TheSamba.com :: View topic - 36hp question... Should I change the fan?

Tue Mar 20, 2007 7:15 am

I asked this in ENGINES section but no-one either knows or cares.

Is there any advantage of using a bastard 40 or 40hp (are they even different?) FAN in a 36hp? I was wondering if any invisible air upgrade (still wanna use control ring) is possible.
Is it correct to assume these even fit? I thought I heard reference to a '40hp' fan ina 36, but not sure if it's bastard 40 or 40 or if that even matters.

Thank you

Tue Mar 20, 2007 11:29 am

incynr8 wrote: I asked this in ENGINES section but no-one either knows or cares.

Is there any advantage of using a bastard 40 or 40hp (are they even different?) FAN in a 36hp? I was wondering if any invisible air upgrade (still wanna use control ring) is possible.
Is it correct to assume these even fit? I thought I heard reference to a '40hp' fan ina 36, but not sure if it's bastard 40 or 40 or if that even matters.

Thank you

Interesting question. If you are using a stock 36hp shroud it is the same as 40hp stale air shroud, right? So, a 40hp fan should work if that is the case. I know there is one year that has a bunch of holes in it, is that the air control ring style fans?
--Dan

Tue Mar 20, 2007 11:39 am

yes 36hp fans have 'speed holes' :)

Just wondering if there is a fan that delivers more air now that I have the motor to longblock

Tue Mar 20, 2007 11:43 am

i put stale air 40hp fans on 36hp engines. they have more blades (and the holes), and i believe they blow more air, and i feel that is important, especially with that tiny engine pushing a bus. i also think it helps with "heat" inside the bus.
the most important thing though, is that the fans absolutely MUST have the holes in the "flat" section if you use the thermostat ring.

Tue Mar 20, 2007 11:49 am

so any 40hp fan with the 'speed holes', and I guess with the associated 6v nut area 'dimple' I will call it, either bastard or stale air 40 is cool?

Is the bastard 40 and the stale air 40 the same fan?

The additonal vanes and possibly therefore more CFM at a given speed is why I was considering it.

Thanks Jon

Tue Mar 20, 2007 12:00 pm

and finally what about the 356 fan?
any further advantage if it fits? It should I expect.

Sat Mar 31, 2007 7:21 am

on a side note, about the thermostat ring. what is the factory cold setting for this? it a later model with the rubber stop, should it be set with the rubber against the fan shroud. or should I set it with a gap?

Sat Mar 31, 2007 8:25 am

I always wondered what those hole were for.

Sat Mar 31, 2007 8:29 am

20 mm opened hot, from edge of ring to closest point on shroud until 1955
25-30mm opened hot after that.

The stop prevents the ring going into the engine too far and the adjustments should be made with the consideration of the opened position being within range.

It is not the 'at rest' position, necessarily, and the 2 36ers I have here are both opened at a slight angle with it not touching adjusted for 30mm (57 and 59 engines)

Sat Mar 31, 2007 8:31 am

the holes I predict, are for a supply of air to cool the generator with the ring in the closed position, and some sort of bleed through of air for the heads (although not much)

Sat Mar 31, 2007 9:20 am

incynr8 wrote: 20 mm opened hot, from edge of ring to closest point on shroud until 1955
25-30mm opened hot after that.

The stop prevents the ring going into the engine too far and the adjustments should be made with the consideration of the opened position being within range.

It is not the 'at rest' position, necessarily, and the 2 36ers I have here are both opened at a slight angle with it not touching adjusted for 30mm (57 and 59 engines)

but it is cold sitting on the bench, what is a factory preset for this?

Sat Mar 31, 2007 9:23 am

"resting slightly preloaded on the flange/stop"

Gotta check hot to make sure you get the sped opened though through t stat adjustment.

opening too far...hit fan..

Sat Mar 31, 2007 10:46 am

BarryL wrote: I always wondered what those hole were for.

Hi BarryL,
To suck cooling air through the generator.
Later in the 1500 upright engine VW redesigned the fan tin with ducting so as to allow pressurized air from inside the shroud to blow through the generator.
One can install the much later SP up to 29 mm, or DP 33, 34, or 35mm wide fans also in earlier engines. At the least drill out the two small holes in the later fans to earlier fan holes size to keep air being sucked through the generator. Laying out, center punching a few more pairs of holes to this area is not that hard. Using a small hole saw is probably the easiest tool to use for making these holes. A full sized drill in a drill press has the tendancy to grab the sheet steel as it goes through, and possibly fling the fan across the room if not locked down properly.
Also make sure to keep the .080 space between the fan, and the fan tin with generator pulley spacers.

Sat Mar 31, 2007 7:09 pm

E&B: Quote: much later SP up to 29 mm, or DP 33, 34, or 35mm wide fans also in earlier engines

Do those fans fit a single width shroud or do they have to have their respective width shrouds (if there is such a thing)?

Sun Apr 01, 2007 8:27 am

Hi BarryL,
All the fan shrouds we have (1952-79) are the same thickness. So installing any fan just depends on shimming.

Sun Apr 01, 2007 9:42 am

I suspect a DP fan and a 36hp air control ring might not get along?

I think the 40hp with holes or later 356 fan with holes is still going to be a significant increase in air over the 16vane 36 stock fan, I'm too paranoid and would have to have the fan balanced after trying to make holes in it.

Sun Apr 01, 2007 11:18 am

Hi incynr8,
Being the DP fan is deeper there should not be any interferance problem with the control ring. As for balancing if you take the same amount of metal off each side it should be no problem. Plus so far inside the outer diameter it is going to affect it much less than any changes on the rim of the fan.
Kind of like that one fellow who went for the worlds land speed record. He picked up a military surplus jet engine that had a broken off blade on one of the turbine fans making it terribly unbalanced. He opened the inspection plate for that fan and counted the blades on it. Then with that fin count figured out which blade would be exactly opposite of the broken off blade, and broke that one off. Result was a perfectly balanced engine. Funny part is when he started to make the news the military stopped by and insisted he could not have a top secret engine like that. He had to show the sales receipt that he had bought the engine legally......

Mon Apr 02, 2007 5:27 am

interesting. I have not heard of the DP fan ever being fitted to a 36hp, seems like an ideal circumstance for Okrasa/Denzel and Judson equipped engines, especially with the oil cooler lines.

I found a 40hp with the 'holes' , so I will be using that, but if anyone has a 36er with a 34/35mm fan, I'd like to hear form them for how the fitment was.

Weird how VW increased the fan size as needed without going for max airflow from the beginning , given space being the same?

Sounds like it would work, since the Doghouse is bigger...at the doghouse only really.

I'm tempted to go with a DP welded and balanced Berg-style fan with the holes added and a 356 pully for a leaf blower in there!

Thu Apr 05, 2007 7:35 am

incynr8 wrote:
Weird how VW increased the fan size as needed without going for max airflow from the beginning , given space being the same?

Hi incynr8,
Is interesting how as the fan got bigger that lower pulley got smaller. Then somewhere starting in the late 1960's this pulley went back up in size up till the 1970s DH "D" lower pulley, but even then that was still smaller than the 36 or even bigger 25 HP lower pullies. Seems the original designer of the fan shroud left the extra space in the fan shroud as a hedge against future engine size increase and/or hotter climate operations. Check out the 1963-67 Transporter Workshop Manual about the suggested bigger lower pulley to be used on 40 HP Bus engines, and the head fin drilling to increase cooling.

Fri Apr 13, 2007 4:29 am

I finally found a chart of fan CFM at particular RPM for engine until about 1968 (who cares after that here).

I will scan it and get it up on the samba for those interested.

The 40hp fan is a 1cfm increase over the 36 btw, and close to the airflow on a 1500 SP.

Most of the fans are close.

Unfort it doesn't show CFM over rpm ranges, just at max working engine RPM.