Front mount blower

[hotrod]

EFI cars use a boost referenced fuel pressure regulator, that adds fuel pressure in direct proportion to the boost pressure so the pressure across the fuel injector is always constant.

I my car the base fuel pressure is 43 psi, at 20 psi boost, the fuel rail pressure would be 63 psi gage, but the actual differential pressure across the fuel injector is still 43 psi.

Fuel flow varies at the square root of the pressure drop across the injector so even small boost pressure can lean you out without a boost referenced fuel pressure regulator.

If you are running a carburetor, many setups enclose the carb in a pressurized box so its air circuits see the same boost pressure as the manifold, or they use a draw through setup where the carb is upstream from the blower so both the fuel and air go through the blower. The fuel in that case helps cool and seal the blower on roots type blowers. On centrifugal blowers there is less advantage to the fuel cooling, but the heat of compression does ensure the fuel is completely atomized.

Larry

Larry

[desotoman]

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 ?

If it were me I would go with what is proven. Which is the chain coupler. My Brother had a Lovejoy coupling on a hydraulic pump on his D-2 Caterpillar, it worked OK but chewed up the star shaped dampeners for some reason. If you want to experiment go with the Lovejoy, if you just want to put it together and forget it go with the chain coupler. JMO.

Tom G.

[maguromic]

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 ?

If it were me I would go with what is proven. Which is the chain coupler. My Brother had a Lovejoy coupling on a hydraulic pump on his D-2 Caterpillar, it worked OK but chewed up the star shaped dampeners for some reason. If you want to experiment go with the Lovejoy, if you just want to put it together and forget it go with the chain coupler. JMO.

Tom G.

Tom, Sounds like your brother might have had a bad coupler.  We used a Lovejoy to connect the alternator to the back of the water pump on an Indy Car engine and spun the engine to 13,000 rpm hitting the rev limiter on and off for 4 hours and had no problems.   But you are correct the chain is the proven path. You might even want to look into a belt set up.  What ever you choose do some research and have fun with it.

I run mechanical fuel injection with my Procharger on the GMC and use  a Hilborn  boost compensator valve that richens and leans the engine under boost.  It was originally developed for the Indy cars on turbos with mechanical injection. Tony

Picture form Hilborn Site:

[Dr Goggles]

...a little aside, I was watching this music clip on youtube, and it has a great bunch of footage of back in the day drags....

when I was reading the comments I saw this
"Oh man, I just love the Potvin front mounted blower setup on the dragmaster. I had one for years, but never knew what it was for, so I sold it for scrap....been kicking myself in the arse ever since ."..

ha ha , here's the clip

Southern Culture on the Skids/ Deja Varoom! : http://www.youtube.com/watch?v=Gd4Aj4tbf50&feature=fvw

[RidgeRunner]

Neat clip, interesting variety of cars/power, thanks for posting.

Looks like could be the Detroit Nationals, '59 or '60 maybe?

[Xoecraft]

 http://www.archive.org/details/Ingenuit1958_2

[Xoecraft]

 Wonder if back in the day anyone went with a Rag Joint ,,like the old Grahams ??  or maybe those turned with less resistance

[desotoman]

 Wonder if back in the day anyone went with a Rag Joint ,,like the old Grahams ??  or maybe those turned with less resistance

You need to think in terms of mass weight. Have you ever turned a 6-71 over by hand? Just a standard blower with out strips has a lot of mass weight to accelerate, and that is not including the power it takes to pump the air. All the blower snouts I have seen are at about 1 inch in diameter. That should give you a good indication of what it takes to turn a Roots blower successfully.

Tom G.