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3.4 or 3.5?

JbrownGTP

JbrownGTP

New member
So i am getting ready to pulley down and i read somewhere that you shouldnt drop to a 3.4 if you cant get higher than 91octane gas. My current mods are cai, zzp1.0 pcm, 180*tstat, ported front manifold, 3'dp, and zzp hv1 tb. I live in colorado and we can only get 91 around here so would i be knocking with a 3.4, those mods, and 91 octane gas? I would have the car dyno tuned after i dropped but idk if that would make a difference in the knock. Or should i just play it safe and get the 3.5?
 


3.5 or 3.4 doesnt matter, youll have some knock depending upon the weather. keep the stock pulley and get a better tune to run more timing. it will be faster.
 
The 91 octane is the Colorado equivalent to 93 octane. It's that way due to the altitude... it's not that we can't get it, but it's supposedly performs the same because we are at a high altitude. I could do some googling to find out the scientic background, but it's been that way in Colorado "forever"...and it's not a performance killer.

Yeah, definatly have Clint give you a tune...but you knew that ;)

FYI for everyone else that hasn't visited Colorado, we have 85, 87, and 91 octanes, not the sea level 87,91, and 93 octanes. (and NO, we don't get to save money because of the lower octane!)

And to answer your orignal question, I have no clue, but I'm going to get a 3.4, but it's not going on until I'm driving to Clint's shop. (and I get more mods). Shor0814 might be able to help you out a little better as he's had lots of experience with GPs and he's in Aurora, and has a pulley puller!

Hope that helps,
Jesse
 
That would be awesome if he would let me borrow his puller! Save me $100 which i could then put towards a tune.


And yes i know nobody likes the zzp pcm, but hey mine is working just fine. I have had it in there for almost 6 months now with no problems. The only complaint i have is that it doesnt always downshift at the right time.

Thaks for the input guys!:th_thumbsup-wink:
 


JbrownGTP said:
That would be awesome if he would let me borrow his puller! Save me $100 which i could then put towards a tune.


And yes i know nobody likes the zzp pcm, but hey mine is working just fine. I have had it in there for almost 6 months now with no problems. The only complaint i have is that it doesnt always downshift at the right time.

Thaks for the input guys!:th_thumbsup-wink:
Click to expand...

I'm not going to get my fingers in the mud of who's PCM is better or worse. Clint @ AIR will dyno tune you, so it doesn't matter if you have an aftermarket or stock PCM, he'll tune your car for what it needs. He's also close to you at I-70 and Kipling. (well....closer than me in Castle Rock)

Shor0814 is on the coloradolsx board as well since he bought an 07 twin turbo vette!!...and sold his turbo GP to his brother... however, coloradolsx just went up in smoke the other day. I'm really hoping it'll come back online soon.

Good luck!
Jesse
 
Provided you get some colder plugs and the car is healthy, you should be fine with a 3.5. I definitely wouldn't try a 3.4 though.

ZZP's PCM is the richest of any I've looked at. So it will probably fight knock off a little better but just dumping a ton of fuel in isn't the right way to handle it.
 
ZZP's was too rich for my car..it would blow up my plugs...i dont think 3.4 or 3.5 will make that much of a difference..
 


I was gonna get autolite 104's, at least i think thats what i had picked out. And im also pretty sure that zzp doesnt lock there pcm's so you can continue to tune it. I could be wrong but yeah it would really suck because they took my original one as a core return.
 
You can reflash them to a stock setting via a tuner even if it is locked...basically you re-write the PCM to match the stock settings via the VIN # if I remember right. ZZP used to lock them because they didn't want people getting their tunes off of the powertuner...
 
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