Ok heres my problem. I am either gonna get a 2.7 pulley and a 2.6 pulley and i need to no how they will react with my gm stage 2 kit. I need to know if one of of them will be to much and also if they effect gas milleage very much. If im not mistaking the 2.7 gets you 17.5 boost i am not sure what the 2.6 does. Basically i need to no if it is gonna be to much for my car to handle and what the safe boost pressure is . I already have gm stage 2. So if someone will help me out it would be grate. Thanx

 

UMM NOT GOOD... definatly retune for that size and you might want to go with the 60 lbers before something blows up... I do know a few people running a 2.7on the gm stg II I just am not sure how safe it is.

 

Well if thats not safe then what could i do to make it safe.

 

get it retuned and get bigger injectors

 

i want to do the same thing, but you keep the same belt? and what about the spark plugs?

 

Get a 2.8 and one step colder coper core plugs and your safe with the GM tune.

I see about 17lb with that setup.

And you dont have to retune it or change the injectors to run that. Tuneing would give more power but its not 100% needed.
I get about 31mpg average and I got 37mpg on a 155 miles trip just last week.

Later

 

dont go below 2.8 with the GM stage 2.... ^ exactly what he said

 

Yeah, the stage 2 belt is only good for down to 2.8 pulley anything smaller and you need either an adjustable tesioner or a bigger tensioner pulley.

 

hey guys what is up okay let me tell ya guys something not to be a ass or anything just telling you the facts my friend it on the fourms he has a 2 tone black and red ss me and him run 2.8 pulleys on gm stage 2 tune i run 17.5lb me and him run 13.5 and 13.4 at the track

 

hey man i run the 2.8 and i get exactly 17.5 with the 2.8 me and my buddy a 2.7 will give you atleast 18.5 to 19 the 2.6 that i have seen in person give you 21 pounds which max out your stock gauge going to a 2.7 will be fine with stage 2 tune cause your no where near max out those 42.5 injectors a guy max out the 42.5 with a 2.5 pulley so that has to answer your question

 

^As well as conflict with a lot of 'actual' data

DO NOT go any lower than the 2.8 on the stg 2 tune, unless you can dyno with Wideband ASAP

There is a lot of debate as to whether or not the 2.8 is even safe on the stg 2 tune

Some claim well over 100% IDC is seen with this setup,,, and thats not safe

 

Exactly 100% IDC is not safe. As a matter of fact 90% IDC is not safe. I wouldn't chance it.

 

This is very true. I would take this guys advice. I don't like the way the car runs on 60# injectors. Good for racing but not so good for a daily driver.

 

I'd also like to see you back those comments up with data. I've seen a few posts by you today and you keep saying the same crap. Don't go filling people's heads with bad info. I'd like to meet the person running a 2.5" pulley and the GM 42lbs injectors.

P.S. - Let's see some slips for those 13.4's and 13.5's.

 

Exactly. Now it should be noted that these IDC in excess of 90% apparently only occur during the last few hundred RPM's, but nonetheless they do get that high.

SO more exhaustive testing is certainly warranted

I'll be the guinea pig if anyone wants to donate some $$ so I can buy HPTuners

Really though

 

Why not? I can see how 100% might be a little scarry, but why would 90% be unsafe? It's not like they are at 100% for more than a second or two. And that's only if you shift at 7k, whitch I think MIGHT be over spinning the blower. ??????

 

all in the tune bud.

 

There is a whole thread about injectors the final outcome that read was basically nothing lower than a 2.8 on 42's, if your going to do 2.7 or 2.6 go with 60's. I was in the same dilema. I ended up with going my sig mods, intense 2.6 pulley snout needs to be machine zzp claims no machining involved. I am using stage 2 belt no oversized tensioner on a intense 2.6 no slip and i was seeing 20.5lbs

 

You're an animal SS33. Yeah guys the high IDCs start around 6,100 rpm. So if you want to run that 2.8" pulley and be pretty safe just use HPtuners to set your redline at 6,100rpm or even up to 6,500 if you want, just not 7,000rpm. That = Boom!

 

if this car you speak of doesn't max out his injectors he's running them at 99% so either way if you want to be safe go with 60lbs injectors they are only 40 more through LFP $200 for injectors and harness then get a tune from a local shop t=shop that has hp tuners probably gonna run you like $350. why are you buying two pulleys that are so similar in size. I'd say it would be ok to have a 3" and a 2.7/2.6 but no reason to have some so close together.

 

Oh no man, people have shown data that at 6,800rpm there is a 112%-118% IDC.
Plus fuel injectors can go static at 90% duty cycle that's why 90% is not safe.

 

i asked paul at steeda about 60's and the driveability for everyday driving and racing, he said with a PROPER tune, the car will ride just as good as when the 42.5's were in.

 

Yeah definitely, it's all about the tune.

 

That was very painful to read.

Now, reference this and look at posted mathematical formulas and IDC logs. 42# injectors and 2.7=not safe.

 

This is true. However, at idle the 60's basicallt have to turn on and off cuz they are too big. The way I figure it (and this is only MY oppinion) my car idles more than it races. Also, At 7k i only saw 60% IDC on the 60's. There is plenty of room for more power with the 60's, but I think if you are gonna stay under 250-300 HP the 42's are fine.

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