Street Class
1) UnderdogSDA 13.3 (Nitrous)
2) S.Bretz 13.35 (Turbo)
3) Poc301 13.50 (Nitrous)
4) BoostedSL2 13.56 (Turbo)
5) Yardbird 13.59 (Nitrous)

Unlimited Class
1) Nefarious 12.26 (Nitrous)
2) LowSC2 12.4 (Nitrous)
3) 92saturnSS 13.33 (Nitrous)

DOHC
1) UnderdogSDA 14.21
2) Green Monstah 14.5
3) DonBaker 14.71
4) Applebit 14.8
5)SaturnMotorsportsOfCary14.84

SOHC
1) ProjectPhase1 16.61
2) Sh1FT 16.90
3) Wraith 16.98
4) jhsl1 17.2
5) SL_Sled 17.96

Ion
1) JGreen 15.48
2) schzzo97sc2 15.60
3) Chris 15.79
4) rascon11 16.06
5) IonJon 16.27

Updated 1/05

For the most recent list of the fastest five cars click here.

Fuel Injectors:

Flow Rates and Horsepower Levels

by: icu_runnin

Fuel injectors meter the amount of fuel delivered into the combustion chamber, which is constantly adjusted by the car’s computer (ECM) via the oxygen sensor feed back. Basically, there are two different types of fuel injectors, saturated and peak and hold. The saturated type injector is a high ohm impedance injector that works fine for a performance vehicle but only up to a certain extent. The larger this type of injector gets the harder it is to deliver fuel precisely. The impedance of these injectors range from 11-13 ohms depending on the injector and the manufacture. All Saturn vehicles from 96+ have this type of injector in them.

The second type of injector is called a peak and hold injector which, is a low ohm impedance injector. This injector is more commonly used in high performance applications because large injectors are easier to control. The peak and hold injector’s ohm impedance ranges from 1.5-3 ohms depending on the manufacture. These injectors are found on first generation Saturn vehicles 91-95.

Converting Injector Flow Rates

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.

When upgrading the injectors on your vehicle there are a few things you need to keep in mind. First, you must know what type of injector is currently on your car. Using a voltmeter can easily do this. Simply take the injector harness off your injector, set the voltmeter to read ohms, and then apply the two terminal leads from the voltmeter to the two male connections on your injector. It does not matter which lead you test with if the test leads are reversed the voltmeter will display a negative sign next to your ohm reading. Now that you have know the type of injector on your car the next step is to find out what the injector is rated at.

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.

Saturn injectors are rated at 19lbs/hr.

Now that you know what size injector you have lets find out how much larger you can go. Typically you should only go 10% over your stock injector anything larger you may run into idle problems when cold and your car may stumble until the vehicle reaches operating temperature. When changing to a larger injector you should reset the computer so it can adjust to the new fuel injector. Resetting the ECM can be accomplished by pulling the battery cable off or pulling the ECM fuse and letting the car sit for 3-5 minutes. 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 stock Saturn 19lb injectors.
1.124 * 19 = 21.35

At 55psi the injector now flows 21.35lbs/hr

Injector Flow Rate Chart

*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.

The turbosaturns.net forum has become one of the best resources for Saturn performance on the net. Our members are constantly pushing their cars to new performance levels. So, log in, share your ideas, and help push your car’s performance to the next level.

• Apexi Safc Install
• Turbo Tuning
• Cams 101
• Wastegate 101
• HP vs Torque
• Ian's Turbo F.A.Q.
• Oxygen Sensors
• DIY Fuel Regulator
• Taming Detonation
• Walbro Install
• Fuel Injectors
• Techedge Wideband
• OEM Fuel Pump Limits
• AVC-R Programming
• Dynosoft
• 220whp or Bust

Archived Articles

HERE

August 2005 TSN will be holding its first ever meet in Chardon, Ohio. Some of the fastest Saturns in the country will be attending. Activities will include drag racing, dyno, tech session, and BBQ. Look for the latest information in the forums.

Different Racing

Jeff and his team Different Racing have big plans on breaking into some really low quarter mile times this year. Last year he posted a 12.40 on a pretty healthy nitrous shot. This year he has a new turbo setup and some serious determination. Visit his website for the latest news and information. I expect we'll be seeing some low 12's from him by the end of the year.