(My blown motor) More boost? 8psi what injectors?
12-09-2006, 06:28 PM
#1
6th Gear Member
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Join Date: Jan 2005
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Posts: 7,657
(My blown motor) More boost? 8psi what injectors?
well where to start? As most of you know i bought a novi 1k and put it on my gt. the car runs awsome and it ran awsome when i pulled it apart, but i knew i had a problem. because under boost it would blow water out of the over flow, so i was getting compression in the water. anyway i tore the motor apart and 5,6,7 and 2,3 were blowing compression into the water. yet it would still kill a ls1 ws6 and some vetts. the motor was also running to rich because i never got it tuned and it fuel washed the cylinders so the motor needs honed again. But i am going to use my other short block that is .20 over and start a new project. anyone know if 24lb injectors will support 8psi. motor is going to be .20 over with a cam and intake. stock heads and no stroker.
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12-09-2006, 06:38 PM
#7
2nd Gear Member
Join Date: Mar 2006
Posts: 164
RE: (My blown motor) More boost? 8psi what injectors?
Yeah i took 2 jpc in maryland im running a 255 walbro fuel pump u should be alright read this and figure it out for your car
Here is a good formula to find out what size injectors you need
(H*B) / (C*D)= estimated injector size
H=horsepower (Rear wheel)
B=*B.S.F.C. (see below)***
C=number of cylinders
D=duty cycle (constant .80-.85)
B.S.F.C.=
Low to med. performance = .50
Performance engine with head work= .45
High performance with lots of head work= .40-.45
S/C or T/C engines= .55-.60
Here is an example using my car,
(300*.45) / (8*.80) = 21.09
Guessing that my 8cyl. car with heads is 300rwhp, and at 80% duty cycle would need somewhere around or above 21lb injectors. That is at 80% duty cycle, which is the most that you would want to run on injectors (to be safe), so 24lb. should be good for my application.
You can use this equation to find what duty cycle your current injectors are running. For example: using x = duty cycle
(300*.45) / (8 * X) = 24lb injectors
x= 70.3% duty cycle
***B.S.F.C. = brake specific fuel consumption, it is the number of pounds of fuel it takes to make 1 horsepower for 1 hour. B.S.F.C values vary from engine to engine depending on its efficiency. The more efficient the lower the B.S.F.C. value, which translates into needing less fuel to make 1 horsepower. This changes for forced induction applications due to the engine needing fuel to cool the combustion chamber, which helps prevent detonation.
Here is a good formula to find out what size injectors you need
(H*B) / (C*D)= estimated injector size
H=horsepower (Rear wheel)
B=*B.S.F.C. (see below)***
C=number of cylinders
D=duty cycle (constant .80-.85)
B.S.F.C.=
Low to med. performance = .50
Performance engine with head work= .45
High performance with lots of head work= .40-.45
S/C or T/C engines= .55-.60
Here is an example using my car,
(300*.45) / (8*.80) = 21.09
Guessing that my 8cyl. car with heads is 300rwhp, and at 80% duty cycle would need somewhere around or above 21lb injectors. That is at 80% duty cycle, which is the most that you would want to run on injectors (to be safe), so 24lb. should be good for my application.
You can use this equation to find what duty cycle your current injectors are running. For example: using x = duty cycle
(300*.45) / (8 * X) = 24lb injectors
x= 70.3% duty cycle
***B.S.F.C. = brake specific fuel consumption, it is the number of pounds of fuel it takes to make 1 horsepower for 1 hour. B.S.F.C values vary from engine to engine depending on its efficiency. The more efficient the lower the B.S.F.C. value, which translates into needing less fuel to make 1 horsepower. This changes for forced induction applications due to the engine needing fuel to cool the combustion chamber, which helps prevent detonation.
12-09-2006, 06:55 PM
#10
6th Gear Member
Thread Starter
Join Date: Jan 2005
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Posts: 7,657
RE: (My blown motor) More boost? 8psi what injectors?
i cant find anyone to do it around here thats not going to charge me out the ***, and i hear a lot of good things about the cometics. do you think they are bad hg's?