so i finished my OTT stage 1 yesterday by installing the pulley. I rented the puller from zzp, and my brother and i did it in about an hour 45 minutes. everything went smoothly until we tried to put on the bigger idler pulley. it was rubbing on the tensioner itself due to the diameter of the pulley. i emailed OTT, and they said to take a dremel or grindwheel to the tensioner...it only needs like an 1/8" removed...which isn't a big deal.

However, last night we were in a pinch, so we put the stock idler pulley on, and i used my buddy's old stage 2 belt from his ion redline. my brother said the belt tension seemed ok. the car runs great, but i'm only boosting about 15-15.5 psi on a 2.8" pulley, and at high rpms while flooring it, or when flooring it from a dead stop, the supercharger spools, whines really good, and then there's a loud TSHHHHHH sound....like the belt is slipping.

OTT said the stage 2 belt would work, and suggested i got some belt dressing to increase traction. I did, and it seemed to help a little. the slipping noise isn't as loud, but is definitely noticeable, and the most boost i've seen is 15.5. There wasn't any damage to my buddy's old belt, no cracking, etc. I'm thinking maybe i should do the large idler pulley anyway, grind down the tensioner a bit, and use my stock belt

thoughts?

 

i have a 2.85 and see 15-16psi depending on air temps and i have no belt slipage. you could try changing the tentioner and going to the stock belt, of another option is an aftermarket tensioner

 

eh, i'm not really interested in the aftermarket tensioner. i would much prefer to make do with what i have. I think my bro and i will grind down the stock tensioner, fit the bigger idler pulley, and use my stock belt. we'll give that a whirl and see how it goes.

 

OTTP stuff is good, i run 15 psi with a 73 mm pulley and that seems about right...

 

is 73mm the 2.8"? i was under the impression that the 2.8" is supposed to yield somewhere in the ballpark of 17psi. considering the 3.0" pulley on my friend's GM S2 cobalt pushes out 15psi...i'm starting to wonder why i'm not higher than that. that reassures me that the TSHHHHH noise i hear under full throttle is my belt slipping.

 

i get 19.3psi at 7k rpms on a 3rd gear pull with a 2.7" pulley

have the vid if you wanna see it

 

that's exactly my point. if my buddy's 3.0 is putting down 15-15.5psi, and you're putting down 19psi with a 2.7...how in the hell am i only putting down 15ish on a 2.8? unless....my belt is slipping

i might get a chance to troubleshoot a little tonight...i'll you all know how it goes. i was really hoping to see 17psi. my car pulls like an absolute monster now...but it's still disappointing to only see 15 on the boost gauge.

 

buy an overdrive pulley from CA.... i think im going that route

 

ok...and what would that do exactly? also, how much we talking? i bet it's more than i'm willing to spend.

 

yep, its the big pulley on below the tension pulley. its a bigger version giving you more boost and less belt slip of course because its bigger

 

keep in mind that the stock boost gauge isnt 100% acurate and they will vary from one to the next. also header, downpipe and cat back exhaust will make a difference with boost levels, aswell as air density, cooling mods, ect. unless both cars are identical and being red with a good mechanical boost gauge you cant compare them. keep in mind that pressure is a restriction, what you are after is airflow. better flowing components will actualy cause boost to drop but the car will be faster because its flowing more air. your mass air flow readings would be better for a comparison.

if you really want to compare 2 cars, dyno them on the same day, or better yet line up with him at the track.

 

i had that problem, it was the belt on the wrong tooth, had my buddy at the dealership fix it and problem was gone.

 

yah i had the same problem as well same ott kit, i ended up just buying a new oem belt and no slipping that i can tell idont know how much i am boosting but, later i am gonna swap to old idler pully and get a stage 2 belt and that will solve any issues. also i had to dremel the crap out of the pully and the tensioner i got pissed off and just threw it on the vehicle and gave it like 2 mins of idling and it melted the plastic ofthe pully to where it wont scrap lol.

psi can change with weather as well as ellevation.. also if you got your mods you will lose a lbs or 2 cause of the easier flowing air in and out.

 

 

Really? So it was the belt that made the noise? the stage 2 belt i'm using right now probably has 25-35k miles on it. it's not new, but it's also not cracked or anything. i know for a fact my oem belt is perfectly fine, so i'll try the bigger idler pulley and my oem belt and see how that goes.

 

your booting about right i boost at 16psi at 5200rpm on a 2.99 its all in where you live air density, temp,....

 

this all makes sense, but it still doesn't sound right. waukegan, il is 201m above see level, and it was 39*F outside last night. My buddy's stage 2 cobalt has the 3" pulley, obviously, and we have the same mods. same intake, same header, downpipe, and catback. He boosts 15.5 in these temps. i boost 15-15.5 as well in these temps. given that we have the same amount of restriction in our exhausts, same intakes, etc. and we live in the same city...shouldn't that be a good comparison? i mean i understand somebody in another state will boost higher or lower than me given elevation....but how do you explain my guy with the SAME setup as me, except he has GM S2, and i have OTT Stage 1?

 

If the belt is slipping you will notice some material by the pulley left from the belt clean it up good take it for a spin and let us know your findings.


Also remember no two cars are made the same. If the car feels strong dont worry about the boost

 

as i said before, the factory boost gauge isnt always accurate. put mechanical boost gauges in both cars, or better yet both get interceptors and compare mass air flow readings.

 

Good point. I guess i'm not worried about the boost nearly as much as i'm worried about the loud TSHHHH sound when i floor it. the supercharger spools up, and then there's the slipping/rubbing noice....like WHAAAAAAAAAAAAA TSHHHHH. It pulls great, i'm not complaining about the butt dyno, but it just doesn't sound good. I'll try my oem belt and grinding down the tensioner with my dremel when i get some time...and i'll post up here and let everyone know what happened. Plus...OTT, this will be good for you as a vendor if i end up fixing it. Adding tips and tricks to pass on to future customers is always good news.

 

As far as it goes with that the tensioner just has to be ground nothing crazy, its a half inch larger than the stock tensioner iirc. I ran the same setup but with a 2.5" with no belt slip at 19 psi.

 

nice. that's what i like to hear. I'll go that route when i get the time...and let you know how it goes. if i do go with the oem belt, and the bigger pulley, and my car STILL makes this noise....i dont know what it could possibly be. it's at the point where if the belt isn't slipping, i dont know what would be making a noise like that.

 

I boost barely 16 psi at the very top of 2nd..but I am on the 3" pulley..and I have no exhaust, so therefore I would be boosting less if I freed up some airflow.

 

Just make sure the belt is a lined up and you have removed enough material to not make conatct and you should be fine.

 

Just out of curiosity if ott knows this is a problem. Why dont yall remove the half inch before you ship it out to customers. Not trying to bash the product or vender just a question.