Z06DIL

What's the smallest pulley I can go on a vortech v2 without over spinning it?
I got a 370 lq9 forge block. I was wondering if I can go 3.4 pulley without overspinning the blower? Run like 14-15 boost.
Or will it be safe to run a 3.6 pulley.
I have not install the motor yet, I'm just getting all the parts together before I install it.

backnblack2003z06

If I remember correctly when I calculated for my pulley. Assuming a stock balancer and 6800 shift point. The max recommend speed on a v2 Si is 52000 rpm
3.6 pulley was 51000 rpm and 3.4 was 54000 rpm.

CamminC5

Link to vortechs impeller speed calculator.

I see your still fixated on "psi". That blower is going to run out of air. Don't expect to make much more power than you are now.

How many threads are you going to make asking the same questions?

Turpid porpoise

According to that calculator the numbers quoted by backnblack are a little off. With a 7.5" crank pulley and 3.4" blower pulley spinning to 6500 RPM you would spin the blower to 51617.50 RPMs.

backnblack2003z06

Numbers work out the same, you're calculating with a 6500 shift point. I used 6800.

Turpid porpoise

MVP'S ZO6

Outside of the internal step up ratio of the blower itself, there are things affect blower impeller speed blower pulley diameter, crank pulley diameter and engine speed. Change any of these things and you will either increase or decrease blower speed. With that said, boost changes with engine volumetric efficiency. In other words, on combo A, if you make 10 lbs of boost and as an example do nothing more than something like change to a more radicle camshafts or better flowing cylinder heads, the car is going to make less boost but probably more power and torque.

If I were you, I'd be less concerned with how much boost your engine makes and focus more on getting your blower to operate in the most efficient spot of the compressor map.

To answer your question, with your combo, in order to be at maximum recommended impeller speed (assuming a stock diameter crank pulley of 7.5" and a max engine speed of 7,000 RPM) the most readily available pulley size to stay at or under the maximum recommended impeller speed would be a 3.48" 6 rib supercharger pulley from Vortech website. This would put your impeller speed at 54,310 @ 7,000 engine RPM's. To get as close as possible to the maximum recommended impeller speed (assuming the aforementioned combo) you would need a blower pulley that is 3.436364 inches in diameter. That would make your impeller speed 54,999.99 RPM at 7,000 engine RPM but good luck finding a pulley exactly that size without paying for it. Take the belt slip into account and it will be spinning less than that. ;-)

My advice to you if your worried about over spinning your blower is to put a 3.6" pulley on the blower or a 3.48 if you don't care about a few hundred rpm over the max recommended impeller speed. NOTE: if you go with the 3.48 blower pulley, you can always reduce engine rpm to 6800 or 6900 and blower speed will be under the max recommended.

CamminC5

The bearings in the V2's are more forgiving than the ones in V3's (self contained units). You can over spin it a little with no issue.

Also, for future info V2, V3, etc are versions of blowers. There are different setups within those groups. You saying you have a V2 is like me saying I have a V7 and not a Ysi. I assume it's a S trim?

Robert 2000

Okay I have an Ls1 stock bottom. With the 3.6 pulley on si trim v2, cam, headers and meth it made 605/530. At a good 10 lbs of boost.

Since then I have swapped heads to ported 317s taken out cats and pullied down to a 3.4. It now shows maybe right at 11 lbs. The heads flowed as much as the pulley swap so not much of a boost gain half pound or so maybe. However the car definitly picked up power up top and runs better than before no doubt. I didn't redyno the car tho to compare numbers.

SpeedwayC5Z06

I have vortech pulleys 2.6, 2.7 and 3.4 if you need one. Fits AA kit