Vortech Supercharger RPM's??? Overspinning?

derrick929 · #1 09-03-2008, 09:13 AM

I"m trying to find the right drive pulley combo for my Vortech. The stock 3.33" got me to 6 psi. A 2.95 gets me roughly 9-10 psi. I'm in the process of adding an intercooler so I want to get to about 12psi. To do this I would need to go to a 2.5" pulley which Vortech does not sell, the smallest they have is 2.75". I'm assuming this would be overspinning the supercharger if I went smaller than the 2.5".

Anyone know the proper calculation to determine the blower RPM's?
I'm assuming it would be engine RPM x the pulley ratio?

derrick929 · #2 09-03-2008, 09:18 AM

Just found it on their website! Didn't realize it was hidden there!
Anyone know right off hand what the crank diameter is on a 2002 5.4?

tarajerame · #3 09-03-2008, 10:47 AM

make sure you account for the loss in psi due to restriction of the innercooler

derrick929 · #4 09-03-2008, 11:15 AM

Yep! Thats what I was trying to do, but I'm thinking the impeller RPM is going to be my issue now....looks like I'll be spinning it a little too fast with the 2.5" pulley.....may have to stick with the 2.75"....

I wasn't real impressed with 6psi, but I put the 9psi pulley on there for one trial run last night(hoping I didn't put a hole in a piston) and it was unreal! Can't wait to get the intercooler on and push it on up a little higher! Hope to get around 10-11 after the intercooler maybe....probably 9-10 is more realistic. But I've got long tubes and 3" exhaust so it flows pretty good, it's actually probably more boost than I'm registering due to less restriction.

tarajerame · #5 09-03-2008, 11:20 AM

worked heads, long tubes anda free flowing exhaust allow you to make more power with less boost since your still pushing the same amount of air into the engine, sorry i dn't know what the stock 5.4 crank pulley size is, does your vortech use a seperate drive belt?

derrick929 · #6 09-03-2008, 12:57 PM

Yep separate belt.... no head work yet but all the rest so thats probably why i'm not getting the high psi like it says I should....

CobraKit · #7 09-03-2008, 04:36 PM

Smaller diameter upper sometimes mean belt slip. What are you running on lower?

ONELOWF · #8 09-03-2008, 05:34 PM

You are only guessing unless you do the math:

(rpms X crank pulley d.) / (s/c pulley d.) X s/c step up = blower speed

derrick929 · #9 09-03-2008, 05:46 PM

Lower is only one option, same diameter as stock .....I was worried about slip as you mentioned with a small upper. But the tensioner on this belt is unreal, it is almost all I can do to get the belt on there(and I aint a little guy).....so I hope it won't be a problem, no issue so far.

1JT · #10 09-04-2008, 01:45 AM

I think a lower that fits on an L may work. If you are going to use an intercooler you will lose about two lbs of boost. You may also have problems with the BOV/Boost pass valve. I had a simular setup and had issues with surging at highway speeds. WOT was no problem

derrick929 · #11 09-04-2008, 08:32 AM

1JT,
That looks exactly like what I'm going to do.... All the parts are on order.. What BOV did you use and why do you think your getting problems? Where did you locate your BOV? In your tune maybe? What size upper pulley are you using and how much boost are you seeing? Looks like the stock pulley.

tarajerame · #12 09-04-2008, 08:40 AM

derrick929 try turboXS the 34mm racing BOV is incredible and increased my low end performance a good bit, if you experience any belt slip you can add an additional idler pulley and switch the tensioner to 100mm for more belt wrap. also I think riechard racing sells high traction / non slip head pullies

1JT nice trucks

derrick929 · #13 09-04-2008, 09:16 AM

Quote:

Originally Posted by tarajerame

derrick929 try turboXS the 34mm racing BOV is incredible and increased my low end performance a good bit, if you experience any belt slip you can add an additional idler pulley and switch the tensioner to 100mm for more belt wrap. also I think riechard racing sells high traction / non slip head pullies

1JT nice trucks

I've already got a Vortech Race BOV that I plan to install once I route all my intercooler pipe.

1JT · #14 09-04-2008, 11:55 AM

PM sent

riceh8r · #15 09-06-2008, 01:51 AM

you should be fine with the vortech BOV. the BOV should be placed after the intercooler. I used 8 rib Reichard pullies and never chewed up a belt. do not go below a 2.9". I put a 2.75 w/a 6.75 crank pullie and overspun my sc and started blowing oil through my i/c and into my motor. which would not be a good thing. you can also have oil blow by. i had a breather installed on the driver's side of the motor and a retune and never had a problem with blow by.