I thought I'd make a thread about the Kennebell blower / KB supercharger and the actual boost psi / lb that everyone with one has acheived with different size pulley / pulleys. They measure the pulley from the top of the grooves in the middle of the pulley.

I have four pulleys, two uppers and two lowers. The two uppers are 3.5" and 2.5". The two lowers are 8.9" and 7.9".

I have the shift points set at 5500 rpm.

With the 3.5" upper and 8.9" lower I just barely make about 15psi.

With the 3.5" upper and the 7.9" lower I made about 10psi.

With the 2.5" upper and the 7.9" lower I don't know exactly how much max boost I made but it was over 20psi before I let off...

I have an autometer electric boost gauge.

I made more boost than what they advertised in the brochure and not sure what the cause is. I thought that I would have made less boost due to the fact that I have ported heads and oversize valves along with headers and no cats...


Edited due to pulley size mix ups...I triple checked this time and it looks good now.

other thread:

you might want to re-edit the other thread to match this one, or something
First you said it was 7.32" lower, then 7.9", to get 20 psi.

I edited one thread a few hours ago. If there is another one which needs editing let me know...

i just did. Thanks for the sarcasm.

but as I said, first you said it was 7.32, then you said it was 7.9, and it looks like you should have said it was 8.9 from the first place.

With 3.5 inch upper and 6 pound lower LFP, i see 11.5psi to 12 psi just before shift at stock shift points 5200rpm . edited using wrong type of guage , autometer boost guage pulled out of my other truck shows 13 psi, sorry about that.

Stock lower and 3.25 upper=13 pounds on my truck. Skip

With my 3.5 upper and 4# lower I am making right at 12# of boost on the autometer gauge.

With 6 pound lower LFP and 3.25 upper i see 15 psi

i fart too much

What lower should I use to achieve 15-16lbs with the 2.75 upper?

8# lower and 3 inch upper 18lbs of boost

8# lower and 2.75 upper whole lot of boost, lol

6# lower 3.5 upper about 18psi
6# lower 2.75 upper about 22/23psi
9#lower 3.25 upper about 21/22 psi
9# lower 3.0 upper about 25psi and I had to let off.

I will probably see some lower boost numbers next time out because my CNC Stage 2 heads will be installed.

Great info, Not to change the direction of this thread but. If you make say 400 rwhp with 12 pounds of boost on the stock blower what hp would be realistic with the same boost on the Kenne Bell?

Well, the answer would be 2.75 upper and 2lb lower. 15-16lbs right on the nose.

My guess would be about 425 hp at the same boost. Skip