V2 SQ Pulley setup question

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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!

[bumblebee03]

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

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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?

[bumblebee03]

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

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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.

[bumblebee03]

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

[bumblebee03]

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

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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?

[redvert]

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.

[midnight]

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..

[sedanman]

What midnight says is correct.

[V2-SQ Jess]

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

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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

[Kepler]

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?

[midnight]

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....