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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50348
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 Posted: Mon May 08, 2017 7:57 pm Post subject: Re: Correct cooling Fan? |
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| raygreenwood wrote: |
| Wildthings wrote: |
| raygreenwood wrote: |
I'm surprised you are not oustide of Skills house with torches for his suggestions of "modifying" the bus. |
I have no problem with Skills as he knows what he is talking about, his experience with mechanical and body work clear shows. You on the other hand can't understand something is simple and straight forward as timing an engine or how a bus heating system works, yet you write page after page in an attempt to obfuscate your audience. |
Not much of a slap in the face judgement actually.....since apparently most of what I write ahout...or the tools and materials I use....go over your head.....and now can we discern that your panties are mainly twisted ....because you read too slowly to keep up with my longer posts?
If the length of my posts piss you off.....just quit reading them and walk on by. Coming from someone who is constantly WHINING....and calling people out who disagree with whatever magic you believe in......for being off topic......your constant ranting about me in this thread is so far off topic....and doing no one any service.
Almost like a troll......hmmmmmmmm
Ray |
I have told you before that I seldom read most of your posts because they are often inane. I don't tend to want to spend my time reading the posts of someone who can expound seemingly forever, but often be very much in error. There may be a kernel of wheat in your post somewhere, but I am unwilling to spend my time trying to find that little bit of wheat when it is mixed in with so much chaff. |
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dawie
Samba Member
Joined: July 27, 2008
Posts: 217
Location: Cape Town, South Africa
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| Posted: Tue May 09, 2017 2:06 am Post subject: Re: Correct cooling Fan? |
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VW did specify the output of their cooling systems:
Type 1 doghouse cooling system: 600 Litre per second at 4000 engine rpms. (Earlier types did less).
Type 4 flat fan setup: 800 Litre per second at 4600 rpms, and 710 litre per second at only 3600 rpms.
An engine-designer once mentioned that "up to half of the heat that needs to be removed from engine enters via the exhaust ports".
Porsche used ceramic liners in the exhaust ports of their last aircooled engines. Which made a big difference. They found that sodium cooling was no longer necessary for the exhaust valves, and could also reduce cooling fan output.
Not sure if adding a thin coating inside an existing exhaust port would be effective over the longer term, say 100 000 miles...
Problem is that, ideally, a thick coating might have to be heated to much more than 400 deg f to properly cure.
(Porsche added their ceramic inserts during casting process).
We could coat the part of heat exchangers where they attach to heads. Coat both inside and outside of at least first few inches of pipes, then heat to cure.
But is this really necessary, especially if a good merged header exhaust system is used? |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50348
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| Posted: Tue May 09, 2017 3:21 am Post subject: Re: Correct cooling Fan? |
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| dawie wrote: |
An engine-designer once mentioned that "up to half of the heat that needs to be removed from engine enters via the exhaust ports".
Porsche used ceramic liners in the exhaust ports of their last aircooled engines. Which made a big difference. They found that sodium cooling was no longer necessary for the exhaust valves, and could also reduce cooling fan output.
? |
Having a liner in the exhaust port would be a nice upgrade, assuming the liner didn't add a failure mode to the system. |
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lil-jinx
Samba Member
Joined: August 14, 2013
Posts: 1109
Location: New Brunswick,Canada
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| Posted: Tue May 09, 2017 7:44 am Post subject: Re: Correct cooling Fan? |
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I think raygreenwood is right, with a bit of research and testing one could improve the air flow,I don't think this is something that should be done willy nilly in a home garage with a slab of aluminium and a tube of JB Weld.
Enjoy your posts Ray,most of which go over my head,but sets me to thinking.keep them coming.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=620186
https://www.thesamba.com/vw/forum/viewtopic.php?t=668799
1974 Bay Westfalia. she likes to be called Ethel.
1968 Dune Buggy
1974 parts bus
A smart man learns from his mistakes,a very smart man learns from other's mistakes. |
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Whaanga
Samba Member
Joined: May 07, 2016
Posts: 627
Location: Rochester, NY
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| Posted: Tue May 09, 2017 8:02 am Post subject: Re: Correct cooling Fan? |
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Wow- I didn't know my simple question could generate so much content.
All I have to say is that I located a fan and am taking for sandblasting and clean up. Here are a few before photos- after will come later.
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Tue May 09, 2017 10:03 am Post subject: Re: Correct cooling Fan? |
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| Whaanga wrote: |
Wow- I didn't know my simple question could generate so much content.
All I have to say is that I located a fan and am taking for sandblasting and clean up. Here are a few before photos- after will come later.
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Simple questions make people think just as much as complicated ones. Its all good if you learn something new in the process.
I am on the road through next week. The following weekend (weekend of the 20/21st....It may be a good time to check and align at least a couple of the pile of fans I have.
I have been meaning to photograph the process of aligning we talked about early in the thread.
At the very least its worth using a similar process to check the fan you have even if it has not been disassembled. I will see if I can get that done and posted if it will help.
Ray |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Tue May 09, 2017 10:50 am Post subject: Re: Correct cooling Fan? |
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| dawie wrote: |
VW did specify the output of their cooling systems:
Type 1 doghouse cooling system: 600 Litre per second at 4000 engine rpms. (Earlier types did less).
Type 4 flat fan setup: 800 Litre per second at 4600 rpms, and 710 litre per second at only 3600 rpms.
An engine-designer once mentioned that "up to half of the heat that needs to be removed from engine enters via the exhaust ports".
Porsche used ceramic liners in the exhaust ports of their last aircooled engines. Which made a big difference. They found that sodium cooling was no longer necessary for the exhaust valves, and could also reduce cooling fan output.
Not sure if adding a thin coating inside an existing exhaust port would be effective over the longer term, say 100 000 miles...
Problem is that, ideally, a thick coating might have to be heated to much more than 400 deg f to properly cure.
(Porsche added their ceramic inserts during casting process).
We could coat the part of heat exchangers where they attach to heads. Coat both inside and outside of at least first few inches of pipes, then heat to cure.
But is this really necessary, especially if a good merged header exhaust system is used? |
The ceramic could be very good.
What VW did not specify though...and its some of what Jake Raby was pointing out during his research for the DTM from some of his postings.....was static pressure and slippage loss (cavitation...not just belt slippage...although that is an issue on type 1).
While the type 4 fan ...at a glance on paper...appears to be much more efficient in..... CFM/volume....the type of fan used on the type 1 actually produces more consistent static pressure......across a wider range.
The type 4 fan is a forward inclined blade system. This type produces better static pressure by "design". In other words if I wanted a blower design to produce the highest air pressure at its outlet (regardless of cfm)...this is the better type for that. But where more static pressure is produced....there is more power requirement. A forward inclined fan like the type 4...used in a type 1 configuration (with a belt)....could reach torque loads at certain rpms that could cause major belt slippage.
There is also a ratio/speed difference on the type 1 fan. Because its a reverse incline fan...it "flings" air out the tips of the blades through centrifugal force....it experiences less air pressure load on the blades and can be "overdriven" at higher speeds...which is also why a properly welded fan is critical on this design.
So there are pluses and minuses for both fans.
These +/- characteristics are "somewhat" taken advantage of with the different styles of cooling shroud.
So with the type 1 fan being a backward inclined fan rotating in the clockwise direction. Because this blade configuration does not produce as much static pressure loading as a forward inclined blade like the type 4 has....it can have larger blades without robbing more power....so its a good mix.
The two cooling systems...type 1 and type 4...are not just different configurations of the same thing. They have very different working methods inside.
Ray |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Tue May 09, 2017 11:15 am Post subject: Re: Correct cooling Fan? |
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| Wildthings wrote: |
| raygreenwood wrote: |
| Wildthings wrote: |
| raygreenwood wrote: |
I'm surprised you are not oustide of Skills house with torches for his suggestions of "modifying" the bus. |
I have no problem with Skills as he knows what he is talking about, his experience with mechanical and body work clear shows. You on the other hand can't understand something is simple and straight forward as timing an engine or how a bus heating system works, yet you write page after page in an attempt to obfuscate your audience. |
Not much of a slap in the face judgement actually.....since apparently most of what I write ahout...or the tools and materials I use....go over your head.....and now can we discern that your panties are mainly twisted ....because you read too slowly to keep up with my longer posts?
If the length of my posts piss you off.....just quit reading them and walk on by. Coming from someone who is constantly WHINING....and calling people out who disagree with whatever magic you believe in......for being off topic......your constant ranting about me in this thread is so far off topic....and doing no one any service.
Almost like a troll......hmmmmmmmm
Ray |
I have told you before that I seldom read most of your posts because they are often inane. I don't tend to want to spend my time reading the posts of someone who can expound seemingly forever, but often be very much in error. There may be a kernel of wheat in your post somewhere, but I am unwilling to spend my time trying to find that little bit of wheat when it is mixed in with so much chaff. |
So...I dont get this. If you dont read them...why are you complaining about the length of them? Your complaints do not make much sense.
Inane?...maybe...to someone who does not know what I am speaking about....sure! I'll buy that!
Too many people hate new technology and new methods because they either dont understand the technology or they are afraid of it.
You lost my respect....when you said this:
| Quote: |
| Jeez, don't go messing with your fan shroud, VW could have easily redesigned the fan shroud and fan when they built the AC Vanagon, but didn't, they just closed off the heater outlets and used a higher pressure fan attached to the alternator for the heat. Run your timing no more advanced that 28°BTDC at 3500+ rpms hoses off. Note that the original timing spec for one of these engines in a light weight car was 27° BTDC at 3500+ rpm, hoses off so going an extra degree or two to the retarded side isn't going to hurt anything. You can also go a jet size richer if running carbs or a tooth richer if running FI. |
That part in red just "drips" with a BS level of ..."you guys are stupid for even discussing this"...attitude. Sure...VW could have (so you speculate)...but they didn't...so we are talking about it here.....and you belittle anyone who wants to discuss it with your piss-poor attitude....and thats just my opinion.
So back to the thought at hand....to steal and butcher a quote....probably from a movie somewhere along the line  ....modern technology can seem like black magic to someone from 200 years ago. So...I guess that makes me a "heretic" at worst.....yeah...that fits...especially that last part!
I guess I am just lucky this is not 300 years ago....I can visualize you ranting "blasphemer!!" from the crowd.... in your ill-fitting, stanky Puritan clothes with spittle flying from your mouth while I am fitted to the stake for burning.....for "automotive heresy"....it would it be horse and buggy heresey?
This all still makes you a "troll" in my book....and your b*tching about me.... does nothing for the topic at hand in this thread....and...in my vision from above...yes....your hair is REALLY blue.... 
Ray |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50348
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| Posted: Tue May 09, 2017 11:47 am Post subject: Re: Correct cooling Fan? |
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| raygreenwood wrote: |
So...I dont get this. If you dont read them...why are you complaining about the length of them? Your complaints do not make much sense.
Inane?...maybe...to someone who does not know what I am speaking about....sure! I'll buy that! |
Yes your posts are inane. You claim that a Vanagon engine is not a Type 4 engine is equivalent to saying a small block Chevy quit being a small block Chevy because Chevrolet changed the valve covers and added a PCV valve in the mid sixties. I have never heard anyone at any time make such a claim, either about a small block Chevy or a Vanagon Type 4.
The Vanagon engine shared with some other year of Type 4 the same:
Heads
Piston
Rods
Crank
Cam
Timing gears
Lifter
Pushrod tube
Rocker assemblies
Valve Covers
Distributor
Distributor drive
Shaft seals
Oil pump
Cooling fan
and many smaller parts as some other year of a Type 4.
And you don't understand they are the same basic engine because there was a change in the crankcase ventilation valve
You also posted at length a week ago about engines running rich and harming the exhaust but had multiple errors in your post. I really don't think you have a clue to what causes this syndrome and are certainly the only person that I have ever seen bring it up on the Bay Window forum. You develop some poorly thought out theory and expound at length on it when the root problem is something else entirely. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Tue May 09, 2017 3:11 pm Post subject: Re: Correct cooling Fan? |
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I never said they were not a type 4 engine....just that they are different enough in several ways (the cast over oil plenum to start with)...and the most important difference that ACTUALLY bears on this conversation....is that they use a CONSIDERABLY DIFFERENT cooling shroud.
The vanagon has a smaller 3/4 side volume...just like I mentioned would be good, no alternator outlet and as you mentioned as well....no right side heat exchanger outlet from the fan ring.....and a very different alternator....with its own fan!....duh...just like this thread was speaking of.
They also reduced the 1/2 side fan output volume...probably to push more air to the now smaller 3/4 side. Something I would not really want to do if I were designing the shroud....but thats just me.
See the picture below....and if you cannot see the significant differences...type 4 on the right...and Vanagon on the left....you should have your prescription checked.
Notice the red squares I put in the lower picture. The square on the right is a clone to the one on the left. See how much has been trimmed off of the 3/4 side?
Also...even though as far as I know the Vanagon uses the same basic flap and rod assembly as the type 4 engines....the 3/4 exit port from the shroud has been reshaped.
The arrows noting the difference were conveniently already there from this thread below. You should remember that thread troll-boi....you were there! 
https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0
And if the differences are not clear enough in that picture:
Vanagon top from this thread https://www.thesamba.com/vw/forum/viewtopic.php?p=4761546
Type 4 bottom from this thread
http://www.itinerant-air-cooled.com/viewtopic.php?t=6874
So for those differences...I do not readily count it as across the board type 4. Its vanagon....
The vanagon shroud has some of the improvements we have been talking about here...except that I do not like the way it changed the flow to the heater boxes.
So I'm posting as much info as I can.....to support the original conversation about the fan ...and the secondary sub-conversation about the shroud.
What are you adding to this other thread than b*tching about me and what you think I know or don't know? Hmmm?....thought so......
Troll.....
Ray |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50348
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| Posted: Tue May 09, 2017 4:41 pm Post subject: Re: Correct cooling Fan? |
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| raygreenwood wrote: |
| I never said they were not a type 4 engine |
Your words exactly "The Vanagon version was quite a different engine in enough ways that I dobt count it as "type 4"."
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just that they are different enough in several ways (the cast over oil plenum to start with)...and the most important difference that ACTUALLY bears on this conversation....is that they use a CONSIDERABLY DIFFERENT cooling shroud.
The vanagon has a smaller 3/4 side volume |
Did you even look at your own pictures before printing this falsehood, this is what I am talking about, you waste lots of words proving how wrong you are. Spend an hour or so trying to absorb the fourth picture down.
| Quote: |
.just like I mentioned would be good, no alternator outlet and as you mentioned as well....no right side heat exchanger outlet from the fan ring.....and a very different alternator....with its own fan!....duh...just like this thread was speaking of.
They also reduced the 1/2 side fan output volume |
By eliminating an unneeded change in duct size they probably increased flow instead of reducing it. Your lack of knowledge in fluid dynamics is showing.
| Quote: |
probably to push more air to the now smaller 3/4 side. Something I would not really want to do if I were designing the shroud....but thats just me.
See the picture below....and if you cannot see the significant differences...type 4 on the right...and Vanagon on the left....you should have your prescription checked. |
If your objective is to show how wrong you can be you are doing a good job. The difference you are pointing out here is totally external to the shroud, the inside of the area shown in your square either is not changed or changed very little. The extent of the changes VW made to the shroud when they upgraded the Type 4 engine for use in the Vanagon was to eliminate the ports for the alternator and the heaters, any other changes were very minimal. They in no way resemble the poorly though out changes your are suggesting for the earlier Type 4 shrouds.
| Quote: |
Notice the red squares I put in the lower picture. The square on the right is a clone to the one on the left. See how much has been trimmed off of the 3/4 side?
Also...even though as far as I know the Vanagon uses the same basic flap and rod assembly as the type 4 engines....the 3/4 exit port from the shroud has been reshaped.
The arrows noting the difference were conveniently already there from this thread below. You should remember that thread troll-boi....you were there!
https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0
And if the differences are not clear enough in that picture:
Vanagon top from this thread https://www.thesamba.com/vw/forum/viewtopic.php?p=4761546
Type 4 bottom from this thread
http://www.itinerant-air-cooled.com/viewtopic.php?t=6874
So for those differences...I do not readily count it as across the board type 4. Its vanagon....
The vanagon shroud has some of the improvements we have been talking about here...except that I do not like the way it changed the flow to the heater boxes.
So I'm posting as much info as I can.....to support the original conversation about the fan ...and the secondary sub-conversation about the shroud.
What are you adding to this other thread than b*tching about me and what you think I know or don't know? Hmmm?....thought so
Troll..... |
Great self portrait by the way, did you have it professionally done?
Oh and by the way which Bosch and Motorola alternators move air from the pulley end back through the alternator. Part numbers and pictures please, I would be very willing to try one is such exists. Sorry but I am just not as familiar with all the various alternators out there as you are.
Why don't you buy yourself a Bay Window bus with L-jet and use it daily for 150,000+/- mile before you you try to come off as a Bay Window Transporter expert?
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Tue May 09, 2017 6:52 pm Post subject: Re: Correct cooling Fan? |
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I have never portrayed myself as a T2 expert....so quit whining......and the pics were spot on for what I posted information wise. While the vanagon shroud is an improvement....and right along the lines of what we have been discussing here...and years ago on the STF.......it changes the ancillary attachments enough that I would rather try my hand at improving my existing type 4 shroud......that slapping on a vanagon shroud and changing all my sheet metal.
Some Motorola's push...some pull. Depends on direction of rotation and fan type. But since you asked I will dig for some part #s. It may help several people.....and its been found by those who have done the Motorola alt swap......that it doesn't much matter which direction you go as long as you have forced cooling for the alternator.....or if the air is particularly cool or not.
The issue to avoid are the Bosch with detachable internal regulator. You cant readily buy replacement regs.
On a different matter......I just remembered that someone noted that your avatar was a prized family pet. Apologies.
Since I'm not known for being a d*ck (like some people)....I will delete my troll spoof pictures. Thats just not nice.
I come here for the type 4 engine interest and a few other tech items. If you want to jump into every thread I post in and rant......go for it. Its a waste of my time to make up snappy replies to your ranting.....so I'll just ignore your bullsh*t.
EDIT:......oh....I see as usual....the moderators have already "CENSORED" my troll pictures. Guess they were afraid you would get butt-hurt......oh well....it WAS mean spirited.....so it just saves me effort.
Ray |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50348
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| Posted: Tue May 09, 2017 8:35 pm Post subject: Re: Correct cooling Fan? |
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| raygreenwood wrote: |
| I have never portrayed myself as a T2 expert....so quit whining......and the pics were spot on for what I posted information wise. While the vanagon shroud is an improvement....and right along the lines of what we have been discussing here...and years ago on the STF.......it changes the ancillary attachments enough that I would rather try my hand at improving my existing type 4 shroud......that slapping on a vanagon shroud and changing all my sheet metal. |
Guess one hour wasn't enough for you to find you mistake, maybe stare at that picture for four hours and see if you can figure out why you are still in error. As usual you are so convinced you are right you can't understand your failings even though they are right before your eyes. Maybe perusing the entire thread a few times might help as well, your error could hardly be more obvious if you are open to seeing it.
| Quote: |
Some Motorola's push...some pull. Depends on direction of rotation and fan type. But since you asked I will dig for some part #s. It may help several people.....and its been found by those who have done the Motorola alt seswap......that it doesn't much matter which direction you go as long as you have forced cooling for the alternator.....or if the air is particularly cool or not.
The issue to avoid are the Bosch with detachable internal regulator. You cant readily buy replacement regs.
On a different matter......I just remembered that someone noted that your avatar was a prized family pet. Apologies.
Since I'm not known for being a d*ck (like some people)....I will delete my troll spoof pictures. Thats just not nice.
I come here for the type 4 engine interest and a few other tech items. If you want to jump into every thread I post in and rant......go for it. Its a waste of my time to make up snappy replies to your ranting.....so I'll just ignore your bullsh*t. |
If you weren't wrong so often I wouldn't be jumping in, but you are always trying to come off as an expert and often wrong while trying to get people with limited mechanical knowledge to make unnecessary alterations to their rigs.
| Quote: |
EDIT:......oh....I see as usual....the moderators have already "CENSORED" my troll pictures. Guess they were afraid you would get butt-hurt......oh well....it WAS mean spirited.....so it just saves me effort.
Ray |
Don't worry, I had assumed that was a portrait you had taken of yourself. |
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Abscate
Samba Member
Joined: October 05, 2014
Posts: 22668
Location: NYC/Upstate/ROW
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| Posted: Thu May 11, 2017 5:25 am Post subject: Re: Correct cooling Fan? |
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You have to seed air flow with oil droplets to get the visual of course, otherwise you can't see much. A nice three point PIV will map both velocity and acceleration which is cool info to have
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Thu May 11, 2017 6:59 am Post subject: Re: Correct cooling Fan? |
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| Abscate wrote: |
| You have to seed air flow with oil droplets to get the visual of course, otherwise you can't see much. A nice three point PIV will map both velocity and acceleration which is cool info to have |
Interesting!.....the PIV work I have seen.....which was primarily used in two different areas:
1. For mapping airflow and dead spots in forced air curing and batch oven designs
2. Mapping flow through cryogenic vacuum pump chambers and connecting plenums
......they did not use an oil. They used a waterbased liquid with a wetting agent. This was to drop surface tension on the liquid so that it dispersed better and closer to surfaces in vessels with small passages and convoluted shapes.
They also did this because they could not reliably decontaminate the part they were testing before it went to production. The fluid vapor make up was important.
A few years back I had a customer that used a version of PIV.....that used a UV trace vapor. Not truely PIV....but same function and was mapped by strobe and camera.
Yes.....it would be interesting to see how the air shroud maps out at various rpm......because there is a lot of difference in both sides. Less at low rpm and more at high rpm. Ray |
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williamM
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Joined: August 07, 2008
Posts: 4333
Location: southwest Arizona
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| Posted: Mon May 15, 2017 8:43 am Post subject: Re: Correct cooling Fan? |
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 not wanting to interrupt,-- but back to the fan story- Has anyone ever put a "pre fan" on the front of the T-4 fan like a 2 stage compressor on a turbine engine-
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opinion untempered by fact is ignorance.
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Spike0180
Samba Member
Joined: June 06, 2015
Posts: 2269
Location: Detroit, Michigan
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| Posted: Mon May 15, 2017 9:15 am Post subject: Re: Correct cooling Fan? |
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| williamM wrote: |
| not wanting to interrupt,-- but back to the fan story- Has anyone ever put a "pre fan" on the front of the T-4 fan like a 2 stage compressor on a turbine engine- |
lol, without different speeds or/and more significant fan sizes/bore (or shroud, which you would probably need a second one) sizes, you probably wont see much difference. Maybe a little more air flow, but I doubt it due to the size of the shroud staying constant. The extra fan would have trouble pushing air into the shroud, might even prevent cooling air getting to the second fan.
Bottom line, you cant slap it on the front, you need a "shroud" of some sort to funnel the air to the second fan which if it isn't a significant change in fan size/speed in comparison to the first fan then it wont be able to compress/speed up the air at all. So it may end up working more as a regulator than a fan. And at some point you have to be concerned with increasing air temps due to compression (though that is something that I would not initially concern myself with). I'd be interested to see what you come up with though. Feel free to test it out, but make sure to put a temp gauge on it.
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Current State: Projects never truly end...
Location: Grosse Pointe, Michigan
Other cars: 2003 F150, 2003 Jetta GLI vr6-6sp
Sambastic: adj; the quality of being nit picky, elitist, expecting everyone to do things the way they believe is best with no regard to situation, "sambastic" |
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williamM
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Joined: August 07, 2008
Posts: 4333
Location: southwest Arizona
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| Posted: Sat May 20, 2017 8:16 am Post subject: Re: Correct cooling Fan? |
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Agree I'm looking for a wood stove adapter for shroud- will go 2" over size from the fan size to the blower - may go more for more compression- will keep you informed.
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some days I get up and just sit and think. Some days I just sit.
opinion untempered by fact is ignorance.
Don't step in any! |
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Amskeptic
Samba Member
Joined: October 18, 2002
Posts: 8568
Location: All Across The Country
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| Posted: Sat May 20, 2017 8:48 am Post subject: Re: Correct cooling Fan? |
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| raygreenwood wrote: |
.......they made really ugly compromises on the 3/4.
Any B grade HVAC tech could explain what happens when high velocity air enters an unducted area of higher volume.........static pressure drops and velocity drops.
To say the ducting tract for the 3/4 side is "well engineered"......is ludicrous.
Ray |
It is well-engineered, Ray. The different "cross sections" of left versus right comes out in the end. The right side has a nice 90* bend to the duct along the short edge of the rectangular outlet, the left side has its 90* along the long edge of its rectangular edge. Add the fact that the left flap is a vane that dedicates air to the cooler, and it all works out in the end. Try doing some IR thermometer work of an actual engine in a good state of tune and it all works just fine.
All this talk, and every day I see real air-cooled engines that impossibly continue to work with filthy fans filthy fins, loose spark plugs rats nests oil leak-caused blobs of dirt, missing bits, bent tins, it goes on and on and on, these assaults against the purity of the engineering, and I cannot say with confidence which engine I visit is in trouble and which engine is good to go based on the above cooling system diminishments. Really, it is the damndest thing.
Colin - B grade HVAC Survivor
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Sat May 20, 2017 1:49 pm Post subject: Re: Correct cooling Fan? |
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| Amskeptic wrote: |
| raygreenwood wrote: |
.......they made really ugly compromises on the 3/4.
Any B grade HVAC tech could explain what happens when high velocity air enters an unducted area of higher volume.........static pressure drops and velocity drops.
To say the ducting tract for the 3/4 side is "well engineered"......is ludicrous.
Ray |
It is well-engineered, Ray. The different "cross sections" of left versus right comes out in the end. The right side has a nice 90* bend to the duct along the short edge of the rectangular outlet, the left side has its 90* along the long edge of its rectangular edge. Add the fact that the left flap is a vane that dedicates air to the cooler, and it all works out in the end. Try doing some IR thermometer work of an actual engine in a good state of tune and it all works just fine.
All this talk, and every day I see real air-cooled engines that impossibly continue to work with filthy fans filthy fins, loose spark plugs rats nests oil leak-caused blobs of dirt, missing bits, bent tins, it goes on and on and on, these assaults against the purity of the engineering, and I cannot say with confidence which engine I visit is in trouble and which engine is good to go based on the above cooling system diminishments. Really, it is the damndest thing.
Colin - B grade HVAC Survivor |
Colin.....as a whole....for all of what it must do...the type 4 shroud is pretty well engineered.
However....as I noted...and I stated a fact that I actually took the time to verify....and Jake Raby verified in his own testing ...and you can easily verify yourself with tools as cheap as they are these days....the 3/4 side is NOT that well engineered. It has some issues when the engine design is pushed.
One "could" accurately say that it was well engineered enough both for the engine and application it was originally designed for (as a 1.7L in a lighter car with higher gearing and better aerodynamics)....and they did really well.
Yes....they work well enough in a bus. Not perfect. Not as well as they did in a 411 or a 914.....simply because you bus guys have higher loads are making more heat and running with higher head and oil temps in general and cruising at higher rpms.....than we do with the lighter cars.
Saying something is "working well"...does not say there is no room for improvement....which is what VW has done to some extent (and which I have not yet tested)...on the Vanagon shroud. Heck..back in the day..DC voltage produced light just as well as AC voltage....but there were issues...
Even with lighter cars....when you modify the engine and/or step into driving environments that are a bit more harsh....say multi-hour drives at speeds of 70+ in ambient conditions of 100 F....in the short term if you have a thermocouple on both heads you will see the difference in cooling from left to right. In the long term even if you dont monitor it....you run into shorter life and and more extensive damage to the 3/4 side when you finally tear them down.
There is always room for improvement....and just because something is well engineered does not mean its perfect and cannot be improved....which my point in this whole discussion....and I have done the testing to show that it actually can be improved.
Now whether you feel the need to modify or improve .....or are happy with how the system works as it is....is entirely up to you.
My point of putting my foot into this discussion rather forcefully..... is that the information I posted has a good bit of data and testing behind it....and has been researched by people other than me as well....and if your engine is modified a bit and needs a little better cooling....and you cannot use something like a DTM or do not want to....its worth looking into.
What I don't tolerate is people who have some kind of personal axe to grind (and I am NOT speaking of you Colin)...who denigrate others who have an interest in doing something different and learning something along the way. Most especially if the those bitching about have not done any of the testing mentioned.
WilliamM said:
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not wanting to interrupt,-- but back to the fan story- Has anyone ever put a "pre fan" on the front of the T-4 fan like a 2 stage compressor on a turbine engine- |
I think I mentioned an experiment from back in the day earlier. I have somewhere in my collection of parts a type 3 outer fan pulley that was machined on a lathe when I lived in Dallas....whose purpose was to install in the front opening of one of my type 4 fans.....so basically installed just like the type 3 fan.
It is a pre-fan "stuffer" for the type 3.
I stopped working on that project because I would have to first decide how deep to install it...drill four holes in the steel type 4 fan pulley ring....install it flush and flat...and then...get the whole mess re-balanced. It was going to take a lot of a time and a bit of money.
At that point in time I was driving 1200-1500 miles per week covering a region in my 412. TX, OK, AR, LA, NM and KS. I had no real issues for about the first two years even in temps up to 115* in West Texas and NM. But after some top end work to get rid of the head gaskets and some tuning which really helped drivability and power (moving compression from 8.2:1 to 8.5:1) ...on the really long high speed drives when ambient was over 105*F.....I would occasionally see some elevated temps.
Part of why I never finished this mod....is that I changed jobs and no longer needed to do that kind of driving....and then some conversations with others on the STF doing similar experiments including Jake Raby who was developing his DTM about that time......at some point Jake had mentioned that he tried a mod similar to this (adding a pre-load fan to the type 4 fan).....and if memory serves....he noted that it had some benefit but that it varied with speed. For what he was looking for I think he noted that it was not worth the work required.
Remember that the type 3 fan this rotor or pre-fan feeds has a different operational characteristic than the type 4 fan.
Ray |
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