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gimmesomeshelter
Samba Member
Joined: May 08, 2004
Posts: 1466
Location: San Carlos, CA
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 Posted: Sun Nov 19, 2017 12:57 pm Post subject: Keeping cool |
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I have a vintage speed oval so I'm always looking for ways to keep my engine cool. I noticed an ad for a generator plate (https://www.thesamba.com/vw/classifieds/detail.php?id=1531838) that's vented in the front. Did the early cars feed air to the fan from the front and the back? If so, does that mean that the fan pulled less air through the generator?
Cheers,
Paul
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splitjunkie
Samba Member
Joined: April 04, 2006
Posts: 4092
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| Posted: Sun Nov 19, 2017 4:17 pm Post subject: Re: Keeping cool |
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That plate goes with a specific type of fan. The holes were for the generator cooling air. Later fans route the air from the back and then through the generator. Installing it with a later fan will reduce the amount of air available to cool the generator which can lead to premature failure.
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Chris
You know, a lot of these scratches will buff right out... Jerry Seinfeld |
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petrol punk
Samba Member
Joined: August 21, 2007
Posts: 975
Location: Las Vegas, NV
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| Posted: Mon Nov 20, 2017 8:59 am Post subject: Re: Keeping cool |
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Isn't a 1600 non-doghouse fan the same dimensions as a 36hp fan with more blades? I believe that is how you get more CFM with a 36hp.
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36hp '56 European DeLuxe oval, '70 bug 1835cc dual 36DRLA, and a '98 4x4 5spd single cab Tacoma |
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56samba
Samba Member
Joined: June 25, 2015
Posts: 262
Location: Germany
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| Posted: Tue Nov 21, 2017 8:48 am Post subject: Re: Keeping cool |
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| gimmesomeshelter wrote: |
I have a vintage speed oval so I'm always looking for ways to keep my engine cool. I noticed an ad for a generator plate (https://www.thesamba.com/vw/classifieds/detail.php?id=1531838) that's vented in the front. Did the early cars feed air to the fan from the front and the back? If so, does that mean that the fan pulled less air through the generator?
Cheers,
Paul |
This plate would give your engine definitely a cool vintage look!
As others aslo mentioned, using a later fan or a fan from an industrial engine, will increase the amount of cool air. This is provably the most "discrete" solution.
Regarding your actual question, I just know, that they used different fans in the 40's.
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Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 24736
Location: Olympia Wash Rinse & Repeat
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| Posted: Wed Nov 29, 2017 4:36 pm Post subject: Re: Keeping cool |
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| petrol punk wrote: |
| Isn't a 1600 non-doghouse fan the same dimensions as a 36hp fan with more blades? I believe that is how you get more CFM with a 36hp. |
Non-DH 1500/1600 fan is wider.
The 1500/1600 single port engines used a 29mm wide fan, which is wider then the 36 or 40HP fans. DH went to 33mm, then 34mm, and finally 35mm wide. These are all inside measurements between the two discs that make up the body of the fan.
Larger lower 25/36 HP pulleys cause more fan RPM and thusly more air pumped with a 20mm wide fan. With 40 HP the fan was widened to 28mm, crank pulley got much smaller, and over the years the pulley got bigger diameter over the years.
More info at:
http://www.oacdp.org/
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petrol punk
Samba Member
Joined: August 21, 2007
Posts: 975
Location: Las Vegas, NV
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| Posted: Wed Nov 29, 2017 5:49 pm Post subject: Re: Keeping cool |
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| Eric&Barb wrote: |
| petrol punk wrote: |
| Isn't a 1600 non-doghouse fan the same dimensions as a 36hp fan with more blades? I believe that is how you get more CFM with a 36hp. |
Non-DH 1500/1600 fan is wider.
The 1500/1600 single port engines used a 29mm wide fan, which is wider then the 36 or 40HP fans. DH went to 33mm, then 34mm, and finally 35mm wide. These are all inside measurements between the two discs that make up the body of the fan.
Larger lower 25/36 HP pulleys cause more fan RPM and thusly more air pumped with a 20mm wide fan. With 40 HP the fan was widened to 28mm, crank pulley got much smaller, and over the years the pulley got bigger diameter over the years.
More info at:
http://www.oacdp.org/ |
Do you know the diameter of various pulleys? I noticed the crank pulley on my 36hp is noticeably smaller than a 1600 pulley. Now I'm not sure if it is correct.
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36hp '56 European DeLuxe oval, '70 bug 1835cc dual 36DRLA, and a '98 4x4 5spd single cab Tacoma |
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Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 24736
Location: Olympia Wash Rinse & Repeat
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| Posted: Wed Nov 29, 2017 6:41 pm Post subject: Re: Keeping cool |
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| petrol punk wrote: |
Do you know the diameter of various pulleys? I noticed the crank pulley on my 36hp is noticeably smaller than a 1600 pulley. Now I'm not sure if it is correct. |
That is a project that has been on our to do list and include all the ratios.
Do keep in mind that just because a pulley has an outer diameter, that the belt does not ride on that. Instead it could be well down inside that due to the taper cut or even worn into it.
25/36 crankshaft pulleys should be bigger than the 40HP thru Dog House shrouds used. DH is about 7" (375mm) diameter. We went from about 1.8:1 ratio with stock DH upper and lower pulley to 2.1:1 with smaller 356 Porsche upper pulley, and DH crankshaft pulley.
In the PR pages posted before, the 36HP had a 2:1 ratio.
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petrol punk
Samba Member
Joined: August 21, 2007
Posts: 975
Location: Las Vegas, NV
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| Posted: Wed Nov 29, 2017 11:35 pm Post subject: Re: Keeping cool |
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| Eric&Barb wrote: |
| petrol punk wrote: |
Do you know the diameter of various pulleys? I noticed the crank pulley on my 36hp is noticeably smaller than a 1600 pulley. Now I'm not sure if it is correct. |
That is a project that has been on our to do list and include all the ratios.
Do keep in mind that just because a pulley has an outer diameter, that the belt does not ride on that. Instead it could be well down inside that due to the taper cut or even worn into it.
25/36 crankshaft pulleys should be bigger than the 40HP thru Dog House shrouds used. DH is about 7" (375mm) diameter. We went from about 1.8:1 ratio with stock DH upper and lower pulley to 2.1:1 with smaller 356 Porsche upper pulley, and DH crankshaft pulley.
In the PR pages posted before, the 36HP had a 2:1 ratio. |
Interesting, I went out an measured it and my 36hp pulley is about 7 1/4". The aftermarket aluminum pulley for my 1600 is 7 7/8" so I measured some pulleys from 1600DPs and they were indeed 7", so I guess my original comparison was based off an over-sized aftermarket pulley. I checked my ratio and it was about 2.1:1, although I have a 356 12v generator installed and can't remember if I have the smaller 356 generator pulley as well. I did test fit the larger 7 7/8 billet pulley on my 36hp when I had the engine out and it did seem to fit with a bit tighter clearance around the breast tin, but I didn't have the rear tin installed since the engine was out.
It would be interesting to see if you could get lower CHTs with a >2:1 pulley ratio. I'm not entirely sure it will as it will be operating at a higher RPM than VW designed and could cause excess cavitation, or maybe it doesn't and just plain cools better. Would be interesting to see some data.
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36hp '56 European DeLuxe oval, '70 bug 1835cc dual 36DRLA, and a '98 4x4 5spd single cab Tacoma |
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Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 24736
Location: Olympia Wash Rinse & Repeat
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| Posted: Thu Nov 30, 2017 12:03 pm Post subject: Re: Keeping cool |
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| petrol punk wrote: |
It would be interesting to see if you could get lower CHTs with a >2:1 pulley ratio. I'm not entirely sure it will as it will be operating at a higher RPM than VW designed and could cause excess cavitation, or maybe it doesn't and just plain cools better. Would be interesting to see some data. |
Wish we had that info for you. Still can say @ 3,000 RPM is well below that cavitation point. Sorry for the long ramble below, but figured it would help to have as much info on our experience with engine cooling.
We used to drive our early 1960s small nut RGB buses at 3,800 RPM and had to rebuild the engines (stock 40HPs and big bore 40HPs) about every 30,000 to 40,000 miles due to being a wore out and loss of compression mess. Had thought we were driving at more like 3,000 RPM by ear, like can be done with the type 1s, but that does not work for the type 2s. Put on gauges and found out we were hitting as high as 280F oil temp on Seattle to Sacramento trips in the heat of mid 90s F. This with camping interior and most often loaded with swap meet goods going to Sacramento. The only special touch to these engines was running an oil filter pump.
Dropped our cruising speed initially to 47 MPH (this was back when 55 MPH was national speed limit) to do 3,000 RPM for cruising, and at most hit 3,500 RPM when up shifting. A bit later increased rear tire diameter so we could do 53 MPH @ 3,000 RPM. Was hoping to keep oil temp well below 230F oil temp. Personally like to keep even below 220F. Next big bore 40HP engine got 80,000 miles and was still running like new, but end play got too much. Mind you up till now these MPH readings were off a bit on the high side due to using 25" diameter beetle tires instead of the 27" that were stock for 55-63 bus. Even with these changes had to drop down at times to 2,500 to 2,800 RPM to keep the oil temp down to about 220F.
Went to a 1641cc SP engine with CW crankshaft, and 7.1:1 CR. Yes, slip in thin wall cylinders that are renowned for warping. Installed the oil filter pump.
Switched to a freeway flier transaxle with 3.875 R&P, .82 fourth, and later large nut RGB that are higher geared. With slightly larger than stock tires on the rear and the stock 27" diameter front tires were are running about 60 MPH @ 3,000 RPM (GPS shows about 59.5 MPH)
Had run dog house before, but now increased cooler size by 40% by adapting shroud tin for type 4 cooler. With largest cooling fan, and lower pulley. This definitely helped, but still needed to drop down now and then in the worst heat to 2,800 RPM to keep the oil temp below 220F, especially when pulling hills.
Finally went with a 356 Porsche generator pulley, and will not say it dropped the the over all oil temp, but helped stabilize the upper oil temps. Enough that even in 95+ F weather on the Seattle to Sacramento trip we never needed to drop from 3,000 RPM cruising along. On that trip we ran into a good head wind both ways between Redding and Sacramento!
Now have over 150,000 miles on the same 1641cc engine, without taking the long block apart. Still runs like new, but does seep a bit more oil than we like. Thinking of taking it down to a short block and resealing it. Then put it in the 1963 SC that gets driven more locally and see how much longer this engine lasts.
So would say that the 356 pulley is not an awesome end all cooling item, but definitely not cavitating the fan at the engine RPMs we do.
Have for fun maybe taken this 1641cc engine up to 70 MPH at about 3,500 RPM for just a few minutes four or five times. In temps 70 and higher oil temp does shoot up. Think that is more due to the wind speed load than any fan cavitation, because of no problem with this at lower outside temps.
Actually had a 928 Porsche driver pull up and was leaning way over into his passenger seat so he could look up at me, when doing 70 MPH once. He had a very surprised look on his face!
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