FAQ: Selecting Proper Supercharger Pulley & Belt Size (Series I)

Welcome to the site!

im new so i dont really know how to do everything like put pics or andything like that. but when i figure it out i will put some on.

justins95riviera wrote:

what are u going to do to it?

im doing a full drive train swap, to post pics post the URL the address but put a behind it

hey i got a question, i am looking for a smaller sc pulley and i was wondering what is the smallest i can go without haveing to do anything else to it?

In short , you can't do anything smaller without doing something , do some searching around , but i think with exhaust , AL104 plugs , 180* tsat , and intake , you'll be ok doing a 2.5' on 95.

so a 2.5 sc pulley wont ruin anything? i am planning on buying a cold air intake for it. so i just want to ask what u guys recomend i do?

you can start out with a Fender well intake

heres the deal i want to get the 2.5 after putting in a 180 thermostat and 104s and i already have a 4" fwi but the only place i can find with it is pulley boys for 90 bucks.ZZP has m62 pulleys for 50 apiece but only in 2.6 and 2.7 i think im just gonna get the 2.6 because its 40 dollars less and probably a little safer since i dont have a scanner.would there be a noticeable difference between the two?

You can get a 2.55" pulley from any eaton M62 from 1992-1993.

The 2.55" pulley was the stock size for those superchargers.

You can differentiate the years, by the casings. The 92-93 had the ridges on the top of the supercharger casing go down all the way to the bottom of the sides.

The 94-95 casing the ridges end half way down the sides.

thats a good idea if only i could find a 92-93 m62.But wouldnt the pulley from it get all mangled when i remove it or is the press fit not as tight as the m90s?

oh cool....another Partsiera will be available soon...

Nope just make sure to use a 3 jaw pulley puller. Takes about 20 mins.

why do you say that?

blown95riv wrote:

thats a good idea if only i could find a 92-93 m62.But wouldnt the pulley from it get all mangled when i remove it or is the press fit not as tight as the m90s?

Nope just make sure to use a 3 jaw pulley puller. Takes about 20 mins.

That's why!

thank you for the info buick man but i was asking chicken why he thought my car was going to be partsiera

What would you guys say is the smallest pulley I could run on a Series I without having to swap the injectors? I know you can go as small as 1.9 but I assume an injector swap is required for that small. I am currently down to a 2.5 atm, but would like a little more, but still have a somewhat reliable car.

The m62 puts out so much heat even at 2.5, I think you would find that you had lost power going to something smaller.

Even the 2.5, without rockers or some porting is gobs of heat and will make it less reliable. Eaton themselves say not to drop past a 2.5" pulley as it takes the blower way out of its efficiency range and the heat goes through the roof. As we know heat makes KR and less power, and less reliability. The only person I've heard of running a sub 2.0 pulley had a custom inter-cooled system and sort of ported heads, plus lots of other fiddly things, and I dunno that it was really what I would call a success.


but that said, and since your question was directly related to injectors: you can get the stockers to run a little more pounds by changing the stock FPR that is at 2.7 BAR to a 3 BAR one. The 2.7 BAR FPR is stock on the 95 for whatever reason, but the 29lb injectors are really only 29lbs at 3.0 BAR. So stock, the 95 has "scaled back" slightly injectors. The 3.0 BAR FPR can be found on a 93 supercharged car, or similar from rockauto.com.

As a guesstimate, ignoring all the other problems of the tiny pulley on the m62, with the stock injectors I wouldn't go lower than 2.2. But its all relative, since you only try and command more fuel for more air processed, and smaller pulley won't mean you are actually flowing much more air, so it doesn't result directly in "injector use."

HMMM, well I think on that note I will save my pennies and stay with the 2.5. I'll just make sure I change my SC oil frequently as I am sure the heat will require it to be changed sooner. I ordered the MSD coil pack for it and they will be here tomorrow. Doubt I'll notice any difference in performance but at least it will look better.

hey guys, Im ordering some mods soon,(2.7 pulley,/exhaust) and was wondering, with exhaust work(prob 2/3'4), autolite 104's, and 180 drilled thermo, would I be looking at any knock by upgrading the pulley size? Does anyone have these mods and how much quicker did it make your Riv? Thanks boys.

are you stock right now?

Heres a good overview:
http://www.pontiacbonnevilleclub.com/forum/viewtopic.php?f=44&t=1660

If you are just dropping the .1 (2.8 to 2.7) you will be fine with cooler plugs and exhaust(check for manifold cracks!), tho the engine would like an intake before exhaust work...

180 stat is useful for keeping that hot little m62 under control... the drilling is really just for sitting in traffic and to help with bleeding out air in the coolant...

I dunno if you will feel that much with only a .1 drop tho....if it were me I'd do:
full tune up
al104s
tstat
check manifolds for cracks
FWI
check fuel pressure(should be around 43 at idle with FPR line off)
find a 2.55" SC pulley from a <=93 m62 SC (from a junk yard)
scan

Does anyone know what is the smallest pulley you can run without changing the belt or tensioner pulley? I'd like to get the 2.55 when I get the supporting mods done and wanted to know if anything else had to be changed too.

you can run the stock belt and tensioner with the 2.55 if the belt is new.

Derek, I think if you read through this entire thread from the beginning, you'll have a good idea of what is require to drop SC pulley size.

Thanks Karma, you and everyone else on here is always very helpful and its much appreciated. And thank you too Aaron, I have read the thread and I know what I'd like to do. I'm in the 'planning' stage now, i.e. I'm broke, and I wanted to make sure not to leave anything out. The devil is in the details as they say. Lol.

can anyone tell me the shank size of the series 1 pulley? If anyone could, or has measured that would help, i looked on all the parts sites but no one lists it