V2 SQ Pulley setup question

I have a brand new V2-SQ S-trim Blower with an 8-rib 3.33" pulley installed. I am considering an 8" crank pulley. If my calculations are correct, at 6500 rpm the impeller will be spinning 56,216 rpm (Crank/Blower x step-up ratio x engine rpm = 8/3.33 x 3.6 x 6500 = 56,216 rpm).

Will the blower handle that and how much boost should I see on a 91 5.0 engine with ported 93 GT-40 heads and port matched 93 Cobra intake and Lunati 'blower cam'?

I realize that exact numbers are impossible but if any of you have experience with this set up I would appracite some info.

Thanks!

Go to www.vortechsuperchargers.com and they have an impeller speed calculator,,, Im pretty sure the S trim SQ is rated for 50,000.... Bee

Thanks.

I checked out Vortech's caulator. According to them the step-up ratio is 3.61 resulting in 56,372 rpm using the 8" pulley.

The max impeller RPM is listed as 50,000. using a 7" crank, 3.33 blower and 6500 rpm the impeller rpm is 49,326.

So my question is still, how much boost does that equate to on my mild 5.0?

Vortech shows maximum boost as 20 psi, does that mean that at maximum impeller speed (50,000) you are making 20 psi?

I have been wondering the same thing,,,, I have the samen SC as you and I want to step up to an 8 rib belt and get a pulleys that will give me 12-14 lbs of boost,,, but you call vortech,, and your on hold for 2 hrs,, and you e-mail them and never get a response,,,, I donno,,, I will try to call next week maybe and see what I can find out,,, bee

Cool, please share what you find out!

I have been told by several people that the 2.95 blower pulley using a 6.875 (or roughtly) 7" crank on a V1 S-Trim is the setup for 12lbs of boost. I was also told that using a Power Pipe with that setup results in 14lbs.

Ok,, May not be until Friday before I have the time (and patience) to call .. Bee

I called Vortech today regarding pulley sizes and boost with the 8" crank pulley,,, they told me a 2.95 will make 12-14 lbs of boost,,, a 2.75 will make 14-16lbs of boost and the 3.33 will make 8 lbs of boost,,, I live in CO and the guy said I should make about 10lbs of boost and this altitude,,, he did not suggest putting on the 2.75 on a stock bottom end motor,,, Hope this helps you,,, I think I may try the 2.95 and see how much boost I get,, also,, he highly recommended the AFM powerpipe,,,, Bee

Thanks for checking with Vortech.

Something just doesn't seem to add up though.

8lbs of boost usuing the 8/3.33 combination? I wonder if the person you spoke to was giving you numbers for the 7 inch crank?

8" Crank with 3.33" blower pulley and powerpipe @ 6500 on 93 cobra motor = 14lbs of boost.

At least that's what my gauge indicated.

I don't claim to be an expert but,have lots of exp w/sc's & w/try to shed some of my exp's w/boost,pullies etc..If you look at the efficiency rpm of the sc,it is45k.what that means is if we spin it higher , we are just building heat w/o regard to poss damage to the bearings. Boost does'nt mean much..the amount of cfm of air is what counts.the sc is rated at 1000 cfm @ rev limiter.as we spin higher the heat expands the O2 molecules,therefore no gain...just heat..poss detonation..now where we gain is in the lower rpm's w/a smaller pulley.w/a smaller pulley at any given rpm( Below 45k)the sc is spining faster and that means a lot more(cfm) hp and torque..I have run every combo (pulleys/crank)known to man, i think, and have found that any pulley smaller than a 2.95,you're just making belt slippage even w/a 10 rib belt..The more efficient the heads are (air flow)the less boost we are going to see on the gauge.as most of you know Boost is a measure of air that is not being used,pressure in the upper intake..but even w/less boost we are still making a ton of hp.Still, the s/c is puting out 1000cfm..does this make sense?Keep in mind the higher the boost gauge reads the less efficient(use of air)the engine is at any given cfm...i've rambled tooooooo...much ask me if i have spun them more than recommended..yes...lots more..however could'nt tell any diff..

What midnight says is correct.

yep, i agree. a big block with a 1000cfm carb will make large amounts of HP, with no boost at all.

I agree with the theory but the results are had to argue with.

My 93 (3775 race wieght) 103k miles on motor and tranny convertible, 93 Iron GT40 heads, Cobra intake, stock short block, AOD w/2800 stall converter, transgo shift kit, stock (not rebuilt) internals, 4.10s, shorty headers, dynomax 2.5" exhaust and running 245 50 16 Nitto drag radials...

10lbs = low 12s
14lbs = mid 11s

I am just finishing off my setup and have gone for a 7.25" crank pulley with a 2.95" S/C pulley. I am a little worried I might do damage to the S/C as I will exceed max rpm by about 2000 rpm on the S/C at 6000rpm engine speed but l wanted to keep my mid range torque up.

Should I be concerned or is this a fairly common occurance?

Kepler: thats common IMHO..I would'nt worry..I think we all well know that the manufacturers would'nt build an SC to blow up if we just over spun it a couple of K..Further, it's not like we stay in that rpm range for long..They obviously would'nt want the negative publicity....

did any one have trouble with their car after the super charger? my car runs fine but when i stiomp on the gas the car shakes, and it acts like it is going to die after a few moments it is ok. what gives?

On a 306 with ported Dart Sr heads, ported Edelbrock RPM intake, Anderson B21 cam, power pipe etc... I made the following boost:

7"-3.33" 10 psi
7"-3.15" 12psi
7"-2.95" 14psi
8"-3.33 16-17psi
8"-3.15 18-19psi

These psi are at 5800-6000rpm with a very tight belt.

The 8" crank pulley was the best thing I bought. You can get the Renegade pulley pack from Vortech for about $225. The pulleys also have a special finish to make the belt grab more. That includes 8" crank pulley, choice of 3 blower pulleys, tensioner and bracket, and belt. Great deal. The 8 rib gives you a lot more choice of belts over the 10 rib. I also glass bead my blower pulleys for more grip and it works. As far as over spinning the blower, i know guys that over spin by 10,000 rpm with no problems. Of course this is not the best way. The right size blower is always the best way to go. You always get some belt slip unless you go to a cog setup. I would not worry about a few thousand rpm over max blower speed.

If you don't mind can you explain glass bead the belt? that is'nt like sand blast is it?

Yes glass beading is like sand blasting. Instead of using sand they use glass. And its on the pulley, not the belt. Vortech does this on their Renegade pulleys.

Sorry my bad, i meant the pulley, past my bed time :) thanks for the info underpsi68

Quote:

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Originally Posted by underpsi68

On a 306 with ported Dart Sr heads, ported Edelbrock RPM intake, Anderson B21 cam, power pipe etc... I made the following boost:

7"-3.33" 10 psi
7"-3.15" 12psi
7"-2.95" 14psi
8"-3.33 16-17psi
8"-3.15 18-19psi

These psi are at 5800-6000rpm with a very tight belt.

The 8" crank pulley was the best thing I bought. You can get the Renegade pulley pack from Vortech for about $225. The pulleys also have a special finish to make the belt grab more. That includes 8" crank pulley, choice of 3 blower pulleys, tensioner and bracket, and belt. Great deal. The 8 rib gives you a lot more choice of belts over the 10 rib. I also glass bead my blower pulleys for more grip and it works. As far as over spinning the blower, i know guys that over spin by 10,000 rpm with no problems. Of course this is not the best way. The right size blower is always the best way to go. You always get some belt slip unless you go to a cog setup. I would not worry about a few thousand rpm over max blower speed.

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Good info, thanks for that underpsi68.

At what point did you take the pressures? At the discharge of the S/C, or off the manifold?

The reason I ask this is that I am getting around 14 Psi at the outlet of the S/C but only about 8 or 9 Psi at the manifold. My setup uses an air to air intercooler and I am concerned that I have a significant pressure drop across the cooler.

What really confuses me is that taking pressure at the manifold at moderate RPM, say 3000 rpm and low load I get an expected 5 psi at both at the S/C and manifold. Then when I stand on it, the S/C pressure climbs as expected with the RPM but the pressure at the manifold rises more slowly and peaks some 4 or 5 psi lower.

Does this suggest that the intercooler I have selected cant handle the flow?

If you are taking pressure before the intercooler you will not be getting an accurate reading. It should be taken after it. I have my hose hooked up to the vacuum tree on the fire wall that the brakes are hooked up to. I had it right after the throttle body but I was not getting true reading so I moved it to the tree and it works much better.

Thats what I was afraid of. I got a good deal on a t-trim w/renegade brackets and pulleys. Im am installing it on a completely stock motor. I have the 8" crank pulley and I THINK its a 3.33 blower pulley - its plain black with no markings on it. Im going to see 20lbs, arent I? ;( BTW, I alos have an aftercooler.

Jeff