume your building a 450hp engine
THERES DOZENS of SOFTWARE programs to help you estimate your combos power potential,
viewtopic.php?f=69&t=2301&p=15105&hilit=dyno+software#p15105
if that was the power range it will require about a 36lb injector ,but a 39 lb or 44 lb would give you some growth room for the future,I,d suggest you use the calculator to verify, but keep in mind the computer varies the pulse duration (the amount of time the injectors spraying fuel based on sensor input like engine temp and oxygen sensor feed back, it can shorten the pulse far easier than it can add fuel above the 80% duty cycle so its best to select the injector size as close to what you need as possible but if your in doubt its better to go up a small step that get an injector that maxs out flow on the upper rpm ranges leaning out the engine to much, a slight too rich mix hurts mileage a slightly too lean mix might damage rings and pistons
GASOLINE 6.073 pounds per US Gallon.
http://www.rceng.com/technical.aspx
Divide the pounds of gas used per hour by the horsepower that is produced.
Use the following example equation as a reference for your calculations:
An engine produces 200 horsepower while consuming 80 lbs. of gasoline (13.17 gallons)in an hour. Therefore, 80 divided by 200 would equal a BSFC of 0.4.
http://www.witchhunter.com/injectorcalc1.php4
To calculate the injector size for a particular application:
Injector Flow Rate (lb/hr) = Engine HP(1) x BSFC(2)
Number of Injectors x Injector duty cycle(3)
Or
Injector Flow Rate (cc/min) = Engine HP(1) x BSFC(2) x 10.5
Number of Injectors x Injector duty cycle(3)
Inj Flow Rate (@ 40psid) Naturally Aspirated hp
19 lb/hr 258 hp @ 85% Duty Cycle
24 lb/hr 326 hp @ 85% Duty Cycle
30 lb/hr 408 hp @ 85% Duty Cycle
32 lb/hr 435 hp @ 85% Duty Cycle
39 lb/hr 530 hp @ 85% Duty Cycle
42 lb/hr 571 hp @ 85% Duty Cycle
47 lb/hr 639 hp @ 85% Duty Cycle
60 lb/hr 816 hp @ 85% Duty Cycle
BOSCH, ACCEL or LUCAS all sell a decent injector , I personally prefer the bosch injectors
don,t forget the high pressure fuel pump may help here
Bosch High Pressure Pump 0-580-254-984
Rated at 44 GPH @ 90 PSI 750+ Hp This pump is identical to the Accel part number 74702 which they boast will handle 870 Hp!
http://www.lucasinjection.com/bosch_and ... _pumps.htm
http://www.expressfuelpumps.com/
http://www.boschfuelpumps.com/
http://www.caspeed.com/boschpump/boschpump.html
read this thread, and its sub linked info
http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1200
http://www.rceng.com/technical.aspx
heres related info
viewtopic.php?f=55&t=493
viewtopic.php?f=55&t=1939
viewtopic.php?f=69&t=519
viewtopic.php?f=69&t=4666
viewtopic.php?f=69&t=4120
viewtopic.php?f=69&t=2645
viewtopic.php?f=44&t=38
viewtopic.php?f=52&t=5078
viewtopic.php?f=32&t=430
http://airflowresearch.com/articles/article085/A-P1.htm
http://airflowresearch.com/articles/article031/A-P1.htm
I'm building a TPI 383 corvette engine and I'm sure the old factory fuel injectors I have are both well worn and more than likely to small for the new application, how do I find the correct injector?"
, ITS not a random guess its an easily calculated figure that you need to know to get the cars engine to run to its full potential, knowing the cylinder head port flow rates and compression ratio and cam timing will help a great deal, here, an engine will burn between 12.6 and about 15 pounds of air for every pound of fuel, the flow rate you need will be fairly easy to calculate if you know the approximate hp level your dealing with.
I don,t know why but its common for guys to assume they can install bigger heads and a radical cam and a free flow exhaust and still keep the stock injectors, the truth is that you MUST maintain a max .80 duty cyscle and a 12.5:1-13:1 f/a ratio and that can easily require a significantly larger than stock injector size upgrade
the sub links in the thread below have 90% or more of the info, youll need the stock computer will require you stay with similar TYPE of injector, (HIGH IMPEDANCE)
measure your current injector resistance its most likely near 12-14 ohms, thats what the computer wants to see, you can get 24lb, 30lb, 32lb, 36lb,38lb, 40lb, 42 lb,44 lb etc. what you need is an injector that supplies fuel at about 80% pulse duration and about 42 psi of fuel pressure that will supply your horsepower level at about a .50 BSF level
lets assume your building a 450hp engine
THERES DOZENS of SOFTWARE programs to help you estimate your combos power potential,
viewtopic.php?f=69&t=2301&p=15105&hilit=dyno+software#p15105
if that was the power range it will require about a 36lb injector ,but a 39 lb or 44 lb would give you some growth room for the future,I,d suggest you use the calculator to verify, but keep in mind the computer varies the pulse duration (the amount of time the injectors spraying fuel based on sensor input like engine temp and oxygen sensor feed back, it can shorten the pulse far easier than it can add fuel above the 80% duty cycle so its best to select the injector size as close to what you need as possible but if your in doubt its better to go up a small step that get an injector that maxs out flow on the upper rpm ranges leaning out the engine to much, a slight too rich mix hurts mileage a slightly too lean mix might damage rings and pistons
GASOLINE 6.073 pounds per US Gallon.
http://www.rceng.com/technical.aspx
Divide the pounds of gas used per hour by the horsepower that is produced.
Use the following example equation as a reference for your calculations:
An engine produces 200 horsepower while consuming 80 lbs. of gasoline (13.17 gallons)in an hour. Therefore, 80 divided by 200 would equal a BSFC of 0.4.
http://www.witchhunter.com/injectorcalc1.php4
To calculate the injector size for a particular application:
Injector Flow Rate (lb/hr) = Engine HP(1) x BSFC(2)
Number of Injectors x Injector duty cycle(3)
Or
Injector Flow Rate (cc/min) = Engine HP(1) x BSFC(2) x 10.5
Number of Injectors x Injector duty cycle(3)
Inj Flow Rate (@ 40psid) Naturally Aspirated hp
19 lb/hr 258 hp @ 85% Duty Cycle
24 lb/hr 326 hp @ 85% Duty Cycle
30 lb/hr 408 hp @ 85% Duty Cycle
32 lb/hr 435 hp @ 85% Duty Cycle
39 lb/hr 530 hp @ 85% Duty Cycle
42 lb/hr 571 hp @ 85% Duty Cycle
47 lb/hr 639 hp @ 85% Duty Cycle
60 lb/hr 816 hp @ 85% Duty Cycle
BOSCH, ACCEL or LUCAS all sell a decent injector , I personally prefer the bosch injectors
don,t forget the high pressure fuel pump may help here
Bosch High Pressure Pump 0-580-254-984
Rated at 44 GPH @ 90 PSI 750+ Hp This pump is identical to the Accel part number 74702 which they boast will handle 870 Hp!
http://www.lucasinjection.com/bosch_and ... _pumps.htm
http://www.expressfuelpumps.com/
http://www.boschfuelpumps.com/
http://www.caspeed.com/boschpump/boschpump.html
read this thread, and its sub linked info
http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1200
http://www.rceng.com/technical.aspx
heres related info
viewtopic.php?f=55&t=493
viewtopic.php?f=55&t=1939
viewtopic.php?f=69&t=519
viewtopic.php?f=69&t=4666
viewtopic.php?f=69&t=4120
viewtopic.php?f=69&t=2645
viewtopic.php?f=44&t=38
viewtopic.php?f=52&t=5078
viewtopic.php?f=32&t=430
http://airflowresearch.com/articles/article085/A-P1.htm
http://airflowresearch.com/articles/article031/A-P1.htm
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