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dannparks
Unregistered
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 Posted Wednesday, August 25, 2010 @ 11:15 AM
Last months issue of Hot VW magazine had an interesting article about cylinder head cooling of aftermarket 1600cc heads. They found that the castings of some heads had the air passages completely filled up so no cooling air was able to circulate around the exhaust ports and through the top fins of the heads. They also showed a photo of a stock original VW 1600cc head and it had huge air passages through the head.
I looked at my heads from Great Plains and there are a few open passages, but many are closed.
The solution in the magazine was to carefully drill out the closed passages. When they did this, cylinder head temps (in the VW car) dropped dramatically.
For those with 1600cc heads, could you take a look at the air passages and see what they look like. I'm curious how widespread the problem is and how much it is a cause of high CHTs in 1600cc engines.
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Jorgen
Unregistered
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Posted Wednesday, August 25, 2010 @ 03:43 PM
Dan,
thanks for beeing vigilant, sounds like an important notice. If you have the opportunity to take some pictures it could help everyone to understand the issue better.
May the 4's be with you/ Jörgen
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Bob Grimstead
Unregistered
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Posted Wednesday, August 25, 2010 @ 03:48 PM
Hi Dann,
I have used many VW heads over the years, in my two RF4s (four engines in total, plus some spare heads) and in my old Turbulent (upgraded from 1500cc to 1600cc).
All of them had blocked air passages to a greater or lesser extent.
In all of them I first drilled out the passages -- very carefully, to leave enough meat around the valves, combustion chambers and inlet and exhaust ports, and then I finished off with Swiss needle files to fully open them. I cheated by putting files in a drill chuck at low speed, but it still takes nearly a full day per head to do it properly and carefully.
As you have already guessed, I believe good air cooling is paramount.
Yours, Bob
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jb92563
Unregistered
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Posted Thursday, August 26, 2010 @ 04:17 PM
Is the blockage due to the casting flash that spans between the fins in some places to some degree?
I have seen that on a number of VW heads and cylinders and always thought that it would be a good thing to clean up
if you are having any kind of heat concerns.
I'm not sure how many of you follow the AirVW yahoo group but there are some that have actually brazed cooling fin extensions
using those duralum rods onto their heads and solved their cooling issues.
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eugenio
Unregistered
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Posted Friday, August 27, 2010 @ 04:14 AM
Old heads are surely better done than the newer ones, and more, original VW are better than aftermarket ones.
This is why probably the poblem is arising now.
Anyway also the engine installation with all his baffling is of paramount importance. As Bob Grimstead already said in some other posts, the baffling must be well sealed and the air must be forced to pass thru the engine cylinders too cool them, so as thru the oil cooler (if installed). Indeed no one of the certified VW (Limbach, Sauer, Stamo, Grob etc.) has modified head fins, only Limbach did his own water cooled heads for the bigger of his engines, injected and turbocharged, all others up to 2500 uses the original heads. Also Great Plains and Aerovee uses standard heads, this means that they works fine.
I follow the VW threads on yahoo, but I think the peoples with the head temperature problems uses the engine in a not properly engineered arrangement without a well engineered cooling system/baffles installation.
Eugenio
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dannparks
Unregistered
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Posted Tuesday, January 25, 2011 @ 11:41 PM
Just following up on this earlier post...
Knowing how critical cooling is going to be on my 1600cc upgrade, I was very concerned about the cooling fins being blocked in the Mexican-made AutoLinea heads I got with the Great Plains kit.
I drilled out the air passages a bit, but was still not happy with the results.
The December 2010 Hot VW magazine had an article on stock VW heads with pictures of 18 different heads and sure enough most seemed to have very restricted air passages compared to the original VW 1600cc head. There was one set that was an exception.
Based on the images and some research, I ordered a set of some new Chinese-made castings heads. The castings are from China, and the machine work is done in the US. Below are pictures of these heads (right) compared to the AutoLinea head that I had drilled out a bit (left).
 
The difference in airflow is substantial. They should provide far better cooling. The rest of the casting seems very clean and well-made for a stock 1600cc head. I am still assembling the engine (more on that in a few weeks). I'll report on how they work as I get it running.
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jb92563
Unregistered
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Posted Wednesday, January 26, 2011 @ 11:13 AM
That is a nice cleanup job.
A good tool for getting in those tight spots is an inline air file, allowing you to use flat files and do a nice job like in your picture.
I'll have to get one from Harbor Freight next time I visit.
Just as important as the cooling fins are the air baffles "Tins" for keeping the air flowing through the fins.
Eugenio is right of course, most problems with cooling are caused by poorly designed cowl and baffles.
The idea is to create two sealed chambers, one above the heads that captures the incoming air and forces it through the head and fins, and the chamber below the heads where the hot air exits, and the "cowl flap" is shaped to create a negative pressure and help suck the hot air out.
Limbach has a good information bulletin on how to design it.
http://www.byrongliding.com/docs/tech/Limbach_Tech_Bulletin_44.1.pdf
[Edit by jb92563 on Wednesday, January 26, 2011 @ 11:19 AM]
[Edit by jb92563 on Wednesday, January 26, 2011 @ 11:20 AM]
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Collin
Unregistered
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Posted Wednesday, January 26, 2011 @ 01:57 PM
Hi,
Link to the Hot VW magazine article
Smaller color version
http://www.cfiamerica.com/images/pdf/Hot_Vws_Type1_Heads.pdf
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Jorgen
Unregistered
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Posted Wednesday, January 26, 2011 @ 02:02 PM
Right honorable Fournieteers,
that's outstanding information! Thanks for the pictures Dan and thanks for that excellent tecnical bulletin, Ray! We have discussed sealing before and Bob challenged us with the statement that if you don't seal your baffles, you've proved that you hate your engine!
I think we could share a lot of pictures of how different challenging sealing problems can be solved. For example, have you found foam for the cowling that is NOT explosively flammable, Bob?
May the 4's be with you/ Jörgen
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Collin
Unregistered
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Posted Wednesday, January 26, 2011 @ 10:53 PM
Not all heads come with the bottom tin installed.
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JamesB
Unregistered
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Posted Wednesday, January 26, 2011 @ 11:05 PM
Thanks Collin -- I've never seen that baffle before. It certainly didn't come on my RF5B.
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Bob Grimstead
Unregistered
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Posted Thursday, January 27, 2011 @ 11:04 AM
Hi Guys,
I've been trying to buy those little inter-head baffles new, but it seems they don't come separetely, so I've either had to rob old heads or make new ones out of sheet steel.
No, I never did find non-flammable foam, but my Design Engineer buddy Wally Thompson did warn me that if the included angle of the upper cowling's faired-in foam exceeded seven degrees, it would be better to leave a sharp lip -- something, like many others, which Rene obviously already knew!
I DID find three useful rubber mouldings for fitting along the top of your rear and side alloy plate baffles. Two smaller ones came from Aircraft Spruce and the other big one from a British company. The latter is very similar to, but cheaper than, the one recommended by Limbach in their TB 44.1. I think I mentioned the part numbers and web sites earlier.
Good luck guys, and remember, a cool engine prevents an overheated pilot!
Yours, Bob
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Jorgen
Unregistered
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Posted Thursday, January 27, 2011 @ 03:12 PM
Thanks Guys,
I still think "forget plates" is a a good name for those inte cylinder baffles, they were fitted to the Limbach 2000 on our RF 5b, but I don't have them on the 4.
Nice to hear that the foam thing is maybe not necessary, but I still need to do some baffle adjustment. One challenge is that the sealing/baffle solution you choose needs to be dismantable each time you do maintenance.
May the 4's be with you/ Jörgen
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Bob Grimstead
Unregistered
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Posted Tuesday, February 1, 2011 @ 04:02 AM
Hi again Folks,
Thanks to Bob Hart, here's what can happen if you leave out those little plates.
You only need to see the first half of the first clip and the second half of the second one.
http://www.youtube.com/user/1968hambone#p/u/4/QSr6C5tnjdI
http://www.youtube.com/user/1968hambone#p/u/5/YrBG3tCeWAE
see also: http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=csdILuScIv2TJEt5nghkgiQ8We&forum=13&thread=284
Yours, Bob
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Bob Grimstead
Unregistered
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Posted Monday, February 13, 2012 @ 00:11 AM
Here's how to make some effective cooling baffles.
You will need these if you have an engine that is bigger than 1400cc, and they're useful for cooling even if you only have a 1400cc enigne.
Simply measure up, make a cardboard template and fiddle and fit (cutting off tiny strips, or adding bits of masking tape) until you're sure it's the right shape, then trace its outline on thin aluminium sheet with a fibre pen.
Cut out four of them, and bend them to fit.
Hold in place with tiny self-tapping screws.
Yours, Bob
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jb92563
Unregistered
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Posted Tuesday, February 21, 2012 @ 03:14 PM
Here is a lightened picture version . I could not make out where it was positioned on the dark one.
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Bob Grimstead
Unregistered
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Posted Tuesday, February 21, 2012 @ 10:23 PM
Thanks Ray,
Of course, you need to be sure the aluminum is touching the fins all the way around or, as usual, the air will whizz past the easy way as always.
They are held in place at the top by tiny stainless steel self-tapping screws.
You can see all of this in much more detail on:
http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=hGRuaBN1CFImkcfoH3fvnisvqB&action=&forum=13&thread=683&user=&query=&msgid=&page=1&sort=&do=&key=&others=
Yours, Bob
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Bob Grimstead
Unregistered
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Posted Wednesday, February 22, 2012 @ 01:32 AM
And there's more baffling info here:
http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=1bsy4l1IGhHHWy8cHgAu6Wwfqj&forum=13&thread=284
Actually, I should say 'more info on baffling'!
Yours, Bob
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