I am looking for info on ASP pulley sizes for a Comptech SC and F20C.

Looking to run 11-13 psi at 9500rpm. If anyone has ordered custom pulleys from them in the past, do you know what size will give me the desired boost without exceeding maximum impellar velocity?

Thanks.

 

A 3.5" will run 9 pounds on the F20 and every .25 of an inch is a pound. I actually found a place that has 3" pulleys in stock. Just ordered mine. I can let you know what I think about it when it comes in Thursday (hopefully). I also had Tech 2 looking into making me a 3.15" pulley which would run about what you are looking for. I think the Comptech is pretty much maxed out at 12psi and you don't want to take it much above that.




PS. the springs are working great

 

ASP made me a 3" pulley and it will yeild around 14 pounds and max out the impeller speed - you can not go any smaller than a 3" w/ the Novi 1000, I have a friend with the same pulley and he has 18 pounds because of his head work - I have an Alaniz built motor so i should see the same boost - 3" is measured where the belt rides and ASP advised me to use steel instead of Aluminum to help prevent slipping!

 

FF2Skip & I recently ordered a 3.25" Pulley for our Comptech Setup w/ Aftercooler. My car is scheduled to go in the shop next Monday for tuning. Soon as I get the car back I'll let you know a list of all mods with dyno results, a/f results & boost level.

 

Thanks for all the response. What is the the correct belt size for the 3.25" pulley?

Ztec, does you friend have a Novi 1000 or 2000? I was told max. boost without exceeding impellar speed is 13psi, I am curious how he got 18psi.

 

We both have the Novi 1000 - My motor isn't here yet so, I cannot give you first hand info - He has had this setup for well over a year and had some head work done and his boost jumped up to 18 pounds after the work done So, I assume it has to do with engine configuration and RPM's.
I had gotten some info from Paxtonauto.com about the max impellar speed and it was around 55,300 but, I was also told that there was some margin of error built into the units allowing you to exceed the "max" speed.
His car hauls ass and I mirrored his build - He is putting down 450 rwhp!

 

[QUOTE=Asura,Jul 8 2005, 05:52 PM] Thanks for all the response.

 

Decreasing a pulley size will not yield linear results. I believe the resulting boost is determined by a percentage of change rather than size alone. 4" pulley ~ 7lbs on a Comptech. 3.5" ~ 9lbs. 3" ~ 14lbs as Ztec stated. In each case, the change is .5", however, the boost gains varies.

Somewhere in this board was a thread where one member posted all the mathematical computations as to the min. size pulley one could safely run on the Novi 1000. Impeller speed used was 55k. Since I remembered his calculations to yield a min size of 3.19", I had 3.25" pulleys made since no major reworking of the head is scheduled immediately. My thought was that pushing the car to the max right now would not be smart- not looking to break any records.

Additionally, I believe(could be wrong) that I'll be able to bump the rev limiter up to about 9500rpm without having to worry about the blower- I'll just need to get the Ti retainers and inner valve springs from Joe.

 

As Nick stated, steel for higher boost applications. Lee @ ASP said the same thing to me. Since we weren't going quite as small as Nick, he stated that the aluminum ones would be fine for us. We'll find out in a few days.

BTW, great folks to work with(Candice and Lee at ASP). They made sure we had our pulleys this week for next weeks dyno time. Feel free to tell them you heard about them from other S owners.

 

Crank Diameter x RPM x Blower Ratio = Impellar Velocity
Blower Diameter

Crank Diameter= 5"
RPM = 9500
Blower Ratio = 3.54

Therefore, a 3.25" pulley @ 9500rpm = 51,738
and a 3.00" pulley @ 9000rpm = 53,100
a 3.00" pulley @ 9500rpm = 56,050

I think a 3.125" pulley would be optimal for me
3.1245" @9500rpm = 53,808

However, I think a 3.25" or 3.375" pulley would leave a nice margin.