one step forward...

Will, you've got the madness indeed. Welcome to the nut-house.

She's a beauty. I'm glad someone else is here to share their madness. It makes me seem almost normal.

Ted

Almost, but not quite.....

We have a place here, a sports bar/restaurant, called Loonies.  I go there when I want to feel normal.

Nicely done, Will.  Glad you are making such good progress with your car!

I always wondered if the 2 VW pulley's and the 2 Porsche pulley's come out to the same fan speed...

If the diameters of the two pairs have the same ratio, then all will be good.  One turn of the engine equals X turns on the fan.  If X is the same for both, you're done.

That's all good El Frazoo but I don't have a VW to measure :-)

This looks like an interesting place to start.

Thank you EDSNOVA that was very interesting...

Being a mechanical engineer, specifically concerned with heat transfer, I found the article very interesting, and correct as far as I can tell.  I just wish I had had enough creativity to think of doing something like this when I was an undergrad.  what a cool way to work and play all at the same time.  the business about the belt slipping is eye-opening.  Might explain why one needs to adjust the belt tension now and then.  Also, suggests keeping a keen eye out for rubber dust in the vicinity, so you can know when things might be getting dicey.  And of course, the business about how much power it takes to run the fan, vs the speed of the fan.  Now we know why there are such things as power pulleys, which the draggers use to give them more top end power.  Yes the sacrufice a bit of cooling, but they get a bunch more HP to the wheels vs into the fan.  A cubic function here is a very strong one.

Also helps to explain why regular cars with water cooling went to fluid drive couplings for the fan, so it would "slip" at high speeds, saving gobs of HP, ans still pushing enough air to keep things kosher.  Of course, going to electrically driven fans ona thermostat is, ultimately more elegant, at the epense of more parts and consequent somewhat lower reliability.  I wonder if the VW/P engineers knew that the belts were slipping, and they were fine with that?

how all this helps to answer the question posed is not clear to me.  Seems like we need some tech specs for VW and 356 fan and crank pulley dimensions.  where do you get that info??  Ed??

The reason I posed my question is I thought somebody might know the answer outright...

dsrtfox posted:

The reason I posed my question is I thought somebody might know the answer outright...

It isn't exactly the same, but it is close. I'll look later; I may have it written down. Al

PS- My apologies if we've done this before- first name?

I was just Googling the original question. The answer I linked to isn't one we'd like: he says the ratio depends on the number of shims in the pulley. He's got some math there that someone with good mathness might be able to reverse-engineer our answer with. Looks to me like a small ratio and easy to check with a dress maker's tape or even a bit of twine. But I did not find a definitive "it's about 1.4-to-1" or whatever, which is what I wanted.

Porsche 356 crankshaft pulley is 5 11/16" diameter and fanbelt "slot" is 3/8" wide at the top of "V".

The generator pulley is at the shop, can have those dimensions on Monday...

edsnova posted:

 ...he says the ratio depends on the number of shims in the pulley. He's got some math there that someone with good mathness might be able to reverse-engineer our answer with. Looks to me like a small ratio and easy to check with a dress maker's tape or even a bit of twine. But I did not find a definitive "it's about 1.4-to-1" or whatever, which is what I wanted.

That's a very good point, Ed, the ratio isn't exact; it depends on the exact length, width, and wear on the belt (some belts all fit ever so slightly different), the wear and the number of shims between the pulley halves, how the crank pulley groove is machined (they're not all exactly the same) and even the amount of wear in that groove if it's a cheap (softer) aluminum instead of hardened to T6.

PS- I have a note in my files- If you are using a 9.5mm belt (stock) and it is too loose (from pulley wear?), try a 10mm belt.

Real name : Curt Vesely  Lives in Mesa Az...

Would the airflow, using a smaller than stock power pulley and a smaller than stock alternator pulley (stock Porsche 356), be similar to the airflow using stock pulleys?

If the airflow is the same, I wonder how much horsepower would be saved, on something like a 2110cc engine producing 140 hp, throughout the engine's rpm range.

edsnova posted:

This looks like an interesting place to start.

What an excellent article.

Thanks, Ed.

Yes, great article.    

I guess the bottom line is where the oil temperature needle sits while cruising down the road...

Will, you are exactly right.  If it ain't broke, don't fix it.  And yes the shims will raise AND LOWER THE RATIO A BIT, BUT THIS WILL BE minor vs. the basic ratio of the pulleys.  Ps, I hate CAPS LOCK key right next to the a . . .