I had my car flashed prior to my stage 2 install for free, updated flash for idle surging. I got my stage 2 installed in January, and got the latest flash at that point. They should be updating you for free dude.

 

That new GM stage 2 flash isn't all that great. I had it done. It got rid of some 1st to 2nd bogging but not knock and detonation.
It fixes little things but with a 2.9 you have to have a true custom tune.

Before my tune I had over 3 deg of knock all the time, my AFR was lean and I had a lot of bogging.

After the tune is like night and day. You can really take advantage of the 2.9
So it all comes down to getting a tune. It's a must for performance and reliability. Check it out.

The 2.9 gives me 16.69 psi at 6,444rpm
Before the tune everything was all over the place. (That's GMs updated reflash), After the tune everything is smoothed out.

The first run



didnt like 18 deg of timing lol... also in need of some 60's


The final run

 

Exactly. I run a 2.8 on the GM Stage 2, my dyno graph was all over the place and A/F was crazy. It's going back to everything Stage 2 until i can afford a tune.

 

I agree 100%. IMO its not very smart going smaller then stage II pulley without HP tuners. Not to mention your injectors (42.5 pounders) are already to small for a 2.9. They are specifically designed for the stage II pulley. Someone posted date logs with a 2.9 with Stage II tune and 121% duty cycle on the injectors.

 

Yep, that was me and those are the logs up above. I may go with 60's in the summer.

121% is a lot. I was very surprised. They didn't have to be 121% we just made the top end a little richer than it was. Either way 121% is high.

Can't imagine a 2.8

60lb. injectors, a 2.9" pulley and a custom tune is a nice setup.

 

I agree!

What HP and TQ gain over GM Stage 2 will that give you?

 

I just installed my Zex plugs and after a short little trip I have noticed I have lost about half the knock I had with bkr7e. I could get as much as 5.3 degrees with the ngks and the most I have currently seen with the zexs is 2.7. Tune is less than 2 weeks away so it'll all be gone soon.

 

What about the stage 3 pulley? thats about 3.0", would that be too much for the stage 2 tune?

 

I'm not so sure about the lean issue...I have a wideband and I'm getting near 10.5:1 near redline. Just cruising around I see about 14.3-15.8 but while cruising it's hard to get an accurate reading because it bounces all around(due to the inconsistent flow of air during cruising)

 

just FYI....I get some knock on just stage 2.
with 94 octane and 1 step colder plugs.

 

Yeah, I did also...

 

so what you guys are saying is that if you go to a 2.9 you have to upgrade the injectors, what about the stage three from gm dont it go to a smaller pulley with the orginal gm flash i am confused

 

A tune will give you anywhere from 5hp to 15 hp depending on how agressive you go.
How much timing you pull, the AFR you set, fuel maps things like that.
A tune is more geared toward making things work right. No knock, AFR of 12, no detonation, things like that. By making things work properly you free up power.

That tune is going to make all the difference in the world.
Keep us posted.

 

I'll definately keep you posted. I'm interested in how you are lean though and we running the same setup???

 

Are you getting a custom tune or the upgraded GM tune?

When you say zex plugs...sorry I'm ignorant on this one...what part number and are they 1 range 2 range or the same cold level?

 

I run a 2.85 pulley, 42 lb injectors, stage II flash and the ZEX plugs. WOT i have zero KR. I am having my wide band bung welded on the weekend so I don't know what my A/R is. I also have a tune for my mods that has not been flashed yet but it will be interesting to see the changes once it is.

PS. I am also at roughly at 3500 ft SL.

 

Have you been on a dyno with that yet?

 

no I have not. I was booked in for the 19th but work has made me cancel it. Thats why I have not flashed the new tune yet. I wanted to do a pull with the current flash and then with the new one so I could do a comparison and possible tweeks to the new tun if needed.

 

Good plan amigo!

 

I also wanted to wait until I had my aeroforce and wideband connected.

The guy that owned the car before me ran a 13.9 at race city i believe so it will be interesting to see what a tune and the minor mods will do.

Cheers

 

now im confused. i thought from reading in other post a 2.9 pulley was safe and 2.8 was pushing it with the gm tune. what is the size of the gm stage 2 pulley 3.1 or 3.0? i was going to buy stage 1 and get an aftermarket 3.0 or 2.9 pulley assuming thoughs sizes would be safe.

 

gm stage 2 pulley ~3.1"
gm stage 3 pulley ~3.0"
stock ss/sc pulley ~3.3"

 

Custom tune by Doc and the part number is 82003-4 for the Zex plugs. I beleive they are 2 steps colder than stock but don't mark my words.

 

stage 2 pulley is also 77.9mm
stage 3 pulley is also 76.0mm

 

Is it just me or is people who are upgrading their stage 2 kits with a stage 3 pulley wasting their money? 1.9mm really gonna make a NOTICABLE difference?