K 8 how fast

I run a K 8 with a spacer and it has been modified on a 526 BAE hemi. When does this blower become inefficient. I started out at 35% over at 8300 motor speed and currently I'm 55% over. having some issues going faster but also made some other changes ignition, converter. Just trying to rule out the supercharger. Thanks

 

I'm guessing this is a high helix? If so, you can go to 65-70 over, that's what the high helix was designed for, but something to remember, boost isn't always horsepower if you make heat by spinning the blower faster, and also parasitic loss the faster you overdrive it, that's where the newer model blower come into effect, less heat, less parasitic loss and more blower efficiency, hope this helps

 

No matter how fast you spin it or what blower you use once the manifold temperature reaches 175 degrees you start to lose effiencey.

 

I run 1/4 mile, At 8300 rpm's plus 55% overdrive I'm only at 12,900 rpm's on the blower so I guess I'm not going "super sonic" Plus its a 2 speed trans so I'm only at 12,900 at the top of first gear and through the traps, the rest of the time I'm below! I Dont know manifold temps as I'm not recording them. I've been going up 5% at a time on overdrive and have made gains until 55%.

 

k8

It all depends on the mods. I had a K9 superman built for 55% with the correct hat. It was pretty average at 34% but around 40% the car started picking up boost and mph until I ran out of fuel pump at 43%.
I've seen kobelcos with the wrong hat spun at high OD and not respond.
DMPE knows a lot but very little effort is put into high OD anymore.

I run a Chevy and have always been told it's faster to 8000rpm than a hemi but then it's over. I saw a huge power difference between 8000 and 8800 so your hemi might like less blower rpm and more crankshaft rpm...lol.

 

Mike,
Are the HH and Std rotors a different dia? that would be the only reason the the tips would change speed?

Just curious as I have STD rotors on a BBC and 9000 rotor rpm seems "slow"? though I'm not turning that hard.

 

The. Rotor diameter is the same as long as there the same style@ k8, k11 older versions, the air speed difference is in the twist of the rotor, the more twist the slower the air speed, because the air goes from the back to the front, the more twist the slower it travels

 

The air travels down the length of the rotor, in simple terms, think about going down a spiral staircase vs a std one, you can't go down as fast, same for the air on a high helix rotor, the slower the air speed, the more efficient and cooler it is, I hope this helps understand a little better, the biggest thing in supercharging now is the inlet side, getting the air in and out efficiently

 

perfect sence thanks to you both.