roots 871 boost levels

Eli

Always funny to read ELI reply to a post , he makes my day !!!

Your Hydroplaneplanes Friends !!!!! Serge.............

 

The flashpoint of Methanol is approx 34 degrees F. So don't worry about things being too cold to burn unless you are racing in the far north. I was told by Norm Drazy that the limits on OD for a roots type blower is 72%. Anything more than that doesn't really flow anymore air. Something to do with supersonic air and everything he said after that was miles over my head. I know lots of guys like to compare boost numbers but they can be incredibly misleading. Depending on things like head flow, ambient air conditions, and camshaft specs boost numbers can change. Thats why the fuel guys use blower dynos- different blowers on the same mule motor will give accurate boost numbers as long as ambient air doesn't change. I don't know if there is anybody who offers to dyno blowers to the general racing public. It would be a service worth paying for. Dave Germain

 

I'm building a blower dyno for myself, probably won't get done this winter, but hopefully next.(it took a couple winters to finish my fuelbench also)
I'm not doing it for a business, I simply have a lot of my own questions.
If someone would want to run on it, I would certainly be open to doing that.
I plan on measuring; CFM, psi, temp, RPM, distribution and consumed HP.

 

i talked to bds and they said that because heads were so efficent and motor was big (540) that this is probably accurate?? I'm not sure I buy that because 18# seems low.

Is there anything that I can do to increase boost besides increasing OD. Its already at 40%, won't I just heat the air and get to the point of demishing returns on HP?

 

You keep O/D ing until the point that it doesn't go any faster,after this point it becomes a waist of time. It's s the same practice you do with everything. Whats wrong with spinning it faster if it makes more power?

 

gotta , oredering more pulleys tomorrow.