well as most here know i had a one off custom cog set up built for my 91 that replaces all the factory pulleys with cog pulleys and it runs a 94 inch long 30mm wide cog belt that installs just like the factory serpentine belt .I really didn't think ahead about the problems you might have with a cog set up until Aaron (aks racing) brought up the fact that a cog system can be hard on the s/c internals when your going full tilt and you let of the throttle the cog system wont allow that bit of belt slip to take the shock of the s/c sudden declaration .I checked out a few option and the only guys who make a sprag clutch pulley are ati performance and there where 2 things i didn't like about it ,number one it is only available in 45 tooth ,that is the smallest they can go and second from what info i got from ati is that it weights 12lbs .so i decided i would build my own ,after searching for over a year for the parts i needed to make one i found what i needed and just finished my first one yesterday .we put it in my friends 88 stang with a d1 and tested the crap out of it and it preformed excellent .we really tried to make it fail from revving it to 6000 rpm in second and letting off the throttle to full tilt power shifts and pedaling the car .so far from the math i did the smallest pulley i can make is a 32 tooth ,the one we tested was a 38 tooth .I am really impressed with what i made ,it really is a great design that i put a lot of time into finding the right parts to build it right ,like i made it so if the spag ever does fail the pulley will not fly off and go through the hood and also i made it so if you want to change the pulley sizes you just swap the cog tooth piece and the internals are reused .this thing should solve all the problem that you get from running a cog blower drive .today we will beat on it some more and see what happens, but so far it has worked like it should .

 

Can you post up some pics? I always like to see things that are new and different. It sounds like a nice piece.
Aaron

 

 

Hey Aaron ,I will post some pics very soon ,I'm planning to take it off his car in a day or two to take it apart and check it out to make sure everything is good .my friend just came by my place at 9 am and called to see if i wanted to to go to pick a part with him (best place to find mustangs) i said no and asked him if the pulley is still performing good ,he did a full tilt drop the clutch at 6 grand launch and told me ''what do you think '' .I really think this is going to be very reliable on a street/strip car and a few days of abuse on my friends stang should put it to the test ,he really drives the **** out of it .I will post a few pics soon .

 

Sounds like a nice set-up, I can't wait to see the pics

 

is this along the lines of an ATI cog pulley w/ clutch?

what crank pulley do you guys (who have cog drive setup) run? i would like to convert to cog drive. sounds like the ultimate "fix" to a slipping belt.

 

my set up is a custom cog drive set up that replaces all the factory pulleys with cog pulleys that use a 30mm wide 8mm pitch cog belt that uses a 94 inch long belt that routes just like the stock serpentine belt .all the pulleys where custom made like the crank,a/c,alt,s/c where cogs and the rest like ,w/p ,p/s,tensioner pulley,s/c idler are smooth pulleys .A cog set up is the ultimate fix for slipping belts and getting all the the power you can get out of your s/c ,i don't care what people say every 6,8,12 rib s/c pulley set up slips .my friends stang that we are testing the sprag pulley on he had a 12 rib s/c belt and he thought he was not getting any belt slip but when we bolted on the cog crank pulley that was the same diameter as the 12 rib pulley and my sprag pulley that was actually bigger then the 12 rib that was on there.so my sprag /cog pulley should of made less boost but he has seen a increase of 4 lbs on the top end .my set up works just like the ati sprag pulley but mine only weights 2lbs compared to the ati units 12lbs and the sprag i use inside can take 400 foot lbs of torque ,not sure what the ati can take but I'm sure its a excellent piece .the smallest ati pulley is a 45 tooth ,i can go as small as a 32 tooth maybe even a 30 tooth ,the ati unit is 75 mm wide ,mine can be anywhere from 30 mm wide to 75 mm wide ,mine if you want to change the tooth count you can just change the cog piece and the internals/center section is reused .it has been 3 days now of pure torture on my friends mustang and it has performed excellent ,yesterday we pulled it off and took it apart and everything was great ,nothing was worn there was no play in the sprag it was as tight as when i installed it, so i threw it back on and hes having fun with it..

 

I agree that a cog pulley is the "ultimate" way to go to eliminate belt slip. I just don't understand why manufactorers don't use this setup to begin with?

I was curious to know why you didn't go with a drive system exlusively for to drive the blower, rather than changing out all the pulleys?

has anyone tried to adapt the cog pulleys from vortech to our application?

 

Any pics?

 

sounds like an awesome part. I have taken a look at the procharger ones as well and they're just too big for my ysi. Now if we can get one in the 2.75-3.00" range... what's approximate cost?

Also, the sprag is relatively new which is why not too many companies have gotten on board yet. I think it came out at sema 2006.

 

The sprag pulley has been going strong now since we put it on my friends car ,it has been working flawlessly .I could get it as small as 2.5 o.d easy ,it would take some machining but its no problem . The ati sprag is a nice piece but the smallest they can go is a 45 tooth and the weight is what i don't like the most ,12 lbs that's just way to much to hang off the s/c imo,mine is under 2lbs .If you got any extra vortech cog pulleys i can see what i can do .how wide is the cog belt you use,a 30mm? if you got a spare cog pulley and you want to send it to me i can see what i can make for the vortech blowers.the price of the pulleys wont be anywhere near the $500 cost of the ati pulley the most expensive part is the actual sprag clutch ,i get them for $130 each and that's only because i ordered 20 of them from germany.I think the vortech's use a 3/4 inch pulley shaft is this correct? the sprag pulley will save you a lot of wear and tear on your s/c internals and should eliminate the cog belts teeth from shearing off when pedaling the car .

 

right now I'm running an 8 rib setup. I looked at cogged setups when I bought the 8 rib but I found that the teeth were shearing off when the car would get pedaled. At $125-150 a belt, I didn't think it was worth it at the time. I'll pm you a few questions later on this week. I just got back from 2 weeks vacation.

Also, I'm curious if this thing will survive with a ysi and 30mm belt. As a far as the vortechs, a s or t trim with a cog will work okay but most problems are run into with the bigger ysi with more inertia(takes more power to drive).

So when you let off the gas, the blower freewheels for a few seconds. Do you hear it out of the bypass like a turbo?

 

Vortech shaft diameter is .785

I need a 50mm sprag pulley. Let me know.

 

hi,when he lets go of the throttle under full boost you do hear the air escaping the bypass valve for sure .he's got the oil feed d1 procharger that is pretty much comparable with the ysi i think .I could throw on my d1r and see what happens,but i really don't think it will have a problem .the problem with a cog is the engine slows down way faster then the s/c impeller can ,causing the cog teeth to shear off .I really don't think the 30mm wide belt breaks from the ''inertia'' of the s/c .If a ysi shears 30mm cog teeth off trying to drive the s/c then i wonder how a flat 6 rib belt can do anything except just slip and burn up trying to drive the ysi.there have been a few guys that have had bad experiences with cog drives but then you look at there set up and they have there s/c mounted onto this flimsy bracket that flexes like crazy and also there pulleys are not in alignment and then there belts fails and they blame it on everything else except the true cause of the problem ,a brace from the s/c bracket to the cylinder head is one of the best things to do ,even on a 6 rib it will help eliminate some belt slip.my sprag pulley on my friends stang after he shuts off the engine the s/c pulley stays spinning for a few more seconds .

 

guys, let us know how these pullies work out, especially with the bigger blowers. By the way, where are you guys getting your crank pullies made? I was told that ati has and can make them but they're pricey(about $1000)

 

http://www.reichardracing.com/

http://www.aspracing.com/index.html

http://www.vortechsuperchargers.com/

http://www.rcdengineering.com/

 

the rcdengineering place looks like a good source for belts. Are most of you guys using a polychain gt2 or standard htd?

 

I've got the new carbon fiber belt from gates but havn't installed it yet. Supposed to be what the top fuel is/was running.

 

nice. Are you able to bend that one back or is it only supposed to be bent inward? If I go with a cog setup, I need to get as strong a belt as possible to retain the teeth on the belt. Do you have any pics of your setup dave?

 

I am looking for a Cog set-up for my 99 Trans Am. It is custom so don't really worry about width. I was hoping one of you may have a old set=-up you might want to sell, that I could give a try. I am running a procharger D1 blower, and I agree the ATI sprag clutch is a lot of money if so please email me at chadthomas82@mac.com