Would I be able to keep my 42.5 lb injectors with a 2.6 pulley, ported supercharger, intake, and exhaust? Or would I have to upgrade to 60 lbers?

 

No, you would have to upgrade the injectors. Many people get the 42.5s at 103% duty cycle with the 2.8" pulley alone.

 

No bro your are going to want the 60lb injectors. This way you won't be maxing out the duty cycle under WOT!

 

you CAN run the 2.6, but if you plan on getting a tune id say go with the 60's

 

Weird thing is I have been monitoring my setup for a few days so far, 2.6 Inch pulley, 42# Injectors and the MAFT at setting (C1) and no knock(only between shifts sometimes) and O2 sensor 880 ms (12.0 AFR) at redline....

I think that somebody mentioned at one point in a thread that the reason you see 100% duty cycle is because at WOT your ECM opens the Injectors at 100% over, regardless of Injector size.


Would it be possible that the 60 Pound injectors could be over rated?

 

Take your narrowband tuning with a grain of salt Denny. Its tough to accurately measure your A/F that way. You need a way to actually measure your injector duty cycle with your interceptor.

http://www.stealth316.com/2-calc-idc.htm
Check out this link, it includes an injector duty cycle calculator. My injectors flowed over 120% at WOT with a 2.6!!!! Also, my 60#'s never come clost to 100% at wOT so I think that disproves the theory too.

 

Nope, technically you need a wideband first of all. You can't go by the O2 voltage because that is the a narrowband. Also, without HP Tuners you have no way of knowing what the duty cycle is. Sp00ner, one of the moderators on rl forums, has HP Tuners and with a 2.8 with the 42.5lb injectors he had them at 103% duty cycle at only 5800rpm.

The only problem is that the PCM on the LSJs is only set up on the graph for 63lbs, which kind of limits how hard you can push the 60lb injectors, but in no way are the 60s overkill.

 

O.k thanks, that what I wanted to know. I am planning a Wideband gauge very soon....not sure which one yet.

 

my idc doesnt go over 75 with my 2.5 n 60lbers

 

On the Interceptor is does show the Injectors Pulse Width...oops I just realised...Duty cycle is not the same thing. My bad.

Damn now I have to sell my brand new used for 3 days 42# Injectors...

 

well I was running the 42.5 lbers with an airbox mod and 3" dp with cat stock catback, I only saw 54% injector duty cycle at 7400 rpm, but I would guess with exhaust and such you might need to go to the 60's, now with a 3" intake I"m running the 60's and only maxing at 34% injector duty... its all about the airflow. even with the w/i I"m only seeing like 35% with 60's

 

Why would the exhaust have anything to do with the duty cycle of injectors? The only thing that messes with the injectors is airflow, fuel, tuning and timing. The exhaust has nothing at all to do with how hard the injectors work.

 

the exhaust has to do with airflow... more air out = more air through the motor which would require more fuel which would up the duty cycle.

 

and timing doesn't impact the injectors, mostly just airflow, i.e. higher boost, intake, exhaust.

 

Also, 06blackg85ss, how are you monitoring what your duty cycle?

 

hp tuners data logging (vcm scanner)

 

if you have the software I can send you the logfile.

 

I do have the proof, not just talking out my ass.... I"ll see If I can copy the graph on the screen and post it if you want.

 

Umm...no, that would require tuning to make the duty cycle increase. Just because you open up that stuff doesn't mean it does that. The ONLY place that will cause that is the MAF sensor monitoring the airflow and then telling the injectors to open up more. That is why there are graphs for the MAF. When the airflow INTO THE ENGINE increases, the MAF sensor tells the injectors how much to pour out based on how it is set up on the chart in the computer system. The amount of air in the engine doesn't mean much because it will always be the same, exhaust or not. That is why people blow parts of their exhaust system up because of the BACKPRESSURE.

The exhaust just clears up that backpressure in the engine, it doesn't allow more. And BTW, all intake systems are 3" already. It is only beneficial putting an aftermarket intake to make sure it has a smooth flow.

 

yeah but the intake isn;t full three inch pull it out and check it crimps down in a few place to less than 2" wide. anyway... I"m just posting what I"ve seen by tuning we did a car with the same mods and a header and catback and thats when we saw inj duty go up to max..

 

which is why I bought the 60's my exhaust is on the way... also gonna be running the 2.5 on the street since I got the water/meth injection...

 

Question: What is the single most important reading that I can read from the Interceptor Gauge, that would tell me I need more Fuel?

I keep watching knock and it only knocks when I change gears sometimes...max I have seen is 1.7.

 

watch inj duty cycle... thats what tells you how much of the injector you are using..

 

I know that is the most important reading. But on the Interceptor Gauge does it read the duty cycle? I dont think so!!

 

sorry can;'t help you there mine won't be in til next week... been using hp tuners for that... what parameters does the scan gauge read anyway??