What size injectors are you running in the STS setups? I'm thinking they need 60 pound injectors. I'm getting my shopping list ready.

Thanks

 

well the injectors come with the kit, so you can scratch it right off the list, and yes they are 60# injectors

 

Correct, I believe the standards size is #42, but in the 03,04, Vette's #60 are standard. The early models cans be easily upgraded for a modest price I do Believe.

Also I was told the #60 injectors have the capability of handling up to a 1000 horsepower If everything else is matched up right

 

42's are standard, 60's are an upgrade. I opted for the 60's.

 

I think 60lb injectors are really overkill. Even 42s are kind of overkill - you 'll be running pretty darn rich. Keep in mind that LS1 fuel pressure is 4 bar. Most injectors are rated at 3 bar. So that "60 lb" injector is all of a sudden a 69.28 lb injector.

Just like a "42" will be a 48.5 lb/hr injector in an LS1

So what right? Well there is a minimum amount of time the injector can stay open. With an injector that large, even the lowest pulse width will be too much fuel... I'm just trying to save you guys some time and money.

Talk to tuner, or engine builder; they should tell you the same.

If you don't believe, at least don't buy the 60s.

 

I think that the main question here has to asked as to what your goal is. At 575 RWHP I had 100% duty cycle with 42# injectors. I don't think the 60# injectors are overkill if you are going for any more than 530 RWHP. Also, there are ways around the minimum injector pulse width scenario you have thrown out here. I have had no issues with maintaining A/F at low RPM and idle, there are plenty of guys around here running these injectors without issue. Again it just depends on your goals.

I personally run the 60's and if you are going to try to really make some power I suggest you do the same.

 

my bad on the first post, i have the 42's it was late. ill be running them probably untill i stroke the motor

 

Depends on how much power you might eventually want. 42s might be fine for now, but if you up the power, you end up buying injectors twice.
I'm running 60s at only about 500 horse (Paxton), and the car idles and drives like a stocker.

 

The size of the injectors you need is directly proportionate to how much power you are making. I ran 42 # injectors successfully on a D-1SC setup, however, with the twins the 42 #'ers were quickly maxed. Upgrading to Mototron 60's solved my problem.

Mark

 

mark turn the boost up!!! when you start maxin out 60pounders @ 8X psi you KNOW your layin' down some power!!!


yeah i know not forged...thatll quickly force you to go forged!! turn it up and hold on!!

 

ECS recommended and installed 60# injecters for my '03. Said it would idle better. Kit comes standard with 42#, 60# are optional. If you want more power later, might as well get the 60# injectors now and be done with it.

 

I personally wouldn't think 42# is overkill. I tried the 36# ones that come with the kit for the ATI and they were very quickly maxed out.

 

First what are your goals today and perhaps later?

Without the above;

#42-44 are fine for an 2002 with a wiring harness, 310 pump.
You can add MSD or BAP if needed. This can be upgarded as well.

#60's 03-, plus wiring harness, pump

Frankly, we could put together a streetable 1,700 rwhp fuel system if you needed it.

If you have not choosen a vendor, give Rick at Synergy a call. He has been working with STS since the beginning.
510-796-3749
http://www.synergymotorsports.net/

Brent

P.S. I have set of low mile (4,000) #42's I would sell for a great price. Moving up to something much, much larger.

 

Guys ... what is the first thing you will notice if injectors are too small for a particular application? Loss of pull about a certain RPM level, idle issues, A/F changes at what point in a dyno?

Whats a good rule of thumb to use when making determinations here?

 

I personally check two things... both directly related.

First I look for injectory duty cycle.. no more than 80% is ok with me.

Second I look at fuel pressure and if the system is holding fuel pressure through redline.

Loss of power and spike in A/F are both results of these two things above.. it is important that both are looked at.. I think the fuel system is more important that the actual injector size.. you can have 160# injectors and still have a fuel system that cannot support them.

I think a simple calculation is enough to determine with proper fuel flow what the best injectors are for your goal.. fuel system is everything to me.

 

The sign...AFR changes quickly as the top when having good pressure.
Time for bigger injectors.

As BlownZ06 has stated, an adequate fuel system is a must have.

 

Yeah, everything depends on your goals. But if you're just going to slap the kit on and go, buying 60s is too much. If that's what you want, go with the 60s then

BlownZ06. Exactly how do you "work around" injector pulse width? It all has to do with fuel pressure, and the physical properties of the injector. If you keep the injector open X amount of time, there's certain amount of fuel that will come out. Unless you have an AFPR, I don't see a work around. Enlighten me please...

 

Just checked duty cycle on a stock 98 a4 with 60s. It was running 7psi and making about 470-480rwhp. Injector duty cycle was about 60%. Plenty of room to grow.

 

The complaint was that if you have 58 psi of FP that at idle you have too much.. so your guess is correct so you can work around that by using a 97-98 referenced system.. at idle my car makes about 47 psi of fuel pressure at at full boost it makes 62-64.

My car idles fine and is not rich.

 

I agree with 90% of what you have stated. The only thing that is different IMO is that at 58psi @ idle...that is not too much. I have no problems with being too rich @ idle...as long as the fuel trims @ idle are as close to zero as possible +/- a couple points.

I used to care a lot more about maintaining 80% or less duty cycle throughout the whole rpm range. Now I don't...if I got to 100% for a couple of seconds, I am not too worried about it, because it is not like I am holding the injector throughout the whole rpm range, a couple of seconds isn't going to hurt anything...imo. I haven't maxed out the 60s yet, but I am going to try here pretty soon.

Once again there are some other people on here (not you blown) that are clueless as too what they are referring too, just spouting off information without having ever even played with a Fuel Injector sizing calculator.

What needs to be understood is injector sizing, fuel pressure, and hp goals all have to be taken into account in the calculation.

One needs to look at what fuel pressure injector is rated at, then based on new fuel pressure be able to understand how that changes the injector.

42lbs injectors can easily support more hp with greater fuel pressure. The mototrons are rated 60lbs @43.5 psi. When used on a C5 my stock pump would push 58psi...that makes the rating go up to like a 75lb injector. I have broke this down (as have others) on numerous other threads. The important thing is matching FP, Injector size, and hp goals. Go play with fuel injector sizing calculator @ www.smokemup.com.

The 60lb mototrons are a fantastic injector, I like them better so far then any of the injectors I have used Delphi, FMS, Accel, RCI,....in fact I have some brand new 48lber sitting in a box on the shelf in my garage if anybody wants them...1/2 price.