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Which Injectors do I need?

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Old Apr 7, 2008 | 10:51 AM
  #21  
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Originally Posted by 405HP_Z06
Looking at the above posted graphs it looks like the peak is at 6400, unless I'm crosseyed from being so tired. I reran the numbers and the calculation didn't change except for the current duty cycle, no big deal. I edited the image to reflect 7000 rpm as peak HP.
lol ok Cool!

Thanks for your help!
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Old Apr 8, 2008 | 07:53 PM
  #22  
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Originally Posted by Urban Legend
On the idling rich part then thats where I pay my tuners the big bucks. Some tuners I have worked with did not have a clue about what they were doing either.
I was one of the ones that started out with 42s, to then have to turn around and get 60s because I was maxing out my 42s. Double the effort and double the money. If I would have known I was that close at the beginning It would have been a different story.
yeh man, my fault too, I wasn't trying to be an ***, just informing of options.

Idling rich, ummm... explain why you have to double the effort and double the money... all you would have to do to get the 60#ers to not run rich at idle would be to get a Fuel pressure regulator, and pay tuners big bucks??

there is a limitation on what an injector can operate at, meaning pulse width and such. At some point you CANNOT control some XXX lb/hr injectors because even with reduced fuel pressure(with fuel pressure regulator) ..etc etc they simply will not operate because they will be out of their specs

they make: (just a few of them) and these are based on 43.5psi rated
32#
37#
38#
42#
48#
52#
60#
63#
71#
79#

and also RCENG makes:
http://www.rceng.com/Peak-Hold-Fuel-Injectors-C5.aspx
A WHOLE LOT!!!! they can make you anything you want....

so you can work out somewhere in between there what you need


just curious, Urban Legend, what is your duty cycle on your 60#ers?
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Old Apr 8, 2008 | 09:41 PM
  #23  
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Go with the 42's as NicD and others stated. He is a local Az tuner that knows his ****! I went with a set of 42's per his recommendation and couldn't be happier after his tune.
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Old Apr 18, 2008 | 01:01 AM
  #24  
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why not just try to find some stock injectors out of a FLEX Fuel vehicle... they come stock with some 36#ers This is what I bought for my car and I just downloaded the map that the injectors came out of since they are stock and updated my map with the new injector flow ratings and battery offsets.

Last edited by IntegraVTEC; Nov 20, 2008 at 04:37 AM.
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Old Apr 19, 2008 | 03:07 PM
  #25  
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Originally Posted by 405HP_Z06
Let's step back and look at the required size injector based on the inputs above. Assuming horsepower levels will remain constant for the near future, you would need an injector that is rated at 34 lbs/hr @ 3 Bar and use 4 Bar of fuel pressure to adequately fuel the car and stay within the 80% max duty cycle recommendation.

Here's the calculation:


So, looking at commonly available injectors on the market. A 36 lb would be the closest to your current requirement and has a little growth potential. A 42 lb would give you very significant growth capacity. This is all assuming you stay naturally aspirated. If you change to forced induction, the calculations significantly change.

Clear as mud?

HTH,
Where's that calculator from? the one in HP Tuner is much simpler as per below.


Injector Scaling and Sizing Write-Up

Robert
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Old Apr 19, 2008 | 05:53 PM
  #26  
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Originally Posted by Robert56
Where's that calculator from? the one in HP Tuner is much simpler as per below.


Injector Scaling and Sizing Write-Up

Robert
Robert,
The program above isn't just a injector scaling utility like the one in HP Tuners. Fuel Injector Calculator from Performance Trends is designed to size injectors for an engine based on inputs. The utility in HP Tuners does not offer anywhere near the capabilities of FIC.
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Old Apr 19, 2008 | 06:40 PM
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Originally Posted by 405HP_Z06
Robert,
The program above isn't just a injector scaling utility like the one in HP Tuners. Fuel Injector Calculator from Performance Trends is designed to size injectors for an engine based on inputs. The utility in HP Tuners does not offer anywhere near the capabilities of FIC.
So, it's some sort of hand held? or a program we can add to our lap top? By the way i understand the difference, but my point was to find out which tuner program had such a feature. I use the math and spread sheets in my web for the same thing, however, I was hoping one of the tuner programs included such features as clearly my HPT does not.
Robert
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Old Apr 19, 2008 | 07:06 PM
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Originally Posted by Robert56
So, it's some sort of hand held? or a program we can add to our lap top? By the way i understand the difference, but my point was to find out which tuner program had such a feature. I use the math and spread sheets in my web for the same thing, however, I was hoping one of the tuner programs included such features as clearly my HPT does not.
Robert
IMHO, the capabilities of Performance Trends FIC really go beyond the intended purpose of any tuning software. The utility in HP Tuners offers a quick and easy way to determine the output of an injector based on a change in fuel pressure, but since it doesn't provide the way by which to generate IFR's it's pretty useless. I don't know why, but it would make sense to me to include a utility in the tuning program that generates the IFR table based on inputs like the spreadsheet everyone uses.

Here's a link to FIC: http://www.performancetrends.com/Fuel_Injector.htm
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