Rear End

[SkylineUSA]

Here is the injector info

Someone elses idea of a basic injector size calculation....To convert cc's to lbs/hr divide the rated cc's by 10.5
450cc / 10.5 = 42.85 lbs/hr or rounding up a 43lb injector.
To convert lbs/hr to cc's multiply the rated lbs/hr by 10.5
26lb * 10.5 = 273 cc/min injector.

Brake Specific Fuel Consumption
Locating information about stock injector flow rates can sometime be quite difficult. If you can’t find your car’s injector size you can get a good idea of the injector flow rate using your car’s factory horsepower rating. To do this calculation you will need to determine your Brake Specific Fuel Consumption (B.S.F.C.). The B.S.F.C. is the number of pounds of fuel it takes to make 1 horsepower for 1 hour.

The B.S.F.C. values very from engine to engine depending on its efficiency. The more efficient the engine the lower the B.S.F.C. value, which translates into needing less fuel to make 1 horsepower for 1 hour. This changes for forced inducted applications as the extra fuel is used to cool the combustion chamber helping to prevent detonation. Here are some basic B.S.F.C. values.

Low to medium performance = .50
Performance engine with head work = .45
Performance engine with expert head work = .40 - .45


Supercharged and turbocharged engines = .55 - .60

Injector Duty Cycle
An injectors duty cycle defines how long the injector stays open. Injectors are always rated at 100% duty cycle so, a 26lb injector will put out 26lb's of fuel under 100% duty cycle. You never want to run your injectors above .85 or 85%. Anything higher puts you at risk of the injectors locking up. Choose an injector that puts out your desired lbs/hr at an 85% duty cycle rather than one at 100% duty cycle. If there isn’t an exact match you can raise your fuel pressure, which makes the injector act like a larger one but this trick is only good if you need a few extra lbs/hr.

Now that you have determined your B.S.F.C. and duty cycle it's time to calculate what your stock injector is rated at.

Here is the formula:
( H * B ) / ( C * D ) = estimated injector size.
H = horsepower
B = B.S.F.C.
C = number of cylinders
D = duty cycle

This is what it should look like for a Saturn.
( H * B ) / ( C * D ) = estimated injector size.
124 * .50 / 4 * .80


62 / 3.2 = 19.375 lbs per hour.


If you’ve installed too large of an injector and your car exhibits erratic idle during cold start or stumbling after it is warm you can attempt to remedy this by lowering the fuel pressure. But beware if you lower the fuel pressure to much it will effect your fuel injectors spray pattern so be careful of how much you lower it.

Injector Upgrade
If you want to upgrade your stock 19lb injectors by 10% but your not sure what the new flow rating will be simply multiply the injector’s lbs/hr rating by .10 then add the original lbs/hr rating of the injector. Example:
19 * .10 = 1.9 + 19 = 20.9 or a 21lb injector.
So this means we can upgrade to a 21 lb injector with no problem.

Injector Flow Rate based on Pressure Changes
To calculate an injector’s flow rate at a new desired fuel pressure you will need a calculator that has a Square Root function. Now this one can get a little tricky but pay close attention and this can help you out tremendously. Most of the injectors on the market today are rated at 43.5 psi. So, when you say you have a 19lb injector what you are saying is that your injector puts out 19lbs of fuel per hour at 43.5 psi of fuel pressure. So, how do we find out what our new desired fuel pressure going to be?


Here's an example:
Lets say we want to up the factory fuel pressure to 55psi. You will need to know the following information lbs/hr of the injectors you currently using (19lbs), original fuel pressure (43.5psi), and the new fuel pressure 55psi.

Here is the formula:
The square root of x multiplied by z divided by the square root of y = new injector flow rate

Where:
X = new fuel pressure
Y = original fuel pressure
Z = lbs per hour

First, find the square root of the new and original fuel pressure.
New fuel pressure: square root of 55 = 7.416
Original fuel pressure: square root of 43.5 = 6.595
Then divide the new fuel pressure square root sum by the original.
7.416 / 6.595 = 1.124
Then multiply this total by the size of the injector. In this case we are using the 19lb injectors.
1.124 * 19 = 21.35


At 55psi the injector now flows 21.35lbs/hr

Injector Flow Rate Chart

30psi
35psi 43.5psi* 45psi
50psi
55psi 60psi

16lb
17lb 19lb 19lb
20lb
21lb 22lb

20lb
22lb 24lb 24lb
26lb
27lb 28lb

22lb
23lb 26lb 26lb
28lb
29lb 30lb

29lb
31lb 35lb 36lb
38lb
39lb 41lb

32lb
35lb 39lb 40lb
42lb
44lb 46lb


*Stock injector size 19lb @ 43.5psi

Injector Size vs. Horsepower
Calculating how much horsepower the injectors can support is relatively straightforward using the following four variables:
Injector size: 26lb in this example
Number of cylinders: 4
Maximum duty cycle: .85
B.S.F.C. .50

Here is the equation:
Q * W * E / R = estimated horsepower for injectors.
26 * 4 * .85 / .50 =176.8 horsepower is what four 26 lb injectors will support.

Q = size of injector
W = cylinders
E = duty cycle
R = B.S.F.C.

[Pimpdady753]

i dont know if im goint to have the money to boost it i dont know i need to find out about the water pump, fuel part and the kmember, im adding it all up. and i probaly wont get the new gears till i get a new rear end, if i do ill probbaly go with the 3.55 or 3.75

[Pimpdady753]

ok with your formula a came up with the 42lb injectors coming to 571hp they will support. i think.

[Pimpdady753]

what about the fuel pump, and water pump, and clutch and fly wheel.

[351wStang]

I'd use an A1000 or equal efi fuel pump. I have a CSI 37gph electric water pump. I would suggest a Spec stage 3 clutch, and about any sfi approved flywheel should be fine.

[giddyup50]

OK Sky, I agree with you. Yes it does make a difference if you have boost or a stroker or whatever the case may be. I wasn't sure what setup Pimp was going with (I don't think were ever sure what setup he's using) I was just going by a mostly stock car with the basic bolt-on parts. So in that case I am right. But I guess if gas was $5-$7 a gallon over here we would care a little more about mileage. Hell I don't even like paying $2.59 a gallon (just went down this weekend WHOOHOOOO). No disrespect to you Sky, your still the Mustang God...well...kind of.

[Pimpdady753]

would it be cheaper to get a kit like this one, http://www.jegs.com/webapp/wcs/store...1913&langId=-1

or bye all the hoses and fitting sepret.
and with the electric water pump will i be able to still have my alt, power stearing, and shit, no air compressor tho.

[351wStang]

Yes you should be able to use all of the mentioned accesories with the electric water pump.

When purchasing your fuel system you need to be sure to get the correct parts. An inadequate fuel system will make tunning the motor an absolute nightmare. Just be sure to get the correct fuel pressure regulator, and the right size fuel lines. Just FYI you can never really go too big on your fuel lines, especially with a return style regulator. You may wasnt to ask around on the Corral and TM as I'm not really sure what all you would need for EFI. I do know that you will want the 100 micron filter pre pump and the lessor filter post pump. Also be sure that you hook your return line to the bottom of the regulator if its the style I'm thinking of. Good luck, you can never do enough research. Just do yourself a favor and remember, just enough is never enough. Dont buy something that will just barely get you buy, you can regulate anything down. Just my personal advice but I dont think saving for instance $20 on a fuel pressure regulator is worth breaking something because your running too lean. Buy parts that are proven for your application by the guys that do it everyday and you will be just fine.

[Pimpdady753]

should i get some new k members, and what about pullyes i cant find any pully systems that will fit my engine, and the ones i can find dont include the power stearing and ever thing.

[351wStang]

You only have one K-member. Changeing it is up to you. Get the pulleys off of a truck or van that had a 5.8l in it, thats what I did.

[Pimpdady753]

ic good i dea

[Pimpdady753]

do i have to do any welding if i get a new k member.