^^^^
well put, i have 60 poudners just incase, too many different stories goin on, when its time to tune we will see what happens at 7k, and if need more fuel the 60 pounders and harness are in the trunk...

 

does nos affect the output as well? if so that would mean stage 3 leans everything out A LOT more than a 2.8" but I dont know much about nos and how a car reacts to it

 

Why can't I see any of my posts untill I post again??

 

push F5?

 

Some of this thread may have turned into a bit of a pissing match, and the "STG 2 w/ 2.8 guys are idiots" fest, but we do obviously have some conflicting info here. Some, while running the MAF-T and 42 lb injectors have allegedly seen well above 100% IDC, while others are claiming well below that with the GM tune. There is nothing wrong with more information being shared on this topic.

True, but what injector duty are we really seeing? I have yet to see my duty cycle even hit 60% and I'm running the 2.8" Sure, I haven't logged her at the track with 2.8 yet, but I doubt I'm ever even seeing 80% duty cycle. I will completely agree that the GM tune cannot support the demands of a 2.7" pulley, but I don't know that the 42 lb injectors are the weak link.

As I recall Pat was only seeing around 30-40% duty cycle on his 60 lb injectors last time I saw him at the track with the 2.5"

Either way the 3" is going back on for the winter, but I am seriously going to log as much as I can until then to try and get a better idea of what IDC I'm actually seeing, especially when near the 7k redline.

 

Maybe we can ask Intense about this?

 

first off:

gm stage 2 has boost control in it and will limit u past 17psi iirc...I can check the tables once i get home.

secondly in PE mode....which is wot the car does not adjust at all...it runs off a preset table..so ur just running leaner with a smaller pulley...and this car does not adjust the fuel pressure at all. or anything for that matter except spark under PE/WOT

Believe who u want but I've had virtually every setup out there and over 5 ppl on this forum have trusted me to tune their cars and all trap 106+ with 1/4 miles in the mid to high 13s depending on driver

anything over 100% means the injectors are maxed and past 92 u cant control fueling so u r at ur fuel pumps mercy at that point. You will be way way past 100% idc with a 2.8

FYI I'm at 74% with a 2.5 and 60lbers @ 7300rpm

 

so far to sum it up cause I read every post we have three opinions and one dyno sheet posted. here is the summary.

1. 2.8" S2 no HPTUNE is good and safe. Dyno posted showing this up to 6500RPM. People want to see this kind of proof running dyno up to 7000RPM.

2. 2.8" or even 2.7" S2 with HPTUNE is safe. 42lbs injectors can support but tune is needed to get more fuel for the upper RPM. running less than 80% duty cycle.

3. 2.8" or 2.7" is not safe. A tune is needed with 60 LBS injectors. bigger injectors are needed as 42lbs injectors are running more than 80% duty cycle which is not safe. max duty cycle should be 80% regardless of what your A/F mix is. the injector will run static at 90% or wide open and is just through alot of fuel at it. an injector can fail at this level.

This is a summary of what I read.

IMO - I think anyone going beyond stock S2 should be checking the A/F and duty cycle to ensure it is operating safely regardless of what someone elses car is doing. suttle differences from one car to the next can affect the results. It is nice to have piece of mind.

 

i may not have a dyno run but i do have multiple 0-100 runs with IDC's from HPtuners...thats how i know its dumb to run a set up like that for long.

the gm injecters are good for a 2.9 to 7k....thats about it.

 

your close...a 2.8 with gm tune at 7k is dam close to bad IDC's...so i would advise agenst it...i'd say a 2.9 is as far as you wanna push it.

2nd...even with a HPTuners tune with a 2.8/2.7 the GM 42's WILL NOT FLOW what you need!!!! remember that IDC's in the 80's are ok but 90%+ IS BAD!!!

a 2.7 with a stage tune can gives IDC's to the 118%mark...i used to run a set up like that untill i found this info out.

anything smaller then a 3.0/2.9 is WAYYYYYYYY hard on the stock injecters but good on 42s with a stage or HP tune.

you will always need a tune with the 60's...and yes if you get tward the 90% IDC you need biger injecters to be SAFE...you can run anything you want how ever you want but it wont be safe with out a tune to go with it or proper size injecters.

 

What happens if your running a S1 with 2.85 injectors with 1 step colder plugs will that richen it up so its not going too lean out?? Will the 1 step colder plugs help this...???

 

Hope you have your flame proof suit ready

 

no. if you don't even have the stage 2 injectors.. thats BAD!

 

That's good info. So it sounds like it's a no go with a 2.8" pulley with 42lb. injectors. So who makes a 2.9" pulley that fits the GM stage 2 hub??

 

exactly!!!!!!
i see anything from 70%-80% IDC's depending on weather and what i have my PE set at...

 

Stg 1 injectors are stg 2 injectors

 

Who makes a 2.9" pulley that fits the GM stage 2 hub??

 

i used to run all BilletFlow pullys untill i jumped down from a 2.7

all my friends run BilletFlow parts and there awesome!...wont fir the GM hub tho..sorry.

as for the 2.8 on the 42's you might be ableto pull it off if you stick with the GM tune...manily stick with the 7k redline....if you want to get into HP and doing all the crazy power stuff with that and the higher rev limit then you will most def need more fuel...

theres a biger jump from 7000-7500 in IDC's then there is from say 6500-7000...it grows like an exponent not a stright percent increse.

 

exactly!

 

OK good stuff. So how about going with a 2.8" pulley with my 42lb. injectors, get it tuned and make the redline 6,800rpm? That should be reliable right?? Thanks again....

 

That's good to hear, I really like the look of the billetflow system. If I ever go beyond where I'm at I'll get the billetflow with the 2.9 and the 2.7 pulleys.

I will seriously start logging my stuff better and try and find out for sure what the GM tune and the 2.8 does to IDC, like I was saying I havent seen anything above 60% yet, but we'll see what colder air does to it.

Anyone else from MI plan on hitting the track soon? I really need to get back out and see where she's at now.

And for the RPM range, I kinda figured anything beyond 7000 would be a huge increase in requirement, like you were saying. I wish I had HPTuners already,,, one of these days

 

exactly why I would like someone to post up a dyno to 7000rpm with stage2 and 2.8 with bolt ons. I would like to see "where" this is happening so as to know when to shift if I do decide on the 2.8 then I will be able to do my own dyno here with my mods to make sure I personalize my driving style as well. Though the revlimit has been raised that doesn't neccisarilly mean that is where you should spend your time driving.

 

a 7k redline with the GM tuneing might be do-able...its hard to say off hand.

i would say your at the border line on that...the gm tune is prety safe and commands a **** load of fuel but thats what your gonna need.

well...on 2nd thought YES you can get away with something like that AS LONG AS you dont run the car to redline alot....cuz under the 6500 mark you'll have fuel control...over that is where your most liely going to get the injecters in to a static mode...so in short....you can do it if you want just keep it away from the limiter...you can hit it while raceing and dickin around just dont do it every chance you get....repeated 95% IDC'S will kill something...eather a motor or an injecter.

look...I used to run a 2.7 with 42's and a CRAZY HPTuners tune and i saw IDC's of 118% but she ran fine...but i only took it into the high revs 1 maybe 2 times a day and you could feel the car loose pull when they started dumpin fuel....

as of rite now i have a friend runing that set-up and i gave him a hell of a speach on how to drive the top end of the car becasue i dont wanna see him blow the car....but we did it becasue i know what can be donw with that set up and how to drive it so nothing ***** out...but hes going 60's after winter when its time to start rampin on the car.

its more of a driver responceiblity(sp?) thing when going that hard on such an important pice of the car.

hope this is of some help.

 

Thats a really good idea.

 

hell yea i wanna hit the track before it gets cold!!!

i've got the car built to where i want it for the year...time to run her!!!