BrianG

Does anyone have a CFM flow rate number for the AutoRotor S/C, running at 8 psi on this car? I'm trying to pick an appropriate air cleaner......

AO

It depends on the RPM of the autorotor, not the psi. Also, what's the displacement of the Autorotor?

If you're running a 1.7l, then you're pumping 1.7l per revolution or 0.06 CF/rev. So at 15k RPM, you'd be flowing about 900CFM assuming 100% efficiency.

I think the Autorotos are roughly 98% efficient IIRC, so that's a pretty good approximation. The key here is knowing the ratio between your crank pulley and the supercharger pulley and the RPMs you're running at.

(Crank pulley circumference/SC pulley circumference) * engine RPM * SC displacement in liters *0.0353

BrianG

I was wondering how one would calculate this and thought that this might work:

5 liter displacement / 2 (4-stroke inhales once per 2 rotations) = 2.5 liters per rotation.

7 psi = 1.5 atmosphere (1.5 X 2.5 = 3.75 liters / rotation)

3.75 liters X 7000 RPM (redline + margin) = 26250 liters / min (927.009 CFM)

So a 1000 CFM filter capacity should be close?

H2

Has this thread no end? 30K viewers and counting! Dadgumnation that's a lot of interest!

H2

Bill Ball

Hey, I just noticed the alternator portion of the stock crank pulley is just the right type and size for a supercharger crank pulley. I just bought a used one off eBay for $30. Plan to cut off that portion and fasten it to an AC pulley with correct spacing, which will end up looking like the late pulley Andy sent out (as Warren received), making sure the center hole is large enough to mount my other stock crank pulley flat to the AC pulley. All should work with stock accessory pulleys and belts except the air pump.

BrianG

Bill....... this is way easier, and fairly elegant........... All you need is a spacer for the P/S pulley and an idler pulley mounted on the alternator pivot bolt location.

Bill Ball

Brian: I saw that before but didn't realize how simple your idler mounting was. That's what stopped me. Also, I wondered how well the PS pump will tolerate all that leverage. Normally it runs a v-belt which is relatively low tension compared to the alternator belt. I know Andy used a ribbed belt for the PS pulley, and that has always bothered me, and you are adding the leverage of the large spacer. Maybe that's not a real problem, that's why I say I'm wondering.

BrianG

I had the same thoughts, but the belt interference at the P/S slide-mount bolts seemed more problematic. I had removed the P/S pump and looked to shift the whole P/S pump forward, but that's easier said than done too.....
Let's call this a "stress test" for the PS-pump bearings...................

Bill Ball

With Andy's configuration, there is inteference of his PS belt and the top alternator bolt. Andy's solution was to leave out the far right PS cassette mount bolt and pull the PS up before snugging down the remaining 3 bolts. That does work.

cfc928gt

Bill, I was thinking a crank pulley could be used as well but I wasn't sure to make it work. How are you going to mount it onto the a/c pulley?

Bill Ball

Not sure on the mounting until I get it and cut it apart. There is room for bolts through the AC pulley. Then it's just a matter of accurate spacing and centering.

Vlocity

Hello :

I have an 85 with the 2.4 liter twinscew and intercooler. A few days ago after some spirited driving I noticed that the RPM had fallen off and that the car was having a hard time maintaining idle.

With a closer look I think that I may be off a couple if inches of vacuum and possibly not making full boost. I say possibly...because I hadn't driven the car in a while, but it looks like it is only making 7 PSI now instead of 8 and candidly I just don't remember exactly how many inches of vacuum it held before at idle.

I checked for obvious vacuum leaks...and I can't hear any. The car runs better after it warms up. With my set up most of the vacuum lines are buried....but I was able to put a vacuum tester on the line that runs to the throttle body and while this I believe would be drawing the vacuum in the wrong direction it did hold vacuum and slowly bleed off. I was looking for a BIG leak so I think I can rule out a disconnected or cut line.

I checked all of the spark plugs and they look uniform, I then ran a compression test and all of the cylinders thankfully are within a few pounds, so I don't think that it is anything major.

During further investigation I was able to "snug up" the blower to manifold bolts on the drivers side by about 2 full turns.

I am guessing that the "right stuff" gasket material may have failed between the manifold and the blower.

Before I pull the blower, is there anything else you guys think I should check or anything obvious I have forgot. The warmup regulator is about 2 years old....but I don't know that it's failure would cause this type of a problem.

Thanks to all.

Ken

Vlocity

BUMP !

Tony

When its running unplug your idle stabilizer...if it still runs..odds are you have a leak as the default postion is closed without power

ooh..just saw...85..you dont have a stabilizer do you?

Bill Ball

What kind of vacuum are you seeing at idle?