Max Power on Aristo Injectors?
01-30-08, 05:40 PM
#2
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A good guideline is that you will not exceed one h.p. per cc injector, usually less. Most USDM 2j engines on the 550cc injectors are @ max duty cycle before 500hp, I'd wager that the 440cc are done before 400hp.
So that's a not to exceed number, but specifically I dk the max you'd get before it goes "bang".
So that's a not to exceed number, but specifically I dk the max you'd get before it goes "bang".
Last edited by SCoupe; 01-30-08 at 10:31 PM.
01-30-08, 06:03 PM
#3
A good guideline is that you will not exceed one h.p. per cc injector, usually less. Most USDM 2j engines on the 550cc injectors are @ max duty cycle before 500hp, I'd wager that the 440cc are done before 400hp.
So that's a not to exceed number, but specifically I dk the max you'd get before go it goes "bang".
So that's a not to exceed number, but specifically I dk the max you'd get before go it goes "bang".
01-30-08, 07:07 PM
#4
http://www.rceng.com/technical.aspx
use this as a guide. to make 500hp(not whp), on a 6 cyl engine, with injector duty cycle at 99% and standard fuel pressure standard you need 580cc injectors.
that high of injector duty cycle is not safe to run. it may cause the injector to get stuck open, or even worse closed causing lean condition and possible detonation and possibly blowing head gasket.
i usually run injector duty cycle at about 80-85%.
use this as a guide. to make 500hp(not whp), on a 6 cyl engine, with injector duty cycle at 99% and standard fuel pressure standard you need 580cc injectors.
that high of injector duty cycle is not safe to run. it may cause the injector to get stuck open, or even worse closed causing lean condition and possible detonation and possibly blowing head gasket.
i usually run injector duty cycle at about 80-85%.
01-30-08, 10:58 PM
#6
glad i could help. if you run a FPR then you have to figure out what your final fuel pressure will be.
when you have more pressure you dont need as much flow from the injector. just dont run like 95% injector duty cycle. its not good for durability. for my sr20 im running 750cc injectors when making about 425hp. that is at .65BSFC and 90% duty cycle.
if you go to www.directignition.com thats the site for Electromotive EFI. they make some awesome stuff.
this is directly from their TEC2 standalone manual:
FUEL INJECTOR SELECTION AND SIZING
When sizing fuel injectors you must keep the following in mind:
1. What is the maximum amount of fuel you need to deliver? This requires knowledge of the break
specific fuel consumption of your engine at maximum output, values can be from .39 (lean and efficient) to
.69 (inefficient cumbustion chambers and lots of boost). When working with supercharged engines, remember
that you need to 'feed the blower', this means that in order to make i.e. 500 HP at the flywheel, you must
not forget that the supercharger may take as much as 100 HP to drive, and this power must be acounted for
when figuring out your fuel requirement. Let us look at an example of how to determine the fuel requirement
of an engine with the supercharger mentioned above, and a BSFC of aproximately .53.
500 HP + 100 HP = 600 HP x .53 BSFC = Fuel requirement of 318 lb/h
2. How many fuel injectors are being used? This is pretty obvious, we need to know the per injector
fuel requirement.
318 lb/h divided by 8 injectors = 39.75 lb/h per injector
3. At what RPM are we making this power? This is probably where most people get stuck. Not unless
you are being so crude as to run your injectors at 100 % duty cycle, can you make do with injectors sized
exactly by the lb/h per injector number. A fuel injector needs a certain amount of time to recover from being
engaged between spraying events. It is important to know when your injector fires for this step, but let us
assume the injector fires once per engine revolution, just like ELECTROMOTIVE's phased sequential injection
for multi-point systems. The engine speed for our ongoing example will be 7,600 RPM, and we need to
know how much time there is between injector events.
60,000 ms (one minute) divided by 7,600 RPM= 7.8947 ms between Top Dead
Centers
4. What is the % of duty cycle that can be used at this point? This is determined by the time it takes the
injector to close after it has been opened, which is usually somewhere around 1 ms. Here we need to know
the ratio between the total amount of time available and what we can actualy use.
7.8947 ms - 1ms = 6.8947 ms 6.8947 ms / 7.8947 ms = 0.8733 or 87.33%
5. Injector Size Requirement! Now we have all the info required to select an injector.
Fuel Requirement of 39.75 lb/h divided by the
maximum duty cycle of 87.33% = 45.5 lb/h
With this information we can now go get an injector, and it looks like Electormotive's part # 83145, a 45
lb/h peak and hold injector will fit the bill. By raising the fuel pressure slightly over 43.5 psi to say 47 psi we
should have the perfect match.
enjoy
when you have more pressure you dont need as much flow from the injector. just dont run like 95% injector duty cycle. its not good for durability. for my sr20 im running 750cc injectors when making about 425hp. that is at .65BSFC and 90% duty cycle.
if you go to www.directignition.com thats the site for Electromotive EFI. they make some awesome stuff.
this is directly from their TEC2 standalone manual:
FUEL INJECTOR SELECTION AND SIZING
When sizing fuel injectors you must keep the following in mind:
1. What is the maximum amount of fuel you need to deliver? This requires knowledge of the break
specific fuel consumption of your engine at maximum output, values can be from .39 (lean and efficient) to
.69 (inefficient cumbustion chambers and lots of boost). When working with supercharged engines, remember
that you need to 'feed the blower', this means that in order to make i.e. 500 HP at the flywheel, you must
not forget that the supercharger may take as much as 100 HP to drive, and this power must be acounted for
when figuring out your fuel requirement. Let us look at an example of how to determine the fuel requirement
of an engine with the supercharger mentioned above, and a BSFC of aproximately .53.
500 HP + 100 HP = 600 HP x .53 BSFC = Fuel requirement of 318 lb/h
2. How many fuel injectors are being used? This is pretty obvious, we need to know the per injector
fuel requirement.
318 lb/h divided by 8 injectors = 39.75 lb/h per injector
3. At what RPM are we making this power? This is probably where most people get stuck. Not unless
you are being so crude as to run your injectors at 100 % duty cycle, can you make do with injectors sized
exactly by the lb/h per injector number. A fuel injector needs a certain amount of time to recover from being
engaged between spraying events. It is important to know when your injector fires for this step, but let us
assume the injector fires once per engine revolution, just like ELECTROMOTIVE's phased sequential injection
for multi-point systems. The engine speed for our ongoing example will be 7,600 RPM, and we need to
know how much time there is between injector events.
60,000 ms (one minute) divided by 7,600 RPM= 7.8947 ms between Top Dead
Centers
4. What is the % of duty cycle that can be used at this point? This is determined by the time it takes the
injector to close after it has been opened, which is usually somewhere around 1 ms. Here we need to know
the ratio between the total amount of time available and what we can actualy use.
7.8947 ms - 1ms = 6.8947 ms 6.8947 ms / 7.8947 ms = 0.8733 or 87.33%
5. Injector Size Requirement! Now we have all the info required to select an injector.
Fuel Requirement of 39.75 lb/h divided by the
maximum duty cycle of 87.33% = 45.5 lb/h
With this information we can now go get an injector, and it looks like Electormotive's part # 83145, a 45
lb/h peak and hold injector will fit the bill. By raising the fuel pressure slightly over 43.5 psi to say 47 psi we
should have the perfect match.
enjoy
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