alicecooperwa

I've been reading up on pully swaps for the SS and what I have found so far is a lot of people just saying that it will blow up your engine without a tune and injectors. I am curious about what the actual AFR's are up top with any pully smaller than stock. I know that if you go too small, you make more heat than power. But how low do the AFRs drop with say a 3.25 or 3.0 pully with stock injectors and a stock tune?

I'm not interested in people simply telling me DON"T DO THIS! I am not stupid enough to do something like this without knowing exactly what it will do to my engine. My other car can go up to a 17% reduction in pully size without a required tune. It has been proven with many cars that that kind of change will not lean out the car enough to cause any kind of pinging or knocking. I know that all cars are different, so I'm inquiring about actual data.

Does anyone have any actual data for this? Are there any people on this forum that have blown their engine from the pully causing the AFR to go too lean?

lsjwannabe

iTrader: (1)

The afr is not going to drop, you eill over work your injectors so when they don't keep up you will lean out. The reason people will tell you not to do it is becuase your injectors can go static and stick open. So in short its not worth your time for the possible hassle.

alicecooperwa

Has this actually happened to people? If you go lean from the injectors crapping out, it should show up on a dyno. I'm not so much doubting what people are saying, I am just the type of person who prefers hard evidence to what the masses say. Does the SS run on the lean side stock? Are the injectors already at their limit in stock form?

lsjwannabe

iTrader: (1)

It runs rich in the 10's. If you dont want to believe it you can do it, there will be gains on the low end.

alicecooperwa

So does that mean that it could safely be done with just injectors? I prefer doing things myself versus relying on dealerships and stage kits from manufacturers. It seems to me that having to reflash for something as simple as a 3" pully is silly. I understand that after an intake, exhaust, and some headwork...it will bring everything together, but it seems so unnecessary. I would prefer to get a custom tune done after I do intake exhaust, and immediately after P&Ping my head.

BTW, thanks for the fast replies!

brett5

if you search on here you can find some data on it but the stock pulley is already pushing the limits on the stock injecters and a 3.0 on 42 lb injectors is pushing it as well

stonny9

The stock tune and stage 2 tune are rich straight from GM AND the idc is over 100%. You can run a stg 2 pulley on the stock tune and a 2.8 on the stage 2 tune. Anything less than a 3.00 and u will want cooling mods. I have yet to hear of an injector going static on a cobalt and I know of severl people who are running smaller pulleys and one of them for 1.5 years.

Area47

my 42's did and i was runnin 90% idc with a 2.8 and water injection.

alicecooperwa

Thanks for the info guys. I would hate to have to do several tunes if not necessary. It's very redundant! So a 3" pulley with just a step up in injectors would be safe? What about if that is coupled with an intake and exhaust? Would that prove detrimental without a tune?

PuSha050

if u plan on eventually having a shop custom tune it.. most will update the tune for free or a small fee as you go along with mods..