Guys my dad is currently in in Detroit and his first cousin is a machinest.

My dads cousin said he can machine down my pulley to any diameter I want.

I have the Code 3 pulley which is 65mm I think? now I'm thinking of giving him my original pulley to machine down to 60mm BUT I'd only use it for drag racing I know it can overrev and fry the supercharger.

My question is how much extra boost and how much quicker will it make me in the q/mile? is it possible to make it even smaller then 60mm? with added bonuses?

John

 

Okay I've done some reading and research and it seems that if it gets machined to 62mm it will rev the s/c to 15,000rpms which is what the 185 crank does, now does anyone know what the supercharger can take as a max? maybe 16,000rpms? remember I'm only planning to use this "super pulley" for drag racing no street driving lol

 

i wouldn't go more

here are some possible problems with your idea:

a) you will have ridiculous belt slip
b) you wont have enough fuel for that much boost. you'll need t upgrade the fuel pump and possibly injectors
c) it overboosts the supercharger way beyond the efficiency range (heck, the 185 is already in that area). WAY shorter life as opposed to just a shorter life
d) you will have overboost problems and will need a map clamp or something to resolve this issue
e) tuning for it

why not just machine the pulley down to 62 and then add a little spray to the car for a little more?

 

Thanks for your response jturkle, right now I'm planning to get it down to 62mm and only use it for track days, then put my C 3 pulley back on for daily driving.

I just wanted to know if the car could take a little more seeing as I'm only going to use it for a few seconds at a time on the track.

I think people have run 191 crank pulleys and/or run a 181 crank with a Code 3 pulley aswell, these combinations would surley be reving the s/c to around 16,000rpms?

I'm only doing this because I have a spare s/c pulley and it will be machined by a proffesional for free, I'm just trying to get the best scenario here. Maybe this will be my easy ticket into the 11s?

 

Oh and belt slip shouldn't be to much of a problem as I've got a custom belt wrap kit on my car at the moment!

 

All this talk of machining down pulleys got me thinking, are you going down to a smooth pulley? I can see then turning it down with keeping the grooves. If so, that would be why it's not cheap to machine... my guess: Smooth = massive belt slip

 

to answer your question, there is a post ,,do a search,, because i am going by memory the sc max is 220000 so to be safe i think it is around 170000,,, at the 22000 you may explode . you also have to remember that you are only running that speed at wot and 6000 rpm. jim

 

Good question about the grooves. Verdict?

 

I'm definatly keeping the groves, I sent it today so I'll see how he goes with it, I decided to get it turned down to 62mm, this will rev the s/c as much as guys that have a 181 crank pulley (15,000rpms) and it should still be big enough so I dont get belt slip. Ive got a belt wrap kit so I'll be okay in that department.

 

the main issue you are going to find is there may not be enough metal available to machine down to 62mm . thats taking approx 10 to 12mm of metal off the center. sounds like enough to cause a failure. thats why most dont want to go smaller than the c3

 

Hrmmm I never thought of that Steve, any experts here that now how much metal can be taken off without risking anything?

 

No - but I would sure hate to turn to much and have to pony up for a replacement...

 

I've got a C3 pulley at the moment, im not fussed if the original breaks, I just dont want it to break anything else under the hood while its breaking lol

 

thats exactly what im thinking. s/c turning 16k pulley lunches and takes the hood and who knows what else!

 

I would tell him to turn it down no smaller than a diameter which leaves you with at least .060" (60 thousandths) metal thickness (margin). And I would feel better with .090" margin but ask him, as margin is best determined considering metal composition, workpiece design and operating load. My vote is 90 thou. minimum.

 

I ask again, can we turn down the stock pulley and forget the grooves, or will slip become a problem???

 

Eliminate the grooves on the supercharger pulley and you reduce the belts points of contact. So, I would say yes slip will become a problem.

 

How did the pulley turning come out?

 

no grooves = massive slip, as the belt has nothing to contact.

also using a grooved belt on a smooth pulley can lead to belt walk when the belt starts to stretch, then it will come off of the snout of the s/c and cause all sorts of havoc

 

I don't know where the no grooves thing started but of course you machine in the grooves...