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Almost Alive
Samba Member
Joined: October 12, 2009
Posts: 1337
Location: Illinois
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 Posted: Thu Mar 04, 2010 6:07 pm Post subject: Puma "Low Profile" Shroud - Dissection&Cooling |
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As far as I know, no one has taken it upon themselves to cut up a Puma shroud to post on here.
I ended up buying a used shroud along with sliced up one from a Samba member so I just drilled out the welds to see exactly what was under it.
What do you guys think? No one has ever tested these yet.... what do you think the cooling capabilities of it are compared to other available shrouds?
For those of you who aren't familiar with the shroud I have posted pictures of it on an engine.
Just an FYI, the cut up shroud was a new one from CB and the other one in the pictures is an original. As far as I can tell construction is 95% the same and quality seems to be the same as well.
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sturgeongeneral
Samba Member
Joined: June 23, 2005
Posts: 2421
Location: Sacramento, California
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| Posted: Thu Mar 04, 2010 7:49 pm Post subject: |
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Fantastic! I really appreciate your sharing the data. I have had faith in them and your efforts show us the quality is there!
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Alexander_Monday
Samba Member
Joined: November 09, 2007
Posts: 307
Location: Springfield Missouri
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| Posted: Fri Mar 05, 2010 4:29 pm Post subject: |
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Glad to see you went ahead and finished up dissecting that shroud and posted the pictures of the airfoils.
The biggest thing about the diverter airfoils in factory shrouds that I have noticed is that they keep the cross sectional volume for the air they are re-directing at a constant value.
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| andk5591 wrote: | The original german engineers have attained sainthood and it is impossible to improve perfection.
Anything that anyone does to deviate from the original designs will be made to wrench on 20 year old Yugos with Harbor Freight tools in hell. |
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W1K1
Samba Member
Joined: March 04, 2004
Posts: 2071
Location: Southern AB
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| Posted: Fri Mar 05, 2010 4:49 pm Post subject: |
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Well seeing as how that's my motor in the top pics.
It is a CB puma shroud, it cools my 2110cc just fine.
It came in basic black with all those clips on the front, so I ground them off and PC'd it eastwood hot rod black.
They don't carry the originals like mine anymore?
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Sigurd
Samba Member
Joined: April 18, 2006
Posts: 2515
Location: Rockford, IL
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| Posted: Fri Mar 05, 2010 5:42 pm Post subject: |
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| Thanks for doing that. It's interesting. Man, now I'm almost tempted to cut open my $75 181 shroud... |
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millerje78
Samba Amishman
Joined: October 16, 2005
Posts: 2525
Location: Holmes County, Ohio
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| Posted: Fri Mar 05, 2010 8:15 pm Post subject: |
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| Sigurd wrote: | | Thanks for doing that. It's interesting. Man, now I'm almost tempted to cut open my $75 181 shroud... |
do it!
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do your research, consult with experts, and buy quality parts. you won't be sorry |
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AlteWagen
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Joined: February 23, 2007
Posts: 5362
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| Posted: Sat Mar 06, 2010 1:26 pm Post subject: |
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| Sigurd wrote: | | Thanks for doing that. It's interesting. Man, now I'm almost tempted to cut open my $75 181 shroud... |
Please do! Raby is the only one who cut one open and said the airfoils are different (blunt) compared to regular DH shrouds. I wold really like to see how different they are and compare to the puma foils as well.
If you do cut it there is a double bonus.
1. now you can make the ultimate 36hp/181 hybrid
2. you can put to rest once and for all if the 181 shroud is what its made out to be.
PLEASE DO IT FOR THE BENEFIT OF ALL HUMANITY!!!! or at least all us samba volks |
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Sigurd
Samba Member
Joined: April 18, 2006
Posts: 2515
Location: Rockford, IL
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| Posted: Sat Mar 06, 2010 3:00 pm Post subject: |
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If I wasn't going to use it on my motor in a month, I'd feel more like it. Plus, the PO spot welded the vanes to the back panel of the shroud. Maybe I can just shoot pictures of the front edges of the vanes. 
I believe I have verified it as a 181. When I blasted it down to metal, there was no evidence of welding where the heaters would have been. Either that, or a damn good job of it. Also, I poked a coat hanger down that dead end vane, and it didn't have the little curved "runway" that a heater shroud would have. |
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AlteWagen
Troll
Joined: February 23, 2007
Posts: 5362
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| Posted: Sat Mar 06, 2010 3:22 pm Post subject: |
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the veins are welded to the back of the shroud from the factory. Ive seen a few 1500 stale air shrouds converted to DH and being sold as 181. No welds or seams just non factory spot welds on the back of the shroud. If you dont know any better you would think it is a 181.
I wish Jake Raby would post pics of his shroud, its already cut up and supposedly confirmed as a true 181. |
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Sigurd
Samba Member
Joined: April 18, 2006
Posts: 2515
Location: Rockford, IL
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| Posted: Sat Mar 06, 2010 3:25 pm Post subject: |
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Just ran out to check, and I'm pretty sure it's been apart before. I'm also not seeing the blunted leading edges that Jake found. The back (back is back) side of the shroud definitely did not have heaters. I can see no metal deformation on the inside of the shroud. Now maybe it was a 181 back attached to a standard front? That's stupid, but maybe I shouldn't rule it out.
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Sigurd
Samba Member
Joined: April 18, 2006
Posts: 2515
Location: Rockford, IL
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| Posted: Sat Mar 06, 2010 3:28 pm Post subject: |
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| derluftwagen wrote: | the veins are welded to the back of the shroud from the factory. Ive seen a few 1500 stale air shrouds converted to DH and being sold as 181. No welds or seams just non factory spot welds on the back of the shroud. If you dont know any better you would think it is a 181.
I wish Jake Raby would post pics of his shroud, its already cut up and supposedly confirmed as a true 181. |
There are amateur looking welds opposite the factory ones. One vane is actually attached a little crooked. It does have a doghouse. A doghouse front side with a 181 back side. Glenn could shoot a picture of just the front edges of the vanes too. It would be some work for me to take mine apart. |
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AlteWagen
Troll
Joined: February 23, 2007
Posts: 5362
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| Posted: Sat Mar 06, 2010 5:51 pm Post subject: |
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| what kind of oil cooler slot do you have? Positive scoop, negative scoop, or peanut slot? |
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Sigurd
Samba Member
Joined: April 18, 2006
Posts: 2515
Location: Rockford, IL
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| Posted: Sat Mar 06, 2010 6:30 pm Post subject: |
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This one
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AlteWagen
Troll
Joined: February 23, 2007
Posts: 5362
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| Posted: Sun Apr 11, 2010 2:50 pm Post subject: |
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Update on Puma cooling.
Here is my engine combo:
1699cc
stock 043 heads hi rev springs
110 cam
9:1 compression
1 3/8 header single muffler
dual ICTs
019/blue coil
Previous cooling:
36hp doghouse with foils
Stock cylinder tin with sleds
Temps:
In town 275 CHT 200 Oil
Freeway with load 300-400 CHT 220-230 Oil
With Puma shroud (with venturi ring and flaps but no thermo) and small lower and industrial tin.
In town 175 CHT 170 Oil
Freeway with load 250-350 210 Oil (I could not get the oil temp to go above 210 even on grapevine!)
Using VDO gauges so the CHT are reportedly lower. Oil temps were verified with a candy thermo in the dip stick hole.
The main difference I noticed besides the overall lower temps was how fast the temps would go down after getting off the freeway. The CHT would drop down to 175 within 1 minute and the oil temps would go down to 170 within 2 minutes!
Test vehicle is a stock 63 bus with 2000lb camping load taken over the grape vine from L.A. to Sacramento. Stock gearing in the trans and still has small nut RBGs I still averaged 29 mpg and cruised at 60 mph the whole way. On the steep grades I dropped down to 45 as to not lug the engine. Weather was great, 70* average
When it starts getting hot here (over 100*)I will run a 356 pulley and welded fan and report back on the temps.
I will need to install the thermo when using the puma shroud and living in NorCal during the fall and winter to get the oil temps up to operating temperature. I will also install a low profile brazilia shroud with the fresh air heater outlets and heater boxes for defrost and a bit of heat.
I LOVE this mini stroker and Puma shroud combo!!
Just wondering, I read in another thread about sled and lower tin was just to keep the cylinders and heads from thermal shock when getting splashed with water. Myth or legend? |
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Matthew
Samba Member
Joined: January 29, 2004
Posts: 1254
Location: Fort Pierce, FL
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| Posted: Sun Apr 11, 2010 6:09 pm Post subject: |
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| derluftwagen wrote: |
Just wondering, I read in another thread about sled and lower tin was just to keep the cylinders and heads from thermal shock when getting splashed with water. Myth or legend? |
The sleds are important for proper function of the thermostat. Without them you will have cool air blowing over the thermostat when you are driving giving it a false cool reading. They direct the hot air away from the engine as well.
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bugninva
Samba Member
Joined: December 14, 2004
Posts: 8888
Location: sound it out.
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| Posted: Sun Apr 11, 2010 6:10 pm Post subject: |
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| derluftwagen wrote: | | Just wondering, I read in another thread about sled and lower tin was just to keep the cylinders and heads from thermal shock when getting splashed with water. Myth or legend? |
myth....no, not a myth, just BS....
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ALB
Samba Member
Joined: August 05, 2008
Posts: 2631
Location: beautiful suburban .....
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| Posted: Mon Apr 12, 2010 7:08 am Post subject: |
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| Matthew wrote: | | derluftwagen wrote: |
Just wondering, I read in another thread about sled and lower tin was just to keep the cylinders and heads from thermal shock when getting splashed with water. Myth or legend? |
The sleds are important for proper function of the thermostat. Without them you will have cool air blowing over the thermostat when you are driving giving it a false cool reading. They direct the hot air away from the engine as well. |
While those things are factors, I think Jimmy111 said it best: "As your speed increases the sled tins keep the air pressure under the car from over coming the fan (as much as 2 psi more under the car). They need either heat exchangers or block off tins to be functional."
Think of the air coming through the cylinders and heads straight down and then hitting a horizontal wall of air. 1- it can't make the abrupt 90 degree transition easily (in fluid dynamics this is called an inefficient corner and is solved with turning vanes) without some of it instantly reversing direction and colliding with the air behind it, causing turbulence that further affects the flow direction and velocity. 2- the faster the speed, the less air is able to join the air stream efficiently, as the air pressure under the car is also greater, pushing the turbulence closer to the fan, making it less effective. The lower tins enable the spent cooling air to make the 90 degree transition, directing the air behind the motor and into the under car airstream cleanly.
If a car seems to run ok around town but gets hot above a certain speed on the highway (this speed will vary according to weather conditions) and doesn't have the sled tins installed, this would be the first thing to correct.
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MURZI
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Joined: August 25, 2005
Posts: 3693
Location: Madisonville, La
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MURZI
Samba Member
Joined: August 25, 2005
Posts: 3693
Location: Madisonville, La
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Sigurd
Samba Member
Joined: April 18, 2006
Posts: 2515
Location: Rockford, IL
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| Posted: Mon Apr 12, 2010 10:22 am Post subject: |
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| derluftwagen wrote: | Update on Puma cooling.
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The Puma shroud alone dropped your CHT by 100 degrees in town??? |
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