I was curious if you needed to upgrade to 60lb/hr injectors and Hptuners when going smaller than a 2.8?

Is it necessary to have supporting mods. like exhaust mods or what?

someone with some knowledge please chime in, id like to go to a smaller pulley than my 2.85, but im only on a stage tune

some more interesting info...on ZZP's site it says thier pulleys allow you to go to 2.6" before machining!......https://www.zzperformance.com/cobalt...ts1.php?id=529

 

Yes to all.

 

anybody else who is running the 2.7?

 

I think Rob taxed out his 42.5 lbs injectors with a 2.5". See the link below

https://www.cobaltss.net/forums/2-0l-lsj-performance-tech-47/dynod-cobalt-again-set-new-record-15418/

 

i understand that the 42.5lb injectors go static with a 2.9 pulley.

 

the question of the hour is how would the car react to a 2.7" with the GM STG2 and colder plugs?

 

It will be fine But the MAF will freak out with the increased airflow going past it.

 

HP Tuners data log, according to my friend who has a redline and hp software, proves that the 42.5LB lean out a bit with a 2.9. And injector duty cycle is a bit higher that 80%. Thats when they go a bit static. Imagine a 2.7?!? Thats why intense carries the 60LB injectors with there 2.7

 

with a 2.7 and 42lb injectors you max the injectors at the upper rpm range
go with 60's and call it a day

and no, you don't need anything other than plugs for the car to run fine, ask kritter.
kritter has a 2.8 (he got it for free) and 60's and he has an awesome car

 

planning on getting a larger fuel pump, why does everyone keep upgrading the fuel injectors?

 

which is easier to install?
injectors take 15 maybe 25 minutes.

 

you make a good point, but i see a larger fuel pump in my future...

 

My injectors go static at 6292 rpm and reached a duty cycle of 109% at 6770 rpm. This is with a 2.8 and K&N Intake on my 2004 Ion. 06black has a 2.7 and I think he gets 115% duty cycle. But the cars aren't running too lean.

 

Iam running a 2.7 billetflow, with the 42.5lb injecotrs, not to sure what my duty cycle is about 100% at high rpms, but the car runs great with the tune from hp tuners i have.

 

ill prob end up running a 2.7" just when i need it, no other times

 

Just stay out of the high rpms all the time and you will be fine. Drive your car like normal and then drive it hard once in a while. no reason to swap pullies all the time.

 

true

i was just going to save the 2.7 for when i get called out

how much boost is a 2.7"?

 

depends on what else you have done and where you are at. my 2.6 and no exhaust with intake would do 18, 18.5. I have a TOG header and a 2.5 now and I still only see 18.5 on warm days.

 

So jut putting on the 2.7 at the track would be fine????? So if it starts to run lean at the Higher RPMS then can we just shift sooner????

 

You will be ok shifting near redline. It's not lean enough to cause a problem. Just don't hold the car at redline for an extended period of time or you will run out of fuel.

 

Thanks alot max...

 

ok my 2.85 keeps my a/f around high 11's with my 42 pounders I think it will be plenty of ammo, I mean you rev it up guys were running around w/o more injectors with a 2.85 and doing ok. My dyno my a/f was rarely above 12.

 

My dyno with GM 42 lbs injectors and ZZP 2.85 and 2.70 pullies - DYNO Run 002 is with the 2.70" - AFR hit 11.9 at 7000 RPM with the 2.70"

 

i heard a rumor that they S/C will overheat unless you have a CAI anyone experiance that?

 

WTF??