roots blower as an air mover??

ivanhoew · Post by **ivanhoew** » Fri Oct 19, 2012 2:50 am

pffft ,yes ,and we british get naff all !!

ps..... fuel here now 1.45/litre...$10.53a gallon

Beetle · Post by **Beetle** » Fri Oct 19, 2012 3:39 pm

OK BOYS........I DID A MOCK UP TEST TODAY AT THE SHOP WHILE i HADE SOME FREE TIME...............AS YOU GUYS SAID, THE MOTOR DID NOT HAVE ENOUGH POWER TO SPIN THE BLOWER. I WAS KIND OF HOPING IT WOULD. LOOKS LIKE IM GOING TO GO THE VACUUM CLEANER MOTOR ROUTE. I HAVE 2 INDUSTRIAL CARPET CLEANER MOTORS AND AT LEAST ONE MORE NORMAL VACUUM CLEANER MOTOR. THANKS FOR ALL THE INPUT!! I WILL KEEP YOU ALL POSTED ON MY PROGRESS.

Post by **1960FL** » Tue Oct 23, 2012 7:34 am

John,
Our uglies are more ugly than your uglies.
We can beat you at anything.

Tony, I think maybe you should try Man Grooming....

Tony · Post by **Tony** » Tue Oct 23, 2012 5:26 pm

1960FL wrote: Tony, I think maybe you should try Man Grooming....

Wazzat ?

jfholm · Post by **jfholm** » Tue Oct 23, 2012 9:59 pm

Beetle wrote:OK BOYS........I DID A MOCK UP TEST TODAY AT THE SHOP WHILE i HADE SOME FREE TIME...............AS YOU GUYS SAID, THE MOTOR DID NOT HAVE ENOUGH POWER TO SPIN THE BLOWER. I WAS KIND OF HOPING IT WOULD. LOOKS LIKE IM GOING TO GO THE VACUUM CLEANER MOTOR ROUTE. I HAVE 2 INDUSTRIAL CARPET CLEANER MOTORS AND AT LEAST ONE MORE NORMAL VACUUM CLEANER MOTOR. THANKS FOR ALL THE INPUT!! I WILL KEEP YOU ALL POSTED ON MY PROGRESS.

Did you notice under "air flow thoughts" the video I posted on how a top fueler works? It makes a statement that the blower uses up 600 hp in parasitic drag. Now true these blowers are much bigger and have teflon seals so there can be a lot of drag. Even the older blowers took a lot of horsepower to turn them.

John

Darcy R · Post by **Darcy R** » Tue Oct 23, 2012 11:46 pm

Some years ago, I used to help out in making some custom cases, and end plates to improve the roots blowers that were used in Top Alcohol ...bout 18 years ago. A rig was put together to bench test the blowers by turning them with a healthy 350 chevy engine. We found the 350 to be a little weak for the job, even with some really good stuff in it.

Tony · Post by **Tony** » Wed Oct 24, 2012 4:19 am

All very true.

But 1.6psi of boost (about 44 inches) and 200 CFM is only about one air horsepower.
A 5.0 Hp motor should do it easily.
What actually happened ?

Beetle · Post by **Beetle** » Wed Oct 24, 2012 9:25 am

i bolted the blower to a piece of plywood with a hole cut out the same size as the inlet to the blower, hooked up the motor and belt. wired it into my welder cord and plugged it in. the starter windings would come in and spin the motor, then it would try to spin up full speed and drop rpm's and the starter would kick back in. kept doing this surge thing up and down. you could tell it was moving a lot of air. im going to try some different size pulleys, see if possibly i was trying to spin it too fast. that might be the whole problem, i was overdriving it pretty good. 4" pulley on the motor and 2" pulley on the blower . the motor spins at 3450 rpm.....if it did my math properly....i was spinning it at 27,600 rpm. this could be the whole problem.

Beetle · Post by **Beetle** » Wed Oct 24, 2012 9:54 am

just did some research....looks like i dont need to spin the blower any faster than 8,000 rpm. at that speed it will flow about 300 CFM, which is more than enough for my needs. back to the drawing board.

Post by **1960FL** » Wed Oct 24, 2012 2:40 pm

Beetle,

The ratio of the 4" to 2" pully is 1:2 thus your were spinning the blower 3450 X 2 or 6900RPM.

That is if it is a direct drive blower.

Rick.

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