Front mount blower

[RichFox]

Those things are more properly called Harmonic dampeners. And are used to dampen whipping of the crankshaft. Most race engines do not use them for balance, that I know.

Thanks I was not aware of that ,,thought it was one of those "must have " things

They are sure good things to have, it's just that the purpose of most of them is not for balance. They are for damping the harmonics that can end up breaking a crank. But again, most, not all, are zero balance. I don't know why people have always called them balancers. Most of the early V8s that I have had any chance to fool with were balanced internally. The flywheel and dampener were zero balance.

[hitz]

Some harmonic balancers have a offset weight that help balance the crank. My 400 small block chevy has one. The flex plate (flywheel) has a small offset weight also. I believe some Fords also use them. It would be wise to check on this before assembly. Like Rich says most don't have offset weights

Harv

[Xoecraft]

Very cool ,,thanks  all this info helps greatly,,( needed to figure out the few cloudy issues )  Think this is gonna work out just fine.

BTW - motor I'm using is a 287 Pontiac

[saltfever]

As mentioned, the dual chain coupler on the Potvin drive did not have a harmonic dampener. Also, mentioned, a dampener is a good thing. However, the lack of a formal dampener may not be as bad as it sounds. The chain coupling and the blower drive with its impellers, all serve to dampen some frequencies. I'm not sure of the resonant frequencies involved but it is probably better than no dampener at all.

On current blower drives using a timing belt, the belt does as good a job as a dampener and it is not needed.

[Xoecraft]

That picture with a centrifugal supercharger reminds me of a time I was at Pomona for the drag races. In the pits I run across Doug Herbert who at the time was running in the Top Alcohol Dragster class. He had a huge centrifugal supercharger mounted in front of the motor. Needless to say NHRA outlawed his setup, but it was cool.

Tom G.

Why was it Outlawed ?

[Stan Back]

Probably cuz nobody else had one.

[desotoman]

Stan is partly correct. In NHRA when you come up with a better mousetrap that no one else has and you start running good or better than everyone else, your mousetrap gets outlawed, or they add weight to your car. When I used to follow NHRA, I saw it happen too many times.

Tom G.

[saltfever]

NHRA "Ingenuity in Action" . . .     not!

[maguromic]

If I were trying to couple the two together I would use a Lovejoy connector.  They can take the abuse and the RPM and they come in many sizes and what they don't have they can build for you.   Tony

[Xoecraft]

OK,another Coupler question.

 Looked at the Lovejoys and have also found the old Chain style. In regards to RPM's , am I basing that on the RPM of the motor itself ? I ask this cause was thinking on the whole "load" issue and that the crank driving the blower seems a rather simple task ( as appose to the coupler driving a transmission or such ) and that the actual load on the coupler would seem minimal.

 So trying to figure in all these things,,are they relevant ? or is it just the coupler uint coming unglued cause the motor is turning 6-7000 RPM's ?

[gearheadeh]

NHRA "Ingenuity in Action" . . .     not!

 

[Xoecraft]

OK,another Coupler question.

 Looked at the Lovejoys and have also found the old Chain style. In regards to RPM's , am I basing that on the RPM of the motor itself ? I ask this cause was thinking on the whole "load" issue and that the crank driving the blower seems a rather simple task ( as appose to the coupler driving a transmission or such ) and that the actual load on the coupler would seem minimal.

 So trying to figure in all these things,,are they relevant ? or is it just the coupler uint coming unglued cause the motor is turning 6-7000 RPM's ?

  aanyone ??

[saltfever]

The load on the coupling is not insignificant! The blower can consume anywhere from a 100HP to 400-500HP depending on the application. You not only have load applied by compression of the air but you have acceleration of the total rotational mass as RPM increases. 400HP at 5252RPM is a torque force of 400lbs/ft. Based on flywheel studies done by David Vizard a 300 RPM/sec increase can cost 85HP alone and is an additional factor. Even though there are no relative RPM differences between the two shafts, there is centrifugal force. The force may be small due to the small diameter but RPM may be important. Be nice to your coupler! Spec the correct size and then add safety factor.   

[Xoecraft]

Thank you

few more questions

 1 : people speak of boost,,I know there are gauges to measure the boost pressure on a system like this where would you mount such a gauge ?

2: using a fuel system that is pressurized ( think its 14 lbs ) do I need to consider that pressure plus the blower for my final ##'s

[saltfever]

(1) After the intercooler if so equipped. If no intercooler it doesn't make any difference where it is. But why a gauge? Why not use a sensor and log the data?

(2) Not sure what you mean. But your fuel pump may need to be referenced to the boost pressure depending on pressure and application (Carb? EFI, MFI?).  If boost is low (<5psi) maybe no fuel pressure augmentation is needed. If >5psi maybe it is needed depending on the fuel delivery method.