liters of air from8-71--14-71, per revolution?

how much air does an 8-71 put out every 1 revolution,compared to a14-71 every 1 revolution? then to a psi screw blower d? 8-71 hh kobelco,14-71 hh ditto, thanx discodean

 

Remember there is now also the "big" diameter rotors.
We have SSI F-2 rotors 8-71 HH and they equate to about 560 cid/rev. But these numbers are subject to cam and heads in my example.
SSI blower dyno told us they were 3494 cfm at 38 lbs of boost.

We also have Littlefields HH retro K-8 rotors and they equate out to about 460 on the same long block.

 

Dean,

From my understanding on the subject, you'll need to call the blower manufacturer on that information.

Each blower is going to put out different CFM rates depending on tolerances and options. Like SoDak said, the size of the lobe on the rotor is just as important as the number of strips sealing the rotor to the case, and sealing between each rotor.

Additional gains can be seen by plugging the ends of the rotor lobes.

Too many variables.

If memory serves correct though, the "71" was the CID of the blower on the old GMC stuff. An 8-71 put out 568 CID of air per revolution (8 * 71 = 568)... I could be wrong though, but it seems like I read it in a book somewhere, so it MUST be true... lol.

 

i have a ssi 14-71 f rotor that has had the mods done by ssi. i was wanting to no if you new that it would put out ruffly. thank you

 

Are you sure you didn't see it on TV.HE HE HE

 

Theoretically speaking you can figure about 29 cid per inch of rotor. So an 8-71 = 16"x29=about 464cid/rev and a 14-71 = 19" long rotor x 29= about 551cid/rev.

Efficiency is what makes it a wishy washy number, its like asking how much power will a 350 sbc make? well,,, one from Jenkins or the one in my '97 GMC Tahoe.

If your trying to compare an 8 to a 14 I probably can help? What exactly are you trying to do?

Years ago we ran 14's, years before that we ran 8's. One of the 14's we had came off of Cy Chesterman's Coke FC. It was modified by Les Davenport and Dan Hutchmeier said it was their fastest roots blower. Now we run 8's again and these 8's are about equal to what that 14 was from back then.

I'd like to help, What exactly are you trying to do?

 

Dammit Gene, no I didn't see it on TV!

 

?????

I am trying to figure the cost / efficency /price per switching to screw, or 14-71, I have a good used screw blower I picked up pretty inexpensive, but by the time i get a inj.front drive,new belt,pulley,cert,new bv,fuel lines it sort of adds up! Will the cost of the screw offset the performance gain/compared 2 going 2 a 14-71 roots? In the long run? or should I just resale this thing? thats where I am right now!!! DiscoDean

 

Definitely too costly to pursue the screw idea further. You should send it here so that it can hang out with some of its other C siblings ....

 

Disco,when You Want To Change Blowers Call Me ..i Have A Ssi-f With All The Mods And Am Interested In Your Screw...

 

size

Detroit Diesel;

6-71 = 6 cylinders @ 71 cu in per cylinder.

The 6-71, 8-71, 8V-92 etc is the engine ID. Each engine had a different size roots blower to handle its air flow needs.

John

 

Thank you John, I was watching to see if any of the young guys out there actually knew what a 6-71 or 8-71 really was. Those motors have been gone for a while now. How many of you knew that they are actually a two-stroke diesel, all the valves in the head are exhaust valves?? Sorry, didn't mean to stray from the blower questions...... Dan

 

Disco by the time you add all those restriping and the hours and hours lost to working on these top of the line 14-71 blowers you can easily understand that screw blower are the way to go. And don't let nobody fool you on cost because its no diference.

However ask any screw blower owner what blower maintenance there is and all will tell you , change the oil once a year and clean every three years!!

 

You didn't mention the beating on the rod's, crank, pistons, if you lean on it. and you know your going too.

 

Dean, I would love to use a screw blower my self but you need to sit back and look at, where can you run it? you don't have a TAD and the only place that you can run that screw is outlaw q8 (not the PROTOPOUTLAWS) and those races are few and far between. The heads up q8 races seem to be getting less and less each year!
Why build a car that you cant run?

 

Disco,
When you say "all the mods", can you ellaborate?
Who did the mods and are they the lastest and greatest from SSI or is it above and beyond?
If I call SSI and place a new order with all the bells and whistles, will I get "all the mods"?

 

soDak

fasttimesracing said" all the mods" I never said that sorry discodean

 

yeah the blower i have has had alot of extra stuff done to it. they was done after it had been bought and ran and then went back to them